Physical activity levels in patients with early knee osteoarthritis measured by accelerometry

OBJECTIVE: Physical activity (PA) is recommended for osteoarthritis (OA) management to reduce pain and improve function. The purpose of this study was to objectively assess the level and pattern of PA in male and female knee OA patients to determine adherence to Centers for Disease Control and Prevention/American College of Sports Medicine and Exercise and Physical Activity Conference recommendations for PA. METHODS: Early OA patients (n = 255, 76% women, mean +/- SD age 54.6 +/- 7.1 years, mean +/- SD body mass index 27.8 +/- 4.3 kg/m(2)) with Kellgren/Lawrence-defined grade II (no higher) radiographic OA in at least 1 knee wore an accelerometer for 6-7 contiguous days. Light (LPA), moderate (MPA), and vigorous (VPA) PA intensities were defined as accelerometer recordings of 100-2,224, 2,225-5,950, and >5,950 counts per minute, respectively. RESULTS: Patients wore accelerometers for a mean +/- SD of 6.8 +/- 0.3 days and 13.8 +/- 2.2 hours/day, and spent much more time (P < 0.001) in MPA (23.6 +/- 17.2 minutes/day) than VPA (0.95 +/- 3.5 minutes/day). Men spent significantly (P < 0.05) more time in all PA intensities than women. Only 30% of patients achieved recommended PA levels. The proportion of men (47%) achieving the recommendation was significantly (P = 0.04) higher than women (24%). CONCLUSION: Knee OA patients accumulate little VPA and most (70%) do not achieve recommended levels for MPA or greater. New strategies to increase levels of PA in this population are needed.