In yesterday's post we discussed Dr. Tim Noake's new paper, which contends that exercise fatigue is not a "physical event" so much as an emotion the brain uses to regulate exercise performance. This idea proved highly stimulating, as well as challenging. After all, how can fatigue not have a physical component? The effects of overtraining--another concept pioneered by Dr. Noakes--seem to suggest otherwise; that even if fatigue is simply an emotion, it does serve to outline certain limitations inherent in particular individuals.
It was at this point in my thinking that I remembered an earlier post discussing the role of one's expectations in determining exercise performance. Written last September, it analyzed an article from The New York Times which described experimental evidence suggesting that changes in a person's expectations of their performance could modestly influence it. To briefly summarize, the study had cyclists perform several 4km time trials on stationary bikes so as to determine their maximum speed over the distance. The cyclists were then told they would race an avatar which had been programmed to move at the cyclists' best time-trial effort. What the cyclists didn't know was that the avatar would actually be racing slightly faster (2% more power, or 1% faster) than the cyclists' best effort. Interestingly, in the subsequent test the cyclists were able to match the faster speed, even though they had already supposedly "maxed-out" in previous solo time-trials. When the test was repeated with the avatar riding with 5% more power, however, the cyclists proved unable to keep up. The author of the Times piece then suggests that the increase in performance may provide evidence of Dr. Noakes Central Governor Theory.
At the time I wondered how this could be true, given the fact that the "Central Governor" is, according to the theory, a sub-conscious network in the brain tasked with maintaining full body homeostasis. How could conscious motivation affect a sub-conscious Governor's tolerances?
Yesterday's post may offer clues. For example, Dr. Noakes' idea that fatigue is an emotion suggests that conscious elements do actually come into play when the Governor (if it exists) begins forcing the body to terminate exercise. So while some systems begin shutting down sub-consciously (for example, a reduced ability to recruit muscle), others require conscious choices (in Dr. Noakes' paper, "somewhere in the final section of the race, the brains of the second, and lower placed finishers accept their respective finishing positions and no longer choose to challenge for a higher finish.").
Synthesizing what we learned from the cycling experiment described above, and Dr. Noakes' notion of fatigue as an emotion, we begin to see a possible hypothesis explaining the extent to which conscious choices affect race performance. As the cycling experiment showed, cyclists registered a modest 2% increase in power when their expectations were "tricked" into believing their previous maximum power-output had not yet been reached. However, this trick proved insufficient when a 5% increase in power was tested; according to the Times article, "The athletes kept up for about half the race, then gave up."
It seems likely, therefore, that the conscious appraisal of fatigue has a modest yet measurable effect on performance. So while sub-conscious elements appear to play the major role in determining when exercise is terminated, but it may be that the final--and in a race, potentially-decisive--decision is ultimately left to conscious choice.
Happy Friday, friends :)
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