Background: Older adults (≥ 65 years [y]) may have difficulty meeting the Physical Activity (PA) Guidelines for Americans. Recent literature suggests that light activity is an important determinant of physical function in older adults. We hypothesized that PA (especially light activity) is associated with gait speed in older adults.
Methods: Framingham Offspring Study examination 9 participants, free of mobility limitations with accelerometry and physical performance data (timed 4 meter walk), were included in this investigation (n=1449, age ≥ 50y). Sedentary time (1486 counts/min) and steps/day were also assessed. We used linear regression to relate gait speed (dependent variable) to PA levels (independent), adjusting for sex and wear time. For interactions observed between PA and age at the p≤0.1 level, regression models were stratified by age group: age 50-64 y (n=422, 55% women), age 65-44 y (n=704, 54% women), and age ≥75 y (n=323, 52% women).
Results: Only 38% of adults aged 50-64 y achieved the PA Guidelines, i.e., 150 min MVPA per week. Guideline achievement dropped to 15% in participants ≥75 y. Average gait speed decreased from 1.23 to 1.08 m/s across age groups. Each 10 min increment in MVPA was associated with a 0.01 m/s higher gait speed in the full sample (p<0.001); no interaction by age group was detected. The association of light activity with gait speed increased in the older age groups; 10% more time spent in light activity was associated with 0.03 m/s higher gait speed in adults 65-64 y (p=0.04, Table 1) or 0.09 m/s higher gait speed in adults ≥75 y (p<0.001). More steps and lower sedentary time were also associated with higher gait speed.
Discussion: Our cross-sectional study demonstrated an association of light-intensity PA with gait speed in adults ≥65 y. These data warrant future research on the impact of light activity on physical function and health outcomes in the elderly.