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 to be 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 and 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 extremely 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 0f 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 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 Kenesia 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 due to 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 2:9:12 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 precisely organized 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 Gebreselassie manages to eclipse this time before his 42nd birthday next April, Foster’s achievement 40 years ago is truly remarkable.

Conclusion

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, ‘the distance is more important than the speed. 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

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.

 

Conclusion

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.

 Conclusions

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

Arrhythmia

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.

Marathon

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

 

Ultra-marathon

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.

 

Synthesis

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.

The big debates of the past decade: 2) shoe design

February 24, 2014

For almost a decade many runners have been captivated by the issue of running shoe design – a preoccupation fuelled two opposing factors.  On the one hand padding is expected to provide protection and in particular, provides shock absorption attenuating the impact of foot-strike.  On the other hand, there is the allure of the idealistic notion of barefoot running – based at least partially on the rational argument that if our distant ancestors survived by persistence hunting, the human frame must be well adapted to barefooted running.   These opposing influences have led to fluctuating enthusiasm for fashions ranging from barefoot (or minimalist shoes such as the Vibram Five Fingers) to the heavily padded Hoka one-one.

In addition to these two opposing influences there is the issue of the effects, either helpful or harmful, that shoes might have on the twisting movements that occur at the joints of foot and leg. Most notable are the compound motion of pronation occurring at the forefoot and ankle that allows the foot to roll inwards transferring weight onto the medial longitudinal arch as the leg is loaded during stance; and the inwards bend of the leg below the knee (varus deformation) that places pressure on the vulnerable medial aspect of the loaded knee joint while also dragging the ilio-tibial band towards the lateral femoral condyle.  Although pronation is a natural movement, shoe companies have placed strong emphasis on the potential dangers of over-pronation.  To prevent this, they have marketed motion control shoes with a medial post, a structure embedded in the medial side of the shoe that arrests the inward roll.  This affects not only the impact absorbing capacity of the foot, but also modifying the varus torque acting at the knee.

Ethics

The question of high technology shoe design also brings with it the issue of the ethics of unfair technical enhancement of natural ability.   While this ethical issue can only be dismissed entirely by adopting barefoot running, it might be argued that in the modern man-made environment, denying at least a modest degree of protection would be unreasonable.  In principle there is a difference between basic protection and the overt assistance provided by embedded springs such as in the Spira.  However, once any layer of fabric is interposed between foot and ground, there is a continuum of assistance provided depending on the elastic properties of the material.   Nonetheless, most runners accept that the assistance provided by the bulk properties of a compressible material primarily designed for protection against either shock or penetrating injury is reasonable.

Cadence and foot-strike

The protective effect of shoes is clearly demonstrated by two automatic responses seen in most habitually shod runners when they change to barefoot running.  Self-selected cadence increases leading to decreased length of airborne time during each gait cycle, thereby decreasing the magnitude of the vertical force required to get airborne.   Furthermore, as discussed in my recent post on style, foot-strike tends to change.  The investigation led by Daniel Lieberman of Harvard University indicates that barefoot runners are more likely to adopt a mid-foot or forefoot strike rather than the rear foot strike typically seen in about 75% of shod runners.  This change in foot strike abolished the potentially harmful sharp rise in vertical ground reaction force that is generated by heel striking.  Nonetheless, it is noteworthy that avoidance of rear foot strike is not necessarily the case in habitual barefoot runners.  For example the study of north Kenyan habitual barefoot runners by Hatala found that 72% were heel strikers at their self-selected endurance pace, though the majority landed on mid or forefoot when sprinting, when vertical forces are greater.

As discussed in the post on style, there is little evidence that fore-foot strike is more metabolically efficient whereas several studies actually show rear-foot strike is most efficient at low speeds.  The situation with regard to risk of injury is mixed, with greater risk to knee with heel strike and greater risk to structures around the ankle with forefoot strike.  The balance of risks favours a mid-foot strike. Therefore, a shoe style that allows this is preferable.

Joint torques

Kerrigan and colleagues reported that the torques acting at ankle, knee and hip occurring in runners wearing Brooks Adrenaline shoes were increased in comparison with barefoot running.  The Adrenaline is described as a neutral shoe, meaning that it is not designed to strongly inhibit pronation, and has midsole thickness ranging for 24 mm at the heel to 12 mm at the front.  The increases in torque when shod were especially marked for knee varus (increased by 38%); knee flexion (36%) and hip internal rotation (54%) around mid-stance.   Only a minor portion of these increases in torque could be accounted for by the lower cadence of the shod runners.

