Background: The factors that regulate the growth hormone (GH) response to physiological stimuli, such as exercise, are not fully understood. The aim of the present study is to determine whether age, body composition, measures of sprint performance or the metabolic response to a sprint are predictors of the GH response to sprint exercise in non-obese young men. Methods: Twenty-seven healthy, non-obese males aged 18-32 years performed an all-out 30-second sprint on a cycle ergometer. Univariate linear regression analysis was employed to evaluate age-, BMI-, performance- and metabolicdependent changes from pre-exercise to peak GH and integrated GH for 60 min after the sprint. Results: GH was elevated following the sprint ( change in GH: 17.0 +/- 14.2 mu g l(-1); integrated GH: 662 +/- 582 min mu g l(-1)). Performance characteristics, the metabolic response to exercise and BMI were not significant predictors of the GH response to exercise. However, age emerged as a significant predictor of both integrated GH (beta = - 0.547, p = 0.003) and change in GH (beta = - 0.448, p = 0.019) after the sprint. Conclusion: In non-obese young men, age is a more important predictor of GH following sprint exercise than BMI, sprint performance or the metabolic response to sprint exercise. Copyright (c) 2006 S. Karger AG, Base.