Effect of Exercise on Mental Work Although fatigue of motor centers is important in the performance of muscular work and sport, fatigue of the sensory centers appears to be more important in the general sensation of fatigue. While fatigue of motor and sensory centers are not related to one another, there is some spreading of fatigue from one type of center to the other. Flicker fusion frequency is depressed after exhausting muscular work (700 yard run) and increased after 30 genuflexions or static work. This indicates that hard muscular work produces a certain degree of central nervous system fatigue, while light or moderate exercise, performed during pauses in sedentary occupations, improves the functional state of the central nervous system. Physical training in the schools should be administered in such a way as to avoid interference with the educational program. The activities during the school period should be short and moderate in order to have a stimulating effect on the capacity for mental work. Severe muscular work should be performed after school in order to avoid the depressing effect on the capacity for classroom work. Effect of Sensory Fatigue on Muscular Work Systematic studies of sensory fatigue induced by a lack or curtailment of sleep show that there are no significant physiological changes with up to 200 hours of sleeplessness. Reaction time and body steadiness are impaired by lack of sleep, but hand steadiness and hand grip strength10 are not affected. Subjective estimation of well-being also bears little relation to work performance. The lack of correlation between fatigue of sensory centers and fatigue of motor centers may explain the confusing experiences of athletes who have performed exceedingly well on days when they have complained of feeling too ill to enter competition, while their performance was unsatisfactory on other days when they had such a feeling of well-being that they felt capable of breaking records.		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