Effects of dorsiflexor endurance exercises on foot drop secondary to multiple sclerosis: a pilot study.

PURPOSE This is a pilot study to determine if endurance exercises for dorsiflexors will improve walking for people with foot drop secondary to MS, and if improvement in muscle endurance for persons with MS can be predicted based on the amount of central fatigue (CF) in the muscle. SUBJECTS Five individuals with foot drop secondary to MS and five age-matched controls. METHODS The intervention was 4 sets of 10 isometric contractions, at 60% of MVC, 3X/week, 8 weeks. Pretests-posttests included a dorsiflexor endurance test with superimposed electrical stimulation to measure CF, and a gait assessment including measurement of dorsiflexion at initial contact. RESULTS Two of 5 subjects with MS had significant improvement in muscle endurance in both legs and in dorsiflexor control during walking. Correlation between CF and improved endurance was not significant (r=-0.07). One of the subjects with significant improvement in endurance had a significant decrease in central activation failure. CONCLUSIONS AND DISCUSSION For individuals with foot drop secondary to MS, endurance exercises for the dorsiflexors can result in improved walking. CF may not be useful in predicting whether a muscle will improve in endurance with exercise. Improvement may result from either a peripheral training effect, a central learning effect, or both.