The aim of the study is to evaluate the safety, feasibility and initial efficacy of an interval-based walking training at low speed performed with blood flow restriction (BFR) on gait speed and functional impairments in patients with Multiple Sclerosis (MS).

Patients with severe MS will be recruited at outpatient rehabilitation clinics (University Hospital of Ferrara). Eligible participants will be randomized to interval walking training with BFR (the experimental group) or conventional exercise therapy (the control group) according to a blocked-randomization stratified by gender with 1:1 ratio. Both groups will receive 12 rehabilitative sessions over 6 weeks, for a 2 sessions/week pattern.

The experimental group will undergo interval-based walking training at a slow speed according to a walk:rest ratio of 1:1 for a total of 6 minutes, to be repeated 5 times. Blood flow restriction, applied to the proximal thigh, will be set at a maximum of 40% of systolic blood pressure. The control group will be treated with conventional therapy.

Changes in gait speed, endurance, balance, lower limbs strength and quality of life will be assessed at baseline, at the end of training, and at follow up.

The proposed training modality has never been tested in patients with MS and, if the hypotheses were supported by the results, might be a novel tool to improve muscle strength with a positive impact on gait disabilities, balance and quality of life for patients with MS.

Inclusion Criteria:

• primary and secondary progressive MS patients according to the diagnostic MS criteria revised by Polman et al.
• Male and females, aged 18 to 65 years;
• Severe gait impairments, defined by an Expanded Disability Status Scale (EDSS) ranging from 5.5 to 6.5;
• Lack of MS worsening in the previous three months prior to the intervention period;
• Cognitive functioning to provide informed consent identified by a Mini-Mental Status Examination (MMSE) score = 24/30.

Exclusion Criteria:

• Neurologic conditions in addition to MS that may affect motor function and other medical conditions likely to interfere with the ability to complete safely the study protocol, independently from the group assignment;
• Considerable muscle spasticity, defined by a Modified Ashworth Scale (MAS) score > 3 or contractures that may limit range of motion or function for hip, knee or ankle flexors/extensor;
• Relapsing of MS-related conditions or changes in drug therapy or any other confounding factor during the study;
• Rehabilitation treatments or Botulinum toxin injections during the three months preceding the start of the study.
• Intermittent claudication and peripheral artery disease
• Contraindication to exercise training (e.g., unstable angina, congestive heart failure)

Individual participant data that underlie the results published at the end of the trial after deidentification. The database of the study will be published in a public repository.

IPD will be available beginning 6 months following study results publication.

Anyone who wishes to access the data

Outcome measures assessors, blinded to group allocation, will not have access to the randomization list and unblinding will not be possible for these researchers.