12 weeks of combined exercise is better than aerobic exercise for increasing growth hormone in middle-aged women.

Background: The purpose of this study was to examine the effects of combined exercise training on growth hormone (GH), insulin-like growth factor-1 (IGF-1), and metabolic-syndrome factors and determine whether the changes in GH and/or IGF-1 induced by exercise correlate to the metabolic-syndrome factors in healthy middle-aged women (50-65 years of age).

Methods: The participants were randomly assigned into an aerobic-exercise training (walking + aerobics) group (AEG; n = 7), a combined-exercise training (walking + resistance training) group (CEG; n = 8), or a control group (CG; n = 7). Exercise sessions were performed 3 times per wk for 12 wk. The aerobic-exercise training consisted of walking and aerobics at 60-80% of heart-rate reserve, and the combined-exercise training consisted of walking and resistance exercise at 50-70% of 1-repetition maximum.

Results: GH, percentage body fat, fasting glucose, systolic blood pressure, and waist circumference were significantly improved in CEG (p < .05). However, GH induced by exercise training showed no correlation with metabolic-syndrome factors. IGF-1 was not significantly increased in either AEG or CEG compared with CG.

Conclusion: These results indicate that the combined-exercise training produced more enhancement of GH, body composition, and metabolic-syndrome factors than did aerobic-exercise training.