Women experience significant changes in endocrine function during aging. Decreasing levels of anabolic hormones may be associated with musculoskeletal atrophy and decrease in function that is observed in older women and, as a result, there has been an increase in the use of pharmacological hormone therapies. It is difficult to distinguish, however, between physiological changes that are truly age related and those that are associated with lifestyle factors such as physical activity participation. Some research has shown that circulating levels of anabolic hormones such as DHEA(S) and IGF-I in older women are related to physical activity, muscle function, and aerobic power. Exercise-intervention studies have generally shown that increasing age blunts the acute hormonal response to exercise, although this might be explained by a lower exercise intensity in older women. There have been relatively few studies that examine hormonal adaptations to exercise training. Physical activity might have an effect on hormone action as a result of changes in protein carriers and receptors, and future research needs to clarify the effect of age and exercise on these other components of the endocrine system. The value and safety of hormone supplements must be examined, especially when used in combination with an exercise program.
Copeland is with the Dept. of Kinesiology at the University of Lethbridge, Lethbridge, Alberta, T1K 3M4 Canada. Chu is with the Biochemistry Dept., Dr. Everett Chalmers Hospital, Fredericton, NB, E3B 5N5 Canada. Tremblay is with the College of Kinesiology, University of Saskatchewan, Saskatoon, SK, S7N 5C2 Canada, as was Copeland at the time of this study.