Alleviating mechanical constraints to ventilation with heliox improves exercise endurance in adult survivors of very preterm birth

Adult survivors of very preterm birth (PRET) have significantly lower aerobic exercise capacities than their counterparts born at term (CONT), but the underlying cause is unknown. To test whether expiratory flow limitation (EFL) during exercise negatively affects exercise endurance in PRET, we had PRET and CONT exercise to exhaustion breathing air and again breathing heliox. In PRET, EFL decreased and time-to-exhaustion increased significantly while breathing heliox. Heliox had a minimal effect on EFL and had no effect on time-to-exhaustion in CONT. We conclude that aerobic exercise endurance in PRET is limited, in part, by mechanical ventilatory constraints, specifically EFL.