The sweet spot

In a comment on my blog in October 2009, Ewen pointed out the contrast between the training of two Kenyans marathoners, Robert Cheruiyot and Sam Wanjiru.  Cheruiyot runs 280Km per week, mostly in 15Km runs at a pace about 1 ½  min per mile slower than his marathon pace, while Sam Wanjiru runs 140 km per week with a much larger proportion of high intensity sessions.  Both have run marathons in around 2:06. The re-assuring conclusion is that both low intensity, high volume programs and high intensity low volume programs can work.  Does it matter which type of program an individual adopts? 

There are clearly pragmatic factors, such as the time a runner has for training each week   For the time being, I can afford to spend  4-5 hours per week training and that rules out a high volume program.  It is probable that physiological factors, especially the proportion of slow twitch (type 1) fibres  in your leg muscles, also affects which option that will work best for you.  In my case, I am fairly sure I have a preponderance of slow twitch fibres, which might indicate that a low intensity, high volume program would play to my strengths.  On the other hand, it might also be argued that as my fast twitch fibres deteriorate with age, I would be ill-advised to ignore them.  

However, I suspect that the most important determinant of success in a training program is adjusting load and intensity to hit the sweet spot, where the amount of stress on the body is sufficient to promote fitness, but a little short of the level that leads to over-training, injury and eventually to ill-health.   

Two recent happening have focused my attention again on the sweet spot.  First, was another comment from Ewen: a reminder of the spectacular achievements of Ed Whitlock, who has assembled an incredible collection of world records during his seventies, based largely on running fairly slowly for three hours per day.   Typically he covers around 200 Km per week mostly running at a pace1-2 minutes per mile slower than his marathon pace, on a 1/3 mile loop in a cemetery near his house on the outskirts of Toronto.  The other was an event in the life of a young woman, whom for present purposes I will refer to as Marie [1], who had contacted me a little over a year ago in response to one of my postings regarding training on the elliptical cross-trainer.  It transpired that Marie and I shared an approach to running that included a delight in running through bluebell woods as much as setting race goals.  Over the past year we have discussed running and training fairly regularly via email though we have never actually met.  I will return to Marie’s story shortly, but first, let us look at some of the features of Ed Whitlock’s training.

Ed Whitlock

Ed Whitlock holds 13 age-group world records for distances ranging from 1 mile to the marathon.   His records include the phenomenal marathon record of 2:54:48 for the 70-74 age-group; and the record of 3:04:58 for the 75-79 age-group.  On the LetsRun forum in April 2009  he confirmed that when he established the 70-74 world record in 2003 that the major component of his training was daily three hour runs at a low intensity.  He wrote:

‘I ran my “2:54” at age 73 in 2004 off an extended base of daily 3 hour slow runs. ……I started extending the duration of my daily runs in my mid 60’s gradually increasing to the occasional 3 hour run by the time I was 70. I always try to increase “mileage” slowly and not make sudden leaps.’  [2]

Further details of his program and some interesting insights into his approach to training are provided in two very interesting interviews: one by  Pete McGill in March 2008 for the Younger Legs for Older Runners website [3], and the other by Scott Douglas, in March 2010 for Running Times [4]

He comes across as a man with an ironic sense of humor who takes impish delight in portraying himself in a curmudgeonly manner.  He emphasizes that he does not run for pleasure, but simply because he wants to break records.  He has no interest in running on woodland trails or pleasant countryside.  He chooses to train in a cemetery for purely pragmatic reasons: it is near to home, free of traffic and during a 1/3 mile loop he does not face long periods battling a head wind.  In fact it appears that he carefully avoids anything that might be acutely stressful. He avoids the one stretch of the path where there an appreciable hill. 

What is the key to his success?

It is clear that Ed Whitlock is naturally gifted.  As a school boy, he beat Gordon Pirie in a cross-country race, but in subsequent years, Pirie’s massive training volume propelled him to a series of dramatic 5000m and 10,000m duels with Vladimir Kuts in 1956, and to a world record in the 3,000m.  Meanwhile Whitlock stopped running for a period of over  15 years before resuming training again in his forties.   In his late forties he achieved his marathon personal best of 2:31:23  Thus he was endowed with a moderate natural talent for running, but it appears to be the high volume, low intensity training that transformed him into one of the most phenomenal veteran distance runners ever.

It is not clear to me what are the most important physiological changes produced by long slow runs.  Dudley’s studies of rats suggest there is little further increase in oxidative capacity of type 1 fibres (assessed by measuring cytochrome oxidase ) after  30-40 minutes of low intensity running [4].  Very long runs might be expected to increase in capacity to store glycogen and also to metabolise fats – but that doesn’t account for Whitlock’s achievement over shorter distances.   It would seem logical to assume that once the type 1 fibres are exhausted, the type 2A fibres are recruited, but Dudley’s data do not provide much evidence for that.  Maybe Dudley did not keep his rats running for long enough at low intensities to fully exhaust the type 1 fibres – or maybe humans are different from rats.

