Ventilatory Efficiency is Unchanged after Physical Training in Healthy Persons Despite an increase in Exercise Tolerance

Abstract

Background: In chronic heart failure, exercise training results in an improvement in exercise capacity and a reduction in the ventilatory response to exercise. The effects of a physical training programme on the ventilatory response in healthy persons is not known.

Methods: Metabolic gas exchange and ventilation were measured in 27 young healthy persons aged 31.4 ± 7.6 years before and after a 19-week training programme of aerobic exercise; exercise was undertaken three times a week for 40 min. Ventilation, the slope of the relationship between ventilation and carbon dioxide production (V_E−V_CO2 slope) and the ventilatory equivalent for carbon dioxide were measured using respiratory mass spectroscopy. The peak expiratory flow rate in 1 s and forced vital capacity were also measured.

Results: Mean ± SEM peak oxygen consumption increased from 39.5 ± 1.5 to 45.4 ± 1.7 ml/kg/min(P < 0.001). Exercise time increased from 817 ± 188 to 896 ± 186s (P < 0.001). The respiratory exchange ratio at peak exercise was slightly lower after training: 1.30 ± 0.02 compared with 1.36 ± 0.03 (P = 0.02). Ventilation at equivalent stages of exercise was unchanged by training. The V_E-V_CO2 slope did not change (24.52 ± 0.67 before training, 25.01 ± 0.80 after training; NS). There was no change in the ventilatory equivalent for carbon dioxide either at rest (38.6 ± 1.4 compared with 36.2 ± 1.1; NS) or at its lowest point (23.3 ± 0.6 compared with 22.9 ± 3.2; NS). Neither exercise capacity nor the training response correlated with any of the measured ventilatory variables.

Conclusion: In contrast to the situation in patients with chronic heart failure, there is no relationship between ventilatory variables and exercise capacity in healthy persons and no change in ventilatory performance as a result of physical training.