Rationale: The Balance-Based Torso-Weighting (BBTW) is a patented evaluation system that uses strategic placement of small or lightweight weights on the trunk to improve balance and stability. BBTW has been found to improve the upright mobility of people with multiple sclerosis, however the mechanism underlying the improvement of balance and gait is still unknown.1-2 Purpose: The purpose of this study is to investigate the immediate effects of BBTW on muscle activation of tibialis anterior and gastrocsoleus and sway using electromyography and force plates during balance tests in people with MS and healthy controls?

Research Questions:

Question #1 - Is there a difference in EMG within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when not wearing weighted vest with eyes open? Question #2 - Is there a difference in EMG within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when not wearing weighted vest with eyes closed? Question #3 - Is there a difference in EMG within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when wearing weighted vest eyes open? Question #4 - Is there a difference in EMG within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when wearing weighted vest eyes closed? Question #5 - Is there a difference in SWAY within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when not wearing weighted vest with eyes open? Question #6 - Is there a difference in SWAY within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when not wearing weighted vest with eyes closed? Question #7 - Is there a difference in SWAY within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when wearing weighted vest eyes open? Question #8 - Is there a difference in SWAY within postural muscles (tibialis anterior and gastrocsoleus) and between healthy and MS when wearing weighted vest eyes closed? Research Design: Quasi-experimental design

Inclusion Criteria for Individuals with Multiple Sclerosis group:

• self-reported diagnosis of multiple sclerosis (MS)
• age 18 to 75 years old
• able to communicate in English
• able to provide informed consent
• able to tolerate up to three hours of testing with rest breaks
• able to walk 20 meters with or without assistive device and without resting (equivalent to Expanded Disability Status Scale of 6.5 or less).

Inclusion criteria for the Healthy Control group:

• able to communicate in English
• able to provide informed consent
• physical criteria that matched each participant with MS which included age (within 7 years), height (within 12.7 cm [5 in]), mass (within 9.1 kg [20 lb]) and sex.

Exclusion Criteria for Individuals with Multiple Sclerosis group:

• exacerbation of MS within the past two months
• had a diagnosis of a concurrent neurological disorder (head injury, stroke, Parkinson's disease, etc.)
• reported pain that could be exacerbated by external perturbations during standing.

Exclusion Criteria for Healthy control group:

• Known diagnoses
• current pain that could affect balance.