Strength is the ability of muscles to produce force in single and maximal effort. This depends upon the following physiological factors.
(a) Muscle cross-sectional area: It is generally measured with girth measurement. The muscle having bigger cross-section area has more strength because larger muscles have better quality of action and myosin filaments.
(b) Types of muscle fibre: There are two basic types of fibres.
(i) Slow twitch fibres
(ii) Fast twitch fibres.
Fast twitch muscle fibres lead to increase in muscle size and strength with greater explosive power. Every individual has different ratios of slow and fast twitch muscle fibres.
(c) Muscle length: Persons with relatively long muscles have greater potential for developing size and strength than person with relatively short muscles.
(d) Age and gender: Muscle strength declines with age due to decrease in muscle cross-sectional area. The strength changes with increase in age specially after 15 years. Men and women have similar tissues but men have bigger muscle size leading to better strength as compared to women.
(e) Nerve impulses: Your brain and nervous system have the power to activate more motor units when they need to generate a large amount of force. So nerve impulses, intensity and the number of motor units determine the muscular strength.