The Neural Mechanisms of Split-belt Treadmill Adaptation in People With Multiple Sclerosis

The Neural Underpinnings and the Impact of Wearable Sensory Stimulation During Split-belt Treadmill Adaptation in People With Multiple Sclerosis

Majority of people with multiple sclerosis experience difficulty with balance and mobility, leading to an increased risk of falls. The goal of this clinical trial is to learn about brain activity during walking adaptation in people with multiple sclerosis. Also, this clinical trial will test a form of nerve stimulation to see if it can improve walking performance. The main questions it aims to answer are: What areas of the brain are the most active during walking adaptation? Can nerve stimulation make walking adaptation more effective? Participants will walk on a treadmill where each leg will go a different speed which will create walking adaptation. At the same time, brain scans will occur. There will be two sessions of walking adaptation, one with nerve stimulation, and one without nerve stimulation. Researchers will compare people with multiple sclerosis to healthy young adults to see if there are differences in brain activity.

Most people with MS (PwMS) experience significant gait asymmetries between the two legs leading to an increased risk of falls and musculoskeletal injury. The objective of this study is to investigate the neural mechanisms of gait adaptation and the effects of transcutaneous electrical nerve stimulation (TENS) on adaptability during split-belt treadmill training in PwMS. Our hypothesis is that TENS will strengthen sensorimotor integration via amplified afferent signaling, thereby enhancing adaptation, and further improving gait symmetry chronically. Functional near-infrared spectroscopy (fNIRS) will be used during a split-belt treadmill training paradigm to assess cortical activation during gait adaptation. Additionally, the effect of split-belt treadmill training coupled with TENS on gait adaptability in PwMS will be tested with experimental and a sham TENS split-belt treadmill sessions. Cortical activation and the effect of TENS on gait adaptability will be compared between young neurotypical adults and PwMS to assess differences that can be attributed to multiple sclerosis.

split-belt treadmill, adaptation, multiple sclerosis, functional near-infrared spectroscopy, cortical activation, gait asymmetry, locomotion, sensorimotor control

During this arm, participants will perform split-belt treadmill training with sensory stimulation equipment outfitted but not active during all adaptation sessions.

During this arm, participants will perform split-belt treadmill training with active sensory stimulation occuring simultaneously during all adaptation sessions.

Split-belt treadmill training, where the speed of each leg is controlled independently has been shown to create gait adaptation where the coordination of each leg is altered, creating improved gait symmetry for people with walking impairments.

TENS is a form of nerve stimulation that stimulates at a frequency below motor threshold, targeting activation of sensory receptors, such as muscle spindles. Electrodes that create this stimulation will be placed on the skin superficial to the muscle bellies of the tibialis anterior and biceps femoris.

Baseline session 1 (day 1), training session 1 (day 1), post-training session 1 (day 1), baseline session 2 (day 14), training session 2, and post-training session 2 (day 14)

The difference in the distance covered by each step, a common measure of gait asymmetry, measured using three-dimensional motion capture and force plates.

Baseline session 1 (day 1), post-training session 1 (day 1), baseline session 2 (day 14), and post-training session 2 (day 14)

The accuracy and consistency of step time compared to stride time, measured using three-dimensional motion capture and force plates.

Baseline session 1 (day 1), post-training session 1 (day 1), baseline session 2 (day 14), and post-training session 2 (day 14)

The anterior-posterior distance traveled by the limb from toe-off to ipsilateral heel strike, measured using three-dimensional motion capture and force plates.

Baseline session 1 (day 1), post-training session 1 (day 1), baseline session 2 (day 14), and post-training session 2 (day 14)

The percentage of time spent with both feet on the ground during walking, measured using three-dimensional motion capture and force plates.

Baseline session 1 (day 1), post-training session 1 (day 1), baseline session 2 (day 14), and post-training session 2 (day 14)

Inclusion Criteria: A diagnosis of relapsing remitting multiple sclerosis OR a neurotypical adult (ages 18-86) Not experiencing an active relapse Able to stand and walk without an assistive device Able to walk for three tenths of a mile without stopping to rest Exclusion Criteria: Unable to walk for three tenths of a mile without assistance Musculoskeletal injury in past 6 months Lower extremity surgery in past 6 months Unable to abstain from medications that impair balance Currently pregnant History of traumatic brain injury History of vestibular disease History of any other balance impairment unrelated to multiple sclerosis