Rationale and design of a randomized controlled clinical trial of functional electrical stimulation cycling in persons with severe multiple sclerosis

Effect of Functional Electrical Stimulation Cycling Exercise on Lower Limb Strength Asymmetry in Persons With Multiple Sclerosis

Background:

Lower limb strength asymmetry (ie, significant difference between contralateral limbs) has been associated with mobility impairment in persons with multiple sclerosis (MS). However, whether an adaptive exercise modality can be used to modify lower limb strength and potentially improve mobility is unclear. The effect of functional electrical stimulation (FES) cycling on lower limb strength asymmetry in persons with MS with mobility impairment was assessed, and the association between change in lower limb strength asymmetries and changes in functional and self-reported mobility outcomes was explored.

Methods:

Eight adults with MS (Expanded Disability Status Scale scores, 5.5–6.5) were included. Outcomes included knee extensor and knee flexor strength asymmetry, Timed 25-Foot Walk (T25FW) test, 2-Minute Walk Test (2MWT), Timed Up and Go (TUG) test, and 12-item Multiple Sclerosis Walking Scale (MSWS-12). Participants received 24 weeks (3 times per week) of FES cycling or passive leg cycling.

Results:

The FES condition demonstrated a small decrease in knee extensor (d = −0.33) and knee flexor (d = −0.23) strength asymmetry compared with passive leg cycling. With both groups combined, weak-to-strong associations were observed between change in knee extensor asymmetry and change in T25FW test time (rs = −0.43), 2MWT time (rs = −0.24), TUG test time (rs = 0.55), and MSWS-12 score (rs = 0.43). Moderate correlations were observed between change in knee flexor asymmetry and change in T25FW test time (rs = −0.31), TUG test time (rs = 0.33), and MSWS-12 score (rs = 0.35).

Conclusions:

FES cycling may be an efficacious exercise modality for reducing lower limb strength asymmetry and improving mobility in persons with MS.

Functional Electrical Stimulation Cycling Exercise in People with Multiple Sclerosis: Secondary Effects on Cognition, Symptoms, and Quality of Life

BACKGROUND

Functional electrical stimulation (FES) cycling is an advanced rehabilitation modality that involves systematic mild electrical stimulation of focal muscle groups to produce leg cycling movement against an adjustable work rate. The present study reports on the efficacy of an assessor-blinded, pilot randomized controlled trial of supervised FES cycling exercise in people with multiple sclerosis (MS) on secondary trial outcomes, including cognition, fatigue, pain, and health-related quality of life.

METHODS

Eleven adult participants with MS were randomized to receive FES cycling exercise (n = 6) or passive leg cycling (n = 5) for 24 weeks. Cognitive processing speed was assessed using the Symbol Digit Modalities Test. Symptoms of fatigue and pain were assessed using the Fatigue Severity Scale, the Modified Fatigue Impact Scale, and the short-form McGill Pain Questionnaire. Physical and psychological health-related quality of life were assessed using the 29-item Multiple Sclerosis Impact Scale.

RESULTS

Eight participants (four, FES; four, passive leg cycling) completed the intervention and outcome assessments. The FES cycling exercise resulted in moderate-to-large improvements in cognitive processing speed (d = 0.53), fatigue severity (d = -0.92), fatigue impact (d = -0.45 to -0.68), and pain symptoms (d = -0.67). The effect of the intervention on cognitive performance resulted in a clinically meaningful change, based on established criteria.

CONCLUSIONS

We provide preliminary evidence for the benefits of FES cycling exercise on cognition and symptoms of fatigue and pain. Appropriately powered randomized controlled trials of FES cycling exercise are necessary to determine its efficacy for people with MS.

Cardiorespiratory demand of acute voluntary cycling with functional electrical stimulation in individuals with multiple sclerosis with severe mobility impairment

Exercise training is one strategy for improving cardiorespiratory fitness (CRF) in multiple sclerosis (MS); however, few modalities are accessible for those with severe mobility impairment. Functional electrical stimulation (FES) cycling is an adapted exercise modality with the potential for improving CRF in people with severe MS. The objective of this study was to characterize the cardiorespiratory response of acute voluntary cycling with FES in people with MS with severe mobility impairment, and to compare this response to passive leg cycling. Eleven participants with MS that required assistance for ambulation completed a single bout of voluntary cycling with FES or passive leg cycling. Oxygen consumption, heart rate (HR), work rate (WR), and ratings of perceived exertion (RPE) were recorded throughout the session. For the FES group, mean exercising oxygen consumption was 8.7 ± 1.8 mL/(kg·min)^-1, or 63.5% of peak oxygen consumption. Mean HR was 102 ± 9.7 bpm, approximately 76.4% of peak HR. Mean WR was 27.0 ± 9.2 W, or 57.3% of peak WR, and median RPE was 13.5 (interquartile range = 5.5). Active cycling with FES was significantly (p < 0.05) more intense than passive leg cycling based on oxygen consumption, HR, WR, and RPE during exercise. In conclusion, voluntary cycling with FES elicited an acute response that corresponded with moderate-to vigorous-intensity activity, suggesting that active cycling with FES can elicit a sufficient stimulus for improving CRF.