Sports physiology is the study of the long and short term effects of training and body conditions of athletes. Indeed, it is the study of how exercise or sport activity alters the function and structure of our body. As a matter of fact, when we take part in games and sports or do physical exercises, certain physiological changes such as aerobic capacity, muscle composition size of muscles, intensity of the nerve impulse, lactic acid tolerance, muscular strength, stroke volume, heart rate, blood pressure, etc take place these physiological changes are witnessed both in young population nd in aged people also. There are various physiological factors that determine the components of physical fitness such as strength speed endurance flexibility etc The various physiological factors that determine physical fitness are described below. The various physiological factors which determine the strength of an individual are started below. The strength of the muscle largely depends upon the size of the muscle. It is a well-known fact that bigger and larger muscles can produce more force. To force produced by the same size of muscle in males and females is approximately same but males are found to be stronger because they have larger and bigger muscles in comparison to females with the help of different methods of strength training such as weight training, the size of the muscle can be increased and thereby strength is improved so the strength is determined by the size of the muscle.