Dynapenic-obesity and physical function in older adults.
BACKGROUND
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.


METHODS
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.


RESULTS
Within both sexes, the dynapenic-obese group had a slower walking speed than the non-dynapenic and non-obese and obese-alone groups (p <or= .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 <or= .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).


CONCLUSIONS
Dynapenic-obesity was associated with a poorer physical function than obesity alone and in most cases with dynapenia alone.
Bouchard
Danielle R
DR
School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada. danielle.bouchard@queensu.ca
Janssen
Ian
I
D015502:Absorptiometry, Photon; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018908:Muscle Weakness / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009765:Obesity / Q000150:complications* / Q000503:physiopathology; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies