Differences in Ventilatory Function Based on Cardiorespiratory Fitness and Sex

This study aimed to evaluate differences in ventilatory function, especially on breathing reserve (BR), across a wide range of cardiorespiratory fitness (CRF).

We examined 198 males and 60 females who performed different spirometry tests to evaluate ventilatory function (vital capacity (VC), inspiratory capacity (IC), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), maximal voluntary ventilation (MVV)), and a ramp incremental exercise test to evaluate maximal oxygen consumption (V̇O 2max ), maximal ventilation (VE max ) and BR. Participants were classified as low, medium, or high CRF based on tertile of V̇O 2max .

VC, IC, FVC, FEV1, MVV, and VE max were associated with CRF (all P < 0.008; R2 = 0.312-0.76). VC, IC, and FVC were lower in low than medium or high CRF; FEV1 and MVV were lower in low than high CRF; and VE max was higher as CRF increased (all P < 0.05). Contrary, BR was weakly associated with CRF ( P < 0.001; R2 = 0.179), observing a lower BR only in high ( P < 0.001) and medium ( P = 0.022) than low CRF, and the number of individuals who depleted the BR was not different between CRF ( P > 0.05). Females showed lower VC, FVC, FEV1, MVV, and VE max than males across different relative CRF ( P < 0.001).

Ventilatory function is greater in individuals with a higher CRF, highlighting that ventilatory function should be considered when assessing CRF. Reaching maximum possible ventilation during exercise (depleting the BR) does not seem a cause for ceasing exercise more prevalent in individuals with a high CRF, indicating that performance limitation by the respiratory system due to BR depletion is not more likely in individuals with the highest CRF. Finally, we reveal a sex difference in ventilatory function regardless CRF.