Sedentary behaviour ups risk of functional limitation in adults with knee OA

Being inactive (zero 10-min bouts/week in moderate-to-vigorous physical activity [MVPA]) is associated with a higher risk of developing functional limitation in adults with knee osteoarthritis (OA), regardless of sedentary category, a study has found.

The investigators classified participants into active-low sedentary (≥1 10-min bout/week of MVPA, lowest tertile for standardized sedentary time), active-high sedentary (≥1 10-min bout/week of MVPA, top 2 tertiles), inactive-low sedentary (zero 10-min bouts/week of MVPA, lowest tertile), and inactive-high sedentary (zero 10-minute bouts/week of MVPA, top 2 tertiles) groups using 48-month (baseline) accelerometry data from the Osteoarthritis Initiative.

Functional limitation was defined as >12 seconds for the 5-repetition sit-to-stand test (5XSST) and <1.22 m/s gait speed during the 20-metre walk test. The investigators assessed the association between exposure groups and the risk of developing functional limitation 4 years later by calculating adjusted risk ratios (ARR; adjusted for potential confounders).

A total of 1,091 and 1,133 participants had no baseline functional limitation based on the 5XSST and 20-metre walk test, respectively, of whom 15 percent and 21 percent developed functional limitation 4 years later.

The risk of developing functional limitations was higher in the inactive-low and inactive-high sedentary groups than in the active-low and active-high sedentary groups. The risk of developing functional limitation based on the 5XSST and 20-metre walk test was higher by 72 percent (ARR, 1.72, 95 percent confidence interval [CI], 1.00–2.94) and 52 percent (ARR, 1.52, 95 percent CI, 1.03–2.25), respectively, in the inactive-low sedentary group compared with the active-low sedentary group.