Cumulative Associations Between Midlife Health Behaviors and Physical Functioning in Early Old Age: A 17-Year Prospective Cohort Study

OBJECTIVES: To examine cumulative associations between midlife health behaviors and walking speed and upper-limb strength in early old age. DESIGN: Prospective cohort study. SETTING: Whitehall II Study. PARTICIPANTS: Individuals (mean age 49.1 ± 5.9 in 1991–93) with health behavior data for at least two of the three assessments (1991–93, 1997–99, 2002–04) and physical functioning measures in 2007–09 (mean age 65.9 ± 5.9) (N = 5,671). MEASUREMENTS: A trained nurse assessed walking speed and upper-limb strength. Unhealthy behaviors were defined as current or recent smoking, nonmoderate alcohol consumption (abstinence or heavy drinking), fruit and vegetable consumption less than twice per day, and physical inactivity (<1 h/wk of moderate and <1 h/wk of vigorous physical activity). For each unhealthy behavior, a cumulative score was calculated as the number of times a person reported the behavior over the three assessments divided by 3. The score ranged between 0 (never) and 1 (all three times). RESULTS: In linear regression models adjusted for age, sex, education, marital status, and height, all unhealthy behaviors in 1991–93 were associated with slower walking speed in 2007–09, with differences ranging from 0.10 (nonmoderate alcohol consumption) to 0.25 (physical inactivity) of a standard deviation between participants with and without the unhealthy behavior (P(t-test)<.001). For walking speed, the accumulation-of-risk model provided the best fit for unhealthy diet (β for a 1-point increment in the low fruit and vegetable consumption score = −0.29, 95% confidence interval (CI) = −0.36 to −0.22) and physical inactivity (β = −0.37, 95% CI = −0.45 to −0.29). For smoking and nonmoderate alcohol consumption, a cumulative effect was also observed, but partial F-tests did not suggest that it provided a better fit than models with behaviors in 1991–93, 1997–99, or 2002–04. All behavioral scores except smoking were associated with grip strength, but F-tests supported the accumulation-of-risk hypothesis only for physical inactivity. CONCLUSION: These findings highlight the importance of duration of unhealthy behaviors, particularly for diet and physical activity, when examining associations with physical functioning.