Forty individuals with MS will be asked to complete questionnaires about fatigue and perform motor tasks. Additionally, blood samples will be taken to measure the levels of cytotoxic CD4+ T-cells. These values will then be correlated with fatigue scores and performance on the motor tasks.
Scores from the fatigue questionnaires and decline in amplitude and frequency from the performance fatiguability test will be correlated to the level of CD4 CTLs from the blood samples. Secondary study parameters include muscle activation patterns measured by EMG, distance walked on 6MWT and voluntary muscle activation.