Muscular Fatigue The fatigue of muscle fibers may be the result of the action of the accumulated metabolites in the muscles. The metabolites appear diffusely through the muscle, interfering with intermediary metabolism in the muscle fiber and with impulse transmission at the neuromuscular junction. The fatigue of muscles is associated with alterations in oxygen utilization and in cell permeability and with the transfer of ions across altered membranes. Constant adjustments to fatigue are occurring in an exercised muscle. A loss of glycogen from the muscle results in a simultaneous release of sufficient potassium to maintain a constant ratio of potassium to non-fat solids inside the muscle. The resultant imbalance between potassium and sodium in fatigued muscle is associated with a higher oxygen consumption than that which exists in normal muscle. If the adjustments to fatigue are effective there is no damage to the muscle's contractile mechanism and no detectable exhaustion of its store of energy-yielding chemical substances. If the adjustments to fatigue are not effective, muscular fatigue can be carried to such a point that there is a reduction in the power of the muscle to do work which outlasts the immediate recovery from fatigue and this may amount to permanent damage to the muscle. Cardiac Fatigue The contractile power of the heart is reduced by fatigue, particularly if it has been weakened by disease. This reduction in contractile power results in a diminished stroke volume and a less complete systolic emptying of the ventricles. The necessary cardiac output is maintained only at the expense of a dilatation of the ventricles and a further increase in the heart rate, both of which increase the likelihood of termination of the exercise through failure of the coronary blood flow to meet the increased metabolic requirements of the heart muscle. Foot Fatigue Standing not only increases fatigue by cerebral anemia and reduction in cardiac minute volume, but also produces local fatigue of the feet which frequently interferes with production in jobs which require prolonged standing. Change in posture from the upright to varying degrees of the recumbent position and periodic elevation of the feet serve as practical measures to reduce cardiovascular strain and fatigue, especially in hot environments. Fatigue and Infections Extreme fatigue lowers the general resistance of the body to pathogenic micro-organisms and appears especially to predispose the subject to respiratory infections such as the common cold. The basis of this relation is not clear.		Home Pace Motivation Measures of Endurance Computation of Dietary Requirement Work Efficiency Maximum Steady State Work Inefficiency of Anaerobic Work Estimation of Work Efficiency Efficiency of Grade Climbing Low Economy of Slow Work Maximum Rate of Work Levers of the Body Fatigue and Recovery General Fatigue Symptoms Anxiety State Organic Fatigue Cortical Motor and Sensory Centers Effect of Exercise on Mental Work Visual Fatigue Muscular Fatigue Fatigue Prevention and Recuperation