Physical Activity Levels in the Early Knee Osteoarthritis Population

Abstract

PURPOSE: The KNEE study is a randomized clinical trial of the effects of resistance exercise in knee osteoarthritis (KOA) patients. For this report, we describe objectively measured physical activity (PA) assessed by accelerometry in KOA subjects and compare their PA to health-related recommendations for the general public. METHODS: Men (n = 61) and women (n = 201) with a radiographic status of grade II OA in at least one knee, as denned by the Kellgren and Lawrence classification, wore the Actigraph accelerometer (model 7164, Manufacturing Technologies Inc. Health Systems, Shalimar, FL) daily (except for sleeping) for 7 days. Activity counts corresponding to light, moderate (MPA) and vigorous (VPA) levels of activity were 50–2,190, 2,191–6,153, > 6,154 counts/min, respectively, based on the literature. Average age, height, weight, and body mass index were as follows: 54.6 ±7.1 years, 168.0 ± 10.1 cm, 78.9 ± 15.6 kg, and 27.9 ± 4.8 kg/m2. RESULTS: Average accelerometer wearing time was 13.5 hours/day. Average daily MPA was significantly (p < 0.05) higher in males (31.1 ± 19.9 minutes/day) than females (21.6 ± 15.3 minutes/day). Males and females accumulated little VPA (0.84 ±3.4 minutes/day). Thus, average daily moderate plus vigorous activity was higher in males (32.7 ± 2.75 minutes/day) than females (22.2 ± 1.2 minutes/day). Weekday MVPA exceeded weekend MVPA by about 3 minutes. CONCLUSIONS: KOA patients were compliant wearers of Actigraph, making it a good tool for objective assessment of PA in this population. Males with KOA are more active than females, meeting recommendations for daily MVPA. Both males and females with KOA achieve significantly less VPA than the recommendations prescribed for the general public. Supported by NIH/NIAMS Grant #5R01 AR047595.