Dynapenic-Obesity and Physical Function in Older Adults

Dynapenia (low muscle strength) and obesity are associated with an impaired physical function. It was hypothesized that older individuals with both conditions (dynapenic-obesity) would have a more impaired physical function than individuals with dynapenia or obesity alone. This cross-sectional study included 2,039 men and women aged 55 years and older from the 1999-2002 National Health and Nutrition Examination Survey. Fat mass was measured by dual-energy x-ray absorptiometry and leg strength by dynamometer. Based on fat mass and leg strength tertiles, four independent groups were identified: non-dynapenic and non-obese, obese alone, dynapenic alone, and dynapenic-obese. An objective physical function measure was obtained from a 20-foot walking speed test, whereas subjective physical function measures were obtained from five self-reported questions. Within both sexes, the dynapenic-obese group had a slower walking speed than the non-dynapenic and non-obese and obese-alone groups (p < .01) but not the dynapenic-alone group. Similarly, with the exception of the dynapenic-alone group in men, the global subjective score was lower in the dynapenic-obese group than in the non-dynapenic and non-obese and obese-alone groups (p < .01). By comparison to the dynapenic-obese group, the adjusted odds ratios (95% confidence interval) for walking disability were 0.21 (0.12-0.35) in the non-dynapenic and non-obese, 0.34 (0.20-0.56) in the obese-alone, and 0.54 (0.33-0.89) in the dynapenic-obese groups. The corresponding odds ratios for a disability based on the global subjective score were 0.20 (0.09-0.42), 0.60 (0.30-1.21), and 0.41 (0.19-0.87). Dynapenic-obesity was associated with a poorer physical function than obesity alone and in most cases with dynapenia alone.