One of the most imprtant factor that affects muscular strength is muscle fibre type. We perform wide variety of activities combinig varying composites of speed, power and endurance and no single type of muscle fibers possesses all the characteristics. We possess two basic types of muscle fibers, frequently mentioned to as “slow twitch” and “fast twitch” muscle fibes.
Slow twitch muscle fibers are best used for cardiovascular (aerobic) activities. They produce low levels of force for long periods of time and so they are better suited for endurance activities. The average person has fifty percent slow-twitch fibers, and this distribution is generally equal throughout the major muscle group.
Fast twitch fibers are best used for anaerobic activities. They bring about high levels of power for short periods of time and are best suited for power activities. These types of muscle fibers are designated as type 2b. These fibers are classic anaerobic fibers because they rely on energy sources from within the muscle (e.g. Creatine phosphate). When an endurance factor is introduced such as in events lasting upward of several minutes, a second type of muscle fibers, type 2a is recruited, type 2a fibers represents the forms between the needs met by the type 1 and type 2b fibers. They have ability to generate a fairly large amount of force, they also have some aerobic capacity, although not as much as that of slow-twitch fibers.
Although both fiber types respond positively to strength training exercises, the fast twitch types experience greater gains in muscle size and strength, and thus may obtain larger and quicker results from a strength training regime.