Effect of endurance versus resistance training on quadriceps muscle dysfunction in COPD:a pilot study

INTRODUCTION: Exercise is an important countermeasure to limb muscle dysfunction in COPD. The two major training modalities in COPD rehabilitation, endurance training (ET) and resistance training (RT), may both be efficient in improving muscle strength, exercise capacity, and health-related quality of life, but the effects on quadriceps muscle characteristics have not been thoroughly described. METHODS: Thirty COPD patients (forced expiratory volume in 1 second: 56% of predicted, standard deviation [SD] 14) were randomized to 8 weeks of ET or RT. Vastus lateralis muscle biopsies were obtained before and after the training intervention to assess muscle morphology and metabolic and angiogenic factors. Symptom burden, exercise capacity (6-minute walking and cycle ergometer tests), and vascular function were also assessed. RESULTS: Both training modalities improved symptom burden and exercise capacity with no difference between the two groups. The mean (SD) proportion of glycolytic type IIa muscle fibers was reduced after ET (from 48% [SD 11] to 42% [SD 10], P<0.05), whereas there was no significant change in muscle fiber distribution with RT. There was no effect of either training modality on muscle capillarization, angiogenic factors, or vascular function. After ET the muscle protein content of phosphofructokinase was reduced (P<0.05) and the citrate synthase content tended increase (P=0.08) but no change was observed after RT. CONCLUSION: Although both ET and RT improve symptoms and exercise capacity, ET induces a more oxidative quadriceps muscle phenotype, counteracting muscle dysfunction in COPD

Effectiveness of pulmonary rehabilitation in COPD with mild symptoms:a systematic review with meta-analyses

PURPOSE: Most guidelines recommend pulmonary rehabilitation (PR) for patients with chronic obstructive pulmonary disease (COPD) and modified Medical Research Council dyspnea scale (mMRC) levels ≥2, but the effectiveness of PR in patients with less advanced disease is not well established. Our aim was to investigate the effects of PR in patients with COPD and mMRC ≤1. METHODS: The methodology was developed as a part of evidence-based guideline development and is in accordance with the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group. We identified randomized controlled trials (RCTs) through a systematic, multidatabase literature search and selected RCTs comparing the effects of PR with usual care in patients with COPD and mMRC ≤1. Predefined critical outcomes were health-related quality of life (HRQoL), adverse effects and mortality, while walking distance, maximal exercise capacity, muscle strength, and dropouts were important outcomes. Two authors independently extracted data, assessed trial eligibility and risk of bias, and graded the evidence. Meta-analyses were performed when deemed feasible. RESULTS: Four RCTs (489 participants) were included. On the basis of moderate-quality evidence, we found a clinically and statistically significant improvement in short-term HRQoL of 4.2 units (95% confidence interval [CI]: [−4.51 to −3.89]) on St George’s Respiratory Questionnaire, but not at the longest follow-up. We also found a statistically significant improvement of 25.71 m (95% CI: [15.76–35.65]) in the 6-minute walk test with PR; however, this improvement was not considered clinically relevant. No difference was found for mortality, and insufficient data prohibited meta-analysis for muscle strength and maximal exercise capacity. No adverse effects were reported. CONCLUSION: We found a moderate quality of evidence suggesting a small, significant improvement in short-term HRQoL and a clinically nonsignificant improvement in walking distance following PR in patients with COPD and mild symptoms. This resulted in a weak recommendation of routine PR in these patients using the GRADE approach