The pursuit of a desired body weight, physique, or specific percentage of body fat is the primary reason why athletes gain or lose body weight. To reach their body composition goals, athletes should concentrate on three basic principles: (1) a good resistance-training program, (2) proper nutrition, and (3) rest.

Before embarking on a program to change body composition, athletes should have a general understanding of their somatotype and, thus, potential genetic limitation. The three basic somatotypes are ectomorph, mesomorph, and endomorph. Athletes usually present a predominance of one body type with some aspects of the other two.<sup>15 Tesch P.A. Skeletal muscle adaptations consequent to long-term heavy resistance exercise Med Sci Sports Exerc 1988 ;  20 (suppl 5) : 132-134

Cliccare qui per andare alla sezione Riferimenti</sup> Ectomorphs typically are lean and slightly muscular. Their genetic makeup does not lend them to easy weight gain. Mesomorphs are naturally muscular and strong, with a long torso and full chest. They can increase muscle size and strength quickly, especially when combined with the proper training and nutrition program. Endomorphs exhibit a stocky build; they have a wide chest and hips and short bones. For endomorphs, weight gain is easy and fat loss is arduous.

A common question of athletes and coaches is: How much lean body mass can a given athlete expect to gain? The rate and amount of weight gain and the specific muscles that are developed depend on an athlete's training program, diet, genetic predisposition, and motivation. Data show that body build has an impact on how much lean body mass an athlete is able to gain.<sup>16 Van Etten L.M.L.A., Verstappen F.T.J., Westerterp K.R. Effect of body build on weight-training–induced adaptations in body composition and muscular strength Med Sci Sports Exerc 1994 ;  26 : 515-521  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> And although it is possible for any athlete to gain some lean body mass, athletes with a solid body build can expect to gain more than athletes with a slender build.<sup>16 Van Etten L.M.L.A., Verstappen F.T.J., Westerterp K.R. Effect of body build on weight-training–induced adaptations in body composition and muscular strength Med Sci Sports Exerc 1994 ;  26 : 515-521  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Furthermore, initial gains greatly exceed subsequent gains because individuals tend to approach their genetic potentials relatively early in a training program.