Journal of Non-lethal Combatives, Sept 2002

FM 21-20 War Department Field Manual, Physical Training, Chapter I, Introduction

Editorís Notes:

  1. First in a series.
  2. In this series, EJMAS will present Chapters 1 and 13, as they are most directly relevant to the topic of less-lethal combatives.
  3. Omitted chapters include program planning, conditioning exercises, rifle exercises, log exercises, the strength course, "guerrilla" exercises, marching, running and grass drills, obstacle and confidence courses, athletics, relays, tumbling, swimming and lifesaving, posture training, and physical fitness testing.
  4. The text is courtesy Doug Walker. This online version is copyright © EJMAS 2002. All rights reserved.
War Department, January 1946

FM 21-20, Physical Training, is published for the information and guidance of all concerned.



Chief of Staff



Major General

Acting The Adjutant General

This manual supersedes FM [Field Manual] 21-20, 6 March 1941; TC [Training Circular] 87, 17 November 1942, and WD [War Department] Pamphlet No. 21-9, May 1944.

1. PURPOSE AND SCOPE. This manual contains ready reference data for use in planning physical training programs for troops. The contents consist primarily of brief descriptions and illustrations of various types of physical training activities. There are also suggestions on the planning and administration of physical training programs to fit various conditions and on effective physical fitness testing.

2. TOTAL MILITARY FITNESS. Total fitness for war includes technical fitness, mental and emotional fitness, and physical fitness. All of these attributes of total military fitness must be combined in the well trained soldier. If any are lacking, the soldierís combat effectiveness suffers proportionately. Without technical fitness a soldier lacks the knowledge and skill to fight; without mental and emotional fitness he lacks the incentive and desire to fight; without physical fitness he lacks the strength and stamina to fight.


  1. Military leaders have always recognized that the effectiveness of fighting men depends to a large degree upon their physical condition. War places a great premium upon the strength, stamina, agility, and coordination of the soldier because victory and his life are so often dependent upon them. Warfare is a grueling ordeal for soldiers and makes many severe physical demands upon them. To march long distances with full pack, weapons, and ammunition through rugged country and to fight effectively upon arriving at the area of combat; to drive fast-moving tanks and motor vehicles over rough terrain; to make assaults and to run and crawl for long distances, to jump into and out of fox holes, craters, and trenches, and over obstacles; to lift and carry heavy objects; to keep going for many hours without sleep or rest Ė all these activities of warfare and many others require superbly conditioned troops.
  2. The fact that warfare has become mechanized has accentuated rather than minimized the importance of physical fitness. Soldiers must still perform most of the arduous tasks which fighting men for thousands of years have had to do. There are always places where mechanized units cannot maneuver, tasks which they cannot accomplish, and situations in which equipment becomes disabled. Furthermore, the machines are no better than the men operating them. Every new advance in the speed, maneuverability, striking power, durability, and destructiveness of our machines must be accompanied by a corresponding improvement in the quality and fitness of their operators.
  3. Physical fitness is important from another point of view. A close relationship exists between physical fitness and mental and emotional fitness or morale. Fatigue, weakness, lack of stamina, and physical exhaustion are usually associated with a low state of morale. The rugged, tough, well-conditioned soldier has a feeling of fitness and confidence, and he is much less susceptible to many of the factors which undermine morale.