But I suspect the key to understanding Whitlock’s success is the steady build up over many years while subjecting himself to minimal acute stress.  His avoidance of hills and troublesome head winds suggests that he was not driven by any sense of necessity to subject his body to harsh discipline, but rather he worked in harmony with his body, gradually increasing the daily distance as he felt able to cope with it.  In other words, I suspect that he continually made gradual adjustments to his training to keep himself near at the ‘sweet spot.’ – the level of training load adequate to provide continual stimulus to improve while avoiding overtraining and risk of injury.  Though it should also be noted that in the midst of his low intensity training he did race fairly frequently.    

There were probably times when Whitlock did pass beyond the sweet spot.  When he ran the Columbus marathon in 2:52:47 in 2000, only months before his 70th birthday, it seemed that the target of setting a 70-74 age group record under 3 hours was easily within reach, but problems with arthritis in his knee, perhaps only partially related to his running, stopped him achieving that target for over two years.  Nonetheless, the striking characteristic of his attitude towards training over the years has been a sense of harmony with his body rather than subjugation, despite the fact that his primary motivation has been the pursuit of records. 



Marie is also a dedicated runner and is undoubtedly in the elite class when it comes to enjoyment of running, but her goals are somewhat different from those of Ed Whitlock.  When she first contacted me to ask about elliptical cross training, she was recovering from an injury to the peroneus longus tendon, and she stated that her primary goal for 2009 was to enjoy running in the English countryside.  We shared anecdotes about the wildflowers, birds and other wildlife that we each encountered during our running, but from the seriousness of her approach to the issue of elliptical cross training, it was fairly clear that she also had her eyes on an additional goal for 2010.  I was not completely surprised when some months later she announced that she and her husband had been successful in the lottery for places in the London marathon in April 2010.  We discussed, via email, her proposed marathon training plan in which the key feature was a series of races of increasing distance.  It seemed to me a sensible plan, though she had included what appeared to be just one too many demanding races in the schedule for February. 

Although I have described her as young woman on account of the freshness of her spirit, she is in fact of an age where natural anabolic processes start to slow down, and recovering fitness after injury tends to be a slow process.    So I was not that surprised that she found increasing the distance of her long runs according to plan to be quite demanding.  Nonetheless, she managed the program almost perfectly.  Most of her runs were at a pace more than a minute per mile slower than I considered she would be capable of in the marathon.  She dropped the excessive race from the schedule for February, but otherwise she stuck to the plan almost exactly.   It seemed to me she was keeping her training load right at the sweet spot.  For a brief period in early March she became a little worried that she was not going to get the planned 20 mile runs done in time, and for a couple of weeks she was inclined to push herself a little too hard, but after a review of the situation, she got back in a good rhythm.  She completed the 20 milers according to plan, and was by this stage finding it easy to maintain a pace faster than planned marathon pace in her shorter runs, despite the fact that most of her earlier training at been a much slower pace.

Two weeks ago, she mentioned that she had been a little distracted that week because she had discovered a suspicious lump and had had a biopsy.  Nonetheless, her training log for the following few days showed that she was feeling exhilarated running at marathon pace over fairly short distances, as she began the taper.  I was reassured, but nonetheless woke up in the night worrying about her several times during that week, and had to remind myself that there wasn’t really much reason to worry.  Then a week ago she sent an email saying that the biopsy had proven positive.  She has cancer and is scheduled for surgery at the beginning of May.   

While I was fairly confident that Marie would develop a strategy for maintaining her equilibrium during the uncertain times ahead, I thought it unlikely that the marathon would be high on her list of priorities.  However I had under estimated her spirit.  Despite the myriad questions regarding the tumour and the operation that must have crowded into her mind during the meeting with her surgeon, she asked whether or not it would still be OK to run the marathon about two weeks before surgery.  The surgeon’s answer was yes. 

She sent me another email telling me of her plan.  She would take part in a five mile fun-run in Oxford the week before the London marathon. After that, she would do one or two more short runs and then the only really important remaining part of the marathon preparation would be getting her hair done the morning before the race.  

I am recounting her story here largely because her spirit is inspiring.  However, it has also brought into sharp focus the question of defining the sweet spot.  As described above, it is the place where the training load provides enough stress on the body to promote fitness, but is a little short of the level that leads to over-training, injury and eventually to ill-health. 

