What’s New ?
By HG Lynn
Thanks to Larry Laursen for bringing this article to our attention.
Posted: 9/1/2007

1. Preamble
Over the past years, exercise scientists have made great strides in understanding exactly how the human body responds and adapts to physical exercise. New science and methods
have enabled them to reveal the shortcomings of many of the accepted theories and dogma of past decades
Professor Tim Noakes MBChB, MD, DSc, FACSM. Head of the Bioenergetics of Exercise Research Unit of the Medical Research Council and the University of Cape Town has kindly given me permission to quote extensively from his latest book “LORE of RUNNING” (fourth edition).
Don’t believe that the book is all about running as it has a tremendous amount of information on every aspect of physical exercise. I shall be quoting a variety of subjects from the book which I found extremely informative about most things that were new to me: And it is my intention in following articles to try to share this information with coaches who have not studied the book and who are interested in hearing more about it, possibly before purchasing it.
As with most scientific literature, Prof Noakes uses references indicating the names of the scientist or scientists whose confirmed work contributed to the achieved level of knowledge of the subject being discussed. If I had to repeat this procedure, it would be very taxing as there are some 72 pages of references in fine print. So when I print the conclusions, there may have been a number contributing scientists.

2. The Cardiovascular / Anaerobic Model of Exercise Physiology
( What we have believed so far, considerably shortened)
• This model, holds that high-intensity exercise is ultimately limited by the development of anaerobic condition in the active muscles. This absence of oxygen results from the heart’s inability to increase its output above some limiting maximum value. As a result, oxygen delivery to the active muscles ‘plateaus’, forcing the muscles to rely on anaerobic metabolism for their energy supply. The by-products of this anaerobic metabolism eventually accumulate in the muscle, causing exhaustion.
• The model was proposed by H.V.Hill more than 75 years ago. But scientists have been less than enthusiastic to acknowledge that Hill understood the fatal flaw of any model which predicts that the heart must fatigue before the exercising muscles.
( Although Hill thought his theory was valid, he also believed that there was some sort of ‘governor’ involved during stressful exercise but could not clearly identify what was happening in the body. Thus Prof Noakes recognizes his contribution.

3. ( The Hill, Noakes ) Central Governor Model (Integrated Neuromuscular Recruitment Model Of Exercise Physiology And Athletic Performance) Considerably shortened
• This new model of maximum exercise performance holds that the heart is the organ at greatest risk of developing an oxygen deficiency during stressful conditions – especially vigorous exercise at extreme altitude. Thus a mechanism must exist to restrain the over-vigorous use of the exercising muscles that would imperil the heart.
• The model proposes the existence of a governor which monitors the state of oxygenation of the heart and perhaps the (brain, diaphragm) and others as well.
When the oxygenation approaches the limits of what is safe, the brain motor cortex, which recruits the exercising muscles, is informed and it stops recruiting muscles.
As a result:
• Fatigue is experienced ( Note: That, like pain, fatigue is always sensed exclusively by the brain, even though it appears to be coming from elsewhere, for example in the muscles ( exhaustion and discomfort ) or on the skin (pain).
• The work output of the muscles and the heart falls.
This leads to a reduction in the oxygen demand of the heart, thereby protecting the more delicate heart from damage caused by oxygen starvation.
Thus, this model predicts that maximum exercise capacity is a process, co-ordinated subconsciously by the brain, limited by the maximum capacity of the coronary blood flow to supply oxygen to he heart, and regulated to prevent heart damage during maximal exercise.
( The above was taken directly from the book but I think that a passage from correspondence with Prof Noakes some years ago, may be easier to understand)
• “The muscle’s function is regulated by both the brain and its own function to insure that anaerobiosis does not develop. If you reduce the blood supply to the muscle it reduces its mechanical performance in proportion to the drop in oxygen supply so that the work done is covered by the available oxygen – hence anaerobiosis does not develop. In addition, for the muscle to become anaerobic requires that the heart first become anaerobic. We know that this does not happen so ipse facto, the other cannot happen either. Prevention of the heart becoming anaerobic comes from a reflex arriving from the brain.”
…“The old idea that muscles stop working because of acidosis and so on is not supported by any firm evidence – it is just accepted dogma. We are also finding that the brain reduces its muscle recruitment progressively during exercise as well – reasons unknown – and this also causes the fatigue of prolonged exercise”.
• “As another issue- I am beginning to think that fatigue is perceived in the brain and is a ‘learned response’- That is we programme ourselves to fatigue at a certain time during exercise. That is another reason why high-speed training is so important – trains the brain as much as anything else.
ooooooo
Throughout the book, proof of the validity of The Central Governor Model is clearly demonstrated in all physical exercise under many differing circumstances and cannot be faulted. Probably the best single proof is in the physiology of high altitude climbers and we can look at some of these proofs in future letters under the following questions:
• How can blood lactate levels fall progressively at peak exercise with increasing altitude, to the point where the oxygen level in the air barely supports life?
• The VO2max of Reinhold Messner, arguably the most remarkable high-altitude climber of all time, is only 48.8ml O2, kg –.1min, essentially the same as Sir Edmund Hillary. The values are little better than those found in untrained but healthy young men.
• How is VO2Max explained?
• Lactate may be one of the most important fuels of the body, what is lactate?