Fatigue Prevention and Recuperation Selection of the man for the job should include considerations of the man's physical and mental competence, and his interest in the work. Heavy muscular work tires the nervous system more quickly than the muscles and, therefore, a combination of heavy muscular work and mental work performed simultaneously should not be required. All planning and processing should be done by those who are not engaged in heavy work. The use of signs, signals and colors should be made to simplify heavy jobs.  Work of great intensity should be of short duration.  Work which must be carried on for long periods should be of low intensity.  Hoists and conveyors should be used where the weight of the material is a factor. A workman who must move a heavy weight every ten minutes is very tired at the end of the day.  Loads to be lifted from the floor should be arranged in a compact form. The job should be planned so that the filter will not have to twist. There should be ample room for good footing and the path should be cleared for the carry. The lifter should face the load squarely with the feet close to the load and spaced apart about the width of the hips. The kneeling position, that is with a knee touching the floor, should not be used as this takes away the power source. A good grasp should be made and a preliminary heft executed in order   to ascertain whether the load is within the lifter's capacity. Usually if the load is greater than 30 per cent of the weight of the lifter's body, and if the load is awkward, the worker should get someone to help him, or he should use a hoist or other mechanical device. To get a firm grasp, lift one end of the load slightly, if necessary, to place one hand underneath. The leg position preparatory to the lift should be such that the knees and hips are bent to slightly less than 90 degrees. The back should be straight, and may be far from a vertical position as long as the back is not arched. An expression used to describe this back position is to "keep the shirt loose." The shoulders should be directly over the knees and the hands should reach straight downward to the load. In the proper position ready to lift, the leg muscles are in tension ready to work while the back muscles hold the back rigid. Lift by straightening the legs in a steady upward thrust and, at the same time, move the back to a vertical position. The load should be kept close to the body and over the feet. As the legs are straightened the back is kept straight. To change direction during a lift, step around and turn the whole body without twisting.  Loads should be carried as close to the center of gravity as possible. The grasp should be firm. The back should be straight, not arched. If the load becomes loose in a long carry, rest it against something and secure a firm grasp. To change direction while carrying a heavy load the whole body should be turned by stepping around.  Loads should be lowered as close to the center of gravity as possible. There should be back ample room for good footing. The legs should be comfortably spread and the load lowered between the feet. The mechanics of lowering are the reverse of lifting. The back should be held straight and rigid (though it may lean far forward from a vertical position) and the legs should be flexed as the load is lowered in a slow and even manner. The arms should extend straight downward and the load should be close to the body. The grasp should be firm when lowering a heavy load. The body should not be twisted. To turn, move the feet.  Work of great intensity should be preceded either by a warming up period of work progressive in intensity from low to great, or should be commenced at a reduced rate, load, or range of movement and then gradually increased. Work should be simplified so as to be adapted to the structure (physical dimensions and space requirements) and functions (strength, speed, and accuracy) of the human body.  Principles of motion economy utilizing momentum; easy and natural rhythm; arrangement of work place, chair, materials and controls; and positioning of levers to achieve greatest mechanical advantage should be employed.  Positions at work and movements such as carrying, pulling and pushing, and lifting should avoid muscular and ligamentous stresses and strains and should be performed with the glottis open to avoid sudden alterations in blood circulation.  Rhythm (the regular repetition of a group of motions) regularizes work labor, makes it easier, lightens it, and enlivens it. Rhythm smooths out semiautomatic activities which would otherwise be jerky and intermittent.  When a worker can set his own rhythm there in less fluctuation in his rate of work; there is a greater interest and satisfaction in the work, and he feels less tired than when working with an imposed rhythm.    The speed of the worker's machine should be synchronized with the worker's customary rhythm.  Where a group of machines is operated by a single prime mover, the speed of the machines should be adjusted to the ability of the workers to keep pace with it.  Workers who are not adept at high speed or cannot keep up with the average pace should be transferred to jobs requiring a slower pace.    In non-machine operations, placement of a worker among others who have superior strength, skill and speed encourages him to attempt to keep up with the swift pace and may lead to injury, He should work alongside those with a similar or only slightly faster pace.  Advantages and limitations due to different structures and functions in different ages, sexes, races and body limits should be considered in the job assignment.  