Comparing aerobic and resistance training in estrogen deficiency: bone and muscle adaptations

The reduction in bone mass and deterioration of bone microarchitecture are hallmark consequences of estrogen deficiency during menopause, increasing susceptibility to osteopenia and osteoporosis. Physical exercise is recognized as an effective non-pharmacological strategy; however, the comparative effects of different exercise modalities on bone remodeling and muscle-bone crosstalk remain unclear. This study investigated the effects of aerobic and resistance training on femoral bone metabolism and skeletal muscle adaptations in ovariectomized (OVX) mice.

Sixty-four female C57BL/6J mice underwent ovariectomy or sham surgery and were allocated to sedentary, aerobic (treadmill running) or resistance (ladder climbing) training protocols for 8 weeks. Bone histological and histochemical analyses, skeletal muscle morphology and gene expression in bone and muscle tissues were evaluated.

Both training modalities significantly increased the osteoblast number and reduced the osteoclast density in OVX animals compared with sedentary controls (p < 0.05), accompanied by a reduction in the RANKL/osteoprotegerin (OPG) ratio (p < 0.001). Resistance training induced more pronounced effects, including higher osteocyte density (p < 0.01), greater RUNX2 expression (p < 0.001) and stronger suppression of osteoclastogenesis. In parallel, resistance training significantly increased the muscle fiber cross-sectional area (p < 0.05) and upregulated IGF-1 (p < 0.01) and FNDC5 expression (p < 0.05).

These findings demonstrate that exercise mitigates estrogen deficiency-induced bone deterioration, with resistance training exerting superior effects on bone remodeling and musculoskeletal integration.