Factors and interpretations of the exercise-induced fatigue phenomenon

For over a century, exercise-induced fatigue has been investigated as a limiting factor for maximum exercise performance. As a phenomenon, it has not been described extensively and comprises central and peripheral fatigue. Peripheral fatigue consists of a sum of peripheral factors: cellular, muscle, metabolic and circulatory. The association of peripheral fatigue and intramuscular perturbation of metabolites to the central nervous system is mediated via sensory nerves in order to regulate accurately the central motor drive. The central fatigue comprises mechanisms of the central nervous system that due to reduction of the neural drive to the working muscle, the following decline of muscle force or power results in compromised muscle performance. There have been suggested different hypotheses for the concept of that phenomenon, more prevailing at the time is the most recent theory of sensory tolerance limit. This hypothetical limit defines the point that after that, continuing strenuous exercise is negative for the athlete's health. As a result, there is a consequent decline in exercise intensity in order to enable the continuation of exercise in tolerance limits. This phenomenon is suggesting a global feedback mechanism that finite level of feedback sensory neural activation stemming from muscles directly and not directly involved in exercise, integrating the corollary discharges of central command resulting in impairment of exercise performance. Exercise-induced fatigue is suggested to be a global concept of integration between central and peripheral fatigue.