Effects of combined endurance and resistance eccentric training on muscle function and functional performance in patients with chronic obstructive pulmonary disease: randomized controlled trial.

OBJECTIVE: To evaluate the adherence to treatment and efficacy of an eccentric-based training (ECC) program on peripheral muscle function and functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD).

DESIGN: Prospective, assessor-blinded, randomized controlled trial.

SETTING: The cardiopulmonary rehabilitation unit of a tertiary subacute referral center.

PARTICIPANTS: Thirty (N=30) stable inpatients (mean age 68 ± 8 years; FEV1 44 ± 18% of predicted) with COPD were included in the study.

INTERVENTIONS: Inpatients were randomly assigned to 4 weeks of a combined endurance and resistance ECC (n=15) or conventional training (CON; n=15).

MAIN OUTCOME MEASURES: Quadriceps peak torque (PT) was the primary outcome measure for muscle function. Rate of force development (RFD), muscle activation and quality (quadriceps PT/leg lean mass), 6-min walk distance (6MWD), 4-metre gait speed (4mGS), 10-metre gait speed (10mGS), 5-repetition sit-to-stand (5STS), dyspnea rate, and mortality risk were the secondary outcomes. Evaluations were performed at baseline and repeated after 4 weeks and 3 months of follow-up.

RESULTS: Quadriceps PT, RFD, and muscle quality improved by 17 ± 23% (P < 0.001), 19 ± 24%, and 16 ± 20% (both P < 0.05) within the ECC group. Besides, a significant between-group difference for RFD (56 ± 94 Nm∙s-1 , P = 0.038) was found after training. Both groups showed clinically relevant improvements in 6MWD, 4mGS, dyspnea rate, and mortality risk, with no significant differences between groups.

CONCLUSION: Combined endurance and resistance ECC improved lower limbs muscle function compared with CON in inpatients with COPD. In contrast, ECC did not further improve functional performance, dyspnea, and mortality risk. ECC may be of particular benefit to impact on skeletal muscle function in patients with COPD.