Effects of Strength Training in Combination With Endurance Training on Exercise Tolerance in Patients With Chronic Obstructive Pulmonary Disease (COPD)

Background. Exercise intolerance is one of the most devastating consequences of chronic obstructive pulmonary disease (COPD). Abnormalities in peripheral muscle function such as weakness and reduction in oxidative enzyme activities are commonly found in these patients and may contribute to exercise intolerance.To evaluate whether a systemic weightlifting exercise may improve exercise capacity better than endurance training, or a combined training is more effective, the investigators compared three different training regimens, endurance training alone, systemic weightlifting training alone or a combination of both endurance and weightlifting training. Methods.36 patients with stable COPD will be evaluated before and after a 4 month training program. Each evaluation include a stepwise exercise test on an ergocycle up to the individual maximal capacity during which minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), and arterial lactic acid concentration will be measured and the peripheral muscle strength will be determined with the one repetition maximum for eight different muscle groups. Percutaneous needle muscle biopsy from the M.vastus lateralis will be performed before and after the training period in order to determine the fiber-type proportions. Patients are assigned to one of the following three groups (1) endurance training consisted of 20 min exercise sessions on a calibrated ergocycle two times a week, with a target training intensity at 60% of individual maximum oxygen uptake, (2) systemic weightlifting training two times a week with eight different exercises, each session consist of 15 repetitions of each muscle group, (3) combination of endurance training and systemic weightlifting training. Statistical analysis. Baseline data for all patients enrolled in the study will be compared by one-way analysis of variance for the three study groups. Results before and after training will be analyzed by two- way analysis of variance.