Chronic Effect Of Photobiomodulation Therapy On Muscle Function In Persons With Multiple Sclerosis

Abstract Background: Recent evidence suggests that skeletal muscle dysfunction is involved in disability progression in people with multiple sclerosis (MS). However, the relationship between muscle dysfunction and walking impairments in MS remains unclear. Thus, the cross-sectional relationships between muscle-specific oxidative capacity and walking endurance in women with MS were evaluated. Methods: Twenty women with MS (11 African American, 9 white) were tested. Muscle oxidative capacity of the medial gastrocnemius was measured using near-infrared spectroscopy after electrical stimulation. Muscle endurance was evaluated using accelerometer-based mechanomyography during electrical stimulation. Muscle strength was measured during maximal voluntary plantarflexion using handheld dynamometry. Walking function was measured using the Timed 25-Foot Walk test and the 6-Minute Walk Test (6MWT). Results: Reduced muscle oxidative capacity (R2 = 0.68–0.71, P < .01) and muscle endurance (R2 = 0.59–0.78, P < .01) were associated with lower Timed 25-Foot Walk time and 6MWT distance. Muscle strength was weakly correlated to 6MWT distance (R2 = 0.21, P = .02). No differences in muscle function or clinical outcome measures were found between African American and white subgroups. Women with moderate-to-severe disability (Expanded Disability Status Scale [EDSS] score, 5.0–6.5) had significantly reduced muscle oxidative capacity, muscle endurance, and walking ability compared with women with mild disability (EDSS score, 2.5–4.5). Conclusions: Reductions in muscle function in people with MS are related to declines in walking function across all levels of disability. Muscle dysfunction is not differentially related to walking impairment in African American and white women with MS.

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Lower Leg Muscle Function: A Contributory Risk Factor of Gait and Balance Impairment after Six Minutes Walk among People with Multiple Sclerosis

Medical Research Archives ◽

10.18103/mra.v9i3.2331 ◽

2021 ◽

Vol 9 (3) ◽

Author(s):

Adeola Sanni ◽

Robert Lynall ◽

Deborah Backus ◽

Kevin McCully

Keyword(s):

Multiple Sclerosis ◽

Muscle Function ◽

Lower Leg ◽

Gait Variability ◽

Eyes Closed ◽

Cohen’S D ◽

Gait Asymmetry ◽

Slight Elevation ◽

Leg Muscle ◽

Cohen's D

Background/Purpose: Multiple sclerosis (MS) is a progressive neurological disease that results in increased fatigue, decreased muscle function, and impaired gait and balance. The purpose of this study was to evaluate the relationship between lower leg muscle function and changes in gait and balance immediately and 20 minutes after 6mins walk-induced fatigue. Methods: Six persons with MS (Patient-Determined Disease Steps 3-5) participated in the study. Perceived fatigue and demographic information were taken at baseline. Muscle fatigability and mitochondria capacity was measured in the lower leg muscles before walking. Reported fatigue (VAFS, 0-10), gait variability, gait asymmetry, and static balance were measured before and immediately after a self-paced 6 minutes treadmill walk with slight elevation, and after 20 minutes of rest. Results: Participant’s baseline MFIS score ranged from 14 - 71. There was a 173% increase in reported fatigue scores after walking. Gait was impaired with a ~26% increase in gait variability and ~40% increase in gait asymmetry immediately after walking (Cohen’s D = 0.4, 0.3 respectively). There was also ~69% increase in balance postural sway with eyes opened and a ~20% increase with eyes closed (Cohen’s D = 0.5, 0.2 respectively). Gait and balance remained impaired after 20 minutes of rest. The decline in gait parameters after walking had a negative correlation with muscle endurance (r=-0.80, p=0.03), and mitochondrial capacity (r=-0.92, p<0.01). The changes in gait and balance were more evident in participants with a higher disability. Conclusions: Six minutes of self-paced walking with slight elevation worsened gait and balance among people with MS (PwMS), which did not completely recover after 20 minutes of rest. The changes in gait after walking were associated with lower leg muscle function. Lower leg muscle function might be an important intervention target to improve gait and balance fall risk among PwMS.

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