The secrets of the enduring ancient marathoners

August 26, 2014

There are seven elite ancient marathoners who have set a marathon age-group world record at age 60 or greater, and in addition, have recorded times ranked within the top 15 in their current age band on multiple occasions spanning more than a decade. These seven elite marathoners with extraordinary staying power are John Gilmour, Eric Ӧstbye, John Keston, Derek Turnbull, Luciano Acquarone, Ed Whitlock and Yoshihisa Hosaka.

John Gilmour (born 1919)

John Gilmour migrated from Scotland to Australia during childhood. He was a keen athlete in his teens but at the outbreak of the war enlisted in the army and became a prisoner of war when the Japanese over-ran Singapore in 1942. He was imprisoned in the notorious Changi prison and subsequently shipped to Japan where he experienced further extreme privation. He suffered permanent loss of much of the sight of both eyes due to malnutrition. His pièce de résistance as a slave labourer was destroying a major Tokyo Steel furnace by contriving to have a heavy naval shell loaded into it. He sustained his spirits with the hope of future athletic achievement and within a year of his return home represented Western Australia in National Championships. However, his most memorable performances were achieved in international masters events ranging from 800m to marathon over a 20 year period from his early 50’s to age 70. At age 59 he ran a marathon in 2:38:19. Three years later he set a world M60-65 record of 2:41:07 and subsequently in Perth in 1989 he set a M70-75 world record of 3:03:04. He continued to race and to coach until in his mid-eighties.

His training and racing were characterised by intense determination grounded on the conviction that if he could survive his experiences as a POW he would not be deterred by the challenges of running. His training and coaching repertoire included demanding tempo sessions, though in all spheres he showed generosity of spirit and humility. In the forward of Gilmour’s biography, Robert de Castella wrote: ‘… this book celebrates his achievements and gives us an opportunity to understand how champions can be ordinary people doing the extraordinary.’

Eric Ӧstbye ( 1921 – 2011)

Ӧstbye was born on Norway but moved to Sweden. He dominated Swedish road racing in the late 1950’s and 1960’s, but rarely ran on the track. He set his first age group world marathon record in the 45-50 category at age 47 and subsequently set records in the 50-55; 55-60 and 60-65 categories. Even at age 70 his time of 3:15:57 placed him 10th on the world ‘all time’ list at that time.

In 1968, he was not included in the Swedish team for the Mexico Olympics because he was considered too old at age 47, despite a best time of 2:20:55 that year. It is interesting to note that Mamo Wolde won the Olympic gold with a time of 2:20:26, though the altitude of Mexico City (2250m) must be borne in mind. Ostbye trained according to the principles of Ernst van Aaken. The key feature was daily long slow runs of 30 Km or more, in the low aerobic range, augmented by only a small amount of fast running.   He was also a dedicated vegetarian.

John Keston (born 1924)

Keston is an English actor and singer who travelled to Washington, and thence to Broadway, with the Royal Shakespeare Company in a touring production of the play, Sherlock Holmes, at age 50. He decided to remain in the US.  At age 55 he took up running to overcome high blood pressure. After doing well in some ‘fun runs’ he began to take running more seriously, and at age 64 achieved his fastest marathon time of 2:52:32. He trained with tigerish ferocity, typically doing sessions such as 20x400m. He set his sights on being the first 70 year old to break 3 hours, and with typical determination he raced 20 marathons that year, without achieving his goal He subsequently accepted ironically that his determination exceeded his sense. He did break Warren Utes’s half-marathon world record with a time of 1:25:36, and the following year he broke Utes’s M70-74 marathon record with a time 3:00:58.  

Then at age 73 he suffered the first of three serious accidents that might have persuaded a less determined man to give up. First, he broke his hip in a bike accident. Then, sixteen months later he broke his left leg when he slipped and fell in icy snow, and a further ten months later, he stubbed his toe on a rock while running seriously injuring his foot and tearing tendons. He resumed running, but perhaps fortunately, guided by his son’s advice he decreased the intensity of training. Similarly to Eric Ӧstbye and Ed Whitlock, he subsequently trained mostly at low intensity for several hours per day, though at an even lower intensity with about half of the distance covered walking in woodland. He loved the outdoors; the sun, the wind and the rain. Typically, he ran for about two hours every third day, and walked for a similar time on each of the intervening two days.   His race times slowed but nonetheless at age 76 he set US national records at 5K and 10K, and he ran a 1500m in 5:47. The following year his marathon time of 3: 19:01 was only about a minute outside Warren Ute’s M75-80 world record, and 5 years later at age 82 his marathon time was 6th in the all-time rankings for the M80-85 category at that time.    

Derek Turnbull (1926-2006)

Derek Turnbull was a New Zealand sheep farmer who dominated the world of veteran distance running from 1977 to 1992. He had been an enthusiastic runner since his teen-age. Despite subsequently down-playing the athletic achievements of his younger days, he had run a half mile in little over 2 minutes, a mile in 4:23, and achieved fourth places in New Zealand three- and six-miles national championships on several occasions. At university, he was awarded an athletics Blue. The tradition of awarding Blues to mark sporting achievement had originated in Oxford and Cambridge, and had been taken up, perhaps with slight tongue-in-cheek enthusiasm, in some antipodean universities. I am wryly amused by the fact that the only surviving tangible memento of my own early athletic achievements is the venerable document recording the Blue awarded to me by Flinders University. My mother had it framed and I have never had the heart to throw it away. But even if in retrospect, a Blue might be seen as a peculiar mark of respect for the venerable universities of the ‘mother country’, it provides me with a tenuous link to Turnbull, while also illustrating that his athletic gifts were recognised when he was a young man.

However, the thing that makes him a world-class athlete was the fact that nearly four decades later at age 60 he broke the M60-65 world marathon record with a time of 2:38:47, in my home town, Adelaide. Five years later, in 1992, he established a M65-70 world marathon record with a time 2:41:57 in London. That record still stands, and is the prize that Yoshisa Hosaka is aiming to take in Toronto in November this year   In the intervening years,Turnbull ran an 800m in 2:14.53, a 1500m in 4:28.00 at age 62.   He continued to run after suffering a stroke in 2001 but sadly died in 2006 at age 79. Like his countryman, Jack Foster, Turnbull did not follow any specified training plan, but ran across the fields and through the forests on his property, Sherwood farm, as the whim took him. Nonetheless, his whims often dictated a fast pace, and it is probable that his training included a good mixture of easy and fast running. In an obituary published in Running Times in February 2007, Roger Robinson stated that ‘a visit to Sherwood Farm revealed that running how Derek felt in fact produced a perfectly balanced program of long runs, tempo, and fast work’.

Luciano Acquarone (born 1930)

In his youth, Luciano Acquarone focussed on middle distance events, enjoying success at regional level in his native Italy. In his early forties he turned his attention to the marathon, achieving a time of 2:20:21 at age 42, while also continuing to perform well at 5,000m and 10,000m. In his late forties he suffered tendonitis requiring surgery, but then his career blossomed on the world stage in his early 50’s. He set a world 50-55 age group record of 30:05 for the 10000m record in 1981. That year he ran a marathon in 2:28:28, placing him 5th on the world ‘all-time’ list of 50-55 year old marathoners. He continued to flourish, setting a M60-65 world marathon record of 2:38:15 at Turku in 1991, in addition to capturing the M60-65 10,000m world record. Over the subsequent 15 years he continued to post times in the marathon and also at shorter distances that placed him high in the world rankings.  Again at age 75 he achieved another age group world marathon record with a time of 3:10:57.    At 81 he set a European half marathon record and the following years a M80-80 world record at 3000m. Thus Acquarone has performed at elite level as a veteran over a period of 40 years, and has set world records spanning distances from 3000m to marathon, spread over a three decades. It is ironic that, apparently on the basis of a superficial examination of the data, Ross Tucker selected Acquarone to illustrate his proposition that most elite veterans appear at the top of the world ranking for only a brief few years, in support of Tim Noakes’ hypothesis that training and racing at elite level damages the legs. We will return to address that interesting hypothesis subsequently.

Ed Whitlock (born 1931)

I discussed Ed Whitlock and his training in detail my post of August 2nd. Here I will summarise only those features that are especially relevant to the topic of this post and the next.   As a school boy he showed promise of athletic talent, running a mile in 4:31 and notably beating the future world champion distance runner, Gordon Pirie in a cross country race. Unfortunately, an Achilles tendon injury at university contributed to his decision to stop running, and lack of opportunity for racing after he moved to Canada to take up a job as a mining engineer consolidated that decision. He began running again in his forties, focussing mainly track racing with a strong determination to win. His training placed a strong emphasis on demanding interval sessions. At age 48 he ran his best marathon in 2:31:23 after a winter of solid high-volume training and later that year won gold in the 1500m at the M45-49 masters world championships in Hannover with a time of 4:09.

But his greatest achievements as a marathoner came after he shifted to a training in which the key feature was daily long runs at a very easy pace, spiced up with occasional fartlek-style speed work and frequent races. In the four years from his impressive time of 2:52:02: in the Columbus Ohio marathon, in 1999 at age 68 to his awe-inspiring 2:54:49 at age 73 in the Toronto Waterfront marathon in 2004 he gradually increased the frequency of 3 hour runs.   In the 20 weeks prior to the 2004 Waterfront he did 67 three hour runs, including 18 on consecutive days. Contrary to the almost inevitable year on year decline observed even among elite elderly marathoners, he actually ran faster at 73 than during the Waterfront marathon the previous year when he became the first man to run a marathon under 3 hours with a time of 2:59:10. It is also noteworthy that his best 1500m time of 5:08,6 at age 73 was less than a second slower than his best at age 72, whereas an increase of about 5 seconds over a year would be expected. Thus, the increased amount of slow running did not harm his speed. He has continued to set world records distances ranging from 3000m to the marathon, including setting the M80-85 marathon world record with a time of 3:15:54 in 2011.

Yoshihisa Hosaka (born 1949)

I discussed the running career of Yoshihisa Hosaka in my post of August 18th and will only give a brief summary here. He was a champion runner at school but during his twenties he focussed on surfing, only returning to running at age 36. Initial success at shorter road races led him eventually to the marathon. He achieved a personal best of 2:25:28 at age 45 and after further refining his training program, set the M60-65 world record with a time of 2:36:30 at the Beppu-Oita Marathon in 2009. As he described in an interview with Brett Larner, his training at that time was based on 5x1Km twice daily at a gradually progressive pace within a total of 32 Km per day.   In the following three years he continued to race well , capturing the M61 and M63 single-age world records, though his marathon time increased at a rate of over 3 minute per year compared with an expected slowing of about 2 minutes per year for an elite runner in his early 60’s. In last year’s Gold Coast marathon he narrowly failed to capture Clive Davies M64 single-age record of 2:42:44 and this year faces the major challenge of capturing Derek Turnbull’s M65-70 record of 2:41:57.  

What do these ancient marathoners share?

First, with the exception of John Keston, all showed evidence of at least a moderate athletic talent in young adult life, but none were of international class at that stage. Gilmour represented his state in national championships in his twenties, within a year of his return for prisoner of war camp; Ӧstbye began to dominate Swedish road racing in his thirties; Turnbull won an athletic Blue at university; Acqualone was a successful middle distance runner at regional level in his twenties; Whitlock famously beat Gordon Pirie in a cross country race as a school boy; and Hosaka was a school-boy champion. Although Keston did not start running until age 55, his immediate success in fun runs made it apparent that he too was gifted.

However the thing that made all seven of these runners great were their performances in their 50’s, 60s, and 70’s and in several instances, in their 80’s.   Their great performances were not confined to the marathon. With the exception of Eric Ӧstbye who rarely ran on the track, all of them have been listed in world masters rankings for 1500m, and several of them set national or world records at 10,000m.  

Thus, even more important than their talent for distance running as young men, was the fact that their performances declined with age at a much slower rate than the average person. This reduced rate of decline applied across the spectrum from 1500m to marathon. Nonetheless, despite a reduced rate of decline from young adult life to middle age, they did all decline. Data from the Master Athletics track and field world rankings indicates that this rate became fairly uniform by the middle years of the seventh decade. At that stage, the rate of their slowing was around 1.5% per year for both marathon and 1500m.

The degree of commonality in these features across all seven athletes suggests at first sight that the type of training did not play a crucial role. All undoubtedly trained consistently and with determination, but the content of their training sessions differed substantially. Ӧstbye, Whitlock and Keston (in his later years) did a high volume of easy running with a small amount of faster training and/or racing over short distances. Turnbull was deliberately more spontaneous in his training but appears to have included a reasonably balanced mixture of training paces. As far as I can gather from the information available to me, Gilmour and Acqualone also included a balanced a mixture of paces. The central feature of Hosaka’s training is 5x1Km intervals twice daily at a gradually progressive pace, within an overall total of 32 Km per day.  

