Joint association of physical activity and BMI with functional limitations among older adults in US

Introduction and Objectives: Loss of the ability to perform basic functional tasks such as activities of daily
living (ADLs) increases with age. This study aimed to examine the joint association of physical activity and
body mass index (BMI) with functional limitations among US older adults.
Methods: This study used the longitudinal data from the Health and Retirement Study (2004–2018 waves), a
nationally representative sample of US adults. The analysis included adults aged 60 years or older, with at
least 2 follow-up assessments. The main outcome measures were physical functioning summary score and
the combined activities of daily living - instrumental activities of daily living (ADL-IADL) index. The
associations of the physical activity and BMI with the functional limitations were estimated using generalized
estimating equations (GEE) models with negative binomial distribution.
Results: Thirteen thousand nine hundred fifty-one participants contributed 77,016 observations, with mean
(SD) follow-up of 9.0 (4.2) years. Participants had a mean (SD) age of 70.9 (8.0) years at baseline, 56.6%
were women, 74.3% were non-Hispanic white, and 15.1% were non-Hispanic black. In covariate-adjusted
model, compared to normal weight with physically inactive, the expected number of physical functioning
limitations were lower among normal weight with active (IRR=0.73, 95% CI: 0.72-0.75), overweight with active
(IRR=0.79, 95% CI: 0.78-0.81), and obese with active (IRR=0.95, 95% CI: 0.93-0.98). In covariate-adjusted
model, compared to normal weight with physically inactive, the expected number of limitations on ADL-IADL
were lower among normal weight with active (IRR=0.39, 95% CI: 0.37-0.41), overweight with active
(IRR=0.39, 95% CI: 0.36-0.41), and obese with active (IRR=0.54, 95% CI: 0.50-0.58).
Discussion: Engagement in moderate/vigorous activities at least once per week is associated with lower
numbers of functional limitations, regardless of weight. Physical activity is likely to be beneficial for functional
activities among older adults.