The relationship between exercise - induced and non - stimulated 24 - hour growth hormone

The purpose of this study was to quantify the relationship between the acute exercise-induced growth hormone (GH) response, gender, fitness, age, and body composition with non-exercise stimulated (NES) 24-hr integrated GH concentration (IGHC). Twenty-nine subjects (16 males, 13 females) completed a 24-hr control session without exercise (NES) on one occasion and a 30min exercise session on a separate occasion. The GH release was analyzed from 10-min intervals using trapezoidal integration during both sessions. Multiple regression analysis in males revealed that significant variability in NES 24-hr IGHC could be adequately explained by subject age and BMI together (P<0.05), but could not be explained by exercise-induced peak GH or 30-min of exercise-induced IGHC on an unrelated day (P=0.750). However, significant variability in NES 24-hr IGHC in females could be uniquely associated with subject age (P<0.05) as well as peak GH and 30-min of exercise-induced IGHC (P<0.05). The findings indicate that in the females only the constant load exercise-induced growth hormone response can adequately predict total 24-hr growth hormone output on a separate day without an exercise stimulus. The data further exemplify gender disparities in exercise-induced growth hormone release and the importance of exercise for females in regards to enhancing total 24-hr growth hormone concentrations.