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: The aim of this study was 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.