Low Frequency Severe-Intensity Interval Training Markedly Alters Respiratory Compensation Point During Incremental Exercise in Untrained Male

Abstract

This study investigated the effect of low-frequency severe-intensity interval training on the respiratory compensation point (RCP) during incremental exercise test. Eighteen healthy males (age; 20.7 ± 2.2 years, range 18 to 29 years, height; 174.0 ± 5.6 cm, weight; 68.8 ± 13.5 kg) were randomly assigned to an interval training group or a control group. Interval training was conducted once weekly for 3 months. Each session consisted of three bouts of bicycle ergometer exercise at 80% maximum work rate until volitional fatigue. Before (baseline) and after the 3-month intervention, incremental exercise test was performed on a bicycle ergometer for determination of ventilatory threshold (VT), RCP, and peak oxygen consumption (V̇_{O 2} peak). The training program resulted in significant increases of V̇_{O 2} peak (+ 14%, p < 0.001, ${\eta }_{\text{p}}^2$ = 0.437), oxygen consumption (V̇_{O 2}) at VT (+ 18%, p < 0.001, ${\eta }_{\text{p}}^2$ = 0.749) and RCP (+ 15%, p = 0.03, ${\eta }_{\text{p}}^2$ = 0.239) during incremental exercise test in the training group. Furthermore, a significant positive correlation was observed between the increase in V̇_{O 2} peak and increase in V̇_{O 2} at RCP after intervention (r = 0.87, p = 0.002) in the training group. Tidal volumes at VT (p = 0.04, ${\eta }_{\text{p}}^2$ = 0.270) and RCP (p = 0.01, ${\eta }_{\text{p}}^2$ = 0.370) also increased significantly after intervention compared to baseline. Low-frequency severe-intensity interval training induced a shift in RCP toward higher work rate accompanied by higher tidal volume during incremental exercise test.

Keywords: high intensity exercise; incremental maximal exercise test; once weekly training; respiratory adaptations; second ventilatory threshold.