Association of body mass index with exercise cardiopulmonary responses in lung function-matched patients with chronic obstructive pulmonary disease

Background and ObjectivesLung function is traditionally used to define the severity of chronic obstructive pulmonary disease (COPD). However, this does not exclude other factors. This study investigated the influence of body mass index (BMI) on exercise responses and quality of life in patients with COPD matched for values of forced expiratory volume in 1 second (FEV1).MethodsUnderweight, normal-weight, and overweight patients with COPD, matched for FEV1, were studied. All patients were evaluated by spirometry, a cardiopulmonary exercise test, respiratory muscle strength, and, St. George's Respiratory Questionnaire (SGRQ).ResultsThe baseline characteristics and mean FEV1 of the 3 groups were similar (P > .05). Respiratory muscle strengths and SGRQ scores were lowest in underweight patients (P < .05). In terms of exercise response, the lowest oxygen uptake at anaerobic threshold and peak exercise, the highest ventilatory equivalent, and the lowest oxygen pulse were evident in underweight patients (P < .05).ConclusionsUnderweight patients with COPD had lower respiratory muscle strength, impaired exercise capacity, earlier anaerobic metabolism, ineffective ventilation, and poorer quality of life.