Knee varus places stress on medial aspect of knee joint at a site especially prone to osteo-arthritis.  It also drags the ilio-tibial band towards the lateral femoral condyle increasing the risk of iliotibal band syndrome.  Knee flexion torque flexion places stress on patella-femoral  joint and increases load on patella tendon and quads.  It should be noted that tension in the patella tendon at mid-stance  is not necessarily bad, as it would be expected to increase the eccentric loading of the quads and facilitate the upward drive of the body that occurs after mid-stance.   Similarly a moderate degree of internal rotation of the hip is required as the pelvis rotates around the hip joint during stance, so a torque promoting internal rotation torque is not necessarily bad, though it is noteworthy that some runners do develop osteo arthritis of the hip.

The heel-toe drop

Elevation of the heel relative to the toe is the most likely explanation for the additional knee flexion torque revealed in Kerrigan’s study of joint torque at the joints. Furthermore despite providing padding, the presence of a bulky heel makes it difficult to avoid localized impact at the heel, and thereby make a substantial contribution in the rapidly rising spike of vertical ground reaction force observed in heel strikers.  As shown by Zadpoor, a rapid of rise of vertical force increases risk of injures such as tibial stress fracture.  Thus, it would appear that shoes with minimal or no drop from heel to toe that allows initial contact further forwards might  be safer, and will tend to be lighter.

An interesting alternative is the Healus, a shoe without a heel.  A slanted sole ensures that the runner avoids heel contact but instead makes contact via a well-padded mid foot.   Force plate data demonstrates that it abolishes the initial spike in vertical ground reaction force.  The padding under midfoot provides maximum protection when vertical ground reaction force is at its peak.  However, despite an endorsement by former European 5,000m record holder Dave Moorcroft , it does not appear to have achieved much popularity, possibly because it is produced by a small company.

Ankle and forefoot motion control

The inward rolling of the foot that occurs with excessive pronation has several potentially adverse consequences.  The ankle tends to be displaced towards the midline thereby increasing varus deformation at the knee, enhancing risk of iliotibial band syndrome and perhaps also osteo arthritis of the medial aspect of the knee joint.   The medial longitudinal arch of the foot is flattened increasing tension in the plantar fascia increasing risk of plantar fasciitis.  Thus, in runners with excessive pronation, a shoe with a medial post that limits pronation might be beneficial.  However it should be noted that Kerrigan observed increased knee varus torque in shod runners relative to barefoot.  The Brooks Adrenaline is a neutral shoe but nonetheless has a modest medial post and hence it might appear surprising that there was increased knee varus torque.  However the shoe had not been matched to the specific needs of individuals.  It is plausible that the one consequence of being shod was that individuals lacked the sensation and freedom of movement within the shoe required to produce optimal adjustment of the motion at the ankle according to their individual needs.   It might be argued that at least for non-injured runners, that light weight shoes or bare feet providing the freedom to adapt the ankle and foot motion according to individual needs and changing surface conditions, would be preferable.

Nonetheless, there is evidence that customised orthotics designed specifically to control ankle motion for each individual can reduce pain in runners with an established problem.  For example, Maclean and colleagues studied the effects of 6 weeks use of customised orthotics in a group of female recreational runners (15 to 40 km per week) who had a history of overuse running knee injury in the 6 months leading up to the study. The intervention decreased pain significantly and led to significant decreases in maxima for ankle inversion moment and angular impulse during the loading phase, impact peak, and vertical loading rate, though the effects at the knee were complex

Efficiency

Because the shoe is at the far end of the swinging leg, its mass makes a relatively large contribution to energy cost of repositioning the leg during the swing phase.   However, there is growing evidence that at least a small amount of padding brings a benefit that compensates for the additional weight.  Franz and colleagues from Roger Kram’s lab in Colorado compared oxygen consumption during running barefoot with that when wearing lightweight cushioned shoes (approximately 150 gm per shoe) in 12 runners with substantial barefoot  experience, running  with midfoot strike on a treadmill.  In additional trials to determine the effect added weight, they attached small lead strips to each foot/shoe (150, 300, and 450 g).   They found that in the absence of added weight there was no significant difference between shod and unshod running.  Adding weight led to an increased metabolic cost of 1% for each 100 gm of added weight.  When adjusting to equalise mass in shod and unshod condition, shod running had ∼3%-4% lower metabolic cost.

