Exercise’s Effect on Mobility Disability in Older Adults With and Without Obesity: The LIFE Study Randomized Clinical Trial

OBJECTIVE: Some data suggests that obesity blunts the benefits of exercise on mobility in older adults. We tested the homogeneity of the effect of a physical activity intervention on major mobility disability across baseline obesity classifications in the Lifestyle Interventions and Independence for Elders (LIFE) Study. LIFE randomized 1,635 sedentary men and women 70–89 years to a moderate intensity physical activity (PA) or health education (HE) program. METHODS: Major mobility disability (MMD), defined as the inability to walk 400m, was determined over an average follow up of 2.6 years. Participants were divided into 4 subgroups: 1) non-obese (BMI < 30 kg/m2; n=437); 2) non-obese with high waist circumference (WC >102 cm [men], >88 cm [women]; n=434); 3) class 1 obesity (30 kg/m2 ≤ BMI < 35 kg/m2; n=430); and 4) class 2+ obesity (BMI ≥ 35 kg/m2; n=312). Cox proportional hazard modeling was used to test an obesity by intervention interaction. RESULTS: The PA intervention had the largest benefit in participants with class 2+ obesity (HR 0.69, 95% CI 0.48, 0.98). However, there was no statistically significant difference in benefit across obesity categories. CONCLUSION: A structured PA program reduced the risk of MMD even in older adults with extreme obesity.