Effect of Nutritional Status on Exercise Performance in Patients with Chronic Obstructive Pulmonary Disease

Abstract

The purpose of our study was to examine the nutritional status of patients with severe chronic obstructive pulmonary disease (COPD) (mean predicted FEV₁, 30 ± 11%) and to explore its relationship to functional capacity. Functional capacity was evaluated by measuring peak oxygen consumption ( O₂max) using an incremental cycle ergometry test, a 6-min walk test, self-perceived level of dyspnea, and quality of life. The percentage ideal body weight (%IBW) was < 90% in 33 of 135 subjects. Triceps skinfold thickness was < 60% of normal in 19 of 33 of these subjects. Total lymphocyte count was not different between groups, whereas hemoglobin (14.9 versus 15.9 g/dl) and albumin (4.0 versus 4.1 g/dl) were marginally reduced in underweight subjects. Dyspnea and overall quality of life were unaffected by nutritional status. Maximal inspiratory (Pimax) and expiratory mouth pressures (Pemax) were weakly associated with %IBW (R² = 0.04; p = 01 and R² = 0.15; p < 0.01, respectively). The %IBW was a predictor of O₂max (percent predicted) after controlling for FEV₁ in regression analysis (partial R² = 0.08; p < 0.001). Despite the association of weight status with O₂max, the 6-min walk was not influenced by %IBW. The perceived intensity of exercise as judged by the Borg score was far greater with the bicycle exercise that with the 6-min walk (mean score, 10.6 ±1.2 versus 4.6 ± 1.9). This was supported by the difference in heart rate after these two tests. Thus, although in underweight subjects the peak exercise performance was decreased, and ventilatory muscle strength was somewhat reduced, submaximal exercise performance and dyspnea were not affected.