COPD: A Leading Cause of Respiratory Disability COPD, primarily linked to smoking, affects 3.5 million people in France and causes 15,000 deaths each year. It is a major source of disability, particularly due to dyspnoea, which affects one in three patients. Around 400,000 patients are registered under long-term conditions (ALD), and 200,000 receive home-based respiratory support. The most severe cases fall under the category of chronic respiratory failure-a term also applicable to other respiratory or neuromuscular diseases.

Walking Exposes Physical Limitations In patients with respiratory failure, walking rapidly induces disabling dyspnoea, as it may represent their maximal effort. This severely limits autonomy and quality of life. To improve exercise tolerance, clinicians rely on pulmonary rehabilitation (exercise reconditioning, bronchodilators, oxygen therapy). When these measures are insufficient, mobility aids such as scooters or electric scooters may help, although they have limitations (cost, bulkiness, muscular deconditioning).

The Six-Minute Walk Test (6MWT): A Key Tool The 6MWT is a standardised test that assesses walking distance, dyspnoea, heart rate, and oxygenation. It is used to evaluate the severity and prognosis of respiratory failure and to measure response to treatment. It is integrated into prognostic indices and criteria for assessing the effectiveness of rehabilitation. The only non-standardised parameter remains the type of footwear worn.

Research Hypothesis Some so-called "active" sports shoes enhance walking by design-through cushioning, rocker soles, and rigid inserts-which store and return impact energy to assist propulsion. We hypothesise that wearing such shoes could improve walking performance in COPD patients, as reflected by a greater distance on the 6MWT. If confirmed, this simple and low-cost solution could meaningfully improve the daily lives of many patients.

Chronic obstructive pulmonary disease (COPD) is a leading cause of respiratory disability and impaired quality of life, particularly due to exertional dyspnoea. In patients with moderate to severe disease, walking can trigger disabling breathlessness, effectively limiting autonomy and social participation. While pulmonary rehabilitation, pharmacological treatments, and oxygen therapy can improve exercise tolerance, some patients continue to experience debilitating limitations. Mobility aids such as scooters are sometimes proposed but carry risks of deconditioning and are not always practical or accessible.

The six-minute walk test (6MWT) is a standardised and widely used measure of submaximal functional capacity in COPD. It provides prognostic and therapeutic insights, but one parameter remains non-standardised: the type of footwear used by patients during the test. This study explores the hypothesis that biomechanically optimised "active" sports shoes-designed to enhance gait efficiency through energy-returning cushioning, curved ("rocker") soles, and stiff inserts-may significantly improve walking performance in individuals with COPD.

ChaussePnée is a randomised, open-label, controlled, cross-over trial comparing two walking conditions in the same patient: wearing "active" sports shoes versus their usual, "normal" shoes. The primary objective is to detect a difference in walking distance during the 6MWT between the two conditions. Secondary objectives include assessments of symptom tolerance (dyspnoea, leg fatigue), physiological responses (heart rate, oxygen saturation), perceived comfort, and biomechanical efficiency during walking and stair climbing.

Patients will be recruited during hospitalisation in a respiratory rehabilitation unit. Eligible participants will be adults with a confirmed diagnosis of COPD, with severe to very severe airflow obstruction (FEV1 < 50% predicted), and dyspnoea classified as grade 3 or 4 on the modified Medical Research Council (mMRC) scale. All participants will have a clinical indication for 6MWT as part of their care.

Each participant will undergo two 6MWTs and two stair climbing tests on the same day, at a dedicated clinical investigation centre. The sequence of shoe conditions will be randomised. Between tests, sufficient rest periods will be ensured. Standardised instructions and outcome measures (including distance, Borg scales, comfort ratings, vital signs, and optional metabolic measurements) will be used.

An ancillary study, offered to a subset of participants, will include continuous spirometric and metabolic assessments during the tests, aiming to clarify underlying physiological mechanisms (e.g., energy expenditure, hyperventilation, dynamic hyperinflation). Motion capture and force platform analysis will quantify gait biomechanics. In-shoe pressure mapping will compare load distribution across footwear conditions.

The study plans to enrol 75 patients. Sample size was calculated based on a minimal clinically important difference of 22.8 metres in 6MWT distance, assuming an SD of 53.6m and a power of 80-90%. The main analysis will compare intra-individual differences in 6MWT distance using paired statistical tests and linear mixed models accounting for period and sequence effects. Secondary outcomes will be analysed similarly.

The study duration is 12 months, with a single study visit for each participant. Risks are minimal, as all procedures are non-invasive and part of standard respiratory evaluation. Participants will travel to the evaluation centre by covered medical transport, and no medication or biological sampling is involved. The anticipated benefit is both individual (raising awareness of the role of footwear in daily life) and collective (identifying a simple, low-cost intervention to support mobility in COPD).

Inclusion Criteria:

• Age 18 or older
• Diagnosed with COPD according to standard criteria
• Severe to very severe airflow obstruction (FEV₁ < 50% predicted, within 12 months)
• Dyspnoea grade 3 or 4 on the mMRC scale
• Currently hospitalised in the respiratory rehabilitation unit
• Clinical indication for six-minute walk test
• Provided written informed consent

Non inlcusion Criteria:

• Any respiratory condition other than COPD
• Neurological, neuromuscular, orthopaedic or rheumatological conditions affecting gait or balance
• Uncorrected visual or hearing impairment
• Cognitive or psychiatric disorders interfering with instructions
• Contraindications to exercise testing (e.g. unstable angina, recent myocardial infarction, severe uncontrolled hypertension, resting HR >120 bpm)
• Pregnancy or breastfeeding
• Inability to understand French
• No health insurance coverage
• Under legal protection (e.g. guardianship)
• Participation in another interventional or randomised clinical trial
• Habitual use of active sports shoes

Data are available upon reasonable request. The procedures carried out with the French data privacy authority (CNIL, Commission nationale de l'informatique et des libertés) do not provide for the transmission of the database, nor do the information and consent documents signed by the patients. Consultation by the editorial board or interested researchers of individual participant data that underlie the results reported in the article after deidentification may nevertheless be considered, subject to prior determination of the terms and conditions of such consultation and in respect for compliance with the applicable regulations.

Beginning 3 months and ending 3 years following article publication. Requests out of these time frame can also be submitted to the sponsor

Researchers who provide a methodologically sound proposal.