Central governor

The central governor is a proposed process in the brain that regulates exercise in regard to a neurally calculated safe exertion by the body. In particular, physical activity is controlled so that its intensity cannot threaten the body’s homeostasis by causing anoxic damage to the heart muscle. The central governor limits exercise by reducing the neural recruitment of muscle fibers. This reduced recruitment causes the sensation of fatigue. The existence of a central governor was suggested to explain fatigue after prolonged strenuous exercise in long-distance running and other endurance sports, but its ideas could also apply to other causes of exertion-induced fatigue.

The existence of a central governor was proposed by Tim Noakes in 1997, but a similar idea was suggested in 1924 by Archibald Hill.

In contrast to this idea is the one that fatigue is due to peripheral ‘limitation’ or ‘catastrophe’. In this view, regulation by fatigue occurs as a consequence of a failure of homeostasis directly in muscles.

The 1922 Nobel Prize in Physiology or Medicine winner Archibald Hill proposed in 1924 that the heart was protected from anoxia in strenuous exercise by the existence of a governor.

the heart is able to regulate its output, to some extent, in accordance with the degree of saturation of the arterial blood ... we suggest that, in the body (either in the heart muscle itself or in the nervous system), there is some mechanism which causes a slowing of the circulation as soon as a serious degree of unsaturation occurs, and vice versa. This mechanism would tend, to some degree, to act as a ‘governor’, maintaining a reasonably high degree of saturation of the blood: the breathing of a gas mixture rich in oxygen would produce a greater degree of saturation of the blood and so allow the output to increase until the ‘governor’ stopped it again. We realise the danger of a hypothesis partly suggested by teleological reasoning: in this case, however, we can see no other explanation of our experimental results pp. 161-163

This hypothesis was disregarded and further research upon exercise fatigue was modeled in terms of it being due to a mechanical failure of the exercising muscles ("peripheral muscle fatigue"). This failure was caused either by an inadequate oxygen supply to the exercising muscles, lactic acid buildup, or total energy depletion in the exhausted muscles.

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