Greater growth hormone and insulin response in women than in men during repeated bouts of sprint exercise

Aim: In a previous study, sprint training has been shown to increase muscle cross-sectional area in women but not in men [Eur J Appl Physiol Occup Physiol 74 (1996) 375]. We hypothesized that sprint exercise induces a different hormonal response in women than in men. Such a difference may contribute to explaining the observed gender difference in training response. Method: Metabolic and hormonal response to three 30-s sprints with 20-min rest between the sprints was studied in 18 physically active men and women. Results: Accumulation of blood lactate [interaction term gender (g) x time (t): P = 0.022], and plasma ammonia (g x t: P < 0.001) after sprint exercise was greater in men. Serum insulin increased after sprint exercise more so in women than in men (g x t: P = 0.020), while plasma glucose increased in men, but not in women (g x t: P < 0.001). Serum growth hormone (GH) increased in both women and men reaching similar peak levels, but with different time courses. In women the peak serum GH level was observed after sprint 1, whereas in men the peak was observed after sprint 3 (g x t; P < 0.001). Serum testosterone tended to decrease in men and increase in women (g x t: P = 0.065). Serum cortisol increased approx. 10-15% after sprint exercise, independent of gender (time: P = 0.005). Conclusion: Women elicited a greater response of serum GH and insulin to sprint exercise. This may contribute to explaining the earlier observed muscle hypertrophy in women in response to sprint training.