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

INTRODUCTION: Low-to-moderate intensity exercise improves muscle contractile properties and endurance capacity in multiple sclerosis (MS). The impact of high intensity exercise remains unknown. METHODS: 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(IT)R, n = 12) or high intensity continuous cardiovascular training (H(CT)R, 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. RESULTS: Compared to SED, 12 weeks of high intensity exercise increased mean fiber CSA (H(IT)R: +21±7%, H(CT)R: +23±5%). Furthermore, fiber type I CSA increased in H(CT)R (+29±6%), whereas type II (+23±7%) and IIa (+23±6%,) CSA increased in H(IT)R. Muscle strength improved in H(IT)R and H(CT)R (between +13±7% and +45±20%) and body fat percentage tended to decrease (H(IT)R: -3.9±2.0% and H(CT)R: -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(IT)R. Finally self-reported physical activity levels increased 73±19% and 86±27% in H(CT)R and H(IT)R, respectively. CONCLUSION: High intensity cardiovascular exercise combined with resistance training was safe, well tolerated and improved muscle contractile characteristics and endurance capacity in MS. TRIAL REGISTRATION: ClinicalTrials.gov NCT01845896