This retrospective collaborative study on persistent exercise intolerance after COVID-19 offers to perform a large descriptive analysis of CPET performed in real-life by pulmonologists, cardiologists and physiologists. Indeed, these practicians are regularly consulted for a persistent intolerance to exercise expressed by dyspnea and/or frank fatigability sometimes associated with muscular or thoracic pain. When these complaints persist beyond 3 months after the first symptoms, it is legitimate to perform a CPET:

• Either to evaluate the functional impact of an identified organ deficiency (e.g. myocarditis, pulmonary fibrosis, etc.),
• Or, in the absence of formal arguments for an identified organ deficiency, to observe possible abnormalities in physiological responses during an incremental exercise test, likely to explain the persistence of symptoms and intolerance to exercise. Indeed, the recent literature highlights the presence of non-specific ventilatory and cardio-circulatory abnormalities leading to various physio-pathological observations. Unfortunately, these reports now concern relatively small numbers of patients with very diverse clinical forms of Covid, comorbidities and habitus.

In order to improve the understanding of persistent symptoms and in particular the diversity of physiological response presentations, the investigators propose to collect a very large amount of data through a web-based platform designed to collect the measurements made throughout the exercise test directly from the ergospirometer.

The relevant data covers the period from January 2, 2020 to December 31, 2022 (i.e. 35 months), The retrospective data collection will be carried out from February 1, 2023 to December 31, 2023.

The descriptive analysis will focus on the kinetics of all the variables measured and calculated on subgroups defined a priori on age, sex, comorbidities, acute covid severity, persistent symptoms post covid, regular habitual physical activity level, etc. according to the sample.

The study is expected to collect data from around 1000 patients and to involve around 40 French-speaking investigators. However, this collaborative study is open on request to all centers wishing to participate, as the web platform has been developed for data collection in English.

Inclusion Criteria:

• Age ≥ 18 years
• Patients with persistent symptoms 3 months after the onset of Covid-19 infection, regardless the severity of the initial illness
• Patients with an ICU stay, primarily following rehabilitation management; that is, in practice, at least 6 months after COVID
• Patients followed by a pulmonologist, cardiologist or physiologist in a public or private facility or in private practice, allowing for CPET
• Patients who have performed a CPET before December 31, 2023
• Patients informed of the possible anonymized processing of the data collected during CPET for research purposes; and who gave informed consent

Exclusion Criteria:

• Age < 18 years
• Patients unable to perform CPET for locomotor reasons
• Patients with severely reduced functional work capacity
• Patient deprived of liberty by judicial or administrative decision
• Patients unable to give informed consent

Patients with exercise intolerance after COVID-19, diagnosed between January 2, 2020 and December 31, 2023, who have been informed that the physiological data collected during the CPET and the clinical data necessary for its interpretation may be used for clinical research.