Physical activity and leg strength predict decline in mobility performance in older persons.
OBJECTIVE
To assess the extent to which physical activity and leg strength are associated with change in mobility in older persons.


METHODS
Prospective, observational cohort study.


METHODS
Retirement communities across the Chicago metropolitan area participating in the Rush Memory and Aging Project.


METHODS
Eight hundred eighty-six ambulatory older persons without dementia.


METHODS
Rate of change in mobility.


RESULTS
In a linear mixed-effects model that controlled for age, sex, education, and a term for baseline physical activity, a higher level of physical activity was associated with a slower rate of mobility decline (estimate=0.006, standard error (SE)=0.003, P=.03); each additional hour of physical activity at baseline was associated with an approximately 3% decrease in the rate of mobility decline. In a similar model, a higher level of baseline leg strength was associated with a slower rate of mobility decline (estimate=0.031, SE=0.132, P=.02); each additional unit of leg strength at baseline was associated with an approximately 20% decrease in the rate of mobility decline. In a final model, which included terms for physical activity and leg strength together, both were associated with decline in mobility. Furthermore, both remained associated with mobility even after controlling for body composition, balance, pulmonary function, cognition, history of joint pain, cardiovascular diseases and risk factors, and medications.


CONCLUSIONS
Physical activity and leg strength are relatively independent predictors of mobility decline in older persons. Although physical activity may improve strength, the beneficial effect of physical activity on mobility is likely to involve other pathways.
Buchman
Aron S
AS
Alzheimer's Disease Center, Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois 60612, USA. Aron_S_Buchman@rush.edu
Wilson
Robert S
RS
Boyle
Patricia A
PA
Tang
Yuxiao
Y
Fleischman
Debra A
DA
Bennett
David A
DA
D000368:Aged; D000369:Aged, 80 and over; D002641:Chicago; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D006801:Humans; D007866:Leg; D016014:Linear Models; D008297:Male; D051346:Mobility Limitation; D009043:Motor Activity; D053580:Muscle Strength / Q000502:physiology*