Presented in such broad brush strokes as this it is difficult to reach any conclusion about training other than that a variety of different training programs can lead to success, provided the athlete has a degree of natural talent for running together with a predisposition to age slowly, and the training is consistent. However, I think that a finer grained analysis does allow us to draw some speculative but potentially useful conclusions about how to train, whatever the level of one’s natural talent.

There is a related question that arises from the hypothesis that an athlete can only expect to remain at his/her peak (relative to the WAVA age norms) for a limited number of years on account of the damaging effect of the training and racing required to attain one’s peak. These seven ancient marathoners were selected for discussion on account of their longevity in the world marathon rankings, and hence do not provide an unbiased sample in which to test that hypothesis. Nonetheless, because they tend to be exceptions to the rule, they do offer interesting insights into the limits to the validity of the hypothesis. Furthermore, a finer grained analysis of features of the training of some of these seven marathoners does provide some clues regarding the way one might remain near to one’s peak for longer.

In my next post, I will examine a few of the finer details of the training of these seven athletes that proved pointers toward how to achieving one’s best in middle-age, and how to sustain that peak relative to WAVA age norms into old-age.

The training of Yoshihisa Hosaka

August 18, 2014

At high school Yoshihisa Hosaka was a champion track athlete. After several years devoted to surfing, he began running again in his mid-thirties, focussing on short road races, but did not seriously contemplate the marathon. At age 42 he won a 7 Km race that earned him a trip to compete in the Honolulu marathon.  He completed it in 2:31:19. In an interview with Brett Larner, editor of Japan Running News, in 2009, he described the way in which he developed his training over the next few years, achieving a marathon personal best time of 2:25:28 at age 45, an impressive performance but appreciably slower than the time of 2:20:28 achieved by Jack Foster at age 50, and well outside the world M45+ record of 2:14:16 set by Jackson Kipngok Yegon of Kenya. Hosaka continued to develop his training and settled on a consistent routine of two sessions daily, both including 5x1Km intervals within a daily total of 32Km. In February 2009 at age 60 he took nearly two minutes of the world M60+ record with a time of 2:36:30 at the Beppu-Oita Marathon.

His best performance in the past 15 months was 2:46:14 at the Gold Coast Airport Marathon in July 2013 at age 64, though this was over three minutes outside Clive Davies’ single-age world record for a 64 year old of 2:42:44 set in 1979. At the Toronto Waterfront marathon last November Hosaka started well but his leg muscles tightened-up during the middle stages of the race and he finished in 2:50:44. At the Gold Coast marathon this year, he won the M65-69 age group in a time of 2:52:13. But he still has his eyes on breaking Derek Turnbull’s M65+ world record of 2:41:57 in Toronto in November.

Hosaka’s peak performance deteriorated by 11 minutes in the 15 years from his personal best at age 45 to his world M60+ at age 60, and by almost 10 minutes in the 4 years from age 60 to his 2013 Gold Coast marathon at age 64. According to WAVA, the deterioration expected for a runner at the highest level would be 20 minutes from age 45 to 60, and 6 minutes 15 seconds from age 60 to 64. Thus, Hosaka deteriorated at only half of the rate predicted by WAVA between his PB at age 45 and his world record at 60 but he has deteriorated at almost 70% more than WAVA would predict from age 60 to his best performance within the past 15 months. One should not base too much on his recent races slower than 2:50 in Toronto in November 2013 and the Gold Coast in July 2014, as the marathon is an unpredictable event in which sub- peak performances are not usual, Nonetheless these two races do provide a further hint at the possibility of a more rapid deterioration in his mid-sixties.

To what extent has his training contributed to his outstanding improvement relative to WAVA prediction in the period from 45 to 60, and might this training have actually led to a faster deterioration than that predicted by WAVA in the years since age 60?

Hosaka’s Training

In the interview with Brett Larner, shortly after he had set the M60+ world record in 2009, Hosaka provided a detailed account of his unvarying daily schedule. The morning session begins with a 1.5 mile jog through mountainous country from his home to a tree-lined riverbank path where he does five 1Km repetitions at a gradually increasing pace, starting at a relaxed 6:25 /mile (about 25 sec/mile slower than his marathon pace at that time) and increasing pace to 5:20 /mile, which is the estimated 10K pace for a 2:36:30 marathoner. In isolation, this would be quite an easy session, gently progressing from a relaxed initial pace to the fifth Km repetition at around 10K pace. He jogs home, and works in his own business from 8:30am to 5:00pm. After work, he drives to a park where he does some strength exercises and then a progressive 12Km warm-up starting at 9:30/mile and increasing pace up to 8 minutes mile. He then does another 5x1Km interval session on a long downhill stretch of a nearby road. He does the first 1Km at marathon pace and gradually increases to estimated 10 Km pace for the final repetition. He finishes with 5 x 100m accelerations on soft earth in the park, to help maintain his speed. In isolation, this session would also be fairly easy, though the day’s total of 32 Km is substantial, and the cumulative effect of repeating this day after day would be appreciable. He races quite frequently, and usually races at least two marathons per year

The key features of Hosaka’s programme

  • The unvarying daily schedule of two sessions, each of which would be only moderately demanding in isolation, allows him to monitor how well his body is coping with the training much more effectively than a program that alternates hard and easy days.   In similar manner, Ed Whitlock, whom I discussed in my previous post, follows a consistent program of daily long runs, though Hosaka’s schedule provides greater variety within each day. While the human mind craves variety, the body adapts very well to a routine. I consider that the doctrine that the body needs fresh challenges in order to improve is over-rated. Consistency is of greater importance, though it is probable that the best results are obtained when demands of training increase gradually over a long period. Frequent racing also adds spice.

There are two occasions in my own running career when I did daily doubles with very little variation over a period of many months. The first was as a youngster when I ran to and from school at a comfortable pace each day for several years. I did not find this irksome, and believe that it laid the foundation for what success I later enjoyed as a distance runner. Then in my early twenties, I ran 10 miles twice daily for several months, guided by a fragmentary knowledge of Lydiard’s recommendation of running at least 100 miles per week. I ran at what I assumed Lydiard meant by a ‘good aerobic pace’ though I ran many of those miles not far below the second ventilatory threshold, which was probably somewhat faster than Lydiard would have recommended. Again I did not find the routine irksome, though at the time I was working very long hours and eventually became increasingly tired. Nonetheless, in the following summer season I ran the best 5000m races of my career and also achieved a memorable victory in the only 10,000m I have ever raced.

  • Both of Hosaka’s daily sessions were gently progressive. Although he ran about 10 Km per day at marathon pace or faster, these moderately effortful segments were only 1 Km in length, and in the evening session, they were downhill. He did not do sustained tempo sessions – which evidence indicates are disproportionality stressful. He himself reports that he finds his body copes better with interval sessions in which the demand for effort comes in small chunks, than with sustained running near lactate threshold. In the interview with Brett Larner he stated: “Most people can’t keep race pace up for a long time as they get older. Doing it in intervals lets you keep your speed without getting hurt.”
  • Perhaps the most surprising aspect of his training is the absence of long runs. However, as indicated by Dudley’s well-known studies of rats, there is little evidence that runs longer than 40-50 minutes are an efficient way to increase aerobic capacity. It is however probable that long runs are effective in developing the ability to withstand the sustained pounding of the legs that is inevitable during a marathon, though it is possible that downhill 1 Km repetitions at marathon pace or faster, are even more effective for developing the required resilience. The other main marathon-specific benefit of long runs is the psychological preparation. But Hosaka considers that his daily routine is well suited to the sustained mental demand of the marathon.   He told Brett Larner: “Early on it’s easy, but after a few days it’s harder and you think, ‘Ah, this is like the 30K point in the marathon,’ then it gets even harder like at 40K. Every day’s training becomes like part of the marathon. Most people run a hard day and then jog an easy day, but the marathon is constant and you have to train yourself to handle that constant.”
  • Although he is not finicky about his life-style, he eats a balanced diet and believes it’s important to let the body use its natural healing processes. He employs strength exercises and weightlifting to prevent and treat injuries. He trains in relaxing surroundings. Although his work as a businessman no doubt creates some pressure, as his own boss he has the opportunity to regulate his own stress level.

I consider that Hosaka’s preparedness to identify a training program that suited him well and enabled him to train consistently were the key features that allowed him to make substantial improvement in marathon performance between age 42 and 45, and then to slow the rate of decline over the following 15 years. In his consistency and his care to avoid undue stress, Hosaka resembles Ed Whitlock. However, while both of them have included a small amount of fast running and frequent racing to maintain their speed, in other respects the content of their programmes is dramatically different. Hosaka focusses on gradually progressive 1 Km repetitions but no long runs, whereas daily 3 hour runs at a slow pace are the key feature of Ed’s programme. Both have been phenomenally successful over a period of a decade or more, confirming that there is no single way to train in order to achieve outstanding marathon performances. Does our understanding of body physiology provide any clues as to which approach is likely to offer the greater prospect of sustained elite performance over several decades? .

Catabolism and anabolism

Training produces benefit by creating a stress that provokes the body to react in a manner that enhances the ability to withstand stress in future. The mechanism of the stress response is only partly understood, but current understanding does provide useful guidance for planning training.

The first general principle is that stress generates a two-phase response. The initial response is the catabolic phase in which the body’s priority is breaking down of tissues to supply fuel for energy production. Glycogen is broken down to release glucose and if the stress is sustained, protein is broken down into amino acids which in turn can be used as fuel. The catabolic hormones adrenaline and cortisol plays a cardinal role in regulating these metabolic processes. In addition, physical trauma, such as the eccentric muscle contraction at foot-strike, produces microscopic tearing of tissues.

After cessation of exercise, the level of adrenaline falls within minutes while the level of cortisol returns to baseline over period of an hour or two. However, a second bout of exercise within 3 hours produces an even greater surge of adrenaline and cortisol, compared with a similar second bout of exercise after 6 hours. This indicates that even after cortisol has returned to baseline, signalling molecules circulating in the bloodstream are a marker of residual stress. This sustained marker of stress diminishes markedly by 6 hours. However other markers of stress such as a fall in blood levels of lymphocytes, which play a role in protecting against infection, can persist for 24 hours.

The second phase is the anabolic phase during which tissues are repaired. Various different processes are involved. Anabolic hormones stimulate the re-synthesis of protein. A complex set of chemical messengers including various cytokines, trigger an inflammatory response. Capillaries become leaky allowing fluid containing scavenging white blood cells and materials required for repair, to reach damaged tissue. The scavenging white cells remove cellular debris, while the deposition of collagen fibres strengthens tissues. Satellite cells, which are a form of stem cell found in muscle, promote regeneration of muscle.

If there is repeated stress before recovery is complete there is a risk of a third phase. Sustained elevation of cortisol can occur, causing continued suppression of the immune system and inhibiting anabolism. Paradoxically, sustained elevation of cortisol can promote chronic inflammation by blunting the body’s response to cortisol. Chronic inflammation leads to disorganized deposition of collagen fibres in body tissues, impeding the function of these tissues. .It is even possible for collagen deposition in the walls of coronary blood vessels to promote atheroma that might eventually increase the risk of heart attack. It is noteworthy that sustained moderate elevation of cortisol is not uncommon in distance runners, and is related to both volume and intensity of training. While there is little compelling evidence that even quite intense training produces harm that outweighs the benefits of vigorous training over a period of several years, I suspect that if one wishes to train at elite level over a period of decades, it is crucial to maintain a healthy balance between catabolism and anabolism, and to avoid the potentially harmful third phase.

It is likely that training programmes that carefully avoid excessive stress, have enabled both Hosaka and Whitlock to remain at elite level for at least a decade, and in Whitlock’s case, for even longer. I see no reason to propose that Hosaka’s carefully calibrated interval sessions are more likely to produce sustained stress than Whitlock’s frequent 3 hour slow runs. However, there is one respect in which I think Whitlock’s approach is safer. Although his programme is not deliberately periodized, by virtue of various circumstances, including arthritis and accidents, he has been forced to cut back his training from time to time, and whenever he does so, he builds up the duration of his long runs very gradually. I suspect that gradual adaptation is a key feature of his success.

Future prospects

Hosaka’s own comments reported in another interview with Brett Larner in Toronto in November 2013 suggest he is considering a change. He acknowledged that he was finding it harder to maintain his daily interval sessions, and perhaps might even change to Ed Whitlock’s high volume, low intensity approach, though maybe this was simply an expression of Japanese politeness while he was a guest in Ed’s home town.

