The influence of reproductive hormones on muscle strength

Muscle strength has been investigated across the menstrual cycle, following the menopause, throughout pregnancy and during in vitro fertilisation treatment. In addition, amenorrheic females, oral contraceptive users and individuals that administer hormone replacement therapy have been used to explore different models of reproductive status. The results of such studies have clinical and athletic significance. If changes in the concentration of reproductive hormones affect muscle strength then functional capacity and exercise performance will change with advancing age. Despite documented changes in strength due to altered reproductive functioning, no consensus has been reached as to the absolute or directional effects of oestrogen and progesterone on muscle strength. Such inconsistencies may arise from differences in the definition and quantification of reproductive status and muscle strength. Future research should focus on measuring the concentration of reproductive hormones at the time of strength assessment, using longitudinal study designs. This review presents the case for and against an inotropic effect of reproductive hormones and suggests why findings from studies in this area are so varied.