Eventually our understanding of the brain will advance to the point where its underlying physiology and biochemistry are understood and the effects of afferent input can be predicted. For the present, however, sports therapist can really only begin to address the question of how afferent input during competition (pain, breathlessness, nausea, audience response) can lead to psychological fatigue. For now, a behavioral (psychological) approach to understanding these questions of psychological fatigue may be beneficial. Through training or intrinsic mechanisms, some athletes learn to minimize the influences of distressing afferent input and therefore approach performance limits set in the musculature. At times, such as at high altitudes, athletes slacken their pace to reduce discomforting inputs to a tolerable level. Consequently, work output decreases, but not because of a muscle limitation.
On the opposite end of the spectrum, sports therapist frequently see examples of inexperienced or foolhardy athletes who set a blistering pace for most of a race, and then experience real muscle fatigue before the end. In track events, these are the competitors who, in the home stretch, look like someone reading the newspaper. In order to perform optimally in an activity, the experiences of prior training and competition are often necessary for an athlete to evaluate afferent inputs properly and to utilize them in determining the maximal rate at which physiological power can be meted out during competition in case of any psychological fatigue.
