Whole-body cooling does not compromise muscle oxidative capacity in subjects with multiple sclerosis.

Abstract

BACKGROUND: Whole-body cooling improves exercise tolerance in patients with multiple sclerosis (pwMS). To be able to exercise at greater intensities and/or for longer durations with whole-body cooling, it should be examined whether this compromises skeletal muscle oxidative capacity (assessed by exercise-onset VO2 kinetics). OBJECTIVE: To study the impact of whole-body cooling on exercise-onset VO2 kinetics in pwMS. METHODS: From 12 pwMS (EDSS 3.5 ± 1.5) and 12 healthy age, BMI, and gender-matched subjects exercise-onset VO2 kinetics (mean response time [MRT]) and body temperature were determined under normothermic and hypothermic (pre-exercise 60-min whole-body cooling) conditions during submaximal exercise testing (two 6-min constant-load exercise bouts). Moreover, heart rate, blood lactate content, expiratory volume and ratings of perceived exertion (RPE) were assessed during exercise. RESULTS: Exercise heart rate (−7 ± 6 beats/min) and end-exercise body temperature (−0.9 ± 0.5◦C) was significantly lower in hypothermic vs. normothermic conditions in both populations (p < 0.05). In pwMS exercise RPE was lower in hypothermic vs. normothermic condition (p = 0.056). No significantly different MRT was found between normothermic vs. hypothermic conditions in both populations. CONCLUSIONS: Lowering body temperature prior to endurance exercise does not affect muscle oxidative capacity in pwMS, but lowers RPE, thus making it possible to prescribe exercises of greater intensity and/or longer duration.