Accelerometer-Measured Physical Activity Percentiles Across Age in Adults With Knee Osteoarthritis
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José Luis Ceballos-Sánchez1, Manuel Reguera Rodríguez2, Rosa M Alfonso-Rosa3
1Department of Education and Sports, Universidad Loyola Andalucía, Dos Hermanas, Seville.
Objective:
To describe age-related percentile distributions of accelerometer-measured physical activity (PA) in adults with knee osteoarthritis (OA) and to examine differences according to sex, pain, income, and body mass index (BMI).
Design:
Cross-sectional secondary analysis.
Setting:
Secondary analysis of data from the accelerometer substudy of the Osteoarthritis Initiative, a multicenter longitudinal cohort study conducted in the United States.
Participants:
Adults with knee OA-related data available for analysis (N=968).
Interventions:
Not applicable.
Main Outcome Measures:
Weekly minutes of moderate-to-vigorous physical activity (MVPA) and total physical activity (TPA), measured using a uniaxial ActiGraph GT1M accelerometer and classified according to the Freedson cut-point approach. Quantile regression was used to estimate age-related percentile curves.
Results:
Median weekly MVPA was 13.93 minutes, and median weekly TPA was 292.07 minutes. This median MVPA value is substantially below the World Health Organization recommendations. Both MVPA and TPA declined with advancing age. Men accumulated significantly more MVPA than women across percentiles, whereas women accumulated significantly more TPA. Lower PA levels were also observed in participants with significant pain and higher BMI, particularly at lower percentiles. No statistically significant differences were detected according to annual income. These findings indicate that percentile position reflects relative activity within this knee OA sample and should not be interpreted as equivalent to meeting guideline-recommended PA levels.
Conclusions:
Adults with knee OA accumulated low levels of device-measured PA, with less favorable patterns observed at older ages and among participants with greater pain and higher BMI. These percentile distributions may help contextualize an individual's activity level relative to comparable adults with knee OA in rehabilitation and research settings; however, they are descriptive reference distributions and do not replace guideline-based PA targets.
