Steiner MC, Barton RL, Singh SJ, Morgan MD Thorax. 2003;58:745-751.
Background: Pulmonary rehabilitation is effective in improving exercise performance and health status in chronic obstructive pulmonary disease (COPD). However, the role of nutritional support in the enhancement of the benefits of exercise training has not been explored. A double blind, randomised, controlled trial of carbohydrate supplementation was undertaken in patients attending outpatient pulmonary rehabilitation.
Methods: 85 patients with COPD were randomised to receive a 570 kcal carbohydrate rich supplement or a non-nutritive placebo daily for the duration of a 7 week outpatient pulmonary rehabilitation programme. Primary outcome measures were peak and submaximal exercise performance using the shuttle walk tests. Changes in health status, body composition, muscle strength, and dietary macronutrient intake were also measured.
Results: Patients in both the supplement and placebo groups increased shuttle walking performance and health status significantly. There was no statistically significant difference between treatment groups in these outcomes. Patients receiving placebo lost weight whereas supplemented patients gained weight. In well nourished patients (BMI .19 kg/m2) improvement in incremental shuttle performance was significantly greater in the supplemented group (mean difference between groups: 27 (95% CI 1 to 53) m, P , 0.05). Increases in incremental shuttle performance correlated with increases in total carbohydrate intake.
Conclusions: When universally prescribed, carbohydrate supplementation does not enhance the rehabilitation of patients with COPD. This study suggests that exercise training results in negative energy balance that can be overcome by supplementation and that, in selected patients, this may improve the outcome of training. The finding of benefit in well nourished patients may suggest a role for nutritional supplementation beyond the treatment of weight loss in COPD.
Comments: Many patients with COPD have significant nutritional impairment, with a decrease in fat-free mass that can contribute to impairment in functional status. In this study, the investigators determined whether carbohydrate supplementation could enhance the benefits of pulmonary rehabilitation. Whereas patients receiving placebo lost weight, those taking the carbohydrate supplement gained weight. Well-nourished patients who took the supplement had greater improvements in exercise tolerance (assessed by the shuttle-walk test) after rehabilitation than did the group who received placebo. This finding demonstrates that nutritional supplementation may benefit selected patients undergoing rehabilitation, perhaps by overcoming the tendency for the exercise program to create a catabolic state. Selected patients may have greater gains in rehabilitation if they receive focused nutritional support during the period of exercise training. Further work is needed to identify which patients are most likely to benefit from nutritional supplementation during rehabilitation.