Midlife hand grip strength as a predictor of old age disability.

CONTEXT Poor muscle strength, functional limitations, and disability often coexist, but whether muscle strength during midlife predicts old age functional ability is not known. OBJECTIVE To determine whether hand grip strength measured during midlife predicts old age functional limitations and disability in initially healthy men. DESIGN AND SETTING A 25-year prospective cohort study, the Honolulu Heart Program, which began in 1965 among Japanese-American men living on Oahu, Hawaii. PARTICIPANTS A total of 608945- to 68-year-old men who were healthy at baseline and whose maximal hand grip strength was measured from 1965 through 1970. Altogether, 2259 men died over the follow-up period and 3218 survivors participated in the disability assessment in 1991 through 1993. MAIN OUTCOME MEASURES Functional limitations including slow customary walking speed (< or =0.4 m/s) and inability to rise from a seated position without using the arms, and multiple self-reported upper extremity, mobility, and self-care disability outcomes. RESULTS After adjustment for multiple potential confounders, risk of functional limitations and disability 25 years later increased as baseline hand grip strength, divided into tertiles, declined. The odds ratio (OR) of walking speed of 0.4 m/s or slower was 2.87 (95% confidence interval [CI], 1.76-4.67) in those in the lowest third and 1.79 (95% CI, 1.14-2.81) in the middle third of grip strength vs those in the highest third. The risk of self-care disability was more than 2 times greater in the lowest vs the highest grip strength tertile. Adding chronic conditions identified at follow-up to the models predicting disability reduced the ORs related to grip strength only minimally. CONCLUSIONS Among healthy 45- to 68-year-old men, hand grip strength was highly predictive of functional limitations and disability 25 years later. Good muscle strength in midlife may protect people from old age disability by providing a greater safety margin above the threshold of disability.