Rationale. Chronic obstructive pulmonary disease (COPD) and heart failure (HF) coexist in approximately one third of patients presenting with one of these conditions. From a clinical standpoint, impaired tissue oxygen (O2) delivery stands as a common pathological mechanism of these cardiorespiratory diseases. Recent evidence suggest that muscle and cerebral blood flow and oxygenation are further impaired during exercise in patients with COPD-HF overlap compared to isolated diseases. However, it remains unknown whether impaired O2 delivery is associated with exaggerated manifestations of peripheral and central fatigue in COPD-HF overlap. In addition, improving cardiopulmonary interactions through non invasive positive pressure ventilation or through the addition of a hyperoxic gas mixture during exercise have been associated with enhanced cerebral and muscle O2 delivery and oxygenation in patients with COPD or HF. It is, therefore, conceivable that improved O2 delivery to these structures have beneficial influence on exercise capacity in patients with COPD-HF overlap due to less peripheral and central fatigue.

Aims. To investigate the influence of impaired O2 delivery during exercise, and its alleviation with different interventions (non invasive positive pressure ventilation or hyperoxia), on neuromuscular fatigue in patients with COPD-HF.

Inclusion Criteria:

• Age ≥ 18 years;
• COPD: mild-to-severe airflow obstruction (forced expiratory volume in 1 second (FEV1)/forced vital capacity ratio <0.70; post-bronchodilator FEV1 > 30% predicted);
• HF: reduced left ventricular ejection fraction (<50%, for COPD-HF patients only);
• HF: New York Heart Association Functional Classification I to III (for COPD-HF patients only);
• Clinical stability for both diseases (COPD and/or HF) and no recent (within 3 months) exacerbation requiring a change in medications;
• Patient benefiting from health care coverage;
• Patient able to provide written informed consent.

Exclusion Criteria:

• Inability to perform cycle ergometry;
• Medical device incompatible with magnetic stimulation;
• Counter-indication to perform exercise test;
• Patient refusing to sign written informed consent;
• Patient not benefiting from health care coverage;
• Patient exceeding the annual ceiling of authorized compensation received following participation to a clinical trial;
• Patient deprived of freedom by judicial or administrative decision;
• Patient subject to a measure of legal protection (safeguard of justice, guardianship, curatorship), who cannot be included in clinical trials;
• Pregnant or nursing woman.

Data will be available on reasonable request to the Investigators (unidentified patients' data).

Data will be available on reasonable request to the Investigators (unidentified patients' data) upon study completion and for an unrestricted period of time.

Data available on reasonable request to the Investigators.

Patients masked from intervention (gas mixture being delivered). Non-randomized (air medical condition tested first).