Greater levels of physical activity are significantly associated with higher functional performance objectively measured by gait speed in adults with confirmed radiographic knee osteoarthritis (OA). There is a consistent graded relationship between physical activity level and better performance in these patients.
Dunlop and associates examined the cross-sectional and longitudinal relationship between self-reported physical activity and observed functional performance in 2589 adults with knee OA from the Osteoarthritis Initiative, a prospective natural history study. A timed 20-m walk test was used to assess prospective annual functional performance. Self-reported physical activity was measured with the Physical Activity Scale for the Elderly. Linear regression was used to estimate differences in subsequent function across physical activity quartiles.
Compared with the lowest group level, the average improvement in baseline functional performance increased with membership in higher baseline physical activity levels (mean baseline gait speed, 4.0, 4.18, 4.29, and 4.49 ft/s, respectively). The same held true for subsequent functional performance (mean gait speed after 1 year, 4.0, 4.2, 4.3, and 4.5 ft/s, respectively).
The authors noted that their findings support guidelines that encourage patients with arthritis who cannot attain minimum recommended physical activity to be as active as possible.