Lower extremity motor performance and body mass index in elderly people: the Italian Longitudinal Study on Aging

OBJECTIVES: To test the association between body mass index (BMI) and lower extremity motor performance in elderly people.
DESIGN: Multicenter, cross-sectional, observational study.
SETTING: A sample of individuals aged 65 and older recruited for the baseline survey of the Italian Longitudinal Study on Aging.
PARTICIPANTS: Two thousand six hundred seventy-two individuals (1,436 men, 1,236 women) independent with transfers and toileting and independent or requiring assistance for bathing or dressing.
MEASUREMENTS: Motor function was assessed using a Motor Performance Test (MPT), with a set of six tasks exploring lower extremity performance (LEP): rising once from a chair, turning in a half circle, tandem walking, standing on one leg, stair climbing, and walking 5 m.
RESULTS: The highest prevalence rates of difficulty in performing the tasks occurred in men and women, respectively, in tandem walking (14%, 28%), stair climbing (17.0%, 43%) and walking 5 m (15%, 30%). In both sexes, moderate (men: odds ratio (OR)=1.99, 95% confidence interval (CI)=1.16–3.43; women OR=2.07, 95% CI=1.18–3.65) and severe obesity (men: OR=3.45, 95% CI=1.21–9.89; women: OR=3.16, 95% CI=1.43–6.95) were each independently associated with overall motor performance impairment after adjusting for age, smoking, and comorbidity. Best performance was generally observed in the normal-weight and overweight groups.
CONCLUSION: The results confirm that, in both sexes, overweight is not related to motor impairment. Only in women, low BMI is associated with higher probability of overall motor performance impairment. These data suggest that moderate obesity should be distinguished from severe obesity when assessing the relationship between BMI and LEP.