Training produces physicochemical changes Training produces physicochemical changes in the tissues which enable the athlete to maintain an almost unchanged internal environment in spite of very strenuous exertion. As athletic condition is improved the decrease in alkali reserve after a standard exercise is lessened. The same is true of other changes which indicate the degree of breakdown of homeostasis under stress. Blood Training diminishes the rate of lactic acid formation in moderate exercise so that the blood lactate concentration is lower than in untrained subjects. The greater alkali reserve of the trained subject allows a larger maximal blood lactate concentration to be tolerated in exhausting exercise. The interaction of these two factors considerably elevates the work tolerance of the trained subject.Extensive training lowers the osmotic resistance of red blood corpuscles, apparently as a result of the repeated rises in body temperalure associated with exercise. Decreased red cell resistance is observed after hot baths, but not after swimming. The number and diameter of the erythrocytes is increased by training, perhaps as an adjustment to their increased fragility, but the increase in hemoglobin concentration is somewhat less. indicating a smaller amount of hemoglobin in each red cell. Respiration Frequently repeated episodes of deep, labored breathing which accompany training exercises may produce extensive changes in the respiratory system. The increased stretching of the lung tissues results in a thickening of the alveolar septa, an increase in elastic fibers and perhaps in the actual production of new alveoli. This excessive multiplication of alveolar tissue represents a true hyperplasia (formation of new elements, not simple enlargement of already existing elements), and is called "sport lung." Training also causes a marked hypertrophy of the diaphragm. The improved respiratory efficiency resulting from training is manifested by a greater absorption of oxygen per liter of ventilation.		Home Components of Physical Fitness Clinical Examination Differences Between Fit and Unfit Men Physiological Elements of Fitness The Step Test The Effects of Training on the Physiological Systems Work Output Physical Condition of Muscle Application of Muscular Force Maintaining Optimum Strength Tests of Muscular Strength Strength and appearance Strength as a measure of physical fitness Strength as affected by organic problems Strength as prophylaxis Role of inactivity in production of disease Lack of Sociability in Work Lactic Acid System Muscular Form Capillary Growth Heart Size Heart Rate Training produces physicochemical changes Muscular Strength Nervous Stimulation and Muscular Strength Quality of Champions Factors Which Limit Skill Kinesthesis Balance Reaction Time Muscular Tension Visual Aim