Copeland, J. L., & Tremblay, M. S. (2003). Resistance training and the GH/IGF-I axis in women; Influence of age, estrogen, and training status. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1363.

Declining levels of anabolic hormones, such as growth hormone (GH) and insulin-like growth factor-1 (IGF-1), may exacerbate age-related losses of lean body mass and physical function in women. This study examined the effect of resistance training on the GH-->IGF-I response in women of different ages and estrogen levels. Postmenopausal women (N = 16) using supplemental estrogen, postmenopausal women (N = 16) not using estrogen, and premenopausal women (N = 13) were recruited as Ss. Ss from each group were assigned to a 12-week resistance-training or a control (no resistance training) group. Resistance exercise performances were compared at weeks 0 and 13. Pre- and post-exercise and 15-min post-exercise blood samples were taken at the same stage of the investigation but when testing coincided with the early follicular phase of the menstrual cycle.

Resting estrogen levels were significantly different between all groups with the supplemented group being the highest and non-supplemented postmenopausal group the lowest. A training effect (post-exercise lactate levels) occurred after the 12-week program. Growth hormone increased significantly in response to exercise sessions. Post-exercise growth hormone levels were similar between all groups, but the rebound response was significantly greater in the premenopausal-exercise group. All training groups exhibited an increased post-exercise IGF-I response. There were no group differences in exercise IGF-I responses.

Implication. Training status and exercise intensity appear to have a greater effect on growth hormone levels in women, more so than age or estrogen levels.

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