Maximal muscle strength is one of the most commonly assessed neuromuscular parameters in people with COPD due to its accessibility and relevance for prescribing an appropriate workload for resistance training. However, maximal force production is very rarely necessary during daily activities which requires production of submaximal and precisely controlled forces. Despite growing research on motor impairments in COPD, very little attention has been given to the effect of this disease on force control. Therefore, this research aims to better understand the potential deficits in force control caused by COPD, through the use of advanced signal processing methods (i.e., nonlinear approaches). We hypothesized that force control would be reduced in people with COPD compared to healthy individuals, particularly at low force levels.

This observational study is based on the analyses of data (force signals) recorded during the first visit of NEUROTIGUE study (NCT04028973).

Force signals were recorded during brief submaximal isometric contractions of the knee extensors performed by both COPD patients and healthy individuals. Each participant performed contractions at different intensity of his/her maximal muscle strength : 10, 20, 30, 40, 50 and 60%. Two contractions of approximately 6s duration were performed at each intensity by all participants. For a given intensity (e.g., 10%), both contractions were performed in a row but different intensities were accomplished in a random order.

Force control will be assess using a conjunction of parameters to provide a comprehensive understanding of force variability (e.g., coefficient of variation, non-linear approaches).

Inclusion Criteria:

COPD patients :

• GOLD II - III or IV
• FEV1 <80% of predicted values
• Men and women aged 40 years and over
• French-speaking participant
• BMI <30 kg / m²
• Stable condition (i.e. without exacerbation) for more than 15 days
• Able to express their consent in writing prior to any participation in the study
• Affiliates or beneficiaries of a social security
• Minimum score of 26 on the MMSE questionnaire of 3 months or less

Healthy volunteers :

• Men and women aged 40 years and over
• French-speaking participant
• BMI <30 kg / m²
• No known chronic respiratory, cardiovascular, metabolic, renal or neuromuscular pathologies
• Able to express their consent in writing prior to any participation in the study
• Affiliates or beneficiaries of a social security
• Minimum score of 26 on the MMSE questionnaire of 3 months or less

For all participants :

-Subject who has not objected to the reuse of data collected

Exclusion Criteria:

COPD patients :

• Alcoholism, i.e. > 21 glasses a week for men and >14 glasses a week for women
• Psychiatric pathologies or antecedent of behavioral disorders
• Patients treated with oral or systemic corticosteroids (> 0.5 mg / kg / day for > 7 days)
• Contraindication to the application of a magnetic field (i.e. right hip arthroplasty, pelvic / abdominal surgeries)
• Severe vision or hearing problems not corrected
• Patient oxygen dependent
• Patients in exclusion period from another research protocol
• Pregnant women (known pregnancy) or lactating women
• Patient deprived of liberty by a judicial or administrative decision
• Patient subject to a legal protection measure or unable to express their consent
• Patient who is not sufficiently fluent in reading and understanding the French language to be able to consent to participate in the study
• Patient unable to follow study procedures and to respect visits throughout the study period
• Person with a medical history that, in the opinion of the investigator, could interfere with the results of the study
• Any condition that, in the opinion of the investigator, could increase and compromise the safety of the person in the event that he / she participates in the study
• Any other reason that, in the opinion of the investigator, could interfere with the evaluation of the aims of the study

Healthy volunteers:

• Alcoholism, i.e. > 21 glasses a week for men and >14 glasses a week for women
• Psychiatric pathologies or antecedent of behavioral disorders
• Patients treated with oral or systemic corticosteroids (> 0.5 mg / kg / day for > 7 days)
• Contraindication to the application of a magnetic field (i.e. right hip arthroplasty, pelvic / abdominal surgeries)
• Severe vision or hearing problems not corrected
• Subjects in exclusion period from another research protocol
• Pregnant women (known pregnancy) or lactating women
• Regular physical activity with a frequency greater than 3 sessions per week
• Participant deprived of liberty by a judicial or administrative decision
• Participant subject to a legal protection measure or unable to express their consent
• Participant who is not sufficiently fluent in reading and understanding the French language to be able to consent to participate in the study
• Participant unable to follow study procedures and to respect visits throughout the study period
• Person with a medical history that, in the opinion of the investigator, could interfere with the results of the study
• Any condition that, in the opinion of the investigator, could increase and compromise the safety of the person in the event that he / she participates in the study
• Any other reason that, in the opinion of the investigator, could interfere with the evaluation of the aims of the study

Participants enrolled in NEUROTIGUE study (NCT04028973)