Only A Difference of Magnitude

In 2005 exercise scientist Dr. Ed Coyle of the University of Texas published a research study based on seven years of physiological data collected on Lance Armstrong (1).  During the seven years covered by the study Lance improved from a young, just-turned-professional, cyclist to “best in the world” and multiple winner of the Tour de France.  What physiological changes accounted for the improvement in Lance’s performance?

Conventional wisdom would point to improvements in Lance’s cardiovascular system – i.e. increases in VO2max, and lactate threshold – as the explanation.  However, conventional wisdom would be wrong.  No changes in VO2max or lactate threshold were measured during the seven year period.  Lance clearly improved during this time but the improvements could not be explained by conventional physiological wisdom.

Instead, Dr. Coyle found that changes in Lance’s muscles were the cause of the improvement.  In the study Dr. Coyle wrote, “…over the 7-yr period, an improvement in muscular efficiency and reduced body fat contributed equally to a remarkable 18% improvement in his steady-state power per kilogram body weight when cycling at a given VO2 (e.g., 5 l/min).”  The 18% increase in relative muscle power meant Lance could ride faster, longer, producing more power than his opponents and allowing him to beat all the competition.

Is Lance unique?  Does everyone else who improves do so by increasing VO2max and lactate threshold while Lance improved by increasing the power output of his muscles?  Conventional wisdom certainly would have you believe that improvements are primarily determined by cardiovascular factors.  Could conventional wisdom be wrong?  This question has recently been addressed by a just published study on world-class cyclists.

A Longitudinal Study of World-Class Cyclists

Intrigued by the Armstrong study a group of physiologists tested 12 world-class cyclists over a five year period “to determine the effect of accumulated years of training and competition on the muscular efficiency in world-class cyclists”(2).  This group of cyclists was truly world-class, consisting of some of the best cyclists in the world and included one winner of the Tour de France, one winner of the Vuelta a Espana, one three-time Tour de France podium, two Vuelta a Espana podia, and one Junior World Time Trial Champion.

Subjects were tested annually for five years but only data from the first and fifth seasons were used for analysis.

The results?  “The most important finding of this study is that DE (i.e. muscular efficiency) increased in world-class professional cyclists during a five-season training/competition periods, whereas VO2max did not change.

The cyclists improved muscular efficiency an average of 14.83% over the five year period.  The range of improvement in efficiency was 0% – ~50% (two riders had no change in efficiency, one rider improved almost 50%, and all other riders fell between the two ends).  Conversely, VO2max actually declined slightly, even though the decline was not significant.

The only difference between Lance’s change and these cyclists is one of magnitude.  We see that Lance Armstrong is not unique; changes within the muscles and not the cardiovascular system enabled improved performance in this group of world-class cyclists, just as changes in muscular efficiency explained Lance’s improvement.

Contrary to what conventional wisdom teaches, this study provides additional evidence that it is the muscles, not the cardiovascular system, that primarily influences both performance and improvement.

Summary

A five year study of world-class cyclists found that muscular efficiency increased nearly 15% while there was no change in VO2max.  The results of this study were the same as those of a previous study of Lance Armstrong that found that improvements within the muscles enabled improvements in performance.  The only difference between this study and the Lance Armstrong study is one of magnitude – the same physiological change occurred in both studies but the magnitude of the change differed.

Reference:

1.       Coyle, E. Improved Muscular Efficiency Displayed as Tour de France Champion Matures, J Appl Physiol, 98: 2191-2196, 2005.

2.       Santalla A, Naranjo J, Terrados N., Muscle Efficiency Improves over Time in World-Class Cyclists, Med Sci Sports Exerc, 41(5); 1096-1101, 2009

 


Comments

Only A Difference of Magnitude — 3 Comments

  1. Pingback: Only A Difference of Magnitude | Training Science

  2. Both Coyle and Santalla misrepresent what they found in the titles of their paper and it drives me crazy. Both found cycling efficiency improved but they call it muscular efficiency. The problem is that muscles contract and do work with an efficiency of around 40% but cyclists ride at efficiencies in the 20% range. While it is possible I suppose that the cycling efficiency improvements seen are from muscle efficiency improvements it seems more likely that these cyclists have learned how to reduce the losses seen between the muscle and the wheel to explain the change. To represent that the study findings show muscle efficiency improvements is simply elevating unsubstantiated speculation to “fact”. It would have been better for these authors to have simply concluded that the mechanism of efficiency improvement is unknown and deserves further study.

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