Time course of strength adaptations following high-intensity resistance training in individuals with multiple sclerosis

PURPOSE: No evidence exists regarding the time course and clinical relevance of
muscle strength improvements following resistance training in people with
multiple sclerosis (PwMS). The purpose of this study was to investigate the
temporal course and the clinical meaningfulness of the changes in strength
induced by high-intensity resistance training and whether these changes impact on
muscle endurance to fatigue and functional outcomes.
METHODS: PwMS with predominantly unilateral hyposthenia of the ankle dorsiflexors
underwent a 6-week isokinetic training of the more affected ankle dorsiflexion
muscles. Maximal strength was measured at baseline, during the training on a
weekly basis, at the end of the intervention (POST) and at the 12-week follow-up.
Muscle endurance to fatigue, mobility and walking outcomes were assessed at
baseline, POST and follow-up. Reproducibility and responsiveness analyses were
performed.
RESULTS: Significant gains in muscle strength were already detected after 3 weeks
of training with no further improvements in the following weeks. These
improvements exceeded the cutoff values for relevant changes and were also
positively correlated to improved muscle endurance to fatigue and mobility
measures. None of the observed changes in muscle performance and functional
outcomes was retained at the follow-up.
CONCLUSIONS: Preliminary evidence showed that 3 weeks of high-intensity
resistance training induces consistent and meaningful improvements in muscle
performance of the ankle dorsiflexors in PwMS. These findings may have practical
dose-response and cost-effectiveness implications in the management of MS-induced
muscle weakness, potentially enhancing the understanding of the response to
training exhibited by PwMS.
TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier NCT02010398; December
2013.