Sports Med 2009;

Over the past 13 years, Noakes and his colleagues have argued repeatedly for the existence of a ‘Central Governor’, a specific brain centre that provides a feed-forward regulation of the intensity of vigorous effort in order to conserve homeostasis, protecting vital organs such as the brain, heart and skeletal muscle against damage from hyperthermia, ischaemia and other manifestations of catastrophic failure. This brief article reviews evidence concerning important corollaries of the hypothesis, examining the extent of evolutionary pressures for the development of such a mechanism, the effectiveness of protection against hyperthermia and ischaemia during exhausting exercise, the absence of peripheral factors limiting peak performance (particularly a plateauing of cardiac output and oxygen consumption) and proof that electromyographic activity is limiting exhausting effort. As yet, there is a lack of convincing experimental evidence to support these corollaries of the hypothesis; furthermore, some findings, such as the rather consistent demonstration of an oxygen consumption plateau in young adults, argue strongly against the limiting role of a ‘Central Governor’. 1. Concept of a ‘Central Governor’ An early graduate textbook made a systematic review of possible factors limiting physical performance. Depending on duration of the bout of effort, critical physiological factors were, in turn, maximal anaerobic power, maximal anaerobic capacity, maximal aerobic power, maximal aerobic capacity, and reserves of food (glycogen and fat), water and minerals. In some situations, environmental constraints such as difficulty in eliminating metabolic heat could also intervene, and with any period of exercise, psychological factors (motivation, arousal and release of cerebral inhibition) could sustain or enhance an individual’s performance. However, this comprehensive evaluation found no need to postulate that a specific subconscious feed-forward control mechanism was setting an upper limit to the intensity of exercise. A more recent systematic review of the causes of fatigue during prolonged endurance cycling made brief mention of the idea of such a control system, tracing its origin to Ulmer. Ulmer had envisaged a feedback of information on force generation, displacement and metabolism to a central regulator, where these data were matched against motor learning and desired objectives to ensure a teleo-anticipatory optimization of the individual’s metabolic rate. In developing the concept of a ‘Central Governor’, Noakes reached back to the classic studies of Hill et al., who had postulated somemechanism (either peripherally, in cardiac muscle or in the CNS) that restricted cardiac output as the arterial oxygen saturation began to fall. Noakes envisaged the central control mechanism as limiting motoneuron output in order to conserve homeostasis and prevent tissue damage from such threats as ischaemia or hyperthermia. CURRENT OPINION Sports Med 2009; 39 (9): 709-721 0112-1642/09/0009-0709/$49.95/0 a 2009 Adis Data Information BV. All rights reserved.