Resistance training for muscle weakness in multiple sclerosis: direct versus contralateral approach in individuals with ankle dorsiflexors' disparity in strength

OBJECTIVE: To compare effects of contralateral strength training (CST) versus
direct strength training (DST) of the more-affected ankle dorsiflexors on muscle
performance and clinical-functional outcomes in people with multiple sclerosis
(MS) exhibiting inter-limb strength asymmetry.
DESIGN: Randomized controlled trial PARTICIPANTS: Individuals with
relapsing-remitting MS and mild-to-moderate disability (EDSS≤6) presenting with
ankle dorsiflexors' strength disparity.
INTERVENTION: Participants were randomly assigned to a CST (n=15) or DST (n=15)
group performing a 6-week maximal-intensity strength training of the less- or
more-affected dorsiflexors, respectively.
MAIN OUTCOME MEASURES: Maximal strength, endurance to fatigue and mobility
outcomes were assessed before (PRE), at the intervention end (POST) and at
12-week follow-up. Strength and fatigue parameters were measured after 3 weeks of
training (mid-intervention).
RESULTS: In the more-affected limb of both groups, PRE-to-POST significant
increases in maximal strength (p≤0.006) and fatigue endurance (p≤0.04) were
detected along with consistent retention of these improvements at follow-up
(p≤0.04). At mid-intervention the DST group showed significant improvements
(p≤0.002), with no further increase at the POST, despite training continuation.
Conversely, the CST group showed non-significant strength gains, increasing to
significance at the POST (p≤0.003). In both groups, significant PRE-to-POST
improvements in mobility outcomes (p≤0.03), not retained at follow-up, were
observed.
CONCLUSIONS: After 6 weeks of training, CST proved as effective as DST in
enhancing performance of the more-affected limb with a different time-course,
which may have practical implications in management of severely weakened limbs
where DST is not initially possible.