What is physical fatigue?

Answer 1

Muscle fatigue is the repeated, intense use of muscles which leads to a decline in performance.Though the actual mechanism for muscle fatigue appears to involve the leakage of calcium.The maximum intensity of exercise is determined by physiological factors such as the maximum rate of O2 uptake, maximum heart rate and stroke volume, maximum muscle strength, etc. In the case of maximum work, a time factor is involved. Muscle fatigue is the transient decrease in performance capacity of muscles, usually evidenced by a failure to maintain or develop a certain expected force or power.

Fatigue curves vary between individuals and within individuals depending upon the conditions that exist. Muscle fatigue can occur in two basic mechanisms: (a) central involves proximal motor neurons (mainly in the brain); and (b) peripheral involves within the motor units (i.e., motor neurons, peripheral nerves, motor endplates, muscle fibers). In peripheral muscle fatigue there are at least two different sites where repeated contractions maycauseimpairment:the"transmission mechanism"(neuromuscular junction, muscle membrane, and endoplasmic reticulum), and the "contractile mechanism" (muscle filaments). As the mechanical response of the individual active muscle fibers decline with fatigue, a certain compensation can be achieved by increasing the innervation frequency and/or the number of active motor units. The reasons for the appearance of peripheral muscle fatigue are local changes in the internal conditions of the muscle. These may be biochemical, depletion of substrates such as glycogen, high energy phosphate compounds in the muscle fibers, and acetylcholine in the terminal motor nerve branches, or they may be due to the accumulation of metabolites, such as lactate or electrolytes liberated from the muscles during activity

Answer 2

Physical Fatigue, is when you are physically tierd. Like your muscles are aching or tensed from doing lots of exersise, or having a big, stressful day.