Ventilatory efficiency is unchanged after physical training in healthy persons despite an increase exercise tolerance.

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 (VE-VCO2 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 +/- 186 s (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 VE-VCO2 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.