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BEST of PEZ ’08: Champion Physiology 2
A huge amount of sport science research over the past century has been dedicated to dissecting the inner workings of the human body and its limits of performance. We have gone over the basics of what it takes to succeed, and we’ll continue today by looking at some of the major unanswered questions facing exercise physiologists.

In my last article on Champion Physiology, we reviewed the basic, fundamental determinants of peak performance in endurance sport. The building blocks consisted of high aerobic capacity (VO2max), being able to sustain a high percentage of that aerobic capacity for a prolonged period of time during exercise (high lactate threshold), and the ability to spend the least amount of energy as possible in performing the work (high economy or efficiency). From these principles derive most of endurance physiology, from intervals through to pedaling drills.

We’re All Individuals!
If it’s really this simple, then why isn’t everyone equally capable of making it to the starting line of the Olympic road race or soloing into the Roubaix velodrome? Sport scientists and coaching have evolved from a mass template of developing athletes (the Eastern Bloc philosophy of throwing a crate of eggs at the wall and keeping those that don’t break) to high levels of individualized training. This individualization necessarily implies that each athlete responds differently to a stimulus, whether it’s training load, recovery, psychology, nutrition, etc. More than anything else, this focus on customization has probably been the single biggest paradigm shift in training.

Continuing our discussion of the nice review on “Champion Physiology” by eminent physiologists Michael Joyner and Edward Coyle (5), I’ve compiled a laundry list here of some of the big questions we still don’t know about how to build perfect athletes:

Genetics
Above all, this is the grand-daddy of mysteries when it comes to any aspect of human physiology. We’ve probably all shaken our head in wonder at Taylor Phinney’s meteoric rise to the top of the pursuiting heap in a scant few months. Given his famous cycling parents, that might seem like destiny. But what’s the algorithm behind the genetic lottery?

Looking at it another way, we’ve determined that qualities like our three major physiological building blocks are good, but they remain black boxes. Is there, for example, a gene that preferentially codes for high hemoglobin levels? Or to be even more “big picture,” a gene that codes for greater ability to recover? Some research suggests that certain polymorphisms (fancy words for ways certain genes are grouped together) have a high prevalence in elite athletes and also sedentary individuals who respond strongly to an exercise stimulus.

Of course, if something like this is ever discovered, it’s pretty evident that it will rapidly degenerate into becoming another path of abuse by unscrupulous individuals. Coupled with the difficulty from figuring out the interactions between genetics and development, training, psychology, and culture, it remains highly unlikely that the common idea of “gene-doping” will become prevalent in the near future.

Realistically, the focus and funding for genetics research is geared towards clinical applications such as understanding heart disease and cancer, and the big money involved is just not happening in the quest for gold medals. A caveat though, is that synthetic EPO was originally developed to remedy the anemia seen with cancer and kidney…

Trainability of Efficiency?
So assuming that help isn’t going to come artificially, the biggest potential bang for the buck in time and energy for endurance athletes would appear to be improving your efficiency of movement. The old axiom is that you may pedal 5400 revolutions in one hour, and even a tiny decrease in the energy requirement for each pedal stroke can quickly add up.

It’s inarguable that there is a huge efficiency learning curve between sedentary and well-trained individuals in any sport, but just how much change is possible within one individual over the course of their career? The closest we have come to answering this question is the landmark paper by Dr. Coyle examining the physiological changes in Lance Armstrong from 1993-1999 (4). Here, Coyle showed that Lance didn’t only improve his power to weight ratio, but at the same time improved his efficiency (the amount of oxygen required to perform a set workload) by an astounding 8% over this period.

Such a study certainly supports the proposal that, even in already elite athletes, minor and major improvements in efficiency are possible. This emphasizes again the importance of continued training of technique, even in seemingly “natural” sports like cycling and running. However, it remains that there are exceeding few similar case studies like this one to be able to generalize, and much of the research in sport science have been done on good but not great athletes at different phases throughout their careers.

What is fatigue?
Ultimately, we stop exercising because of one or more of a nearly infinite list of reasons. They fall into many categories, ranging from the microscopic workings within individual cells through to psychology. Any of these factors can contribute or be the weak link in elite performance. Where then, is the biggest bang for the buck in terms of targeting improvement?

Personally, if I had to pick one area, it would be in psychological training and improving your mental game (no, this is not just because of Marvin Zauderer’s great writing). Despite my being a physiologist and interested mainly in the mechanics of the human body, the work I’ve been doing on exercise tolerance in hot environments certainly points towards the overwhelming importance of input from the central nervous system and the brain’s capacity.

• My 1998 paper (3)comparing fit versus untrained individuals exercising in very hot conditions demonstrated that the fit group consistently stopped exercising at a much higher core temperature than untrained subjects. This was verified by a colleague Glen Selkirk in 2001 (6), who showed that aerobic fitness alone was primarily responsible for this change.

• My colleague Martin Barwood has just published a nice 2008 paper (2) demonstrating that a few weeks of specific psychological skills training was able to significantly improve exercise capacity in the heat. This follows his 2006 study that psychological skills training was also able to prolong breath-hold duration with immersion into cold water (1).

• Over the past five years, the famous physiologist Tim Noakes from South Africa has proposed that much of exercise capacity is determined by the brain integrating a variety of “discomfort” signals from throughout the body, including thermal, muscular, and other signals.

We’ve all heard elite riders talking about how their career took a big jump upwards once they’ve “learned how to suffer.” Indeed, I’d go so far as to say that the dominant purpose of training is to teach your brain to ignore the discomfort signals and therefore how to suffer!

Summary
To conclude this two-parter, I would say that:
• Scientists are a long, long, long time away from understanding what, physiologically, constitutes the perfect athlete. So like the old saying goes, pick your parents wisely and then train with what you have.

• Yes, technique, at least judging from Lance’s case, is trainable and can extend your genetic ceiling.

• Work on your sport psychology and becoming a mentally-fit athlete, because that is going to give you the biggest return on investment once you achieve a decent level of fitness, and will again push you well beyond your genetic ceiling.

Reference

1. Barwood MJ, Dalzell J, Datta AK, Thelwell RC, and Tipton MJ. Breath-hold performance during cold water immersion: effects of psychological skills training. Aviat Space Environ Med 77: 1136-1142, 2006.
2. Barwood MJ, Thelwell RC, and Tipton MJ. Psychological skills training improves exercise performance in the heat. Med Sci Sports Exerc 40: 387-396, 2008.
3. Cheung SS, and McLellan TM. Influence of heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress. Journal of Applied Physiology 84: 1731-1739, 1998.
4. Coyle EF. Improved muscular efficiency displayed as Tour de France champion matures. J Appl Physiol 98: 2191-2196, 2005.
5. Joyner MJ, and Coyle EF. Endurance exercise performance: the physiology of champions. J Physiol 586: 35-44, 2008.
6. Selkirk GA, and McLellan TM. Influence of aerobic fitness and body fatness on tolerance to uncompensable heat stress. Journal of Applied Physiology 91: 2055-2063., 2001.




About Stephen:
Stephen Cheung is a Canada Research Chair in Kinesiology at Brock University, with a research specialization in the effects of thermal stress on human physiology and performance. He can be reached for comments at thermal.doc@gmail.com.

 

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