MUSCLE FATIGUE
Muscle weakness, also known as muscle fatigue, (or "lack of strength") is a direct term for the inability to exert force with one's muscles to the degree that would be expected given the individual's general physical fitness. A test of strength is often used during a diagnosis of a muscular disorder before the etiology can be identified. Such etiology depends on the type of muscle weakness, which can be true or perceived as well as variable topically. True weakness is substantial, while perceived rather is a sensation of having to put more effort to do the same task.[1] On the other hand, various topic locations for muscle weakness are central, neural and peripheral. Central muscle weakness is an overall exhaustion of the whole body, while peripheral weakness is an exhaustion of individual muscles. Neural weakness is somewhere between.
Muscle weakness can be a result of vigorous exercise but abnormal fatigue may be caused by barriers to or interference with the different stages of muscle contraction. True weakness, as in amyotrophic lateral sclerosis (ALS) describes a condition where the instantaneous force exerted by the muscles is less than would be expected. Perceived weakness, as seen in chronic fatigue syndrome describes a condition where it seems to the patient that more effort than normal is required to exert a given amount of force.[2]
(Sources: Enoka RM, Stuart DG (1992). "Neurobiology of muscle fatigue". J. Appl. Physiol. 72 (5): 1631–48. PMID 1601767/ Wikipedia with links to Wikipedia)
