Sex hormone effects on the nervous system and their impact on muscle strength and motor performance in women

Abstract

The endocrine system, of which sex hormones are a part, and the nervous system both can exert strong effects far beyond their local tissue of origin. This chapter first examines how sex hormones and their metabolites affect the nervous system at the molecular level. Since singular sex hormones do not exist in isolation in humans, the effect of sex hormones on strength and motor performance are then viewed through the lens of the menstrual cycle. While there are clear and repeatable effects of sex hormones on the nervous system at the molecular level, reliably reproducing these effects on motor activity at the clinical level remains a challenge. Evidence suggests that maximal strength may be lower, but fine motor control may be higher in the mid luteal phase of the menstrual cycle. However, not all studies have replicated these findings; the probable causes of this discrepancy are unrecognized menstrual cycle irregularities, intraindividual differences and a nonuniform distribution of sex hormones in tissues around the human body. Given the potential for sex hormones to both enhance and limit human performance, clinicians should be aware of their patients or clients menstrual status but cautious in attempting to leverage the nervous system effects of sex hormones towards training or rehabilitation enhancement.