Skeletal muscle comprises 40-45% of the mass of the body of a health individual (Rooyacker et al., 1997). The functional demands placed upon skeletal musele vary greatly throughout the day, from repetitive tasks against very low resistance, to explosi...
Skeletal muscle comprises 40-45% of the mass of the body of a health individual (Rooyacker et al., 1997). The functional demands placed upon skeletal musele vary greatly throughout the day, from repetitive tasks against very low resistance, to explosive powerful contraction against very high resistance. Training for athletic competition takes advantage of the muscle's ability to adapt to the functional demands placed upon it over weeks and years of training. Critical to the adaptation produced is the manner in which the muscle is trained, whether it be repeated contractions against relative light loads muscle mass. Due to the fact that many of the most popular sports in the world, such as soccer, basketball, baseball, and football require intermittent bursts of very powerful movements, there is a great interest in increasing muscle mass. Maximal force is directly cross sectional area of muscle and maximal power is derived from the maximal force that can be developed per unit of time, usually in terms of milliseconds. Over the years many researchers have attempted to develop models to better understand how the alterations of mechanical load and hormonal milieu might optimize increases in muscle mass and concomitant increases in power. This article will primarily focus on animal models that have been utilized to increase muscle mass. Included in this review will be models that elevated mechanical load upon skeletal muscle, either chronically or intermittently, as well as the influence of IGF-1, a hormone that has both a myogenic and mitogenic efect upon skeletal muscle.