In 2013, Hosaka missed the single-age M64 world record, after capturing M59, 60, 61, 63 world records in the previous five years. It is interesting to speculate that he might be beginning to experience the accelerating deterioration that many runners experience in the mid to late sixties, but only time will tell. Whitlock had also shown slight hints of a stutter in performance for two or three years after his superb 2:52:50 in the 1999 Columbus Ohio marathon at age 69, but he came back with a tremendous improvement to achieve 2:54:48 in Toronto at age 73. Although Ed has slowed appreciably in the subsequent decade, nonetheless in his early eighties, he still breaks world records at distances from 1500m to marathon with remarkable regularity. Undoubtedly his training regimen has combined with his apparently inherited predisposition to longevity to delay the inevitable deterioration of performance with age, whereas the effectiveness of Hosaka’s regimen beyond the mid-sixties remains un-tested . So it will be very interesting to see how well Hosaka can hold his form over the next few years, and in particular, to see whether or not he moves to lower intensity long training runs. But whatever he does, the records that Ed set in his early 70’s are going to be very hard to beat.

The training of Ed Whitlock

August 2, 2014

In a recent post I expressed my hope to run a ‘good’ marathon once again, almost half a century since I last did serious marathon training.   In that intervening half century several outstanding individuals have demonstrated that even in old age it is possible to run a marathon in a manner that would be creditable at any age.   These elite veterans include Ed Whitlock, John Keston, Derek Turnbull and Yoshihisa Hosaka. Nonetheless, despite their incredible feats, even these outstanding veteran marathoners have suffered decline with age. It is clear that outstanding performances depend on both intrinsic talent for distance running and remarkable ability to slow the progress of the inevitable age-related decline, in addition to the determination and ability to train well.

These veteran marathoners have demolished previous concepts of what training the elderly frame can withstand. While it is almost certain that genetic factors set them apart from the average person, it is worth asking if the way which they have trained has played a substantial role in their ability to slow the progress of decline, and in particular, to allow them to continue train at the level required for elite performance in old age.

All four of these elite veterans have trained in different ways, though there are common themes. In this post I will focus on the training of Whitlock, and in my next post on Hosaka, but also draw on some observations of the training of Turnbull and Keston in an attempt to tease out some of the key issues.

Ed Whitlock

Whitlock was the first person over 70 years of age to break 3 hours for the marathon with a time of 2:59:09 in the Toronto Waterfront Marathon in September 2003 at age 72.  A year later in the Waterfront Marathon he took more than 4 minutes off that time, achieving the phenomenal time of 2:54:48.   In last year’s Waterfront Marathon, he set a new world record for an 82 year old of 3:41:57.  He remains the only person over 70 to have run a marathon in less than 3 hours, ten years after achieving that feat, and therefore stands as a colossus among ancient marathoners.

To what extent can these colossal performances be attributed to intrinsic talent for distance running; to inherent ability to withstand the ravages of time; or to training?

As a school-boy, Ed ran a mile in 4:31 and on one occasion beat Gordon Pirie in a cross country race.   At that stage he was a gifted distance runner but not extraordinary. He gave up running at University due to recurrent Achilles problems but returned to track running in his early forties. In a discussion on the Let’s Run website, to which he is a frequent and gracious contributor, he reports: ‘My best marathon at age 48 was 2:31:23 at Ottawa in May 1979. This was done off a winter of quite high mileage done in preparation for middle distance track in the summer.’   After some speed work on the track during the summer, he won the M45 world masters 1500m championship in 4:09.   By that stage, it was clear that he was not only a gifted distance runner, but was also showing evidence of the ability to withstand aging.

However, it is noteworthy, that Jack Foster (discussed in my post on July 23rd) who born a year after Whitlock, ran 2:20:28 at age 50 in 1982.   The current world best for a 48 year old is 2:18:57 by Ayele Setegne of Israel, in 2011. Thus, Whitlock’s best marathon time was creditable, but not extraordinary for a 48 year old, despite the evidence that he had done both high volume training and high intensity training sufficient to take him to top place on the podium at the World Maters championship for 1500m that year. Thus, one must look for evidence that a combination of training and extraordinary resistance to aging to explain the extraordinary performances in his seventies and eighties.

In an interview for Runners World in 2005, Amby Burfoot asked Ed what he considered to be the secret of his success. Ed replied: ‘I think it’s the ability to absorb a fair amount of mileage in my training. And that’s probably genetic. I had an uncle who lived to the ripe old age of 107. The mileage I’ve done in the past few years is something I built up to gradually. I was very conscious about not making big leaps in my training. I was also conscious about keeping the speed relatively slow. I shuffle along to reduce the impact, rather than bounding. I don’t know what the relative importance of these things is, but the mileage is what has turned me into a marathoner.’

Ed almost certainly inherited some genes for longevity as not only did his uncle reach 107 but also his father lived into his eighties and his mother into her nineties.   Laboratory tests done at The High Performance Specialists clinic in North Toronto tests shortly before his 70th birthday do provide some hints concerning the inherited features that have contributed to his extraordinary running.   There was nothing remarkable in the various blood tests. The three noteworthy findings were a body fat proportion of 9.5% (about half that expected), a maximum heart rate of 168 (compared with predicted value of 151 based on the best recent estimate of the relationship between age and HRmax) and VO2max of 52.8 ml/min/Kg compared with the average of 35 for a 70 year old.

Ed’s high VO2max was extraordinary for a 70 year old, but was not extraordinary for a three hour marathoner.   The formula derived by Jack Daniels to estimate race performance based on VO2max predicts a marathon time of 3:01:00 for an athlete with VO2max of 52.8. Ed ran 3:00:33 in London, Ontario a month or so later. Thus, the task of identifying the source of Ed’s extraordinary marathon performance becomes the task of identifying the source of his high VO2max.

How much of Ed’s aerobic capacity is attributable to genes?

Can Ed’s high VO2 max can be accounted for by his high HRmax? At first sight there appears to be only a weak relationship between the variation between individuals in HRmax and variation in either VO2max or performance. This is because the delivery of oxygen to muscle cells depends not only on heart rate but also stroke volume and the ability of muscles to extract oxygen from blood, which in turn depend on capillary density, aerobic enzyme capacity and ability to recruit muscle fibres.   Variation between individuals in these various factors obscures the relationship between HRmax and performance. However, if all of these other variables are optimised by optimal training, a 10% increase in HR reserve (HR max- resting HR) would be expected to produce approximately a 10 % increase in VO2max. Since a 10% increase in HR max would usually produce at least a 10% increase in HR reserve, it is reasonable to assume that the Ed’s increase of HRmax above the average accounts for about 10% of his VO2max . Daniels’ formula indicates that a 10% increase in VO2max would account for an improvement of about 17 minutes for a 3 hour marathoner.

The mechanism that regulates decline of HRmax with age is not fully understood though it is at least partly dependent to the number of ion channels that allow the transport of calcium ions across the membranes of cardiac pacemaker cells. Much evidence indicates that HRmax is not related to training.  If anything training actually reduces HRmax a little, though cardiac output increases due to the increase in stroke volume produced by increased blood volume. Twin studies indicate that HRmax is largely determined by genetic factors.

Thus, it is very plausible that Ed’s high HRmax, likely attributable largely to his genes, contributed to a reduction of around 17 minutes in his marathon time at age 70. Without this benefit, his time in the London, Ontario marathon in 2001 might have been nearer to 3:17:23 than 3:00:23. While 3:17:23 would be outstanding for a 70 year old , it is not phenomenal.

Nonetheless to conclude simply that Ed’s phenomenal performances are due to factors such as high HRmax that are more influenced by genes than training, is to miss a crucial point.   The evidence has been discernible since the day he beat Gordon Pirie in a school-boy cross country race that he is an intrinsically gifted distance runner, and the evidence that he is aging well was already apparent when he won the M45-49 1500m at the world masters championship in Hanover in 1979.  For anyone hoping to learn from his example, the crucial issue is that he has been able to cope with the training required to optimise all those other attributes: cardiac stroke volume, and the factors that determine the ability to extract oxygen from blood, in a manner that has allowed him to exploit his gift of high HRmax to an extraordinary degree.  To what extent is the nature of his training responsible for this?


Ed Whitlock’s training

Ed became a good, but not exceptional, masters marathoner at age 48 by virtue of his intrinsic gifts and a training program comprising high volume in the winter and speed work in the summer. In his sixties he increased the volume of training with a focus on long slow long runs most days of the week, while reducing the speed work, largely relying on occasional fartlek session and frequent races. For example in a Runners web interview in 2003 in the week after he ran 2:59:10 in the Toroto Waterfront Marathon, his first sub 3 hour marathon at age greater than 70, he stated : ‘My training is now without coaching and consists of daily long runs, typically 2 hours I don’t measure the distance and purposely keep the speed down. I don’t have any streak going but try to run every day, no hard easy day routine. I do the odd semi “speed” work out, but not on the track. I race frequently to give me speed and to make me race tough.’  In fact, from his various posts on the Lets Run thread, it was clear than some of the long runs were actually of 3 hours duration.

Was it the introduction of almost daily long slow runs, or was it the inherited predisposition to longevity that contributed most to the transition from a ‘good’ masters marathoner at age 48 to the first (and still the only) man to run a marathon under 3 hours at age greater than 70? I think that the evidence that the long slow runs played a major part came in the Waterfront Marathon the following year (2004) when he achieved the phenomenal time of 2:54:48 at age 73.   In the intervening period, he increased the proportion of long runs of 3 hours duration.

In an interview with Scott Douglas  for Running Times he reported in the six months leading up to the Waterfront Marathon in 2004 he ran 15 races of 5K-15K and built up his long run time to three hours a day.  In a response to a question on the Let’s Run thread, he stated that in the 20 weeks prior to the 2004 Waterfront he did 67 three hour runs, including 18 on consecutive days. He trained for 15.9 hours per week.

While not conclusive proof, I think that the fact that an increase in the number of 3 hours runs was associated with an improvement of over 4 minutes from age 72 to 73 is strongly suggestive that the frequent very long runs played a key role.   There is of course no guarantee that emulating Ed’s training would allow another individual to achieve the same benefits from that training. It is far from certain that the average 70 year old could emulate his training without devastating physical breakdown.   However, few individuals have made a serious attempt to emulate Ed’s training. It would be premature to conclude that his training would not work for others before careful examination of how Ed does it.

It’s not simply a matter of high volume

From his various comments on the Let’s Run thread over the years, and from the interviews with Amby Burfoot and with Scott Douglas, there are three noteworthy features of Ed’s training apart from the mere fact that he does very long runs:

  • He builds up the duration of runs very gradually. The number of three hour runs  increased gradually over a period of 6 years from occasional three hour runs during preparation from his race in Columbic Ohio in 1998 to an average of 3.2 per week prior to the Waterfront Marathon in 2004. Furthermore, when he has to rebuild following injury, he starts with daily runs of less than an hour and increases the daily run duration gradually by 10 minutes per week.
  • He takes great care to minimise wear and tear on his legs. He trains at a slow shuffling pace designed to minimise impact forces. He does virtually all of his training on 500-600 metre loops of the level paths of Milton Evergreen Cemetery, near to his home, so that he can return home immediately if he develops an injury.
  • He sustains his speed via short distance races and occasional fartlek-style speed sessions.  It is noteworthy that during races he does not shuffle, as illustrated by this picture of him during the 2011 Longboat Toronto Island 10Km race at age 80.

In light of the evidence that high volume training is associated with harmful accumulation of cortisol and that large increases in training volume are associated with a greater risk of the over-training syndrome than increases in intensity (discussed in detail in my post on 14th April 2009) I consider that the secret to Ed’s success is the gradual build up and his care to avoid wear and tear. He trains with respect for his body.

In my previous post on July 23rd I examined the training of Haile Gebrselassie and Jack Foster, both great athletes who succeeded in maintaining world-class performances into middle age. This same theme of respect for the body emerged, though in different ways: in the case of Haile, the carefulness was deliberate; while Jack’s approach was deliberately carefree. To perform maximally over a sustained period, one must train with determination, but merely training hard is not enough.   Hard training must be accompanied by sensitivity to the body’s response.   In my next post I will examine the training of another great veteran marathoner, Yoshihisa Hosaka, whose training is radically different from that of Ed Whitlock, but in its own way, is also sensitive to the way the body is responding to training.

