Inclusion Criteria:

• - Aged over 18 years.

• - With a confirmed MS diagnosis according to 2017 McDonald's revised criteria.

• - Having an EDSS score comprised between 0 and 6.5.

• - With a fatigue score ≥ 43 on MFIS scale.

• - Able to walk with or with walking aids.

• - Owning a personal smartphone with a mobile operating system version higher than 14 for IOS (iPhone) and 8 for Android.

• - Able to read the language in which the mobile application is available and able to understand pictograms.

• - Affiliated to a social security system.

• - Having signed the free and informed consent.

• - Having accepted to wear an actimeter during the whole duration of study participation.

• - Having been on a stable disease-modifying therapy for MS for at least 6 months.

Exclusion Criteria:

• - Psychiatric disorder, major visual or cognitive deficiency, as assessed by the investigator.

• - Participation in an exercise reconditioning program at a rehabilitation center within the 6 weeks prior to inclusion.

• - Major comorbidities that could influence fatigue management (lupus, rheumatoid arthritis, chronic obstructive pulmonary disease, chronic fatigue syndrome, etc).

• - Contraindication to physical activity: - History of cardiac events: - Abnormal cardiac examination at last medical check-up.

• - Palpitations, tachycardia or irregular heartbeat.

• - Pain and shortness of breath: - Cramp-like pain in the lower limbs when walking, disappearing when walking stops, except for MS-related pain (neuropathic or spastic).

• - Chest pain.

• - Shortness of breath at rest (appearing or worsening in the lying position) - Shortness of breath during low-intensity exercise or usual activities.

• - Pain, discomfort or heaviness in the chest at rest or during exertion.

• - Unstable chronic diseases : - Unstable metabolic disease.

• - Unstable renal disease.

• - Uncontrolled chronic disease.

• - Ankle edema.

• - Dizziness or syncope.

• - Having received fampridine, corticosteroid therapy or therapeutic cannabis within the 2 months prior to inclusion.

• - Psychoactive substances and/or alcohol consumption likely to influence test performance (investigator's judgment).

• - Patients confined to bed or whose daily activity is less than 2 hours.

• - Persons under guardianship or curatorship.

• - Pregnant or breast-feeding women.

• - Subjects who have participated in another clinical study within 30 days prior to selection, or who are participating in another study that, in the opinion of the investigator, could interfere with full participation in the study or confound the participant's assessment or the study results.

Arms

Interventions