  1. Freedom from disease and defect. Freedom from anatomical defect or disease, the discovery and treatment of which are functions of the medical department, is the first requirement of physical fitness. Physiological soundness, however, does not in itself constitute physical fitness; it is merely the foundation upon which physical fitness is built. Before a soldier is fit for combat operations good health and the absence of handicapping defects must be supplemented by strength, endurance, agility, and coordination.
  2. Strength. (1) Every soldier must have sufficient strength for the heaviest tasks he may encounter in routine and emergency activities. Arduous military duties require a considerable degree of leg, back, abdominal and arm and shoulder girdle strength. (2) Muscles increase in size and strength with regular and strenuous exercise. They atrophy and grow weaker when not exercised. Strength is best developed in muscles when their power of contracting is challenged by maximum loads. The closer a muscle works to its capacity load, the greater will be its development of strength. Strenuous conditioning exercises, rifle and log exercises, weight lifting, wrestling, and sprint running are excellent strength-developing exercises.
  3. Endurance. Every soldier needs enough endurance to go through the most rigorous day without undue fatigue and to complete the most strenuous duty to which he may be assigned. There are two types of endurance: (1) Muscular endurance. This type of endurance permits an individual to continue strenuous activity for many hours without undue fatigue. The soldier needs muscular endurance to make long marches, to keep going for hours on end, and to perform the fatiguing duties of battle. Muscular endurance is characterized by a greater than average amount of muscular strength and an enriched blood capillary network within the muscles. This network makes it possible for the blood stream to deliver increased amounts of oxygen and nutrition to the muscle mass, and to carry away waste products more rapidly. The kinds of exercise needed to build up muscular endurance are the same as those indicated under strength. (2) Circulo-respiratory endurance. This type of endurance is required for prolonged activity at more than normal speed, such as long distance running. The soldier needs circulo-respiratory endurance when he must cover a considerable distance at great speed. It is composed of muscular endurance plus an increased efficiency in the functioning of the heart, vascular system, and lungs. Running is the best way to develop circulo-respiratory endurance.
  4. Agility. Agility is characterized by an ability to change direction and the position of the body in space with great rapidity. It enables the soldier to fall to the ground or leap to his feet quickly; it makes him a fraction of a second faster at ducking into a fox hole or into a trench under sudden machine gun fire; it is of great value in hand-to-hand fighting. This important constituent of physical fitness is best developed by conditioning exercises which require extensive and rapid changes of position, and by such activities as tumbling, sports and games and combative activities.
  5. Coordination. Coordination is the ability to integrate all parts of the body into efficient, purposeful effort. In the well coordinated individual, superfluous movements are eliminated, precision and accuracy are increased, energy is conserved, and endurance increased.
5. NECESSITY FOR PHYSICAL TRAINING. The physical fitness required of the soldier can be acquired only through physical training. The performance of purely military exercises such as drill and marching, is not alone sufficient to bring the soldier up to the desired standard of physical fitness. Experience has demonstrated that few recruits enter the Army physically fit for the arduous duties ahead of them. The softening influences of our modern machine civilization make the problem of condition men more important than ever before. Within the Army itself labor-saving devices and mechanized equipment exert the same debilitating effect. If troops are to be brought up to the desired standard of physical fitness, a well-conceived plan of physical training must be an integral part of every training program. In no other way will the soldier be adequately prepared for the strenuous duties associated with military service.


  1. Unit commanders are responsible for the physical condition of their men just as they are responsible for all other aspects of their training. For this reason it is essential that company, battery and squadron commanders be cognizant of the importance of physical fitness and the activities and methods by which it is attained.
  2. Commanding officers themselves must take part regularly in the physical training activities. With the welfare of his organization and all his men dependent upon him, no commanding officer can afford to be lacking in physical fitness. Besides, his participation invariably results in better physical training programs. His presence inspires the men to their very best efforts. If the commanding officer delegates the leadership of physical training to another officer or non-commissioned officer his presence will bring forth their best efforts.



  1. If there is a proper concept of physical fitness, the physical training program will be directed toward the total conditioning of all the men. Since physical fitness includes strength, endurance, agility and coordination, it is apparent that no one activity is sufficient for its full development. Marching is a splendid conditioning activity, but it alone is not sufficient for the conditioning of troops because it does not adequately develop abdominal, arm and shoulder girdle strength, agility, coordination, or the type of endurance which is called for in running.
  2. The quality of a unit is determined by the over-all picture of physical condition and totally military fitness of all its members. It is more important that all men in a unit receive the benefits of a balanced and well directed program of physical training than that a few members achieve record performances. The physical training program, therefore, is directed toward the total conditioning of all men.
8. OBJECTIVES OF THE PHYSICAL TRAINING PROGRAM. The primary purpose of a physical training program is to develop and maintain a high level of physical fitness among the troops. However, while attaining this fundamental purpose, other valuable outcomes may be obtained.
  1. It is possible to develop through physical training many basic military skills which are essential to personal safety or to effective performance in combat operations. Swimming, running, jumping, vaulting, climbing, crawling, both with and without equipment are basic skills which should be taught to or further developed in all soldiers. Maneuverability, alertness, and ability to anticipate may be the means of saving a soldierís life and these can be developed through boxing, wrestling, and other competitive activities.
  2. Teamwork, aggressiveness, confidence, resourcefulness, a will to win, unit solidarity, and the ability to think and act quickly under pressure are other valuable products of the well conducted program of physical training.
  3. Recreation is another important objective of physical training provided it can be accomplished without sacrificing the physical fitness value of the program. Interesting and enjoyable physical activities not only provide a desirable diversion in the daily routine, but they also motivate men to participate more enthusiastically in the total physical training program.



  1. A wide variety of activities is available. These activities vary as to their values, limitations, interest, and facilities and equipment required. Those locally responsible must choose the activities best suited to the needs of the man being trained, and to the conditions at hand. The activities treated in this manual include: Conditioning exercises, Rifle exercises, Log exercises, Guerrilla exercises, Marching, running and grass drills, Obstacle and confidence courses, Strength course, Tumbling, Athletics, Relays, Combative activities, Swimming; Posture training.
  2. Many military and work activities also contribute to the development of physical fitness. While these activities are not included in the physical training program they must be considered as the program is planned (see par. 33a (3)).



