Exercise-induced effects on growth hormone levels are associated with ghrelin changes only in presence of prolonged exercise bouts in male athletes

Aim. The aim of this study was to evaluate growth hormone (GH) and ghrelin levels in response to physical exercise in athletes. Methods. Two different exercise workloads were administered in two different groups of athletes. Group A athletes (19 males, 18 females; mean age ± standard deviation: 25±6.7 years), performing a 60-90 min training session at approximately 80% of VO₂max, were sampled for GH and ghrelin determinations before and immediately at the end of a training session on-the-field. Group B athletes (4 males; mean age: 28.2±7.2 years) performed two consecutive 30-min cycling sessions at 80% of individual VO₂max at different time intervals between bouts (2 and 6 h) in two different days. GH and ghrelin concentrations were determined in blood samples collected at 15-min intervals during exercise and following 1 h of recovery. Results. In group A athletes, GH levels increased after the training session (P