In a further experiment for the same lab, Tung and colleagues measured the metabolic costs of  barefoot running  on an unpadded treadmill and after adding strips of padding of either 10mm or 20 mm thickness to the surface of the treadmill.  They also measured the costs of running shod in lightweight shoes on the unpadded treadmill.  They found that when running barefoot, 10 mm of foam cushioning (approximately the thickness of the forefoot shoe midsole) afforded a benefit of 1.91%.   There was no significant difference between metabolic costs of shod and unshod running on the unpadded treadmill, indicating that the positive effect of shoe cushioning counteracts the negative effects of added mass.

Thus, running barefoot offers no metabolic advantage over running in lightweight, cushioned shoes. The explanation for this remains speculative.  One possible explanation is that when running barefoot, a runner maintains a lesser degree of stiffness in the legs, resulting in less efficient capture of impact energy as elastic energy, in the same manner as a floppy spring produced a less efficient recoil that a stiff spring.

While light weight shoes might offer adequate protection in short and medium distance events, it is necessary to consider the possibility that in a marathon or ultra-marathon, the cumulative damage from repeated eccentric contraction will result in a significant loss of power.  A little more padding might protect against this loss of power.    Similar issues apply during periods of high volume training.  Last summer, while training for a half-marathon, I built up my total training load to a substantially higher volume than during any recent year and found that I suffered a gradual accumulation of aches in my legs.  Hence, at least for an elderly person, light weight shoes should be employed sparingly, but nonetheless, frequently enough to produce the adaptive changes required if they are to be used for racing.

Conclusion

My overall conclusion is that for racing distance up to half a marathon, light weight shoes with near zero drop from heel to toe are preferable, as these give the optimum combination of efficiency and protection.  Unless the legs have been very well conditioned to the rigours of long races, for the marathon and ultra-marathons it might be preferable to use a little more padding.  Similarly, during periods of very high volume training, a modest amount of additional padding might provide helpful additional protection.  Motion control is only sensible if there is a clear need

The big debates of the past decade: 1) Running style

February 17, 2014

In those distant days when I was a fairly serious athlete, we did not think much about style.  Emil Zatopek’s three gold medals in Helsinki a few years previously had suggested that training mattered far more than style.   The ungainly tension in his neck and shoulders was an irrelevancy. We were much more interested in the word-of-mouth rumours of his prodigious training sessions.  At the time, we debated the merits of Percy Cerutty’s advocacy of running up sand-hills in contrast to Arthur Lydiard’s advocacy of 100+ miles per week.  Neither style nor injuries were a major preoccupation.

In contrast, during the past decade, running style has become a focus of attention among elite and recreational athletes.  The focus of the elites is illustrated by Alberto Salazar’s efforts to improve Mo Farah’s efficiency prior to his attempt at the London marathon this year. But perhaps even more importantly, style has been a focus of attention of recreational runners concerned about repeated injury.

A decade ago, distance running had blossomed into a mass participation sport and injuries were rife. Marketing of running shoes had become a major commercial enterprise.   The running world was primed to embrace the idea that running no longer came naturally to modern man.  Was it a consequence of wearing shoes all day or sitting for hours at a desk?  Maybe even it was the training shoes that large commercial companies encouraged us to buy.

The time was ripe for the emergence of gurus with messages about how to run naturally.  Techniques such as Pose and Chi became popular.  These techniques were embraced with almost religious fervour and many of the disciples found relief from their recurrent injuries.  Unfortunately other novices came away from their flirtation with these techniques with new injuries, especially problems with the Achilles tendon.  Now, a decade or so later, the reasons for these contrasting experiences are fairly easy to identify.   Although a few important issues about running style remain unresolved, the decade of experience and of research has provide fairly clear answers to the major questions.

Natural running: forefoot or heel strike?

