Cortical Motor and Sensory Centers The fatigue which influences performance in muscular work and sport is more directly related to the motor centers of the brain. Fatigue of the sensory centers is more significant in certain types of work involving small, accurate movements or requiring continual visual or auditory attention. There is little or no correlation between fatigue of motor centers and fatigue of sensory centers in different types of work. Fatigue of the motor and sensory centers may be measured by several techniques. In the tapping test, the maximal frequency with which a telegraphic key can be tapped gives an index of the functional condition of the motor centers. The results of this test are not influenced by peripheral factors such as circulation, metabolism, etc. Fatigue of the retinocortical (visual) center is indicated by a decrease in the fusion frequency of flicker (the rate at which alternating periods of light and dark produced by an electronic tube 5 can be discriminated before "flicker" disappears, being replaced by a visual impression of uniform grayness). In truck driving, which has a considerable manual component, the results of the tapping test and other tests of motor function, such as simple reaction time, reaction coordination ability and manual steadiness, bear a closer relation to the number of hours of driving time than do tests of sensory function. The same is true of laundry workers. The relation between fatigue resulting from muscular activity and changes in the motor centers is further established by a rise in scalp potential over the area of the motor cortex at the height of physical exercise. This is followed by a drop in potential with fatigue and a change in polarity at exhaustion. Fatigue occurs within the reflex arcs during both mental and physical work. The threshold stimulus of the Achilles tendon reflex and of the knee jerk gradually rises during the working period. The rise in threshold accelerates slightly during mental work and markedly during physical work. Determination of the threshold stimulus for the Achilles tendon reflex before work is resumed indicates whether or not the fatigue of the previous work period has been relieved by rest.		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