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 the 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 yr). 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 the sex-specific differences in musculoskeletal aging, emphasizing the importance of strength preservation, particularly in female participants, for mitigating bone loss and osteoporosis risk.NEW & NOTEWORTHY This study reveals that upper-body strength declines more rapidly in males than females with age, whereas trending results suggest that bone mineral density may show a stronger decline in female participants. We found that upper-body strength and lean mass predict arm bone mineral density, and these relationships strengthen with age. These findings highlight the importance of maintaining upper-body strength for skeletal health, particularly in female participants, to mitigate osteoporosis risk.