Attenuated growth hormone response to resistance exercise with prior sprint exercise

Purpose: This study examined effects of prior sprint exercise on hormonal responses to subsequent resistance exercise with different recovery periods between exercise bouts. Methods: Nine men performed three types of exercise regimens: 1) resistance exercise only (R), 2) resistance exercise with prior sprint exercise and 60 min of rest (SR60), and 3) resistance exercise with prior sprint exercise and 180 min of rest (SR180). Sprint exercises consisted of maximal sprint cycling (eight sets of 5-s sprints with 30-s rest periods between sets) with prior 10-min warm-up. Resistance exercise consisted of five exercises, each with three sets at a 10-repetition maximum with 1-min rest periods. Results: Prior sprint exercise significantly increased blood lactate, glycerol, epinephrine, norepinephrine, growth hormone (GH), and free testosterone concentrations (P < 0.05). Before the resistance exercise, free fatty acids concentration was higher in the SR180 trial than in the SR60 and R trials (P < 0.05), whereas GH concentration was significantly higher in the SR60 trial (P < 0.01). After the resistance exercise, no significant difference was found in responses of pH, epinephrine, norepinephrine, and free testosterone among trials. The SR180 trial showed a smaller GH response (peak value: 7.8 +/- 1.6 (SE) ng(.)mL(-1)) than in the R trial (12.8 +/- 3.7 ng(.)mL(-1)), with no significant difference between trials. In the SR60 trial, GH response to resistance exercise was attenuated (3.3 +/- 1.2 ng(.)mL(-1), P < 0.01). Maximal strength and power measured immediately before the resistance exercise showed no difference among trials. Conclusion: These results indicate that GH response to resistance exercise was attenuated strongly when the exercise was preceded by sprint exercise and a shorter (60 min) recovery period.