Low intensity blood flow restriction exercise for rehabilitation in chronic obstructive pulmonary disease

Abstract

Background: Pulmonary rehabilitation (PR) improves dyspnoea, exercise capacity and health-related quality of life in people with chronic obstructive pulmonary disease (COPD), yet access, uptake and completion remain suboptimal, supporting the need for flexible, home-based models of rehabilitation. Blood flow restriction (BFR) training may offer a muscle-targeted stimulus at lower external load, with a lower ventilatory cost than traditional high-load strength exercise. However, in COPD, the evidence base remains sparse, limited to a small number of supervised studies, and does not address how BFR might be configured as a simple, home-compatible adjunct to routine PR. Consistent with complex-intervention guidance, staged feasibility work should precede any definitive multicentre evaluation. Methods: Four linked objectives were examined across four experimental chapters. In Chapter 3, healthy male and female adults (n = 15, 45-65 y) performed low-intensity interval cycling at 90% of the gas-exchange threshold with or without intermittent BFR (50% limb occlusion pressure [LOP]). Repeated measures included heart rate (HR), peripheral oxygen saturation (SpO₂), brachial blood pressure (BP), and rating of perceived exertion (RPE) during exercise and recovery; central BP indices pre- and 20 min post-exercise; and circulating biomarkers (creatine kinase [CK], C-reactive protein [CRP], interleukin-6 [IL-6]) and muscle soreness up to 72 h post-exercise. In Chapter 4, healthy male and female adults (n = 13, 50-65 y) performed functional body-weight exercise (involving five lower-limb exercises) with or without BFR (50% LOP). The same outcome measures as the interval cycling protocol were assessed. In Chapter 5, male and female patients with COPD (n = 25, 43-83 y) were randomised to a single-centre, parallel-group external feasibility trial (BFR = 13; control = 12) in which they performed a 6-week, home-based body-weight programme with individualised BFR (40-60% LOP) or control (exercise only). Primary outcomes were feasibility (recruitment, retention, and adherence), acceptability, and safety were determined; exploratory outcomes included pre- to post-intervention changes in functional capacity, lower-limb function, quadriceps strength, and health-related quality of life. In Chapter 6, male and female patients with COPD (n = 24, 43-83 y; who were recruited to the feasibility study) completed the first body-weight exercise session with or without BFR (40% LOP) which characterised the physiological (HR, BP, SpO₂), perceptual (RPE, dyspnoea, perceived soreness) and circulating biomarker (CK, CRP, IL-6) responses at baseline, ~20 min and 48 h post-exercise and after the 6-week home-based exercise intervention. Results: In healthy adults, adding BFR to interval cycling (Chapter 3) yielded modest additional brachial pressor responses (+6/+4/+5 mmHg for systolic, diastolic, and mean arterial BP, respectively) and higher RPE (+2 units), without meaningful differences in HR or SpO₂; central haemodynamics were unchanged, and CK, CRP and IL-6 remained stable over 72 h. Functional body-weight exercise with BFR (Chapter 4) produced similarly conservative response profile (smaller haemodynamic differences, higher RPE but within the “very light” to “light” range, similar low transient soreness, and stable CK, CRP, and IL-6. In the COPD feasibility trial (Chapter 5), recruitment was 20.3%, and 6-week retention was 80%. Among those who commenced the home phase, 75% (18/24) achieved ≥14/18 sessions, with high fidelity in attended sessions (~94% exercise fidelity and ~95% target LOP pressure fidelity). Exposure-adjusted adverse event rates were low and similar between arms; nine events (~5.5/100 sessions) were probably/definitely BFR-related, all reflecting transient cuff intolerance, and there were no BFR-related serious adverse events. Exploratory functional and strength outcomes tended to favour BFR but were heterogeneous and imprecise, consistent with the feasibility design. In COPD, adding 40% LOP BFR to body-weight exercise (Chapter 6) did not add haemodynamic burden versus control, RPE and dyspnoea ratings remained low to moderate, and circulating markers (CK, CRP, IL-6) showed no clinically important BFR-related increases. Conclusions: Conservative, intermittent at low external load BFR (40-60% LOP) can be delivered as a home-based adjunct in a selected, stable, PR-referred COPD cohort with acceptable recruitment, good adherence, high exercise and target pressure fidelity, low adverse-event rates, and no BFR-related serious adverse events. This thesis establishes key feasibility and safety parameters, together with a pragmatic screening and prescription framework, to support a definitive multicentre trial prioritising responsive functional endpoint, objective pressure-dose capture, and key implementation outcomes including adherence, fidelity, acceptability, and safety.