Correlates of physical activity in chronic obstructive pulmonary disease

Background: Physical activity is a key dimension of functional status in people with chronic obstructive pulmonary disease (COPD), and the central target of interventions in this group. Objectives: To determine the relationships among functional performance measured as physical activity, functional capacity, symptom experiences, and health-related quality of life in people with COPD. Method: Cross-sectional, descriptive study. Convenience sample of 63 outpatients with COPD studied prior to entry into a pulmonary rehabilitation program. Results: Daily physical activity, as measured by an accelerometer, was strongly associated with maximal distance walked during a 6-minute walk test (r = .60, p < .00), level of airway obstruction (r = .37, p < .01), walking self-efficacy (r = .27, p < .05), and physical health status (r = .40, p < .01). Physical activity was not correlated with self-report of functional status. The only predictor of physical activity was the 6-minute walk test. Conclusions: Accelerometer measurement of functional performance was most significantly related to walking abilities. This methodology represents a novel approach to measuring an important dimension of functional status not previously well quantified.