The paper deals with changes in body composition (muscle mass, adipose tissue and bone mass), and changes in manifestations of maximal strength of extensors and flexors of lower and upper limbs in relation to different periods of rest (30 s, 60 s, 120 s). The research was carried out on 23 participants aged 18-30 years in natural bodybuilders of top performance, in a 5-week training intervention of bodybuilding training. At a statistical significance level of 5%, there was no significant difference in muscle tissue hypertrophy, although Group 2 (60 p.) Achieved a two-fold increase in percentage FFM compared to the other two groups, achieving a change of 1.18 %. At a statistical significance level of 5%, we noticed significant differences in the maximum force increase in knee joint flexors, and only in group 3 (120 s) by up to 11%. Significant differences in muscle strength increase were also observed in groups 2 and 3 in the elbow joint extensors and in the elbow joint flexors only in group 1.