The training of Haile Gebrselassie and Jack Foster

July 23, 2014

In recent months I have been re-building the base fitness required for another marathon. I would like to run a ‘good’ marathon, though after my somewhat disappointing performance in the Robin Hood half-marathon last September and apparent acceleration of age-related deterioration since then, it is difficult to estimate what would a reasonable target time.   However my definition of a good marathon is based more on how I run it than on the time achieved. I want to be fit enough to maintain a pace near lactate threshold for the entire distance. While I anticipate that the final 10 Km will be demanding, I would nonetheless hope to have enough resilience in my legs to allow me to maintain reasonable fluency over that final 10Km.

Marathoning in the 1960’s

When I last trained seriously for a marathon, well over 40 years ago, the two most influential figures shaping opinions about how to train were Emil Zatopek, the giant who had dominated distance running from 1948 until 1954, and Arthur Lydiard, whose athletes had created a sensation at the Rome Olympics in 1960. In retrospect it is surprising how slowly ideas travelled though the running community. In the pre-internet era, we relied largely on word-of-mouth rumours. Lydiard’s first book, ‘Run to the Top’ had been in print since 1962, but the apparent conflict between Lydiard’s emphasis on running 100 miles per week, mostly at a ‘good aerobic pace’ and the fragmentary information about Zatopek’s punishing training regimen, fuelled continuing debate.   Nonetheless, the 1960’s was a golden age for marathoning in which the world record tumbled from Abebe Bikila’s 2:15:16 in the Rome Olympics of 1960 to Derek Clayton’s 2:08:33 (over a disputed course) in Antwerp in 1969.

My training was mainly shaped by Lydiard’s ideas. I ran a fairly large volume (though rarely 100 miles per week) at a good aerobic pace, including long runs in the hills, together with occasional interval sessions. In those days we were less concerned about actual finishing times because it was recognised that the time in a marathon was dependent on the course. I have no record of my best time. I was by no means elite. The only time I have been able to recover from internet archives was 2:33:07 recorded in the Australian Marathon championship in 1970 though at my best I ran quite a lot faster than that.   But sadly, age has taken a serious toll. My capacity to recover from long runs at a good aerobic pace has deteriorated markedly.   So how should I train now?

Polarized training

In my recent post on the debates of the past decade, I concluded that the evidence is in favour of polarised training: a large volume of easy running spiced with a small volume of higher intensity training.   However there are many variants that might be described as polarised. In this post and the next, I will compare pairs of great marathoners, past and present, who I believe provide some thought provoking illustrations of training principles. I will start with a comparison of Haile Gebrselassie and Jack Foster, both exponents of polarised training sharing some key features, but also differences. In my next post I will discuss two amazing veterans: Ed Whitlock, who practises an extreme form of polarised training, based on a very large volume of easy running together with a small volume of high intensity running provided by fairy frequent races over distances from 1500m to 10K; and Yoshihisa Hosaka, whose daily interval training is the antithesis of polarised training, apparently owing more to the example of Zatopek than Lydiard.

Haile Gebrselassie

Geb has a strong claim to stand beside Emil Zatopek in the pantheon of distance running legends. In the 16 years from the 1993 World Championships in Stuttgart, where he won gold in the 10,000m and silver in the 5000m to his marathon world record of 2:03:59 in the 2008 Berlin marathon, Geb was as dominant a figure as Zatopek had been over the 7 years from his gold medal in the 10,000m at the 1948 London Olympics to his gold in the 10,000m and silver in 5000m at the 1954 European Championships.

Zatopek had reached his zenith with gold in the 5000m, 10,000m and marathon at Helsinki in 1952, just before his 30th birthday. He struggled into 6th place at the Melbourne Olympics four years later, admittedly shortly after surgery for a hernia. He retired from competition at age 35, having created a legend based on gruelling training that combined high volume with high intensity.   In contrast, although Geb had achieved international prominence at a slightly younger age than Zatopek, he was 35 when he achieved his fastest marathon in Berlin in 2008, and is still competing in 2014. He has struggled to be competitive at the highest level since his failure to finish the New York marathon in 2010, but nonetheless achieved a creditable third behind Kenenesa Bekele and Mo Farah with a half-marathon time of 60:41 in the Great North Run last year, at age 40.

Geb has been generous in providing information about his attitude to training and racing, but is understandably reticent about the details of his training. In a BBC question and answer session in 2002 he stated that his training schedule was secret. Nonetheless a sample week of his base training from 2006 was published on the Powerbar website and is still accessible on the Runzone website.

As is typical of African runners, his training is polarised. Almost 60% (110 km of his 190km a week) was at 6:15 min/mile or slower. About 8 % was at paces near marathon pace, and 6% faster than marathon pace (approximately 4:48 /mile that year)   As noted in the discussion on Runzone, he trained at Addis Ababa at an altitude above 8000 feet. Thus the training performed near to marathon pace would have been more demanding than marathon pace at sea level. The difference in effort between sea level and high altitude depends on how well the individual is acclimatised. The experienced coach, Tinman estimates that the effort at altitude 8000’ would be equivalent to that at a pace around 7% faster at sea level. According to this estimate, Geb’s easy pace of 6:15 per mile would probably be equivalent to around 5:50 per mile at sea level, which is a little over a minute per mile slower than his pace in the Berlin marathon that year. Whatever plausible estimate of the altitude effect one makes, it is clear that Geb was doing a substantial proportion of his training at pace which would have been fairly easy for him.

Elsewhere Geb makes it clear that he was careful to avoid too much stress. In his BBC Q&A session in 2002 he states: ‘I generally have 13 training sessions a week. On Sunday I only run once. Each week, I try to do 3 speed sessions, one long run (1½/2 hours) and one or two Fartlek sessions. The rest of the sessions are endurance runs that I try not to run too fast. They help my muscles to recover from the hard training’. Thus 8 of his 13 sessions are not too fast in order to facilitate recovery. He takes delight in running in the forest. He considers that one of the best pieces of advice about running he ever received was from his agent Jos Hermens. He states: ‘Jos taught me not to run too many races and to train and rest well. When I started to do this, my performances got even better’.

In a response to a question about recovering for the hard sessions he emphasises the importance of adequate sleep and rest: ‘I go to bed early (9.30 pm), but also wake up early (6 am). During the daytime …it is not so important to sleep, as long as I can take a rest. In the afternoon, I try to rest for two hours.’

Though one cannot draw general conclusions from the experiences of two individuals, it is noteworthy that Geb remained at the top of the field for over twice as long as Emil Zatopek. In an interview with Adharanand Finn, of the Guardian newspaper in 2013, Finn asked how he had managed to keep going for so long. Geb replied: ‘You know, there is no secret. I am just always very careful when I’m training. All athletes need three things: commitment, discipline and hard work’. The reference to being very careful suggests that the required discipline is the discipline to balance the hard work with recovery.

At age 41, Geb is still eager to set records the Masters age group. His sub 61 minute half marathon in the GNR in September 2013 suggests that the M40-44 marathon world record of 2:08:46 is still within his reach. But the marathon is a far greater challenge than the half, and Geb has not completed a marathon since February 2012, when he was placed 4th in Tokyo with a time of 2:08:17. He had been aiming for the M40-44world record in the Hamburg marathon in May of this year, but withdrew due to concern about possible breathing difficulties arising from high pollen levels. It remains to be seen whether or not he can achieve the Masters record. Meanwhile it is worth examining the training and achievements of a remarkable athlete who laid down a challenge the limitation of age, 40 years ago.

Jack Foster

As a young man Jack discovered the joys of cycling over the moorland of northern England and the hills of nearby Wales as an escape from the dreariness of his factory job in post-war Liverpool. The opportunity to escape to even wider open spaces came in the form of £10 assisted passage to New Zealand when he was 24. He returned to Britain to marry, and five year later, once again emigrated to New Zealand. At age 32 with a young family to support and faced with the anticipated expenses of competitive cycling, he decided to run. On his first run he was breathless within minutes, but nonetheless took to running with enthusiasm and impish delight. Much of the story of the following decade is told in his short 48 page book, ‘The Tale of the Ancient Marathoner’ (World Publications, 1974).

He claimed not to train, by which he meant that he rejected prescribed training schedules, and ran as he felt inclined. His favourite runs were cross country for an hour or two over the sheep pastures of the Rotorua district of New Zealand’s north island. However he was no stranger to pushing himself hard, and reports that during races he ‘ran his tripes out’. In 1971, at age 39, he established a world record at 20 miles on the track. In his diary he wrote: ‘80 bloody laps, must be stupid! ….world best for 20; not bad for an old bugger’.

He represented New Zealand in the Olympic marathon in Munich in 1972, and again in the Montreal Games four years later. But his most striking performance was his run in the marathon in the Christchurch Commonwealth Games in 1974. Though by this stage a 41 year old, he took the silver medal with a time of 2:11:18.6, a little over two minutes behind the winner, Ian Thompson, whose time of 2:09:12 was the second fastest ever recorded, less than a minute slower than Derek Clayton’s disputed record set in Antwerp in 1969.  Thus, at age 41, Foster was among the world leaders at the end of that golden decade of marathoning that followed Bikila’s barefoot run in Rome in 1960. .

In an appendix of ‘The Tale of the Ancient Marathoner’ Foster gives a verbatim account from his diary of his running in the four weeks prior to his 20 mile world record in August 1971. He did 28 training sessions, though he was reluctant to call them training. Eighteen of the runs were easy, mostly described as jogging across country. He ran three hard hilly runs, and did four interval sessions (4×1 miles on a horse race track). He ran a 2-mile time trial, a cross country County Championship race and a 20 mile road run in 2:03. He ran doubles on three occasions, but did not run on three days: once because he felt too tired, once after being delayed getting home from work due to a car break-down, and once due to a stomach upset. He covered about 70 miles per week. Overall, the balance of hard and easy sessions is similar to the Haile’s training in the period 2003 to 2006, though the total volume was appreciably less, and there is a somewhat greater sense of spontaneity in Jack’s choice of sessions.

A glimpse of his spontaneity is provided in the latter part of the inspiring film ‘On the Run’ released by the New Zealand Film Unit in 1979. As an aside, although that short film was released almost a decade after my own heyday as a runner, and the landscapes of New Zealand are grander than the gum-tree covered slopes and gullies of the Adelaide hills in which I ran, it evokes so vividly the era in which I fell in love with running. On the one hand there was the precise organization but undeniably amateur atmosphere of track events run under the auspices of the Amateur Athletic Association; on the other hand, the freedom of running across farmland and hill country.   Perhaps a crucial snippet was Arthur Lydiard’s slightly breathless remark to 3000m runner, Heather Thompson, as they ran together though the scrub: ‘just slow down Heather, the distance is more important than the speed. You have just got to keep it at a pleasant effort’.   Although at the time we had debated the merits of Arthur’s ideas, in retrospect, it is clear that those ideas played a key part in shaping that golden era.

After the Montreal Olympics Jack continued to run and race. His achievements included a M50-54 world marathon record of 2:20:28 in Auckland in 1982. He was disappointed not to be the first 50 year old to break 2:20. The current M50-54 world record is 2:19:29. In later years Jack returned to cycling, though he did a small amount of running. In a letter written to James Doran in January 2004 at age 72, he mentioned that he was no longer running but was cycling, “200-300km most weeks”   Poignantly, he added that cycling was “much more fun than running, and no injuries, unless one crashes!” Sadly he was knocked from his bicycle and killed when out cycling on the roads of Rotorua five months later.

Foster’s M40-44 record set in Christchurch remained unbroken for 16 years and even now, his time of 2:11:18.6 remains the fastest ever marathon by a 41 year old. Whether or not Haile Gebrselassie manages to eclipse this time before his 42nd birthday next April, Foster’s achievement 40 years ago is truly remarkable.


Both Haile Gebrselassie and Jack Foster balanced a relatively small amount of intense training with a large volume of easy running. Both took delight in soft, natural surfaces: Geb runs in the mountain forests near Addis Ababa; Jack ran over the hilly farmland of Rotorua. There is something special about sheep-clipped pastures. Unlike the hooves of heavier cattle, the smaller cloven hooves of sheep do not break the ground but merely create enticing tracks as they contour around the hills. Perhaps most important of all, both Geb and Jack ran with a sensitivity to their bodies. Jack was willing to ‘run his tripes out’ in a race but also prepared to cancel a training run when he felt tired. Geb considers that one of the best pieces of advice he ever received about running was to train and rest well. In the words of Arthur Lydiard, ‘You have just got to keep it at a pleasant effort.’

