Exercise type and fat mass loss regulate breast cancer-related sex hormones in obese and overweight postmenopausal women

Purpose The aim of the study was to examine the effects of a time-matched endurance versus concurrent training on circulating sex hormone levels and body composition in postmenopausal women. Methods Thirty-five sedentary and obese postmenopausal women were recruited and randomly divided into endurance training (EN, n = 10), concurrent training (CON, n = 13), or control group (C, n = 12). Participants took part in a 12-week supervised intervention, training 3 days/week and 60 min/session. Before and after the intervention, body composition was assessed, and blood samples were obtained to evaluate estradiol, testosterone, DHEA-S, and SHBG. Result In response to training, a reduction in total fat mass was found (5.3%; P < 0.05), while an increase in lean body mass was observed in the CON group (1.5%; P < 0.05). There was a significant decrease in DHEA-S (− 13%), total (− 40%) and free testosterone (− 41%) in the EN group, while in the CON group, total (25%) and free testosterone (21%) increased significantly ( P < 0.05). When participants were stratified according to fat mass loss (> or < 2 kg), a statistically significant increase in circulating SHBG (21%) and decrease in DHEA-S (− 13%) were found. Conclusion The type of exercise and exercise-induced fat mass loss seem to modify the sex hormone profile in postmenopausal women that is an established risk factor of breast cancer. Thus, this study provides additional evidences to the intricated interaction among sex hormones, adipose tissue, and muscle mass in postmenopausal women.