No influence of body composition on serum growth hormone response to acute dynamic exercise.

Physical effort is a strong physiological stimulus that provokes an increase in blood growth hormone (GH) concentration. Interactions between GH and body composition are very complex. Seven athletes and seven age-matched controls completed a single 30-min bout of upright cycling exercise (5 % of VO(2max).) in order to estimate the influence of body composition on serum GH concentration during exercise. The serum GH concentration was measured in blood samples by standard immunoradiometric (IRMA) method. Anthropometric measurements were used for the calculation of body composition. There were no significant differences in total body mass or body mass index between the groups. The athletes had significantly less fat and higher bone and muscle mass. Serum GH concentration was 2.39 times higher in the athlets versus the control in the period of rest. During acute exercise, the serum GH concentration increased in both groups. No statistically significant differences between the groups in serum GH concentration were found either during the exercise or in the recovery. No correlation between body composition and serum GH concentration was found. Body composition depends on the level of physical activities but if the total body mass is in physiologycal range it does not influence the serum GH response to acute exercise.