One of the most hotly debated issues has been the question of heel striking versus fore foot striking.   In part, this debate arose from an idealistic quest to identify mankind’s natural running style, unsullied by the influence of modern life styles.  I will focus predominantly on Pose because its strengths and weaknesses are fairly well documented in books, research papers and on the Pose Tech website.  The second chapter of ‘Pose Method of Running’ (Pose Tech Corp, 2002) opens with an examination of images of runners on classical Greek pottery.  One of the images is from an amphora depicting runners at the panthenaic games in 530 BC.   The inventor of Pose, Nicholas Romanov writes:  ‘Look at these drawings and you will see quite clearly that all the athletes run on the front part of the foot without landing on the heel.  As barefoot runners this was the obvious technique for efficiency and to avoid injury.  To my mind this barefoot running style of landing on the forefoot is the purest example of the proper nature of running….As the Golden Age of Greece passed mankind appeared to leave these values far behind’.

Fig 1: Runners at the panathenaic games 530 BC .   These athletes were competitors in the stadion, a sprint over a single length of the track (over 200 meters).   Terracotta Panathenaic prize amphora, attributed to the Euphiletos Painter.  Copyright, The Metropolitan Museum of Art,  www.metmuseum.org

Fig 1: Runners at the panathenaic games 530 BC . These athletes were competitors in the stadion, a sprint over a single length of the track (over 200 meters). Terracotta Panathenaic prize amphora, attributed to the Euphiletos Painter. Copyright, The Metropolitan Museum of Art, http://www.metmuseum.org

The appeal to a golden age of classical Greece subsequently received some support from rigorous science.   Based on evidence that  our distant ancestors living on the African Savanah around 2 million years ago were probably persistence hunters who relied on the their capacity to chase their prey to exhaustion, Daniel Lieberman and colleagues at Harvard University examined the foot strike pattern of barefoot runners in comparison with runners wearing modern running shoes.  He found that barefoot runners tended to land on the forefoot or midfoot whereas runners wearing shoes tended to be heel strikers.  The heel strikers experienced a more rapid rise in the loading of the legs in early stance, although Lieberman was careful to avoid claiming at that stage that fore-foot striking would result in a lower injury rate.

Further investigation casts some doubt on the conclusion that habitual barefoot runners are not heel strikers.  A study of habitual barefoot runners from north Kenya by Hatala and colleagues did provide further evidence that forefoot strike reduces the magnitude of impact loading.  However, these habitually barefoot Kenyan runners tended to land on midfoot or forefoot only when running at sprinting speed, where impact loading is high.  The majority of them landed on the heel at endurance running speeds (5 m/sec or less).  At their preferred endurance speed (average of 3.3 m/sec) 72% were heel strikers.  Could it be that heel striking is actually more efficient at endurance paces?

Is heel striking more efficient at endurance paces?

Ogueta and colleagues from Spain compared efficiency in two well matched groups of sub-elite distance runners and found that heel strikers are more efficient than midfoot strikers, across a range of speeds.  Heel  strikers were 5.4%,, 9.3% and 5.0% more economical than mid-foot strikers at speeds of 11, 13 and 15 km/h respectively. The difference was statistically significant at 11 and 13 km/hr, but only showed a trend towards significance at 15 Km/hr.  DiMichele and Merni from Italy, who tested runners only at a single speed of 14 Km/hour, found no significant difference in efficiency between sub-elite heel strikers and mid foot strikers.  Overall, the evidence suggests that at paces typical of recreational endurance running, heel striking is more efficient but the advantage diminishes as pace increases.  This is consistent with the observation that in most runners the point of contact at footfall moves forward along the sole of the foot as speed increases.

These studies were cross sectional studies comparing different runners.   Indirect evidence of the effect of a change to forefoot landing within an individual is provided by the longitudinal study by Dallam and colleagues of 8 athletes who changed to Pose.  They found that 12 weeks after changing to Pose, the athletes were on average of 7.6 percent less efficient than before the change.    Perhaps 12 weeks is not long enough to achieve facility with a new style, but the consistency of the magnitude of the penalty associated with forefoot/midfoot striking in the study by Ogueta and the penalty attributable to Pose in the study by Dallam adds weight to the conclusion that heel-striking is more efficient at endurance paces.

With regard to risk of injury, the evidence is more complex.  In a retrospective study of US collegiate distance runners, Daoud and colleagues found that habitually rear-foot strike had approximately twice the rate of repetitive stress injuries than individuals who habitually landed on the forefoot. Traumatic injury rates were not significantly different between the two groups.    The sharp initial rise of ground reaction force observed with heel strikers is a likely factor in the risk of injures such as tibial stress fracture.  It is noteworthy that during  a session that included a total of approximately an hour of running at lactate threshold pace, Clansey and colleagues found that several kinematic variables, including rate of rise of ground reaction force in early stance, increased significantly, suggesting an increased risk of stress fracture with increasing fatigue.

