Physical activity in daily life in patients with chronic low back pain

Objectives: To evaluate disuse (ie, a decreased daily physical activity lev el) in patients with chronic low back pain (LBP) and to evaluate the constr uct validity of accelerometry for measuring physical activity in daily life . Design: Case-control study in a cross-sectional design; comparison of accel erometry to the criterion standard (doubly labeled water technique). Setting: Normal daily living (unrestricted by the measurement devices). Patients: Thirteen patients with chronic nonspecific LBP and 13 age- and ge nder-matched healthy controls. Main Outcome Measures: Physical activity in daily life, expressed as whole- body acceleration measured with a triaxial accelerometer (Tracmor), and as the ratio between average daily metabolic rate (ADMR), measured by the doub ly labeled water technique, and resting metabolic rate (RMR), measured by t he ventilated hood. Both techniques were used simultaneously for 14 days. Results: Mean physical activity level in patients and controls did not diff er significantly. The correlation between the Tracmor and ADMR and RMR was .72 (p < .01). Conclusions: Decreased physical activity levels in this sample of chronic L BP patients was not confirmed. The Tracmor is a valid instrument for measur ing daily activity in LBP patients. (C) 2001 by the American Congress of Rehabilitation Medicine and the Americ an Academy of Physical Medicine and Rehabilitation.