  1. The low level of physical fitness of most recruits now entering service makes it necessary to devote more time to their conditioning than was formerly required. A daily period of at least 1 hour (1½ hours is recommended when training schedules permit) is required for this purpose until the troops acquire satisfactory condition. This will usually take from 10 to 15 weeks, depending upon the condition of the men at the outset. Once attained, a high level of fitness can be maintained on a somewhat reduced daily schedule when necessary, provided the time allotted for this purpose is properly used.
  2. It is the unit commanderís responsibility to ascertain that the time allotted to physical training is effectively used for that purpose. The complexities of modern warfare require so much technical training that all too frequently there is a tendency to subordinate physical training to other training activities. The utilization of physical training time for other training activities, or for routine military duties, is an unsound and unwise practice.



  1. Mental and Emotional Health. (1) Physical health cannot be dissociated from mental and emotional health. Ill health is almost as often due to conditions of the mind and emotions resulting in bodily ailment as it is due to purely physical causes. Therefore, some consideration must be given to mental and emotional as well as physical hygiene. (2) A healthy state of mind is characterized by cheerfulness, confidence and interest. An unhealthy state of mind is characterized by indifference, discouragement, worry, and a feeling of inferiority which may be due to lack of success or progress. Physical training can help to develop healthy mental states if: (a) The instructor is a worthy example to his men. (b) The instructor has an understanding, fair, and sympathetic attitude. (c) Work is interesting and varied. (d) Work is arranged to result in gradual and progressive development. (e) Individual physiological differences are considered.
  2. Personal Habits. Proper personal habits, such as cleanliness, proper eating, rest, and elimination should be stressed during instruction in physical training. The matter of a well-balanced diet is of particular importance. Many men increase their weight to such an extent that their physical condition is impaired. Proper diet is as important as exercise in improving the physical condition of men who are considerably overweight.
  3. Scheduling the program. (1) Physical training periods should not be scheduled for at least one hour after meals. After exercise at least 30 minutes should elapse before meals. It has been established that moderate exercise before breakfast is not harmful. However, the men should not begin with extremely vigorous running or strenuous conditioning exercises immediately after rising. If exercises are begun in a gradual manner, a vigorous activity period can be engaged in before breakfast without harmful results. In fact, in very hot climates, the best time to exercise is before breakfast. However, at least 30 minutes should elapse after exercising before the men eat breakfast. (2) The question is often raised as to the best time of the day for the physical training period. Since muscle cells do not recognize time, it is immaterial from the physiological standpoint when exercise is taken so long as it does not interfere with digestion. Where there are not enough physical training facilities and equipment for all units to use simultaneously, the physical training periods for various organizations should be distributed at different hours throughout the day if possible. If it is necessary to schedule all organizations at the same hour the last period of the afternoon is best since it enables the men to bathe immediately after the exercise. Objection is raised to this late afternoon physical training period on the ground that the men will be fatigued from their duties of the day and will be in no condition to put forth their best effort. It has been found, however, that a change of activity invigorates the men. It has been repeatedly demonstrated that the troops begin exercising in a fatigued condition and finish an hour later feeling considerably refreshed.
  4. Exercise in high temperature. Strenuous physical activity can be performed in extremely hot temperatures if men are given an opportunity to become acclimated to the heat and if they consume a sufficient quantity of salt and water. It is essential that physical training programs be continued in hot climates because men can better withstand high temperature when they are well conditioned.
  5. "Warm-Up." It is a fundamental physiological principle that the men should be "warmed up" gradually before engaging in strenuous exercise. The conditioning drills (see par. 48) are arranged to provide a "warm up." The men should double-time to the exercise area whenever possible.
  6. "Cooling Off." Upon finishing exercise, the men should be left mildly active, walking or performing some other muscular activity, until their respiration and temperature have returned to normal. In cool or cold weather, additional clothing should be worn. The men should never be allowed to cool down too rapidly.
  7. Uniform. (1) The uniform worn will depend upon the season of the year and the state of the weather. At no time should a uniform be worn which does not admit of the freest possible movement of the body. (2) Whenever practicable the men should dress in undershirt and shorts. Under favorable circumstances it is recommended that undershirts be removed. If fatigue uniforms are worn, the jackets should be removed for exercise where weather permits.
  8. Age. In combat, where severe physical demands are made upon the troops, all men, regardless of their age, must have the strength, stamina, agility and coordination to meet the situation. When individuals pass 30 years of age, it becomes increasingly difficult for them to reach and maintain a high level of physical fitness. Ample evidence is available that this can be done. But these men must work harder, longer, and more conscientiously at conditioning themselves; they must practice hygienic health habits; and they must learn how to conserve themselves.
  9. High Altitude. Certain problems are encountered in conditioning soldiers who are stationed in high altitudes. Physiologists have shown that under such conditions the heart undergoes greater exertion during exercises. It is particularly important that only light exercises be given in the early days of residence at such altitudes. Troops become physiologically adjusted to high altitudes within a few weeks by means of adaptation of the blood circulatory mechanism. After this has occurred, they may take a progressively greater amount of exercise. The amount and intensity of exercise which can be given safely is governed by the degree of respiratory distress, which should not exceed the limit for low altitudes.
JNC Nov 2002