Hyper and hypokalaemia in athletes

June 8, 2014

Potassium ions are of key importance for health and for athletic performance. The level of potassium in the blood must be regulated within fairly narrow limits: at concentrations above 12 mM there is a very high risk of sudden cardiac arrest*.  Steady state levels above 6.5 mM are considered dangerous in clinical practice, while levels below 3.5 mM are associated with slow repolarization of heart muscle and risk of various disturbances of cardiac rhythm, and also with risk of additional serious disorders such as high blood pressure and stroke (reviewed by Sica and colleagues). Low blood levels are also associated with fatigue of skeletal muscles, but so too is the loss of the normal gradient of potassium ions across muscle cell membranes that arises when potassium moves out of muscle cells into the extracelular fluid.

*[As summarised in the discussion with Michael below, the highest published potassium level in  a person who subsequently survived is 14 mM (possibly arising from muscle damage sustained during cardiac resuscitation.)  However survival after potassium exceeds 10 mM is very rare. ]

Potassium is lost from the body via the kidneys and in sweat. But more important than the maintenance of total body levels is the distribution between the inside of cells and the extra-cellular fluids (including blood plasma). While typical concentration outside of cells is around 4.5 mM, the concentration inside nerve and muscle cells is in the vicinity of 150 mM. About 98% of the body’s potassium is contained within cells. This gradient in ion concentration across the cell membrane is essential for conduction of neural impulses and for muscular contraction. Normal neural conduction and muscle contraction entail flow of potassium though ion channels in the cell membrane, thereby depleting intracellular levels and causing extracellular concentration to rise appreciably. This reduction in the gradient across the membrane contributes to fatigue. Extracellular levels of potassium are regulated by the renin-angiotensin-aldosterone hormonal system, which promotes potassium loss when levels are high.   Thus, higher extra-cellular levels promote potassium loss for the body. Molecular pumps that move potassium (K+) ions back into calls in exchange for sodium (Na+ ) ions minimise loss of potassium form cells during exercise and reducing fatigue, but continue to pump after exercise stops, resulting in a net fall of potassium below the pre-exercise levels.

The first concern of the athlete the development of effective Na/K pumping, and the second concern is ensuring that dietary intake is adequate so that total body store is not depleted. In long endurance races and even more catastrophic issue arises: damage to muscle cells during prolonged exercise can release potassium together with protein myoglobin, which damages the kidneys, and can result in potassium rising to dangerous levels. This is one of the causes of the rare sudden deaths that occur in the late stages of a marathon.   Thus, it is worthwhile understanding how training can promote effective Na/K pumping and the role of both electrolyte replacement and diet in maintaining the appropriate total body level of potassium.


The role of potassium in skeletal muscle contraction

The contraction of skeletal muscles is elicited by a rapid influx of Na+ and an equivalent efflux of K+ ions across cell membranes.  Skeletal muscles contain the largest pool of K+ in the body. During intense exercise, the Na/K-pumps cannot readily return K+ into the muscle cells. Therefore, the working muscles undergo a net loss of K+, while the K+ concentration in the arterial blood plasma can double in less than 1 minute. Even larger increases in K+ in interstitial tissues surrounding the muscle cells. This results in degradation in the electrical potential gradient across membranes, thereby resulting in loss of excitability and force. During continuous stimulation of isolated muscles, there is a strong correlation between the rise in extracellular K+ and the rate of force decline. These events present a major challenge for the Na/K-pumps.   Excitation of the muscle itself, together with the stimulating effects of adrenaline and insulin, increases the Na/K-pumping rate. If all available pumps are engaged, the rate of pumping can increase up to 20-fold above the resting transport rate within 10 seconds. Thus in working muscles, the Na/K-pumps play a dynamic regulatory role in the maintenance of excitability and force. Down-regulation of pump capacity reduces contractile endurance in isolated muscles. The Na/K-pump capacity is a limiting factor for contractile force and endurance, especially when their capacity is reduced as a result of de-training.

The pumping capacity of Na/K-pumps is influenced by hormones, such as thyroid hormone, adrenal steroids including cortisol, insulin, and by fasting and potassium-deficiency (as reviewed by Torben Clausen from University of Aarhus in Denmark). Thus, an adequate intake of dietary potassium is important. Good sources are leafy greens, dried apricots, yoghurt, salmon, mushrooms, and bananas. Perhaps even more importantly, physical inactivity degrades pumping capacity while training enhances it. High intensity interval training is especially effective in enhancing Na/K pump capacity. For example, Bangsbo and colleagues form Copenhagen reported that six to twelve 30-s sprint runs 3-4 times/week for 9 weeks produced a 68% increase in Na/K-pump units (p<0,05) and a significant reduction of blood plasma K+ level, compared with observations in a control group who continued with endurance training (approximately 55 km/Km). The intense sprint training was associated with significant improvement in performance. In those doing the intense sprints, 3-km time was reduced by 18 seconds from 10 min 24 sec to 10 min 6sec while 10-km time improved from 37 min18 sec to 36 min18 sec.


The effect of potassium on the heart

Unlike the situation in skeletal muscle, under normal circumstances, in the heart the rise in intracellular Na+ concretion associated with activation of the muscle activate the Na/K pump adequately to completely compensate for the increased K+ release (evidence reviewed by Sejersted).  Thus, whereas the K+ shifts during intense exercise can contribute substantially to fatigue in skeletal muscle in the heart, the K(+) balance is normally controlled much more effectively. This might not be the case during abnormal circumstances such as ischemia.

If there is serious elevation of blood levels of potassium due to muscle damage (see the section on rhabdomyolysis below) or due to dietary excess in the presence of a disorder of the renin-angiotension –aldosterone mechanism that normally regulates potassium, there is a risk of serious reduction of the electrical gradient across the heart muscle membrane essential for conduction of the excitation signal thought the heart muscle. The consequence can be cardiac arrest, which is usually fatal.

Conversely, when blood levels of potassium are low, due to serious loss and failure of dietary replacement, the re-establishment of the electrical gradient is slower. This delayed re-polarization is, manifest as an increase in the interval between the Q wave and the T wave in the electro cardiogram. The delayed re-polarization can lead to rhythm disturbances due to alteration of the conduction pathways. The most serious of these is the rare but potentially fatal rhythm disturbance known as Torsade de Pointes. However, because of the normally tight regulation of sodium and potassium ion level by the renin-angiotensin aldosterone system, this is very unlikely in otherwise healthy individuals.


Regulation of potassium levels by the renin-angiotensin-aldosterone system

Renin is an enzyme secreted by the kidneys that acts on a substance called angiotensinogen that is produced in the liver. Renin splits angiotensinogen releasing the peptide angiotensin, which has various actions in the body directed towards retaining sodium, conserving blood volume and maintaining blood pressure. One of the important actions of angiotensin is stimulation of release of the steroid hormone, aldosterone, from the adrenal glands. Aldosterone acts on the kidney to promote retention of sodium and excretion of potassium. During exercise, aldosterone production is increased, thereby decreasing urine production and conserving fluid volume, while promoting excretion of potassium. This helps reduce the accumulation of potassium in blood due to efflux from active skeletal muscle, but contributes to the fall in potassium levels after exercise ceases. Maintenance of blood volume by moderate fluid intake is likely to minimise excessive engagement of the renin-angiotensin-aldosterone system.

On one occasion when I made an overly ambitious attempt to find a novel route across a mountain ridge for my return journey during a long run in the Sierra Nevada in southern Spain on a hot dry day with an inadequate supply of water, I became quite dehydrated. I was somewhat alarmed to experience an increase in ectopic heart beats. I suspect that the dehydration had led to excessive activity of the renin-angiotensin-aldosterone system, depletion of potassium and consequent disturbance of heart rhythm. I am now much more careful about hydration during long runs.

For runs greater than 20 Km, I generally prepare a drink containing 4 tablespoons of sugar and one quarter of a teaspoon of salt in four cups of water, together with lemon juice to make it palatable. I do not add any potassium salts to this mixture, as any added potassium might promote excessive activation of the renin-angiotensin-aldosterone system, thereby defeating the purpose. I adjust rate of intake to keep just ahead of appreciable thirst. Typically I find that consuming a mouthful of this drink per Km keeps me adequately hydrated.



Rhabdomyolysis is a condition produced by the breakdown of muscle, resulting in the release of the protein myoglobin, along with potassium in to the blood stream. The myoglobin damages the kidney with multiple adverse consequences including failure of potassium excretion.   In extreme cases the increase in blood potassium can produce fatal cardiac arrest.   In slightly less extreme cases, the kidney failure is nonetheless a serious medical emergency. Severe rhabdomyolysis arises rarely as a result of the muscle damage sustained during endurance events. However, some evidence indicates that mild degrees are not uncommon in males. For example a study by Maxwell and Bloor that tested for evidence of muscle damage after a 14 mile run at 8 min/mile pace in three groups of well-conditioned male athletes who had undergone training regimes differing in volume of running for a period of one months, found that the 14 mile run produced evidence of substantial muscle damage, including increases in serum myoglobin ranging from of 52-405%. The increases were most marked in those who had trained less for 8 miles/day on alternate days. Rhabdomyolysis is much less in females, possible because oestrogen stabilises muscle membranes.

 It should also be noted that exercise induced rhabdomyolysis does not always lead to increased levels of potassium. In a series cases of exercise indices rhabdomyolysis reported by Sinert and colleagues there were no cases of hyperkalaemia.



Efficient regulation of potassium is essential for both good athletic performance and for health. One key issue for endurance athletes is maintaining the capacity of the Na/K-pumps that return potassium excreted by muscle cells as result of muscular activation back into the muscle cells. Inadequate pumping results in fatigue. Training, especially high intensity interval training, enhances the activity of the Na/K pumps. Potassium is lost from the body during exercise and dietary replacement of potassium is necessary though this is not generally an issue provide diet is reasonably well balanced.   However, sustained potassium depletion has adverse effects including heart rhythm disturbances, increased blood pressure and risk of stroke.

The renin-angiotensin-aldosterone system acts to maintain fluid volume during exercise, but promotes potassium loss. It is important to avoid serious dehydration to minimise the risk of excessive activation of the renin-angiotensin-aldosterone system.

In rare instances, muscle damage during endurance events results in life-threatening rhabdomyolysis. This can lead to a dangerous excess of potassium in the blood.  More common is moderate muscle damage that leads to accumulation of myoglobin.  However, training reduces this risk.

Cortisol and the stress response

June 2, 2014

Cortisol, a steroid hormone produced by the adrenal gland, plays a key role in mobilizing the body’s resources to cope with stressful challenges, including the challenge of running. Among its many roles is the regulation of blood glucose. When demands are high, cortisol acts to conserve glucose for the brain by minimizing uptake of glucose into other tissues and by promoting the production of glucose in the liver.   Because healing is not a priority when dealing with an acute challenge, cortisol suppresses inflammation and the immune system. In a healthy person, cortisol levels return to normal over a time scale of 30-60 minutes after the stress resolves. However if the transient surge of cortisol required to deal with acute stress is not switched off, cortisol inhibits healing by suppressing the formation of collagen while promoting breakdown of protein, thereby damaging many tissues of the body.

Recent evidence from a study by Skoluda and colleagues indicates that endurance athletes tend to have persistently high levels of cortisol. This increases in proportion to training volume. Thus the regulation of cortisol is potentially of great importance not only for ensuring that an athlete obtains benefits from training, but also for long term health.

The relationship between cortisol and inflammation is complex. In the short term cortisol suppresses inflammation, but sustained elevation of cortisol can lead to a suppression of the receptors that mediate the effects of cortisol on body tissues, and consequently, sustained elevation of cortisol can actually promote chronic inflammation which in turn damages tissues by laying down non-functional fibrous tissue as described in my recent post.

Although excessive cortisol is harmful, reduced ability to generate cortisol when required can be even more harmful. Addison’s disease, a rare condition in which the adrenal gland is damaged by autoimmune attack, is characterised by non-specific symptoms such as weakness and fatigue, and can be result in fatal inability to respond to stress. There is some evidence that sustained stress can reduce the capacity of the adrenal glands to produce cortisol when required, though the concept of adrenal fatigue, popularized by some alternative-medicine practitioners, remains an ill-defined entity.

Cortisol production is regulated by a feedback mechanism that takes account of information about the overall metabolic state of the body. This feedback system acts via the hypothalamo-pituitary-adrenal axis (HPA). The release of cortisol from the adrenal glands is stimulated by a hormone, ACTH, that is produced in the pituitary gland. The release of ACTH is in turn stimulated by a hormone, corticotrophin releasing factor, that is secreted by the hypothalamus. Information about the state of the body is funnelled via the amygdala and hippocampus in the temporal lobe of the brain, to the hypothalamus. This complex feedback system allows a diverse array of neural and hormonal signals to control cortisol release in a way that balances the catabolic effects of cortisol, promoting tissues breakdown, with the anabolic effects of other hormones, such as DHEA (a steroid hormone produced in the adrenal glands) and growth hormone, produced in the pituitary gland, that play a role in promoting the repair and strengthening of damaged tissues.  Thus many complex, interacting processes are involved in ensuring the optimal balance between mobilising body resources to deal with acute challenge and subsequent healing. Factors such as levels of ongoing stress from life circumstances and age contribute to the balance.