However, mid-foot and forefoot strike have their own risks, especially for the muscles and connective tissues acting at the ankle, as indicated by the Capetown study of Pose.  Consistent with this, Almonroaeder and colleagues found a 15% greater load (averaged over stance) and an 11% greater rate of rise of tension in the Achilles tendon in mid-foot and forefoot strikers compared with heel-strikers.

Should the push be conscious?

One of the features that appears to account for some of the success of Pose in reducing injury rates among its dedicated disciples is the avoidance of a conscious push against the ground.   In reality, force plate data clearly demonstrates that runners do push against the ground, with peak vertical forces often exceeding three times body weight.  A study by Weyand and colleagues demonstrates that faster runners push harder against the ground.   Many elite sprinters, including Usain Bolt, report that they do consciously push.   However, my own speculation is that for recreational distance runners, a conscious push can be harmful if it encourages a delay on stance, and an associated increase in braking.  Paradoxically, since the delay decreases airborne time, a lesser vertical push is required to maintain the airborne phase, but a greater horizontal push is required to overcome braking.   Excessive horizontal push is potentially harmful, as we will discuss in the section on risks of braking, below.

Perhaps serendipitously, Pose discourages this potentially harmful conscious push by investing faith in the illusion of gravitational free energy.  According to Nicholas Romanov, one of the most important principles of Pose is the ‘Do Nothing Concept’ which he describes on pages 88 and  89 of Pose Method of Running:   ‘We must learn to get out of the way and let gravity propel us forward while we preserve as much of our energy as possible by the simple act of picking our feet off the ground.’

In the words of Romanov and Fletcher: ‘Runners do not push off the ground but fall forwards via a gravitational torque’.  Pose theory draws on the observation that pivoting forwards is an effective way to initiate the action of running to explain how gravitational free energy can allegedly be harnessed even during running at a steady speed. The theory proposes that this can be achieved by employing the sequence of Pose, Fall, Pull, in the period from mid-stance to lift-off.  Romanov’s description of the Pose does in fact match the balance posture of many good runners at mid-stance: knees and hips are slightly flexed while the hips and shoulders are aligned over the point of support through which force is transmitted from foot to ground.  However, the Fall, which Romanov claims provides gravitational free energy, simply does not occur.

The body’s mass rises rather than falls in the second half of stance. This is clearly predicted by computation based on the time course of ground reaction forces, and also clearly apparent from video clips.  The Pose Tech website claims that Usain Bolt employs Pose style, yet examination of the stills from the video of Bolt winning the 100m World Championship in Berlin in 2009 depicted on the PoseTech site, indicates that his hips and torso  rise about 7 cm between mid-stance and lift-off.   The origin of Romanov’s erroneous concept of the fall is revealed in fig 7 from his paper published with Graham Fletcher in Sports Biomechanics in 2007.  In that figure, the authors mistakenly assume that the vertical component of ground reaction force is equal to body weight whereas force plate data show that is several times body weight at mid-stance. I discussed this issue in greater detail in my post of  14 Feb 2010.   And finally, it no is more possible to get airborne by pulling the foot towards the hips than it is to self-elevate by pulling on one’s boot straps.

However, despite being based on fallacious theory, Pose does offer some benefits to at least some recreational runners.  The discouragement of harmful excessive  conscious pushing is balanced by focus on drills such as Change of Stance that help develop the neuromuscular coordination required to get off stance quickly.   However, a greater vertical push would be required to maintain the longer airborne time if stance time were to be decreased at constant cadence.  Pose technique averts this problem by encouraging increased cadence.   For recreational runners who tend to spend too long on stance and to run with cadence that is too low, Pose can be helpful.   However, short stance and high cadence each create their own problems.   A rational approach to the challenge of identifying the optimum foot-strike , duration of stance and cadence for an individual runner under particular circumstances requires an understanding of the benefits and risk associated with the three major  energy costs of running: overcoming braking while on stance; getting airborne; and repositioning the swinging leg during the airborne phase.

