Walking speed and endurance in persons with relapsing-remitting multiple sclerosis (RRMS) were reduced in individuals with longer interspike intervals (ISIs), weaker dorsiflexors, and worse plantar flexor force steadiness, according to a recent study that examined walking performance and disability status in individuals with self-reported walking disabilities due to MS. 23 individuals with RRMS (aged 56±7 years) participated. They completed 1-3 evaluation sessions that involved 2 walking tests (25-ft. walk and 6-min. walk), a manual dexterity test, health-related questionnaires, and measurement of strength, force steadiness, and motor unit discharge characteristics of lower leg muscles. Researchers found:

• There were statistically significant differences between the 3 muscles in mean ISI and ISI distributions during steady submaximal contractions with the plantar flexor and dorsiflexor muscles.
• The regression models explained 40% of the variance in the 6-min. walk distance and 47% of the variance in 25-ft. walk time with 2 or 3 variables that included mean ISI for 1 of the plantar flexor muscles, dorsiflexor strength, and force steadiness.