High Intensity Exercise in Multiple Sclerosis: Effects on Muscle Contractile Characteristics and Exercise Capacity, a Randomised Controlled Trial

<div><p>Introduction</p><p>Low-to-moderate intensity exercise improves muscle contractile properties and endurance capacity in multiple sclerosis (MS). The impact of high intensity exercise remains unknown.</p><p>Methods</p><p>Thirty-four MS patients were randomized into a sedentary control group (SED, n = 11) and 2 exercise groups that performed 12 weeks of a high intensity interval (H_ITR, n = 12) or high intensity continuous cardiovascular training (H_CTR, n = 11), both in combination with resistance training. M.vastus lateralis fiber cross sectional area (CSA) and proportion, knee-flexor/extensor strength, body composition, maximal endurance capacity and self-reported physical activity levels were assessed before and after 12 weeks.</p><p>Results</p><p>Compared to SED, 12 weeks of high intensity exercise increased mean fiber CSA (H_ITR: +21±7%, H_CTR: +23±5%). Furthermore, fiber type I CSA increased in H_CTR (+29±6%), whereas type II (+23±7%) and IIa (+23±6%,) CSA increased in H_ITR. Muscle strength improved in H_ITR and H_CTR (between +13±7% and +45±20%) and body fat percentage tended to decrease (H_ITR: -3.9±2.0% and H_CTR: -2.5±1.2%). Furthermore, endurance capacity (W_max +21±4%, time to exhaustion +24±5%, VO_2max +17±5%) and lean tissue mass (+1.4±0.5%) only increased in H_ITR. Finally self-reported physical activity levels increased 73±19% and 86±27% in H_CTR and H_ITR, respectively.</p><p>Conclusion</p><p>High intensity cardiovascular exercise combined with resistance training was safe, well tolerated and improved muscle contractile characteristics and endurance capacity in MS.</p><p>Trial Registration</p><p>ClinicalTrials.gov <a href="http://clinicaltrials.gov/ct2/show/NCT01845896" target="_blank">NCT01845896</a></p>