Associations of Sarcopenic Obesity and Dynapenic Obesity with Bone Mineral Density and Incident Fractures Over 5-10 Years in Community-Dwelling Older Adults

The purpose of this study is to determine whether low muscle mass (sarcopenia) or strength (dynapenia), in the presence of obesity, are associated with increased risk for osteoporosis and non-vertebral fracture over 5-10 years in community-dwelling older adults. N = 1089 volunteers (mean +/- SD age 62 +/- 7 years; 51 % female) participated at baseline and 761 attended follow-up clinics (mean 5.1 +/- 0.5 years later). Total body, total hip and spine BMD, and appendicular lean and total fat mass were assessed by DXA. Sarcopenic obesity and dynapenic obesity were defined as the lowest sex-specific tertiles for appendicular lean mass or lower-limb strength, respectively, and the highest sex-specific tertile for total fat mass. Fractures were self-reported on three occasions over 10.7 +/- 0.7 years in 563 participants. Obese alone participants had significantly higher BMD at all sites compared with non-sarcopenic non-obese. Sarcopenic obese and dynapenic obese men had lower spine and total body BMD, respectively, and sarcopenic obese women had lower total hip BMD, compared with obese alone (all P < 0.05). Sarcopenic obese men had higher non-vertebral fracture rates compared to non-sarcopenic non-obese (incidence rate ratio: 3.0; 95 % CI 1.7-5.5), and obese alone (3.6; 1.7-7.4). Sarcopenic obese women had higher fracture rates compared with obese alone (2.8; 1.4-5.6), but this was non-significant after adjustment for total hip BMD. Sarcopenic and dynapenic obese older adults may have increased risk of osteoporosis and non-vertebral fracture relative to obese alone counterparts. Sarcopenic and dynapenic obese individuals potentially represent a subset of the obese older adult population who require closer monitoring of bone health during ageing.