Sex Differences in Upper-Body Strength, Lean Mass, and Bone Density Across the Adult Lifespan: Insights into Musculoskeletal Aging and Strength Preservation

Aging is associated with declines in upper-body strength, lean mass, and bone mineral density (BMD), yet sex-specific patterns of musculoskeletal aging remain unclear. This study examined relationships between upper-body strength, lean mass, and arm BMD across the adult lifespan in male and female participants. Upper-body strength (free-weight bench press one-repetition maximum [1RM]), arm BMD (g/cm² via dual-energy X-ray absorptiometry [DXA]), and lean body mass (kg via DXA) were assessed in 174 adults (105 females, 69 males; mean age = 53.5 ± 17.4 years). Hierarchical linear regression models examined associations between strength, BMD, and lean mass. Age was associated with lower bench press 1RM (β=−0.32, p<0.001) and arm BMD (β=−0.27, p<0.001) and was marginally significant with lean mass (β=−0.13, p=0.08). Male participants exhibited a stronger negative association between age and strength (β=−0.19, p<0.05). Female participants exhibited a marginally stronger negative association between age and arm BMD (β=0.22, p=0.061). Upper-body strength was positively associated with arm BMD (β=0.34, p<0.001), and the strength of this relationship increased with age (β=0.11, p<0.05) and was stronger in female participants (β=−0.56, p<0.001). Upper-body lean mass was associated with strength (β=0.62, p < 0.001) and BMD (β=0.43, p<0.001), but the strength-mass association weakened with age (β=−0.15, p<0.001) and was stronger in males (β=0.39, p<0.001). These findings highlight sex-specific differences in musculoskeletal aging, emphasizing the importance of strength preservation, particularly in female participants, for mitigating bone loss and osteoporosis risk.