Effect of modified Total Body Recumbent Stepper training on exercise capacity and thioredoxin in COPD: a randomized clinical trial

Exercise intolerance is one of the major symptoms of chronic obstructive pulmonary disease (COPD). Exercise training can benefit COPD patients, but the underlying mechanism remains unclear. The modified Total Body Recumbent Stepper (TBRS, Nustep-T4) can benefit patients with stroke, spinal cord injury and amyotrophic lateral sclerosis. Nevertheless, the effect of TBRS training alone on pulmonary rehabilitation (PR) in COPD patients remains largely unknown. We aimed to explore the effect of TBRS training on exercise capacity and the thioredoxin system (TRXS) in COPD patients to provide a novel rehabilitation modality and new theoretical basis for PR of COPD patients. Ninety stable COPD patients were randomly divided into a control group (NC group) and a TBRS training group (TBRS group), with 45 cases in each group. Subjects in the TBRS training group were scheduled to undergo TBRS endurance training triweekly for 12 weeks under the guidance of a rehabilitation therapist. We assessed the primary outcome: exercise capacity (6-min walking distance, 6MWD); and secondary outcomes: perception of dyspnoea (mMRC, Borg), the COPD assessment test (CAT), the BODE index, pulmonary function, the number of acute exacerbations of COPD and oxidative stress (TRXS) at one-year follow-up. Compared with before the intervention and the control group, after the intervention, the TBRS training group, exhibited an increase in the 6MWD (from 366.92 ± 85.81 to 484.10 ± 71.90, 484.10 ± 71.90 vs 370.63 ± 79.87, P < 0.01), while the scores on the BORG, mMRC, BODE index, CAT, and the number of acute exacerbations of COPD were reduced, and the protein and mRNA expression levels of TRXS was significantly increased (P < 0.01). However, no differences were found in PF parameters in the comparison with before the intervention or between groups. TBRS training can effectively increase exercise capacity, while there are indications that it can alleviate COPD-related dyspnoea and reduce the number of acute exacerbations of COPD. Interestingly, long-term regular TBRS training may reduce oxidative stress associated with COPD to increase exercise capacity.