This study examined the effect of high-intensity interval training on the V*O2 response during severe, constant-load exercise. Prior to, and following training, ten females (V*O2 peak 37.4 ' 6.0ml.kg-1.min-1) performed a graded exercise test to determine V*O2 peak and lactate threshold (LT) and a 6-min cycle test (CT) at the pre-training V*O2 peak intensity. Training involved high-intensity intervals (2 min work, 1 min rest) performed 3 x week for 8 weeks. Breath-by-breath data from 0 to 6 min during the CT were smoothed using 5-s averages and fit to a bi-exponential model starting from 20 s. Training resulted in significant improvements in V*O2 max (2.34 ± 0.37 ' 2.78 ± 0.30 L'min-1), power at V*O2 max (170 ± 26 ' 204 ± 25 W) and power at LT (113 ± 17 ' 136 ± 20 W) (p<0.05). Following training, the V*O2 response showed a significant increase in the amplitude of the primary phase (A1) (1396 ± 103 ' 1695 ± 100 mL'min-1; p<0.05) and end-exercise V*O2 (V*O2 EE), with no difference (p>0.05) in the time constants of either phase or the amplitude of the slow component (318 ± 67 ' 380 ± 48 mL; p= 0.15). In conjunction, accumulated oxygen deficit (AOD) (43.7 ± 9.8 ' 17.2 ± 2.8 mL O2 eq'kg-1) and anaerobic contribution to the CT (19.4 ± 4.4 ' 7.2 ± 1.2 %) were significantly reduced. In contrast to previous moderate-intensity research, a high-intensity interval training program increased A1 and V*O2 EE for the same absolute exercise intensity, decreasing the AOD during a severe-intensity CT.
Duffield, R., Edge, J., & Bishop, D. (2006). Effects of high-intensity interval training on the VO2 response during severe exercise. Journal of Science and Medicine in Sport, 9(3), 249-255. https://doi.org/10.1016/j.jsams.2006.03.014