Isolated Resistance Training Programs to Improve Peripheral Muscle Function in Outpatients with Chronic Obstructive Pulmonary Diseases: A Systematic Review

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-meter gait speed (4mGS), 10-meter gait speed, 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<.001), 19±24%, and 16±20% (both P<.05) within the ECC group. Besides, a significant between-group difference for RFD (56±94 Nm/s, P=.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 effect on skeletal muscle function in patients with COPD.

Muscle Power in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-analysis

This study aimed to review the impact of training on muscle power in patients with chronic obstructive pulmonary disease (COPD). Randomized controlled trials evaluating the effects of exercise-based interventions on limbs muscle power and rate of force development in COPD patients were investigated. Five international databases were searched until October 2022. Meta-analyses were performed calculating the mean difference or standardized mean difference. Risk of bias in studies was assessed using Cochrane Risk of Bias tool 2.0. A total of nine studies were included in the analysis. There were concerns about risk of bias in seven out of nine studies. Comparison of exercising and non-exercising groups showed a significant effect of exercise in improving muscle power (P=0.0004) and rate of force development (P<0.001), in five and three trials, respectively. Four studies comparing different trainings showed no significant results on muscle power (P=0.45). Eight to 16 weeks of exercise-based intervention versus no intervention might be beneficial to enhance upper and lower limbs muscle power and rate of force development in people with COPD. In contrast, muscle power did not improve when different training modalities were compared. Future studies performing power training in COPD patients are encouraged.

Performance Score (T2D)-A New Perspective in the Assessment of Six-Minute Walking Tests in Pulmonary Rehabilitation

Because absolute changes in outcomes are difficult to interpret and the minimal clinically important difference (MCID) is not suitable to address this challenge, a novel method of classifying outcomes by relating changes to baseline values is warranted. We used the "performance score" (T2D), which reflects individual performance, enabling us to consider the functional status at the beginning of rehabilitation without dealing with the problems of mathematical coupling or regression effects, as encountered in ANCOVA. To illustrate the T2D, we retrospectively analyzed changes in the six-minute walking test (6MWT) in COPD patients undergoing outpatient pulmonary rehabilitation and compared the results with absolute differences related to a predetermined MCID. We evaluated a total of 575 COPD patients with a mean age of 61.4 ± 9.2 years. 6MWT improved significantly, with a mean change of 32.3 ± 71.2. A total of 105/311 participants who had reached the MCID were still classified as "below average" by the T2D. Conversely, 76/264 patients who had not reached the MCID were classified as "above average". This new performance measure accounts for the patient's current status and for changes over time, potentially representing a simple and user-friendly tool that can be used to quantify a patient's performance and response to rehabilitation.

Muscle function and functional performance after pulmonary rehabilitation in patients with chronic obstructive pulmonary disease: a prospective observational study

This study aimed to measure changes in different properties of skeletal muscles and evaluate their contribution and relationship to changes in functional performance after pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). COPD outpatients attending 5 weeks of conventional PR were recruited. Functional performance [5-repetitions sit-to-stand (5STS), and 4-m gait speed (4mGS)], and muscle function (maximal isometric strength, power, force control, and relative concentric and eccentric activation during 5STS) were assessed after PR and 3 months of follow-up. Twenty patients (71 years; 52% of predicted FEV₁) completed the study. 4mGS and relative concentric activation during 5STS decreased respectively by 7.7% and 26% between the beginning of PR and follow-up. Quadriceps strength, power, and force control improved by 10.4%, 27.3%, and 15.2%, respectively, from the beginning of PR to follow-up the relative eccentric activation during 5STS explained 31% of the variance in 4mGS changes. In conclusion, functional performance appeared to decline after conventional PR, whereas several properties of skeletal muscles were maintained at follow-up in COPD outpatients. Of note, eccentric contractions might play a role in the improvement of functional performance. Therefore, future studies with interventional design should include eccentric training in PR programs during clinical COPD practice.