Influence of high-intensity interval training on ventilatory efficiency in trained athletes

The aim of this study was to investigate the effects of 3 weeks high-intensity interval training (HIIT) on ventilatory efficiency (V_E/VCO₂ slope) in endurance athletes. Sixteen male well-trained (67.72 ml kg min^-1) athletes participated in this study. Each participant performed an incremental exercise test with gas analysis (i.e. V_E, VO₂) and a 400 m running field test (T400m) before and after the 3 weeks intervention period. HIIT group (HIITG) performed 11 HIIT sessions consisting of four 4-min interval bouts at an exercise intensity of 90-95% of the VO_2max, separated by 4-min active recovery periods (work/rest ratio = 1:1). No significant differences were found in the parameters studied. Ventilatory efficiency (up to VT₂ and up to exhaustion) did not show any change in HIITG after training intervention (ES = 0.24 HIITG; ES = 0.21 CG). No significant changes were observed on ventilation (V_Emax; ES = 0.38). VO_2max and T400 m did not show a significant improvement after the training period (no interaction time × group, p < .05) (ES = 0.43 and ES = 0.75 respectively). These results do not support the hypothesis that 3 weeks of HIIT could modify the ventilatory efficiency response in well-trained athletes. Furthermore, they show the lack of relationship between ventilatory efficiency and sport performance.