This study aims to understand the mechanisms of a novel intervention involving breathing short durations of low levels of oxygen for persons with multiple sclerosis (MS). This intervention with low levels of oxygen is called Acute Intermittent Hypoxia (AIH), the levels of oxygen experienced are similar to breathing the air on a tall mountain, for less than 1 minute at a time. Previous studies have shown that AIH is a safe and effective way to increase strength in persons with MS. Here the investigators aim to look at brain activation and ankle strength before and after AIH to gain a better understanding of how the AIH may improve strength in those persons with MS.
Diagnoses of relapsing form of MS (including relapsing-remitting MS and secondary-progressive MS)
Expanded Disability Status Scale (EDSS) score of at least 3 and no more than 6.5
Motor Functional System Scale (FSS) between 2-4
Relapse free for at least 1 year
Active contrast-enhancing MS lesions, or diffusion positive lesions suggestive of acute cerebrovascular disease on baseline MRI scan
Uncontrolled hypertension (Systolic between 85 and 140, diastolic between 90 and 55)
History of epilepsy
Chronic obstructive pulmonary disease
Crossover
Acute Intermittent Hypoxia
Other interventionDuring each AIH session, the participant will be equipped with a non-rebreathing face mask, and provided with the AIH intervention. The AIH intervention involves alternating breathing cycles: one with lower oxygen concentration (9-10% Oxygen) than that at sea level (\~21% Oxygen) lasting between 30 and 60 seconds, followed by a similar duration of normal room air (21% Oxygen). This cycle will be repeated 15 times in one session, continuous blood oxygen levels and heart rate will be monitored.
Sham-Acute Intermittent Hypoxia
Other interventionDuring each Sham-AIH session, the participant will be equipped with a non-rebreathing face mask, and provided with the Sham-AIH intervention. The Sham-AIH intervention involves alternating breathing cycles: both with oxygen concentrations of \~21% Oxygen lasting between 30 and 60 seconds, followed by another similar duration of normal room air (21% Oxygen). This cycle will be repeated 15 times in one session, continuous blood oxygen levels and heart rate will be monitored.
Ankle Plantarflexion Strength
Participants will be seated in an adjustable chair with tested foot secured to a foot plate with the ankle in line with a rotational load cell. Participants will be asked to produce maximal ankle plantarflexion contractions, Electromyographic signals of the gastrocnemius, tibialis anterior, and soleus will be recorded simultaneously
Task fMRI
This outcome observes neural activations during voluntary muscle activations
Timed 25 Feet Walk test
A part of the MS functional composite. Participants will be directed to walk across a 25-foot course as quickly and safely as possible.
Six-Minute Walk test
The Six-minute walk test is an assessment to measure the distance able to be traversed by a participant in 6-minutes
Stride length
This assessment involves walking at normal walking pace over flat ground. The GAITRite®, a pressure sensitive walkway, will be used to measure and analyze spatiotemporal gait parameters, particularly stride length in meters
12-Item Multiple Sclerosis walk scale (MSWS-12)
This is a self-reported measure of the impact of MS on an individual's walking ability Minimum score: 12 Maximum score: 60 A lower score indicates better walking ability, less affected by the multiple sclerosis
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Shirley Ryan AbilityLab
Lead sponsor
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Collaborator
Northwestern University
Collaborator
