Acute Muscular and Vascular Responses to a Single Session of Exercise With BFR in COPD

Exercise training is a cornerstone of pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). However, some patients derive limited benefits from conventional exercise programs. Previous studies suggest that the magnitude of exercise-induced muscle fatigue is associated with training effectiveness, with patients unable to develop significant muscle fatigue ("non-fatiguers") showing smaller improvements in functional capacity and quality of life. Blood flow restriction (BFR) exercise consists in performing physical exercise while applying external pressure to the proximal part of the exercising limb, thereby reducing oxygen delivery to the muscles and limiting metabolite clearance. This approach has been shown to induce significant muscular adaptations despite the use of low exercise intensities. Because exercise intensity in COPD patients is often constrained by ventilatory limitations, BFR training may enhance muscle adaptations while reducing respiratory stress, potentially improving the effectiveness of PR. The primary objective of this monocentric randomized crossover study is to compare lower-limb muscle fatigue induced by a single exercise session performed with BFR versus a standard exercise session in patients with COPD.

Inclusion Criteria: * Negative pregnancy test and use of an acceptable contraceptive method throughout the study duration for women of childbearing potential * Established COPD defined as obstructive ventilatory defect (FEV1/FVC \< 0.70 or below the 5th percentile) * Resting lung hyperinflation defined as functional residual capacity \> 2.5 z-scores according to the Global Lung Function Initiative (GLI) * Clinical stability of COPD for at least 3 months, with no recent exacerbation requiring treatment modification * Covered by a national health insurance system * Able and willing to provide written informed consent Non-inclusion Criteria: * Presence of a medical device incompatible with magnetic stimulation * Inability to perform an exercise test on a cycle ergometer * Any usual contraindication to exercise testing, including: * Recent myocardial infarction (3-5 days) * Unstable coronary insufficiency * Severe stenotic valvular disease * Uncontrolled arrhythmia with hemodynamic instability * Recent unexplained syncope * Uncontrolled heart failure * Uncontrolled arterial hypertension (systolic blood pressure ≥200 mmHg and/or diastolic blood pressure ≥110 mmHg at rest) * Acute thromboembolic disease and/or pulmonary edema * Conditions contraindicating the use of blood flow restriction (BFR), including: * Coagulation disorder * Peripheral neuropathy * Uncontrolled hypertension (\>160/100 mmHg) * Peripheral arterial disease * History of venous thrombosis * Intensive care unit stay within the last 3 months * Participation in another study during an exclusion period * Inability to be contacted in case of emergency * Individuals covered under Articles L1121-5 to L1121-8 of the French Public Health Code (protected populations, including pregnant or breastfeeding women, prisoners, minors, individuals under legal protection, psychiatric inpatients, etc.) * Staff members with a hierarchical relationship with the principal investigator