Waste movement should be reduced. Muscular tension in addition to that required to support postures and perform work should be reduced.  Fatigue from office work requiring close concentration can often be remedied by frequent and regular physical exercise.  Periodic physical examinations should be made to aid in the early detection of diseases such as tuberculosis, diabetes and cardiovascular-renal conditions.  Weaknesses in vision and hearing, poor posture habits and foot trouble, and chronic infection such as tonsilitis and tooth infections should be corrected.  Physical fitness in terms of the muscular strength, cardiovascular endurance and joint flexibility required for easy performance of the task should be achieved and maintained.  Housing should be comfortable and clean, and should have pleasant surroundings and facilities for relaxation and entertainment.  Sources of worry arising from fears of loss of employment or reduction in wages, and, in hazardous occupations, death or serious injury should be relieved through the publicizing of personnel policies and through improved protection against accidents.  Social and economic conditions at work and at home should provide incentive and security.  Education and assistance should be available to those who desire help in the management of personal affairs.  Recreational activities such as dramatic clubs, music clubs, sports clubs, hunting and fishing clubs, literary clubs, photographic clubs, free lectures and concerts, and libraries which provide for the active participation of everyone should be planned and promoted through an employees' association and supervised and coordinated by a trained recreation director to obtain their maximum values.  Frequent attention, encouragement and expression of appreciation should be offered the worker to keep him highly motivated.  A change of activity should be provided especially during periods when work output falls off.  A midafternoon snack should be eaten when work has been continuous throughout the day. Rest periods from 5 minutes duration at hourly intervals in moderate work to 45 minutes in strenuous work, such as between running races in track, should be provided.  A greater work output can be achieved by working steadily for short periods, and then resting, than by working steadily without rest periods.  Workers voluntarily take rest periods ranging from three minutes an hour in light work to 12 minutes an hour in heavier work. When such rest periods are authorized, the worker in able to relax without tension.    Accuracy of mental work requiring close concentration is improved if a rest period of five minutes at the beginning of each hour is provided.    Rest in a horizontal position, preferably with the legs elevated, should be allowed between bouts of strenuous work. Relaxation techniques should be taught if the worker is incapable of voluntary, complete relaxation. Massage will provide additional recovery. If it is not feasible to recline, mild exercise which promotes blood flow through working muscles is preferable to inactivity in a standing or seated position.  Broadcasts of music and entertainment through a public address system should be provided during periods when work output ordinarily falls off, except in work requiring intense concentration in which the broadcasts would be distracting.  Rest is generally much more effective if taken in a quiet rest room instead of in the work shop, as noise in inseparable from most industrial work.  The performer should get 8 hours of sleep nightly, preferably in a comfortable bed in a dark, quiet, cool room.  The work area should have ample space for free movement and vision; should be air conditioned if necessary to achieve comfort in temperature, humidity, ventilation and clean air free from dust, fumes, and undesirable odors; the light source should illuminate the work surface providing about 100 foot-candles of illumination without glare; and noise and vibration should be reduced. Machine design should provide for normal postures and positions. The dimensions of the machine should not require undue stretching, reaching or stooping.  The height of the work bench and chair should be determined by the kind of work to be performed. The chair seat should be broad, front edge rounded, not too deep (so circulation will not be cut off), and slightly saddle-shaped. The seat back should be designed so as not to interfere with arm movement. Standing or sitting positions are tiresome if either is constantly maintained throughout the day without change. An operation which requires alternate standing and sitting is the ideal combination of work to keep fatigue at a minimum level.    Diet should provide essential elements of nutrition and should be in sufficient quantity to maintain normal body weight.  Food intake at mealtimes, especially at breakfast, should be adequate to support subsequent activity.  Midmorning and midafternoon snacks (glass of milk and piece of cake) increase work output.  Lunch rooms, separated from the workrooms, where hot nourishing food can be eaten in an inviting and cheerful atmosphere are an asset to production.  Overindulgence in alcohol and tobacco should be avoided.  Work at high altitudes should be progressive in intensity to allow for acclimatization. Supplementary oxygen during work is useful at altitudes above 8,000 feet.  The use of drugs to allay sensations of fatigue should be restricted to very severe emergency situations.  Exposure to extreme fatigue, or to very high altitudes or deep dives, should be followed by ample periods of rest to promote full recovery and prevent progressive deterioration resulting in excessive aging.		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