Muscular and functional effects of partitioning exercising muscle mass in patients with chronic obstructive pulmonary disease - a study protocol for a randomized controlled trial

Background: Low-load, high-repetitive single-limb resistance training may increase limb muscle function and functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD) while minimizing the occurrence of limiting exertional symptoms. Whether high-repetitive single-limb resistance training would perform better than high-repetitive two-limb resistance training is unknown. In addition, the mechanisms underlying possible benefits of high-repetitive resistance training has not been investigated. The aims of this study are to compare single versus two-limb high-repetitive resistance training in patients with COPD and to investigate mechanisms of action of these training modalities. Methods/Design: This trial is a prospective, assessor-blind, randomized controlled trial. The participants are patients with stable severe to very severe COPD who are older than 40 years of age and healthy controls. The intervention is single-limb, high-repetitive, resistance training with elastic bands, three times/week for 8 weeks. The control is two-limb high-repetitive resistance training with elastic bands, three times/week for 8 weeks. The primary outcomes is change in the 6-min walking distance after 8 weeks of single-limb or two-limb high-repetitive resistance training. The secondary outcomes are changes in limb muscle strength and endurance capacity, key protein involved in quadriceps anabolic/catabolic signalization, fiber-type distribution and capillarization, subjective dyspnea and muscle fatigue, muscle oxygenation, cardiorespiratory demand and health-related quality-of-life after 8 weeks of single-limb or two-limb high-repetitive resistance training. The acute effects of single-limb versus two-limb high-repetitive resistance training on contractile fatigue, exercise stimulus (the product of number of repetition and load), subjective dyspnea and muscle fatigue, muscle oxygenation, and cardiorespiratory demand during upper and lower limb exercises will also be investigated in patients with COPD and healthy controls. Randomization will be performed using a random number generator by a person independent of the recruitment process, using 1:1 allocation to the intervention and the control group using random block sizes. Blinding: All outcome assessors will be blinded to group assignment. Discussion: The results of this project will provide important information to help developing and implementing customized exercise training programs for patients with COPD.