 Strategies for optimising the stress response

In summary, an athlete requires healthy adrenal glands which can generate enough cortisol to meet the challenge of stress but then to switch off cortisol production to promote recovery. The simple principle is that for optimum training benefit and long term health, we need to avoid excessive stress. However, the best way of achieving this is likely to determined by individual’s genes and life circumstances. While each individual has to find what works for him or her, there are several issues likely to be relevant to most athletes.

1)      Avoiding over-training. As demonstrated by Skoluda, the sustained excess of cortisol is greater in those who train more. Both volume and intensity matter though it is noteworthy that prolonged duration of exercise promotes increase in cortisol, whereas high intensity promotes hormones such as growth hormone and anabolic steroid hormones that promote strengthening of tissues. Consistent with this, some evidence indicates that the over-training syndrome is more strongly linked to high volume training than to high intensity training.

2)      Recovery from training and racing is crucial.   Not only does inadequate recovery increase the risk of persisting inflammation (as discussed in my previous post) but it impedes the transition from the cortisol induced catabolic state to the anabolic state required to rebuild and strengthen body tissues. This raises the major question of how best to determine if recovery is adequate. Subjective indices such as the Profile of Mood States, and autonomic measures such as resting heart rate and heart rate variability provide a guide, but no single test provides the full answer.  This is an issue I will return to again in the near future.

3)      Resistance training promotes the release of anabolic hormones and has many other beneficial effects on metabolism including increased sensitively to insulin. The major metabolic benefits of resistance training can be achieved by two 15 minute sessions per week.

4)      Life-stress and relaxation. Many of us have relatively limited control over the pressures of work and other responsibilities. However the way we react to these pressures is largely under our own control. Sleep plays a cardinal role. During sleep, cortisol levels fall while release of growth hormone is promoted. During our waking hours we can do a great deal to minimise stress. In recent years, the practice of Mindfulness has been proven to be effective in treating clinical disorders including anxiety and depression. It is a technique derived from Eastern meditative practices in which the aim is cultivation of a calm, non-judgmental awareness of one’s present physical and mental state.   Accumulating evidence indicates that this mental state is the optimum state for individuals such as US Navy Seals for whom remaining calm and focussed under intense pressure is crucial. Some studies show that Mindfulness lowers cortisol levels, while other studies have found evidence of beneficial reduction in stress and improved sleep but did not observe significant reduction of cortisol levels. Mindfulness is a knack that can be acquired by practice. Although the evidence for its effectiveness is still preliminary, my own experience is that it is effective in lowering mental and physical tension. I practice it at any time when I feel pressure is building, and also experiment with employing it while running to promote a constructive focussed mental state.

5)      Fuelling before and during training is a debateable topic. Some evidence indicates that training in a fasting state leads to improved endurance performance, perhaps mediated by the development of increased capacity to utilise fat as fuel, but overall the studies have yielded mixed results, as I have discussed in a previous post. I suspect this is because training in a fasted state also promotes increased cortisol levels that might be harmful. I have made appreciable gains in fitness in the past following training in a fasted state, but suffered one of the few serious muscle strains I have ever experienced after three weeks of high volume training predominantly in a fasted state.   This is mere anecdote, but when combined with the mixed evidence from scientific studies, leads me to conclude that training in a fasted state should be done cautiously, ensuring that overall stress levels are not excessive.

6)      Long term nutrition.  In light of the mechanism by which the hypothalamo-pituitary axis (HPA) adjusts cortisol levels in order to maintain metabolic homeostasis, it would be expected that a diet that promotes healthy energy metabolism would also be expected to promote healthy regulation of cortisol. As discussed in several of my recent posts, there is growing evidence that a Mediterranean diet promotes healthy metabolism. In accord with this, the available evidence indicates that a Mediterranean diet does promote healthy regulation of cortisol. For example a study of Spanish women found that those who chose a dietary pattern closer to the Mediterranean diet, with high mono-unsaturated fatty acid intake, showed more stable regulation of cortisol by the HPA.


The evidence obtaind by Skoluda indicating that endurance athletes suffer sustained elevation of cortisol suggests that taking steps to maintain healthy regulation of cortisol is likely to result not only in a better response to endurance training but also in better long term health. This might be achieved by avoidance of over-training, ensuing good recovery, incorporation of some resistance training into the schedule and a number of life-style adaptations including adequate sleep, stress reduction via strategies such as Mindfulness, and a healthy diet, such as the Mediterranean diet.

Minimising the risks: chronic inflammation

May 24, 2014

In my recent post I summarised the evidence indicating that running, at least in amounts up to 50 minutes of vigorous activity per day, is likely to increase your life expectancy, but nonetheless some endurance runners suffer serious ill-health attributable at least in part to their running. There is unequivocal evidence indicating transient heart muscle damage after endurance event such as a marathon; and unequivocal evidence that endurance athletes are at increased long-term risk of heart rhythm disturbance, such as atrial fibrillation. There is quite strong evidence that many years of marathon training increases the risk of fibrosis of the heart muscle and calcification of the coronary arteries. While the beneficial effects appears to outweigh the adverse effects for the majority, at least some endurance athletes suffer serious adverse effects. On the other hand, the evidence that the benefits appear to outweigh the adverse effects in the majority suggests that is sensible to try to identify what causes the serious adverse effects and take steps to minimise them, thereby increasing the likelihood of being among those who derive more benefit than harm.

Although the mechanisms of cardiac damage are not well established, there is a great deal of evidence regarding plausible mechanisms. We are not detached observers who can afford the luxury of waiting until the mechanisms are established beyond doubt, like climate change deniers who prefer to wait until the outcome is certain before acting. Rather, we are each an experiment of one, and we must make our decision for action or inaction based on the current evidence.

Inflammation and myocardial fibrosis

Perhaps the most plausible mechanism for adverse cardiac effects is a mechanism based on inflammation. Prolonged mechanical stress on heart muscle produces damage, which in turn elicits an increase in cytokines, the chemical messengers that circulate in the blood and trigger the events of inflammation which lead to laying down of fibrous tissue. This is the body’s mechanism for repairing damage and increasing the strength of tissues. But the initial deposition of fibrous tissue is slap-dash and unless redundant fibres are removed, the future function of the relevant body tissue is likely to be impaired. In the long term calcium is deposited at the site of damage, making the tissues stiff and inflexible.

In the case of tissues such as the plantar fascia, the misaligned fibres cause the pain of plantar fasciitis and the deposited calcium gives rise to the heel spurs visible on x-ray. In the case of the heart muscle, misplaced fibrous tissue has the potential to interfere with the electrical conduction pathways producing disturbance of rhythm. In the case of the lining of blood vessels such as the coronary arteries, the process is a bit more complex. The accumulation of cholesterol at the sites of damage to the lining of the artery plays a key role in triggering the inflammatory response. The Wellcome Trust have produced an excellent video depicting the sequence of events.

Minimising the risks

From what we understand of the mechanism, there are three key things we can do to minimise the risk of damage:

1)      Allow adequate recovery after heavy training and racing. Studies in animals and humans demonstrate that much of the fibrosis, though perhaps not all, resolves during an adequate recovery period.

2)      Build up training gradually. The tissue trauma that initiates the inflammatory process is less if the tissues have been strengthened by gradual adaptation. This is illustrated by the fact that DOMS is more marked if you suddenly increase training volume.

3)      Consume a diet that minimises chronic inflammation. Current evidence indicates that a Mediterranean diet, in which the pro-inflammatory omega 6 fats prevalent in the Western diet are balanced by omega 3 fats from fish and/or nuts and green leafy vegetables, is a heart-healthy diet.


It is noteworthy that these three strategies not only have the potential to reduce the risk of serious long term adverse effects on the heart, but are also likely to maximises the long term improvement in running performance.

In future posts I will discuss the more complex issue of cortisol and also the exacerbation of rhythm disturbances by excess potassium that is released from damaged muscle cells

The big debates of the past decade: 5) Is running good for your health?

May 19, 2014

Is running good for your health? Once the answer seemed simple.  However, the sadly premature deaths of several charismatic advocates of endurance running, Jim Fixx, John (Hadd) Walsh and Caballero Blanco, have provided grounds for questioning the claim that a large volume of running is healthy.

The past decade has seen a vigorous debate driven by enthusiasts who claim that the evidence indicates that any more than about 2.5 hours of moderate intensity exercise per week is harmful.   The high priest preaching warnings about the risks is James O’Keefe, a cardiologist from Kansas City, who summarised his views in a review in the respected Mayo Clinic Proceedings and also popularised them in an evangelistic TED talk.   I have discussed O’Keefe’s views previously in a post in Jan 2013. Though I consider that he himself comes across as something of an evangelist, the evidence that he assembles does indeed confirm beyond reasonable doubt that endurance athletes are not immune from either coronary heart disease or from potentially fatal disturbances of cardiac rhythm.

My own belief is that the overall balance between health benefit and harm of running is inclined towards greater benefit than harm, at least up to upper limit of running done by the majority of recreational runners. I reviewed the evidence in my post in Jan 2013, and will not present the details again here. Instead, I will provide an update on the evidence that has been assembled since Jan 2013.

However, my main interest is not on the statistical evidence for or against harm, but rather on what research of the past decade has revealed about likely mechanisms by which running might be expected to cause harm, with the ultimate goal of developing strategies for minimising the risk of harm. Even if the balance of evidence suggests that running is of greater benefit than harm to health, the undeniable evidence that at least some runners do suffer harm suggests to me that the sensible approach is to take what steps we can to minimise the risk of unnecessary harm.

Life expectancy

The picture is moderately clear: life expectancy increases with increasing amount of exercise, but the rate of increase levels off at higher levels. For example, in the study by Wen and colleagues, the reduction in mortality rate (that is the number of deaths that occurred compared with the number expected during the follow-up period) was observed to increase with increasing amount of exercise, but levelled off at a mortality reduction of around 45%  for 50 minutes or more of vigorous exercise per day.   Although there was little evidence of an actual decrease in life expectancy with very large amounts of exercise, the number of individuals exercising at extreme levels is small, so it is difficult to draw statically robust conclusions.

Perhaps the most thought provoking evidence comes from the Copenhagen Heart Risk study, a longitudinal study of nearly 18000 people followed over a period of up to 35 years. As in other relevant studies, the main conclusion regarding the effects of exercise is that jogging reduces mortality. The age-adjusted increase in survival with jogging was 6.2 years in men and 5.6 years in women. However the investigators reported a U-shaped relationship, with best outcome in those who jogged less than 2.5 hours a week at a slow pace. But the numbers in the relevant groups were very small. In those reporting that they jogged slowly, there were 3 deaths in 178 people, whereas among the fast group there were 5 deaths among 201.   These numbers are too small to justify robust conclusions.

In contrast , a study of mortality in a cohort of 49 219 men and 24 403 women who participated in any of the Vasaloppet long-distance ski races in Sweden (90Km for men; 90 and 30Km for women) during 1989–1998,revealed substantially reduced standardised mortality rate (SMR) from all major causes of death including heart disease and cancer. Overall, 410 deaths occurred up to Dec 1999, compared with 851 expected, yielding an SMR of 0.48.   It is reasonable to assume that the majority of competitors in these races had undertaken extensive training.

More recently, a study by Dr Jodi Zilinki and colleagues at Massachusetts General Hospital, reported at this year’s American College of Cardiology meeting in Washington, found evidence of decreased cardiac risk factors following marathon training in 45 recreational runners aged 35-65 who had not achieved Boston Qualifying time for the 2013 event but had nonetheless obtained places to raise money for charity. Half had run at least three marathons in their lifetime. Prior to an 18 week training program, over half had at least one risk factor for heart disease, such as high cholesterol, high blood pressure or a family history of heart disease. During training, potentially harmful low density lipoprotein (LDL) cholesterol decreased by 5% while triglycerides decreased by 15%. Thus for the majority of recreational runners, it appears that marathon training is likely to be good for their health

Specific cardiovascular risks


With regard to cardiovascular risks, the most compelling evidence indicates increased risk of disturbance of heart rhythm, such as atrial fibrillation, in middle-aged male endurance athletes. This is revealed by many studies (which I reviewed in a post in Jan 2012), though the question of whether or not this results in greater mortality is not clearly established. It is possible that other health benefits of running might outweigh the risks associated with arrhythmia. For example, the reduced blood pressure, lower levels of harmful low density lipoprotein cholesterol associated with endurance training would be expected to confer protection.

