Ventilatory function during exercise in multiple sclerosis and impact of training intervention: cross-sectional and randomized controlled trial

Abstract

Background Patients with MS (pwMS) often experience resting ventilatory anomalies. Ventilatory function during exercise and impact of long-term training intervention remains however uncertain. Aim To examine the ventilatory function during exercise and impact of a 6-month training intervention in pwMS. Design Combination of a cross-sectional (part 1) and randomized controlled trial (part 2). Setting University rehabilitation facility. Population Caucasian patients with MS and healthy controls. Methods In part 1, the ventilatory function during submaximal endurance exercise was compared between pwMS (n=37) and healthy participants (n=15). In part 2, pwMS were then randomly assigned to a 6-month training intervention (n=16) or usual care (n=11). Following training intervention, ventilatory function during exercise was re-evaluated. Results Despite comparable relative exercise testing intensities between groups in part 1, significantly elevated steady-state exercise dead space/tidal volume ratio, O2 uptake and CO2 output equivalent, end-tidal O2 pressure, ratings of perceived exertion and lowered end-tidal CO2 pressure and O2 pulse was observed in pwMS (p<0.05). The degree of ventilatory dysfunction during exercise correlated significantly with ratings of perceived exertion and blood lactate content (p<0.05). In part 2, despite an improved exercise tolerance (based on reductions in heart rate, blood lactate content and ratings of perceived exertion during exercise at similar workload) after a 6-month training intervention, ventilatory dysfunction remained present during endurance exercise (p>0.05). Conclusion Patients with MS experience a ventilatory dysfunction during endurance exercise, which is related to worse exercise tolerance. This ventilatory anomaly remains present after long-term training intervention. Clinical rehabilitation impact Patients with MS experience ventilatory dysfunction during exercise. This dysfunction is related to exercise tolerance and ratings of perceived exertion. Long-term exercise training did not remediate this ventilatory dysfunction. The systematic examination of the pulmonary/cardiovascular system at rest and during exercise is recommended in MS.