Balancing the three main costs

It is clear that efficient running requires a trade-off between the three major energy costs of running: getting airborne, overcoming braking and repositioning the limbs.  We can minimise the energy cost of braking by getting off stance quickly, but that creates a demand for greater energy expenditure to maintain a longer airborne phase, unless cadence is increased.  However, as described in my post of April 2012, increased cadence demands more energy expenditure to reposition the swinging leg, so we need to find a compromise that minimses total cost.  The optimum balance between the three costs  depends on pace and other circumstances, such as level of fatigue.   We also need to take account of the need to minimise injury.

Risks of getting airborne

Getting airborne demands a strong push against the ground.  It appears at first sight plausible that the stronger the push the greater the risk of injury. Surprisingly, studies that compare injury rates between individuals who differ in the magnitude of the vertical push they exert against the ground do not consistently find a significant association with injury rate.  This might well be because the strength that allows faster runners to push more strongly also helps protect them against injury.  Thus comparison between different runners might obscure a relationship between intensity of push and injury risk for an individual.

Some studies, reviewed by Zadpoor, do demonstrate an association between rate of rise of the vertical forces and risk of injures such as tibial stress fracture.  Rate of rise of force is related to both duration over which the force rises to a peak (determined largely by the type of foot-strike, with heel striking creating a steeper rise), and also by the magnitude of the average force (which is inversely proportional to the fraction of the gait cycle spent on stance).  Thus it is likely that at high speeds a strong push combined with mid or forefoot landing produces optimum efficiency and safety, though forefoot landing is only safe if the Achilles is well enough conditioned to take the strain.  For most runners it is probably safer to ensure that at least some of the load is taken on the heel in longer races.  At slower speeds, efficiency is greater with heel striking, and the risk of injury depends on whether the individual is more prone to adverse effects of stress at the knee or the ankle.  Stress on the knee is greater with heel-strike, but greater at the ankle with forefoot strike, as demonstrated in the Capetown study of Pose.

It should also be noted that precise timing of the vertical push is crucial.  For many runners, attempting to control the push consciously is counter-productive.   In contrast, most of us are capable of much more precise timing of hand movements.  Arm and leg on the opposite side are linked in their representation in the brain, and also, more tangibly, by the latissimus dorsi muscle and lumbar-sacral fascia that link the upper arm to the pelvis on the opposite side.  Therefore, conscious focus on a sharp down and backward movement of the arm can help ensure precise timing of the push by the opposite leg.  This sharp downswing of the arm should be accompanied by conscious relaxation of the shoulders.   I personally find this strategy more helpful than the cultivating an illusion of falling after mid-stance

Risks of braking

Braking generates both compression forces and shear forces at joints, and also increases stress on hip extensors which must overcome the excessive hip flexion associated with the forward angle of the leg at foot-strike.   One possible consequence is pain at the point of attachment of the hamstrings to the pelvis.   Therefore from the injury perspective excessive braking must be avoided but it is necessary to bear in mind that there is a trade off between the low braking costs of short time on stance and the costs of being airborne for a greater propotion of the gait cycle.  If excessive braking is to be avoided, it is crucial to avoid reaching forwards with the swinging leg, and ensure that the foot lands only a short distance in front of the centre of mass.  The jarring associated with braking can be reduced by ensuring that the knee is flexed slightly more than the hip at foot-strike, but the penalty is a loss of rigidity of the leg which might reduce the efficiency of the capture of elastic energy.  As discussed above there is a trade-off between braking and getting airborne.  Excessive braking demands excessive horizontal push after mid-stance, and an inevitable increase in total stance time.  For a runner prone to spend too long on stance focus on a precise push off, governed by conscious down-swing of the opposite arm can promote a good balance between the cost of braking and the costs of getting airborne.