Coronary artery disease

Perhaps the most worrying issue is the possibility of increased coronary artery disease.   There have been a many of reports of clogged coronary arteries revealed by coronary angiography in endurance athletes. The most substantial of these was a study of 50 men who had competed in the Twin Cities (Minneapolis-St Paul) Marathon for twenty five consecutive years. The proportion of individuals with atheroma was similar in the two groups (atheroma in 60% on marathon runners, and 52% percent of controls), while the extent of the atheroma was significantly greater in the runners. This finding was initially reported at the American College of Cardiology meeting in Atlanta, Georgia in 2010. However, only an abstract was published at that time.

The definitive publication by Robert Schwartz and colleagues appeared in 2014 in a relatively obscure journal, Missouri Medicine. The list of co-authors includes James O’Keefe, who is an Editorial Board Member of Missouri Medicine Preventive Medicine.  I mention the details about publication because when a paper as potentially important as this appears belatedly in a relatively low profile journal, the first question that occurs to me is: why was this not published in a more authoritative journal.   Was it was rejected by other journals?

I am not a cardiologist, though I do frequently provide peer review of scientific and medical manuscripts submitted to high-profile journals. If I had been asked to review this manuscript, my greatest concern would have been for the procedure used to match runners and controls. In any study in which participants of interest are compared with a control group it is important that the two groups are matched on factors that might have an independent effect on outcome. For example, it is usually necessary to match for age, sex and social class. It is often desirable to match for other factors relevant to the condition of interest, such as family history of heart disease. However it is usually undesirable to match for factors that reflect the mechanism by which the ‘treatment’ (in this case, running multiple marathons) might achieve its benefit or harm. For example, because exercise tends to decrease the levels of harmful lipids in the blood, it might be misleading to match the groups on these variables. Such matching would be expected to produce a control group who happen to exhibit below-average risk of cardiovascular disease for incidental reasons related to their genes or environment.   But this is precisely what Schwartz and colleagues did. In effect, they determined the effect of marathon running after allowing for some of the anticipated benefits of marathon running.  Thus the statistical comparison of the two groups is biased and must be interpreted with extreme caution.

Nonetheless, whatever one makes of the statistical comparison, the number of marathon runners with atheroma in their coronary arteries and the extent of their atheroma was alarmingly high.  If I had been the referee reviewing this manuscript, I would have recommended publication subject to a critical discussion of the possible bias introduced by the matching procedure. I think it would be unwise to brush aside these findings simply because of some flaws in the science – there are very few medical studies that are totally free of all possible bias.  In evaluating medical evidence it is necessary to weigh up the whole picture, including the plausibility of the findings on the basis of what we know of human physiology.

Plausible mechanism for cardiovascular damage

I consider that there are at least three plausible mechanisms by which prolonged or intense endurance exercise might lead to cardiovascular damage. These are elevation of cortisol, chronic inflammation and acute release of potassium due to breakdown of muscle cell membranes.

Cortisol is a key hormone that mediates the body’s acute response to stress, but if elevation of cortisol is sustained, it damages most tissues of the body.   Skoluda and colleagues have presented evidence that endurance athletes tend to have sustained elevation of cortisol.

Inflammation is the process by which the body repairs itself following acute damage. It is probable that acute inflammation plays a central role in the repair and strengthening of the body after vigorous training. Thus, it is a key mediator of training effects. However inflammation that becomes chronic is harmful and probably plays a large part in the over-training syndrome. Furthermore, chronic inflammation promotes the formation of coronary atheroma.

The imbalance of concentration of potassium ions across cell membranes plays a central role in nerve conduction and muscle contraction, in both skeletal muscle and in the heart. Potassium concentration within cells is normally high while levels in extra-cellular tissues including blood are low. Damage to muscle cell membranes during vigorous exercise releases potassium into the extracellular tissues. The mechanism for pumping potassium back into muscle cells and also the action of the kidneys can normally cope with this tendency towards excess extra-cellular potassium. But under some rare circumstances, potassium can rise to high levels causing fatal cardiac arrest.

The important thing about all three of these mechanisms is that there are things we can adjust about our training and our lifestyle, including diet, that have the potential to ameliorate all of these risks. Thus, even though for most of us, the health risks of endurance training and racing are small and likely to be outweighed by the benefits, we can shift the balance even further in the direction of benefit by adjusting our training and lifestyle. In future posts I will present my conclusions regarding the best strategies for achieving this.

The big debates of the past decade: 4) high carbohydrate v Paleo diet

April 26, 2014

Debates about diet for general health and specifically about the optimum nutrition for athletes have raged for many decades, but in the past decade this debate has largely been dominated by the polarization of opinions for or against the Paleo diet, the presumed diet rich in fat and protein consumed by our distant ancestors who hunted on the African savannah.   In recent years, Tim Noakes’ rejection of the high carbohydrate diet that he had advocated in his authoritative ‘Lore of Running’ added momentum to the shift away from carbohydrate towards fat, but on the whole professional dieticians have remained sceptical of fat. The debate is far from over, but I think that there has been substantial progress in assembling evidence regarding optimal nutrition for endurance athletes.   As with virtually all studies of something as complex as human physiology, no single study is definitive. Staunch advocates of either side of the argument can point to the limitations of any single study, but the overall body of evidence does provide a fairly consistent picture. Perhaps it even allows us to speculate on how difference between individuals might account for some for the contradictory findings from studies.

There have also been numerous debates about specific micronutrients, food supplements and ‘super-foods’, ranging from beetroot to chocolate, which I will scarcely touch on here to avoid the post being excessively long. My overall conclusion is that while taking a particular additive might have beneficial effects in some individuals in some circumstances, the unforeseen consequences of many additives often nullify the potential benefits, because the body is a homeostatic system that acts to compensate for any abrupt changes. This is perhaps best illustrated by the antioxidants which have the potential to avert the tissue damage due to free radicals that are a by-product of energy metabolism. Nonetheless, many studies of anti-oxidant supplementation do not show a net benefit. In general, I aim to achieve the required intake of micronutrients via a fairly diverse diet, including a diverse range of fatty acids, rather than by taking supplements.  Despite my general scepticism, I am moderately convinced by the evidence that green tea does have an overall beneficial effect on well-being. It contains moderate amounts of antioxidants along with many other compounds with potential health benefits, including catechins with beneficial effects on cardiovascular health. I myself drink modest amount so green tea as I enjoy it as a beverage.

Nutrition during training and while racing.

There are two aspects of the physiology of running that are established beyond debate and provide the starting point when planning nutrition during preparation for a race and during the race itself.   The first is that the metabolism of glucose (via glycolysis and subsequent oxidative metabolism via the Krebs cycle) produces energy at a faster rate than metabolism of either fat or protein. The second is that the supply of the glucose precursor, glycogen, is limited, whereas even lean runners carry a virtually inexhaustible supply of fat.

Up to the half marathon

The fact that metabolism of glucose generates energy more rapidly makes it essential to burn glucose for events run at speeds near or above lactate threshold pace. Provided we consume enough carbohydrate in the pre-race period  to ensure that glycogen stocks are full before the race, the stored glycogen will last for events lasting up to 90 minutes or even longer. Consistent with this, in a meta-analysis of 20 studies comparing the effects of high carbohydrate with high fat with diet on endurance exercise, Erlenbusch and colleagues found that overall, subjects consuming a high-carbohydrate diet exercised significantly longer until exhaustion, but there was substantial variation in finding between different studies. I myself do a modest amount of carbohydrate loading before a half marathon but consume nothing apart from water during the event itself.


In a marathon, the fact that the store of glycogen is limited comes into play.   To avoid running out of glucose we need to do two things: increase our capacity to utilise fat during the preparatory period and augment our glucose supply by ingestion of carbohydrate during the race.  Irrespective of specific nutritional strategies, training itself – both high volume, low intensity training and also high intensity interval training, enhance the production of the enzymes involved in fat metabolism and thereby increase the ability to utilise fat.

Two other strategies have been studied fairly intensively but with inconclusive overall outcome. First, training in a fasted state might be expected to enhance the ability to utilise fats. Indeed it does, and at least in some studies it enhances endurance performance. However, another factor comes into play. Training in a carbohydrate depleted state encourages the adrenal glands to release cortisol, which acts to ensure that blood glucose is reserved for use by the brain. In the short term cortisol promotes an effective response to stress but if the elevation of cortisol is sustained, it has a damaging effect on many tissues. A study by Skoluda, using measurement of cortisol in hair to assess sustained cortisol levels revealed that many endurance athletes have excessive sustained levels of cortisol. I believe that elevation of cortisol might be one reason why studies of training in a carbohydrate depleted state yield inconsistent findings. My personal conclusion is that as an elderly runner, for me the risks of tissue damage due to sustained cortisol levels are too high. However, for a younger athlete, training in a carbohydrate depleted state might be beneficial provided care is taken to minimize any unnecessary stresses. It is probably useful to monitor for signs of excessive cortisol – though direct measurement is impractical for the recreational athlete. Perhaps assessment of mood via the Profile of Mood States questionnaire provides the most practical proxy measurement.

The other widely studied strategy is consumption of a high fat diet to promote preferential use of fats until a few days before the race and then topping up the glycogen supply via carbohydrate loading.  A few studies have found this to be beneficial in endurance events. For example a study from Noakes’ lab using the nutritional periodization strategy found that high-fat consumption for 10 days prior to carbohydrate loading was associated with an increased utilization of fat, a decreased reliance on muscle glycogen, and improved time trial performance in a 20 Km time-trial following 150 minutes of medium intensity cycling. However, other studies, such as that by Carey and colleagues, have not shown improved endurance performance and overall the results are inconclusive. I suspect that this is because the body is a homeostatic system that adjusts to compensate for any abrupt change in circumstances. Therefore the body is likely to react to thwart any strategy that entails abrupt changes.

My own approach to marathon training is a balanced diet during the period of heavy training (for reasons discussed in the section on healthy nutrition below), moderate carbohydrate loading immediately preceding the event and the consumption of carbohydrate in small amount during the event – though I have yet more experimenting to do to identify the within-race fuelling schedule that suits me best



Developing a high capacity to utilise fats is a high priority in training for an ultra-marathon.  Nonetheless, as in the case of marathon training, I would be inclined to recommend a balanced diet during high volume training, and rely on the high volume of training, augmented by a small amount of high intensity interval training, to maximise the capacity to utilise fat. But it is pre-race and within race nutrition that raises the big issues. An ultra challenges virtually all systems within the body including the brain. The first issue is ensuring an adequate supply of glucose for the brain.  Thus in the pre-race period it is important to ensure that the liver is well stocked with glycogen. Furthermore, because pace is below threshold pace, metabolism of fat is fast enough to provide a large proportion of the energy required by muscles, but at least some glucose metabolism is required. Fat metabolism leads to energy production via the Krebs cycle, but unlike glucose metabolism, fat metabolism cannot restock the pool of Krebs cycle metabolites. This pool gets depleted due to the production of glutamine – an amino acid produced in muscle by an offshoot of the Krebs cycle. Glutamine is transported from the muscle to other organs, most importantly to the gut where it plays a key role in keeping the gut functioning well. So an ultra-runner relies on a modest amount of glucose metabolism within muscle.   What does this tell us about nutrition during an ultra? Clearly a supply of carbs is required but the stomach rejects simple sugars after a few hours. In part this might be a matter of the consistency of the food, but probably even more importantly, the body craves additional things – not only amino acids including glutamine but other things as well. The several possible mechanisms by which augmentation of carbohydrate ingestion with protein might enhance endurance performance has been reviewed by Saunders. In my limited experience of 24 hour events, I have relied on solid food with a fairly high carbohydrate content augmented by protein.


Nutrition for long term health

For the athlete, heart health is of special importance. Not only is heart disease the major cause of mortality in the general population but in addition there is some evidence that extensive endurance training and racing might in fact increase the risk of cardiovascular disease in athletes. Furthermore, most evidence suggests that a healthy diet for the heart minimises cancer. For many years, public health professionals have expressed concern about the unhealthiness of the typical Western diet. Concerns have focussed on the excessive total calories, saturated fats, high salt content, and more recently, high sugar content.

