Puhan MA, Schunemann HJ, Frey M, Scharplatz M, Bachmann LM
Thorax. 2005;60(5):367-375.
BACKGROUND:
Physical exercise is an important component of respiratory rehabilitation because it reverses skeletal muscle dysfunction, a clinically important manifestation of chronic obstructive pulmonary disease (COPD) associated with reduced health-related quality of life (HRQL) and survival. However, there is controversy regarding the components of the optimal exercise protocol. A study was undertaken to systematically evaluate and summarize randomized controlled trials (RCTs) comparing different exercise protocols for COPD patients.
METHODS:
Six electronic databases, congress proceedings, and bibliographies of included studies were searched without imposing language restrictions. Two reviewers independently screened all records and extracted data on the study samples, interventions, and methodological characteristics of included studies.
RESULTS:
The methodological quality of the 15 included RCTs was low to moderate. Strength exercise led to larger improvements of HRQL than endurance exercise did (weighted mean difference for Chronic Respiratory Questionnaire [CRQ], 0.27; 95% CI, 0.02 to 0.52). Interval exercise seems to be of similar effectiveness as continuous exercise, but there are few data on clinically relevant outcomes. One small RCT that included patients with mild COPD compared the effect of high- and low-intensity exercise (at 80% and 40% of the maximum exercise capacity, respectively) and found larger physiological training effects from high-intensity exercise.
CONCLUSIONS:
Strength exercise should be routinely incorporated in respiratory rehabilitation. There is insufficient evidence to recommend high-intensity exercise for COPD patients, and investigators should conduct larger high-quality trials to evaluate exercise intensities in patients with moderate to severe COPD.
COMMENTARY:
A second recent study investigated the different forms of exercise training within PR because, although it is clearly established that exercise training improves exercise tolerance and skeletal muscle function among patients with COPD, widely differing methods and intensity of exercise training are included in inpatient, outpatient, and home-based PR programs worldwide. In this study, the investigators conducted a systematic analysis of 15 randomized controlled trials of PR. The results revealed that the inclusion of strength training in PR leads to greater improvements in HRLQ (as assessed by the CRQ) than endurance exercise training alone. Also, high-intensity endurance training (eg, at 60%-80% of patient's maximal work capacity) leads to greater gains in physiologic, aerobic fitness than does low-intensity training, although the extent of data in this area included in randomized controlled trials remains limited. For persons who may not be able to exercise continuously at high intensity (eg, because of severe ventilatory limitation and dyspnea), interval training is a viable option.
Overall, although one can conclude in general that both strength and endurance training should be included in PR, it is still not possible, despite this study's analysis, to render conclusions regarding the exact modes of exercise training and components to be included in individual PR programs because the components may also be dictated at individual sites by available resources (such as equipment and staff), by the number of patients in the program concurrently, and by patient abilities and preferences. As such, exercise training must be individualized to meet the needs of both the patient and the program, as long as minimal standards for conducting supervised exercise sessions (based on a preprogram established exercise prescription), according to published guidelines for PR and exercise training, local quality assurance, and/or accreditation standards are met and relevant outcomes (eg exercise tolerance, health status, and dyspnea) are assessed by each program to assure program efficacy. For patients not found to benefit from the traditional training measures, adjunct means of improving gains in exercise training (such as use of noninvasive ventilation during training sessions or use of interval training) should be considered to optimize the benefits of PR for individual patients.
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