Reduced muscle strength (dynapenia) in women with obesity confers a greater risk of falls and fractures in the UK Biobank.

OBJECTIVE: This study aimed to determine the independent effects of obesity and dynapenia on falls risk, areal bone mineral density, and fracture risk (lower extremity or all other fractures). METHODS: A total of 16,147 women (aged 60-82 years) from the UK Biobank were categorized by handgrip strength (HGS; dynapenia status: HGS ≤ 21 kg) and body weight (BMI: normal weight, overweight, or obesity). Multiple logistic regression models examined the association among dynapenia and obesity and self-reported falls (previous 12 months), lower extremity fractures, and all other fractures (previous 5 years). RESULTS: A total of 3793/16,147 women fell, and 1413/15,570 (9.1%) eligible women experienced fall-related fractures. Obesity (odds ratio [OR] 1.25; 95% CI: 1.12-1.38) and dynapenia (OR 0.87; 95% CI: 0.77-0.98) were both independently associated with greater lower extremity fracture risk, independently of areal bone mineral density. However, considering all other fracture sites, obesity conferred protection (OR 0.77; 95% CI: 0.61-0.96), except in those with low HGS, who had an equivalent fracture risk to those with normal weight (OR 1.06; 95% CI: 0.82-1.38). CONCLUSIONS: Dynapenia further increases the increased risk of leg and ankle fractures in obesity and counteracts the protective effects of obesity on fracture risk at all other sites (wrist, arm, hip, spine, other bones).