Foods with high sugar content produce a rapid rise in blood glucose that stimulates release of insulin thereby promoting increased resistance to the effects of insulin, while also producing an associated increase in arachidonic acid, an omega-6 fatty acid which is pro-inflammatory.  This exacerbates the problems arising for the fact that the typical Western diet is already unbalanced by an excess of omega-6 fatty acids.  However, the effects of arachidonic acid and inflammation are not all bad. Acute inflammation is probably crucial for recovery and strengthening after training. The crucial issue is achieving the right balance between omega-6 fats and omega-3 fats that are much less inflammatory and reduce the inflammatory effect of omega-6 fats.

The recent comprehensive review of nutritional recommendations for heart health, Eilat-Adar and colleagues reported that both low fat and low carbohydrate diets are a healthy alternative to the typical Western diet. They found that low carbohydrate diets, which typically derive 30%–40% of calories from carbohydrates and are low in saturated fat but higher in monounsaturated fat, are associated with a healthy balance of fats in the blood, with lower levels of potentially harmful tryglycerides and with higher levels of beneficial high density lipoprotein (HDL).   Eliat-Adar also found good evidence that Mediterranean diets, which include high consumption of fruit, vegetables and legumes, together with moderately large amounts of fish but less red meat may improve quality and life expectancy in healthy people, as well as in patients with diabetes, and heart disease. Mediterranean diets are preferable to a low-fat diet in reducing triglyceride levels, increasing HDL cholesterol, and improving insulin sensitivity.

A rigorous meta-analysis of trials by the Cochrane Collaboration also concluded that the evidence suggests favourable effects of the Mediterranean diet on cardiovascular risk factors, though with their usual caution, they stated that more trials are needed.

Because of many confounding effects in studies of self-selected diet, there is special value in large studies in which people are randomly allocated to different diets. One such study is the Spanish Prevención con Dieta Mediterránea (PREDIMED) trial, in which 7,216 men and women aged 55 to 80 years were randomized to 1 of 3 interventions: Mediterranean diets supplemented with nuts or olive oil or a control diet, and followed for a period of approximately 5 years. The Mediterranean diets were healther than the control diet. Nut supplementation was especially protective. Subjects on the Mediterranean diet consuming more than 3 servings/week of nuts had a 39% lower mortality risk than those on the control diet, due to protective effects against both cardiovascular and cancer mortality.

The debate about the merits of saturated versus mono-unsaturated fats has thrown up some surprising evidence contrary to the prominent advice to substitute polyunsaturated fats for saturated fats in worldwide dietary guidelines for reducing risk of coronary heart disease. Recent re-analysis of the large West Sydney Heart study found that replacing dietary saturated fat with omega- 6 linoleic acid, for subjects with known cardiovascular disease, actually led to higher all-cause death rate, and to higher death rate from cardiovascular disease. The most plausible explanation is that the increased death rate was due to the pro-inflammatory effects of omega-6 fatty acids.  Since the typical Western diet contains a high proportion of omega-6 fats, at least a modest intake of omega-3 fats, typically found in oily fish, is likely to be more healthy than increasing omega-6 fats.



There is overwhelming evidence that diet plays a large role in health and longevity, and after many years of confusing debate, there is emerging clarity that the healthiest diet is neither a high fat/low carbohydrate Paleo diet nor a low fat/high carbohydrate diet. Rather, the evidence suggests that a Mediterranean diet is preferable. Augmentation with extra nuts is probably worthwhile. It is also important to achieve a good balance between the pro-inflammatory omega-6 fats and the less inflammatory omega-3 fats, typically found in oily fish. Such a diet is likely to be optimal for athletes during periods of sustained heavy training. For longer endurance events, increased carbohydrate consumption in the immediate pre-race period will ensure that glycogen stores are replenished. During a marathon, regular intake of a small amount of carbohydrate will help maintain the supply of glucose to both brain and muscle, while in an ultra, more complex and palatable food including both carbohydrate and protein is better able to meet the more complex metabolic demands.

The big debates of the past decade: 3) High intensity v high volume training

March 31, 2014

The debate between high intensity and high volume training has been a perennial topic since the early days of scientifically-grounded training.   Interval training was developed in the 1930’s by the German coach and academic, Woldemar Gerschler. He based his recommendations on the theory that the heart muscle would be strengthened by the increase in cardiac stroke volume that occurs as heart rate drops immediately following an intense effort. A decade later, Gerschler’s compatriot, sports physician Ernst van Aaken proposed that the crucial requirement was delivering copious amounts of oxygen to the heart, and this could best be achieved by running long distances at relatively slow paces. It is noteworthy that a large volume of slow running also increases delivery of oxygen to the leg muscles. Van Aaken’s approach was later developed by New Zealander, Arthur Lydiard, based largely on trial-and-error adjustments of his own training. Lydiard’s method led to medals for his athletes, Peter Snell, Murray Halberg and Barry Magee in distances from 800m to the marathon at the Rome Olympics in 1960. While Lydiard promoted a high volume approach to building basic aerobic fitness, his program also included periodization – a progression from base building to a period of race specific training and final sharpening immediately prior to competition.

Meanwhile, interval training retained its devotees and underpinned the golden age of British middle distance running that reached its pinnacle with Seb Coe’s Olympic gold medals in the 1500m in 1980 and 1984.   By the end of the century, Japanese academic, Izumi Tabata had demonstrated that repeated very intense brief maximal efforts lasting only 20 seconds separated by even briefer recovery periods, produced impressive increases in aerobic capacity (reflected in increases in VO2max) while also enhancing anaerobic capability.

Meanwhile, devotees of high volume, less intense training, led by charismatic individuals such as John Hadd and Phil Maffetone, emphasized the risk that focussing on high intensity training might undermine sound long term development.   So what has the past decade contributed to this long-standing debate?

I think that three main strands of evidence have advanced the debate. These strands are: evidence from physiological investigations; the training of African distance runners; and evidence from a small number of fairly well conducted controlled comparisons of different training protocols

Physiological investigations

The fundamental principle of training is that training produces stress on the various physiological systems within the body, such as the cardiovascular system, skeletal muscles and the nervous system, and subsequent adaptive change as the body responds to that stress leads to increased fitness. The past decade has seen an explosion of knowledge about the multitude of biochemical signalling processes that trigger these adaptive changes. In addition to the hormones produced by the major endocrine glands, there are a vast number of other relevant signalling molecules, including the numerous cytokines that regulate inflammation (the cardinal process that mobilises repair in tissues throughout the body) and growth factors that promote changes in many tissues. In particular, growth factors and hormones promote the activation of satellite cells in muscle. These satellite cells are a type of stem cell that fuse with muscle cells to repair and strengthen them.

While this explosion of knowledge does provide useful clues regarding the way the body might react to various forms of training, at present the complexity of the information precludes any simple answer to the high volume v high intensity debate. It does however provide support to both sides, indicating that the best answer will prove to be a combination of the two.

In light of concerns that high intensity training might destroy the aerobic enzymes that catalyse the chemical transformations involved in aerobic metabolism in the mitochondria of muscle cells, it is of particular relevant to note that a series of studies, Gibala and colleagues at McMaster University in Canada have demonstrated that high intensity interval training is as effective as high volume training for developing these aerobic enzymes. Furthermore, Bangsbo and colleagues in Copenhagen reported that speed endurance training consisting of six to twelve 30 second sprints 3-4 times/week for 6 – 9 weeks improved ability to pump the potassium ions back into muscle cells. Potassium ions are expelled from muscle during exercise. The depletion of potassium within the muscle probably plays an important role in fatigue.   Bangsbo demonstrated that the improved ability to pump potassium back into muscle cells was accompanied by an average improvement of 18 seconds in 3 Km race time, and an average improvement of 60 seconds in 10 Km time, in a group of 17 moderately trained male endurance runners


Elite Africans

The most striking feature of elite distance running in the past decade has been the dominance of African runners, mainly from the highlands of Kenya and Ethiopia. There have been many anecdotal accounts that make it clear that high volume training, with several training sessions per day, is an important aspect of the training program of virtually all elite Africans. Usually the day’s program includes one session of quite low intensity running, but many accounts also describe other sessions of quite intense running – especially sustained tempo efforts.  I will not attempt to review all this information here, in part because of its diversity but even more importantly, it remains unclear just how much cultural factors (such as running to school in childhood); multiple genetic factors; and up-bringing at high altitude have contributed to the African dominance.   It remains to be demonstrated convincingly that the training methods employed in Africa can adapted to produce similarly impressive performances by non-Africans.

I will nonetheless draw attention specifically to the training methods adopted by Renato Canova, coach to many of the leading African half-marathoners and marathoners. I have described Canova’s training previously. In his lectures and writing, Canova places little emphasis on low intensity running, perhaps because the athletes he trains have already achieved extensive development of capillaries and other aspects of type 1 fibre development. Nonetheless, the training dairies of the athletes he coaches reveal that in addition to the relatively intense sessions there is a large amount of low intensity running. For example about 80% of the training of Moses Mosop is at an easy pace, with occasional sessions as slow as 5 min/Km (which should be compared with his marathon pace of around 3 min/Km). Canova advocates a periodized approach. The crucial feature of the race specific phase is long runs at near race pace.

Controlled comparisons of training programs

As mentioned above, some of the studies comparing high intensity interval training with standard endurance training, such as the study by Bangsbo and colleagues, demonstrate greater improvement in performances over distances from 3Km to 10Km with the high intensity training, while others, such as those by Gibala and colleagues report similar gains in performance with high intensity training and conventional endurance training, although the high intensity programs achieved similar benefit from a much smaller volume of training. However, those studies were performed over a time scale of approximately 8 weeks. This is scarcely long enough to exclude the possibility that high intensity training might result in a harmful accumulation of stress.

The question of longer term effects was tested in a study by Esteve-Laneo and colleagues from Spain.  They randomly allocated 12 sub-elite distance runners to one of two training programs: a polarised program involving a large amount of low intensity training and small volume of moderate and high intensity training; and a threshold program involving a predominance of training near lactate threshold and a small amount of higher intensity training, for a period of five months. Training was classified in three zones: low intensity below the first ventilatory threshold (VT1) corresponding to the point where lactate rises to around 2 mM/litre; moderate intensity between VT1 and the second ventilatory threshold (VT2) corresponding to the point where lactate exceeds 4 mM/litre; and high intensity, above VT2 during which lactate accumulates rapidly. In the polarised program the proportions of low-, moderate- and high-intensity training were 82%, 10% and 8% while the proportions in the threshold program were 67%, 25% and 8%. At the end of the program, the group allocated to polarised training achieved significantly better performances in a 10.4Km cross country race.

More recently, Stoggl and Sterlich from Austria performed a study comparing a 9 week polarised training program with three other programs: high intensity; high volume (low intensity) and predominantly tempo training, in a sample of national class endurance runners, triathletes, cyclists, and nordic skiiers. The polarized training group exhibited the greatest improvement in VO2 max (+ 11.7%) and time to exhaustion (+17.4%). The high intensity group achieved a 4.8% increase in VO2 max and an 8.8% time to exhaustion 8.8 percent.  The high intensity group lost 3.8% of body weight, which Stoggl and Sterlich attributed to a harmful catabolic state. Improvements were small and insignificant for the other two training programs. It should be noted that these athletes were a national standard and had probably achieved the improvement that might be expected from either a high volume of low intensity training or from a predominance of tempo training.

Neal and colleagues used a cross-over study design in which a group of well-trained cyclists underwent polarised training and threshold training, each for 6 weeks in randomised order. Similar baseline fitness was established by a 4 week de-training period before each training period. The proportion of training time in low-, moderate and high intensity zones was 80%, 0%, 20% in the polarised program, and 57%, 43% and 0% in the threshold program.The polarised training produced greater increases in peak power output, lactate threshold and high-intensity exercise capacity (time to exhaustion at 95% maximum work rate).


Summary and Conclusions

Stephen Seiler, a Texan sports scientist based in Norway for the past decade, presented a summary of the evidence from the controlled comparisons of different training programs and also from studies that have examined the proportions of training time that elite athletes spend in different intensity zones, at a lecture delivered in Paris in October 2013. He provided a compelling argument for polarised training. However, despite the evidence that many elites follow a polarised program, the role of key sessions at a pace near to race pace in the training recommended by Renato Canova indicates that at least a modest proportion of threshold training is beneficial for marathoners. Furthermore, Canova recommends a moderate degree of periodization with a clearly defined period of specific preparation for key races.

Overall, it is likely that any sensible training program will produce benefit for an unfit athlete provided it is consistent. However for an athlete who has achieved a plateau of fitness, it is probable that a polarised program with proportions of low-, moderate- and high-intensity of approximately 80%, 10%, 10% is most effective. Nonetheless, during a period of preparation for a specific race the key sessions should incorporate running at a pace near to race pace.


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