Repositioning cost and cadence

The third element, leg repositioning cost, increases with increasing cadence, but conversely, the energy cost of getting airborne decreases with increasing cadence.  The  stresses on the tissues of the body associated with getting airborne, and therefore, the likely risk of injury, decrease with increasing cadence.    Therefore, many runners, both recreational runners and even some elites, including Mo Farah, might benefit from increasing their cadence, but not so far that the increased energy cost of repositioning become excessive.  The optimum cadence depends on various circumstances.  Based on observation of elite runners and the calculations presented in my blog posts in Feb and March 2012 suggest that optimum cadence is at least 180 steps/min at  4 m/sec, and  200 steps/min at 5.5 m/sec.   However the precise optimum for each individual will depend on leg strength and elasticity.  For runners with lesser power  and elasticity it is probably best to employ higher cadence, thereby reducing the need for vertical push.   As my leg muscle power and elasticity have deteriorated with age, I have been forced to increase cadence.  Typically my cadence is around 200 even at a pace of 4 m/sec.  This involuntary increase in cadence has helped minimise the risk of damage to my elderly legs, at the price of inefficient expenditure of energy on repositioning my swinging leg.  I am therefore working on increasing power and elasticity so that I can push off more powerfully and thereby decrease cadence safely.

Conclusion

Perhaps the most serious error promulgated by gurus is the claim that there is a single best style that is most efficient and safest.  The evidence regarding the greater efficiency of heel-striking at endurance paces, yet greater risk of at least some repetitive strain injuries with heel strike illustrates the fallacy of this claim.  The most efficient foot strike pattern, time on stance and cadence vary with pace, and in addition, the risk of injury depends on factors that vary between individuals, such as strength of muscles, tendons, ligament and bones.  Perhaps the most important strategy of all for minimising injury is building-up of training load slowly over time, and being aware of the effects of fatigue on form during demanding sessions.

Running style does play a crucial role but a much more nuanced approach based on an understanding of the costs and benefits of each aspect of form must be taken to identify what is best for each individual in their current circumstances.   The debate and the scientific studies of the past decade have indeed provided us with much information to make these nuanced judgments.

The five big debates of the past 10 years

February 6, 2014

The past decade has seen a continued growth of distance running as a mass participation sport.   The major city marathons continue to attract many thousands of entrants with aspirations ranging from sub 2:30 to simply completing the distance in whatever time it takes.  Perhaps more dramatically, parkrun has grown from a local weekly gathering of a few club runners in south-west London to an event that attracts many tens of thousands of individuals at hundreds of local parks, not only in the UK but world-wide, on Saturday mornings to run 5Km in times ranging from 15 min to 45 min before getting on with their usual weekend activities. Over this same period, the ubiquity of internet communication has allowed the exchange of ideas about running in a manner unimaginable in the days when distance running was a minority sport pursued by small numbers of wiry, tough-minded individuals whose main access to training lore was word- of-mouth communication.

Not surprisingly, within this hugely expanded and diverse but inter-connected community there have been lively debates about many aspects of running, with diverse gurus proposing answers to the challenges of avoiding injury and getting fit enough to achieve one’s goals.   Pendulums have swung wildly between extremes.  My impression is that the fire in most of the debates has lost much of its heat as the claims of gurus have been scrutinised in the light of evidence.   However, definitive answers have remained elusive.   What have we learned that us useful from this turbulent ten years?

There have been 5 major topics of debate:

1) Does running style matter and if so, is there a style that minimises risk of injury while maximising efficiency?

2) Are minimalist running shoes preferable to the heavily engineered shoes promoted by the major companies?

3) What is the optimal balance between high volume and high intensity training in producing fitness for distance running?

4) Is a paleo-diet preferable to a high carbohydrate diet?

5) Does a large amount of distance running actually damage health, and in particular, does it increase the risk of heart disease.

In all five topics, debate still simmers.  I have scrutinised the scientific evidence related to all five of these question in my blog over the past seven years, and I hope I will still be examining interesting fresh evidence for many years to come.   However whatever answers might emerge from future science, in our quest to determine the answers that will help us reach out running goals we are each an experiment of one and now is the point in time when we must act. I think that the evidence that has emerged in the past decade has allowed me to make better-informed choices in all five of these areas of debate than would have been possible ten years ago.   In my next few posts, I will summarise what I consider to be the clear conclusions for the past decade of debate, what issue remain uncertain, and what decisions I have made with regard to my own training and racing.

For me personally, the greatest challenge as I approach my eighth decade is minimising the rate of inexorable deterioration of muscle power, cardiac output and neuro-muscular coordination that age brings.  Therefore my approach to these debates is coloured by the added complications of aging.  Nonetheless, my goal is not only to continue to run for as many  years as possible, but also to perform at the highest level my aging body will allow during these years.  I hope that the conclusions I have reached will be of interest to any runner aiming in to achieve their best possible performance, whatever their age.


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