Effects of downhill walking in pulmonary rehabilitation for patients with COPD: a randomised controlled trial

Abstract

BackgroundThe development of contractile muscle fatigue (CMF) affects training responses in patients with COPD. Downhill walking induces CMF with lower dyspnoea and fatigue than level walking. This study compared the effect of pulmonary rehabilitation (PR) comprising downhill walking training (DT) to PR comprising level walking (conventional training, CT) in patients with COPD.MethodsIn this randomised controlled trial, thirty five patients (62±8 years; FEV1 50±17%pred) were randomised to DT or CT. Exercise tolerance (6-minute walk test distance, 6MWD [primary outcome]), muscle function, symptoms, quality-of-life and physical activity levels were assessed before and after PR. Absolute training changes and the proportion of patients exceeding the 30 m 6MWD minimally important difference (MID) were compared between groups. Quadriceps muscle biopsies were collected after PR in a subset of patients to examine physiological responses to long-term eccentric training.ResultsNo between-group differences were observed in absolute 6MWD improvement (mean 6MWD Δ77±46 m DT versus 56±47 m CT; p=0.45), however 94% of patients in DT exceeded the 6MWD MID compared to 65% in CT (p=0.03). Patients in DT tended to have larger improvements than CT in other outcomes. Muscle biopsy analyses did not differ between groups.ConclusionPR incorporating downhill walking confers similar magnitudes of effects to PR with conventional walking across clinical outcomes in patients with COPD, however offers a more reliable stimulus to maximise the achievement of clinically relevant gains in functional exercise tolerance in people with COPD.

Eccentric Exercise in COPD

“…The latter is in line with the low metabolic responses at the muscle level observed in Ward et al 8 Interestingly, literature suggests that eccentric training (both eccentric cycling and downhill walking) can enhance whole-body exercise capacity, possibly to a similar extent as concentric training. 3,5 This matches with the observed strong relationship between muscle strength and exercise capacity in COPD. Lower limb muscle weakness is common in COPD and related to exercise intolerance, impaired postural control, poor quality of life, and premature death.…”

“…Eccentric training has been proposed as a therapeutic alternative to concentric training in symptom-limited individuals with COPD who are unable to tolerate conventional exercise, because up to four times greater muscle forces can be generated with lower ventilatory demands. 1 Scientific evidence on eccentric training in COPD has emerged in the past decade, [2][3][4][5][6][7] and studies have shown that endurance training with the use of eccentric muscle contractions is well-tolerated, safe and feasible. 7 However, evidence on its ability to elicit sufficient physiologic responses to induce a training effect similar to concentric training is still under debate, and it is unclear whether responses are comparable between patients with COPD and healthy individuals.…”

Respiratory Impairment, Limited Activity, and Pulmonary Rehabilitation in Patients with Interstitial Lung Disease

“…Some strategies have been proposed to optimize training intensity and decrease dyspnea in patients with COPD during exercise training. These interventions in clinical settings include single-limb partitioning 35 ) , Nordic walking 36 ) , and downhill walking 37) . These strategies may be useful in patients who cannot tolerate high-intensity exercises due to EIH or dyspnea.…”

Current developments and future directions in COPD

“…However, many patients with COPD appear not to achieve contractile muscle fatigue during conventional pulmonary rehabilitation exercise training, perhaps because exercise is limited by other factors. CAMILLO et al [85] investigated how incorporating downhill walking training, rather than level walking, might help improve functional exercise tolerance. While the resulting differences in 6-min walk distance following rehabilitation were not significantly different (77±46 m versus 56±47 m in the downhill versus the level walking group p=0.45), more patients from the downhill walking group exceeded the minimally importance difference following rehabilitation (94% versus 65%, respectively; p=0.03) [85].…”

“…CAMILLO et al [85] investigated how incorporating downhill walking training, rather than level walking, might help improve functional exercise tolerance. While the resulting differences in 6-min walk distance following rehabilitation were not significantly different (77±46 m versus 56±47 m in the downhill versus the level walking group p=0.45), more patients from the downhill walking group exceeded the minimally importance difference following rehabilitation (94% versus 65%, respectively; p=0.03) [85]. The study also showed that this cheap and simple intervention was safe, suggesting that it is worthy of further research, especially given that this was a relatively small study.…”