Muscular Form Muscular form is changed if the training is begun at an early age. The skeleton of the youth is also affected by training so that running may actually produce a "runner type." Active muscles of animals are often redder than less active muscles due, perhaps, to an increased hemoglobin content. Oxygen Consumption The ability of the muscles to absorb and utilize oxygen in rest and during exercise is increased by training. The trained athlete can consume considerably larger volumes of oxygen during exhausting work than he could before training started. While in training he is not only able to consume more oxygen, but he can also contract a much larger oxygen debt. Training also decreases the length of time which is necessary to attain a steady state of oxygen consumption during moderate activity. If the work is longcontinued, the oxygen consumption of the trained subject remains constant throughout, whereas in untrained subjects the oxygen consumption is increased as exhaustion is approached. The increased oxygen consumption at the onset of exhaustion is attributed in part to the inefficiency of movement as coordination begins to be impaired by fatigue. Basal Metabolic Rate The basal metabolic rate of athletes often increases slightly (about 2 per cent) during training and falls to the pro-training level after the season of competition is over. This is probably related to the increase in mass and tone of the skeletal muscles during the period of training. Seasonal changes in the basal metabolic rate were greater than the changes due to training. The lowest rates were recorded in late December and the highest rates in early March. The drop in December was probably the result of a general reduction in physical activity due to examinations and holidays. The rise in metabolic rate in March was perhaps due to a general increase in physical activity, since most of the athletic competition took place at that time.		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 Kinesthesis Balance Reaction Time Muscular Tension Visual Aim