Effects of aerobic and resistance training on bone and muscle remodeling in an ovariectomy-induced osteopenia murine model

Abstract

Estrogen deficiency associated with ovarian senescence leads to an imbalance in bone remodeling, resulting in reduced bone mineral density, microarchitectural deterioration, and increased fracture risk. In this context, physical exercise has been widely investigated as a nonpharmacological strategy capable of modulating bone metabolism and the muscle–bone axis. The present study was structured into two complementary chapters, comprising a systematic review with meta-analysis and a preclinical experimental study. Chapter 2, entitled “Resistance training and bone mineral density in rodent models of menopause: review and meta-analysis”, aimed to synthesize and quantify the effects of resistance training on bone mineral density in ovariectomy-induced osteopenia models. The protocol was registered in PROSPERO and conducted in accordance with PRISMA guidelines. The meta-analysis, including nine studies, demonstrated a significant increase in bone mineral density compared to sedentary groups, with a standardized effect size of 3.02 (95% CI 1.81–4.24) for climbing protocols and 1.27 (95% CI 0.72–1.82) for jumping protocols. Chapter 2, entitled “Aerobic and resistance training in estrogen deficiency: a comparative study of bone remodeling and skeletal muscle adaptations”, investigated the effects of aerobic and resistance training in ovariectomized mice. Both exercise protocols significantly reduced osteoclast number and increased osteoblastic activity (p < 0.05), along with a marked reduction in the RANKL/OPG ratio (p < 0.001). However, resistance training elicited superior effects, including higher osteocyte density (p < 0.01), increased RUNX2 expression (p < 0.001), and greater muscle fiber cross-sectional area, accompanied by elevated IGF-1 and FNDC5 expression, indicating enhanced osteogenic stimulus and intensified muscle–bone crosstalk. Taken together, these findings demonstrate that physical exercise attenuates bone deterioration associated with estrogen deficiency, with resistance training emerging as a more effective strategy for promoting integrated bone and muscle health.