Walking distance in incremental shuttle walking test as a predictor of physical activity in patients diagnosed with low-risk chronic obstructive pulmonary disease

OBJECTIVES: Research on the determinants of physical activity in mildly symptomatic patients with chronic obstructive pulmonary disease is lacking. This study examined the predictors of physical activity in patients with low-risk chronic obstructive pulmonary disease. METHODS: A total of 41 male patients with chronic obstructive pulmonary disease belonging to Group A of the Global Initiative for Chronic Obstructive Lung Disease were included. Regarding the objective index, the physical activity (number of steps/day and the amount of Ex (metabolic equivalent × hours)/day) of the participants was measured with a tri-axis accelerometer. In addition, regarding the evaluation index, respiratory function and dynamic lung hyperinflation were measured by a spirometer, skeletal muscle mass was measured using bioelectrical impedance analysis, skeletal muscle strength (grip and lower limb muscle strength) was measured using a dynamometer, exercise capacity was measured by the incremental shuttle walking test, and health-related quality of life was measured. RESULTS: Significant correlations were found between the number of steps per day and age (ρ = −0.501, p < 0.01), forced vital capacity predictive values (ρ = 0.381, p < 0.05), dynamic lung hyperinflation (ρ = 0.454, p < 0.01), grip strength (ρ = 0.318, p < 0.05), and walking distance in incremental shuttle walking test (ρ = 0.779, p < 0.01), but not skeletal muscle mass, lower limb muscle strength, or health-related quality of life. A multiple-regression analysis with the number of steps per day as the dependent variable extracted only walking distance in incremental shuttle walking test, yielding a moderate single-regression equation (steps/day = −934.909 + 11.052 × walking distance in incremental shuttle walking test, adjusted R(2) = 0.548, p < 0.001). CONCLUSION: It was suggested that the amount of physical activity of patients with low-risk chronic obstructive pulmonary disease could be predicted by walking distance in incremental shuttle walking test.