physical therapy or physiotherapy, treatment of disorders of the muscles, bones, or joints by means of physical agents—heat, light, water, manual and electronic massage, and exercise. Stroke, arthritis, fractures, and nerve damage are common conditions treated. The type of treatment needed is prescribed by a physician and carried out by trained physiotherapists. The therapist attempts to prevent pain or further damage and may also train different muscles to compensate for ones that have been damaged. Whirlpool baths are valuable in treating injuries and chronic inflammatory conditions. Ultrasound and short-wave diathermy may be employed for some disorders. Massage (a passive form of exercise) provides stimulation of nerves and prevents muscular atrophy in body areas disabled by paralysis or rheumatic disorders. Active exercises are also prescribed as treatment for various conditions. Physiotherapy is important in sports, not only as part of the conditioning program but also in treating injuries.

physical geography: see geography.

physical fitness, combined good health and physical development. The object of any program of physical fitness is to maximize an individual's health, strength, endurance, and skill relative to age, sex, body build, and physiology. These ends can only be realized through conscientious regulation of exercise, rest, diet, and periodic medical and dental examinations. Exercise should be regular and vigorous, but begun slowly and only gradually increased in strenuousness. Popular exercise methods include jogging, cycling, and the use of body-building machines. It is more important that periods of sleep be regular and restful than that they extend any fixed number of hours. A properly balanced diet in proteins, carbohydrates, vitamins, and minerals is essential. Conscientious dental hygiene and periodic checkups are also strongly advised. Complete and regular physical examinations should be the basis of any program of physical development. Tobacco smoking, as well as alcohol and drug consumption, are counterproductive to any physical fitness program. Although sports are related to physical fitness, care must be taken that injuries do not occur, and that the skin is adequately protected against the cancerous effects of solar radiation.

physical examination: see diagnosis.

physical education and training, organized instruction in motor activities that contribute to the physical growth, health, and body image of the individual. The historical roots of physical education go back as far as the ancient Chinese (c.2500 B.C.), who had a well-developed system of exercise and physical training. In ancient Greece the Athenians were concerned with both physical and mental development and consequently they accorded gymnastics, sports, and rhythms an important educational role. During the period of the Roman Empire, and later during the Middle Ages, physical education was primarily used as a form of military training.

Interest in physical education as a part of the total individual's development was revived during the Renaissance. It was not until the 19th cent., however, that systems of gymnastics were developed in several European countries, notably Germany, Sweden, and England. In the same century gymnastics spread to the United States. Interest in the new system led to a movement to have compulsory physical training in American public schools and to establish physical education in colleges and universities. The first department of physical education at an American college was established at Amherst (1860).

Today, physical education is a required part of most school curricula, and a number of colleges and universities offer degrees in the field. Physical education classes generally include formal exercises, sports, and contests, although an increasing emphasis has been given to such Asian techniques as yoga, karate, and judo. The American Alliance for Health, Physical Education, Recreation and Dance (founded 1885) is concerned with improving its fields of education and with increasing the public's knowledge and appreciation of physical education.

physical chemistry, branch of science that combines the principles and methods of physics and chemistry. It provides a fundamental theoretical and experimental basis for all of chemistry, including organic, inorganic, and analytical chemistry. In addition, it is the foundation of chemical engineering. Topics of interest are chemical equilibrium, reaction rates, solutions, molecular weights, molecular structure, and the properties of gases, liquids, crystals, and colloids. Among other factors, the influence of temperature, pressure, electricity, light, concentration, and turbulence are considered. There are three principal approaches in physical chemistry: thermodynamics, involving large numbers of molecules in equilibrium; kinetics, involving chemical changes with time; and molecular structure, involving the electronic and atomic arrangements that follow from the quantum theory. The latter approach is primarily theoretical and provides an understanding of the chemical bonds which are responsible for the structure of all materials.

or physiatry or physical therapy or rehabilitation medicine

Medical specialty treating chronic disabilities through physical means to help patients return to a comfortable, productive life despite a medical problem. Its objectives are pain relief, functional improvement or maintenance, training in essential activities, and functional testing of areas such as strength, mobility, breathing capacity, and coordination. Physical medicine may use diathermy, hydrotherapy, massage, exercise, and functional training. The last can mean learning to work with a guide dog or a prosthesis or learning new ways to carry out everyday activities with a limb missing, sometimes by using assistive devices. Physician specialists head rehabilitation teams including a physical therapist, rehabilitation engineer, rehabilitation nurse, psychological counselor, and sometimes a respiratory or speech therapist. Seealso occupational therapy; orthopedics.

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Training in physical fitness and in skills requiring or promoting it. In the U.S. it is required in most primary and secondary schools. It generally includes calisthenics, gymnastics, various sports, and some study of health. College majors in physical education have been available since the early 20th century. Most teaching is done in gymnasiums, though outdoor sports are also emphasized.

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