Acute breathing patterns in healthy and heart disease participants during cycling at different levels of immersion

We aimed to determine the effect of aquatic cycling and different levels of immersion on respiratory responses in healthy and heart disease (HD) volunteers. Thirty-four age matched volunteers, 21 HD and 13 healthy controls (HC) took part in this study. The ventilatory pattern, phase 1 VE and steady-state ventilatory responses to progressive exercise from 40 to peak rpm, were measured while participants exercised on a water stationary bike (WSB) at different levels of immersion. No effect of immersion was observed on steady-state respiratory responses in the HD group, but immersion reduced VE phase 1 by ∼79% at pedaling cadences of 40, 50 and 60 rpm. In conclusion, immersion at hips and xiphoid process blunted the fast drive to breathe in the HD group. This transient effect on the respiratory response to immersed exercise cannot be considered a contraindication for exercise in HD individuals.