Hormone Therapy and Skeletal Muscle Strength

Background. Our objective was to perform a systematic review and meta-analysis of the research literature that compared muscle strength in postmenopausal women who were and were not on estrogen-based hormone therapy (HT). Methods. Twenty-three relevant studies were found. Effect sizes (ESs) were calculated as the standardized mean difference, and meta-analyses were completed using a random effects model. Results. HT was found to result in a small benefi cial effect on muscle strength in postmenopausal women (overall ES = 0.23; p = .003) that equated to an ~ 5% greater strength for women on HT. Among the 23 studies, various muscle groups were assessed for strength, and those that benefi tted the most were the thumb adductors (ES = 1.14; p < .001). Ten studies that compared muscle strength in rodents that were and were not estradiol defi cient were also analyzed. The ES for absolute strength was moderate but not statistically signifi cant (ES = 0.44; p = .12), whereas estradiol had a large effect on strength normalized to muscle size (ES = 0.66; p = .03).