A substantial body of evidence indicates that exercise reduces the risk of onset of cancer and also that continuation of exercise following diagnosis of cancer increases survival rates. For example in early-stage breast or colon cancer, exercise can increase survival rate by 30-50%  [5]  This is not surprising because it is well established that moderate exercise increases immune responses and other potentially beneficial responses to inflammation.   However, excessive exercise can suppress immune responses, so one would expect that beyond a certain sweet spot, the benefits of exercise might be lost.  There is little clear evidence to indicate where this sweet spot might lie, though the available evidence suggests that that it might lie well into the range of quite strenuous exercise.

This question was addressed in a study of the rate of growth of lymphoid tumours in mice by Zielinski and colleagues [6].  The investigators set out to test the hypothesis that strenuous exercise in the form of running on a treadmill for three hours daily, or until exhaustion, might actually accelerate the rate of tumour growth.  However, in contrast to the investigators prediction, even this strenuous level of exercise delayed the growth and resulted to a more rapid regression of the tumours, in comparison with tumours in mice who led a sedentary lifestyle.  While this observation is encouraging, one must be cautious in applying lessons learned in mice to humans.  So I am inclined to think that running oneself to a state of utter exhaustion unlikely to be sensible, but provided one stops well short of utter exhaustion, the evidence indicates that running might inhibit tumour growth.

 Marie, if you read this, it is clearly important to be guided by what your surgeon recommends.  I am certainly not an expert, but I was delighted to hear the surgeon’s advice that running the marathon would be OK.  It fits with the evidence from the study by Zielinski.  Nonetheless, I think you are being very wise to be treating VLM 2010 as a race to enjoy – not a test of endurance.   If you and your husband run together down the Mall at the end of 26.2 miles that will be wonderful, but above all, look after yourself on Sunday.  It is the fact that you are going to be on the starting line together that is the real tribute to your spirit.  Nonetheless in the months ahead, continuing to run – or if needs be, combining walking and running – is likely to be the path to the sweet spot.

[1] Marie is a pseudonym




[5] Dudley et al (1982) ‘Influence of Exercise Intensity and Duration on Biochemical Adaptations in Skeletal Muscle,’ Journal of Applied Physiology, vol. 53, pp. 844-850.

[6] Jones et al (2010) Effect of aerobic exercise on tumor physiology in an animal model of human breast cancer J Appl Physiol 108:343-348,

[7] Zielinski et al (2004) Exercise delays allogeneic tumor growth and reduces intratumoral inflammation and vascularisation J Appl Physiol 96:2249-2256.


3 Responses to “The sweet spot”

  1. Ewen Says:

    Marie’s is an inspiring story. I hope she enjoys the London Marathon as she’s dreamed it.

    Canute, I like your point about making a very gradual progression of the sweet spot. Obviously Whitlock has been able to do this successfully, and your point about him being naturally gifted is a good one. A less gifted runner doing the same training wouldn’t run as fast. Another point helping him keep the stress of such training down would be the fact that he’s retired and doesn’t lead a busy life in retirement.

    I agree with your argument about not ignoring the fast twitch fibres in older age — especially if using a higher intensity type of training program.

    I’m always wondering what provides the ‘best value’ out of the various training strategies and methods. Having a good ‘spring’ and stride makes running at the slower (10k-half marathon) speeds feel easier, but is that of more value than aerobic endurance? For example, if one is ‘flat out’ running a 200 in 40 seconds, is that sufficient speed to run 50 200s with no break in 52 seconds each?

  2. canute1 Says:

    Ewen, Thanks for your comment. I feel quite excited on Marie’s behalf on the day before the race. If she is similarly excited, the greatest challenge she will face is avoiding starting too fast. But whatever happens tomorrow, she is truly an inspiration.

    I think you have probably thought more deeply than any other amateur athlete I know about the question of which training program might be best. However for what my opinion is worth, I think that for many individuals, efficient preparation for any distance race up the marathon should include some training at a pace somewhat faster than race pace if one wants to achieve one’s full potential. Having a reserve of muscle power greater than that required to maintain race pace is almost certainly beneficial. In the later stages of the race, whether it be 5000m or marathon, it is likely that recruitment of additional type 2a fibres will be required to sustain the pace. In fact I think this is especially the case in the marathon. Marathon pace is not all that far below the anaerobic threshold and relying on reserve energy from fat metabolism is not likely to be adequate.

    The prerequisites for running a good marathon certainly include very good development of type 1 fibres, but if one want to run at the limit of ones natural ability, it is also necessary to have well developed type 2a fibres to call upon when the type 1 fibres begin to fail. I suspect that one reason why Wanjiru might have had the edge over Cheriuyot despite the fact that both have run marathons in around 2:06, is Wanjiru’s focus on higher intensity training. The intriguing thing about Ed Whitlock is the question of whether or not it was the extreme duration of this training, such that he was often calling upon type 2a fibres towards the end of his training sessions, or perhaps his fairly frequent racing, that allowed him to maximize development of both type 1 and type 2a fibres.

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