Decreased Time To Achieve VO2MAX During Successive High Intensity Intervals

Abstract

Research examining the effect of priming exercise (hard effort preceding an intense bout of exercise), has been shown to significantly alter oxygen kinetics in favor of more rapid adjustment to the workload. It is unclear if multiple hard efforts would further this effect. PURPOSE: This study was conducted to evaluate if VO2max would be achieved at a consistent time point during consecutive high intensity intervals. METHODS: Eleven male trained cyclists (Height: 183.4±4.3 cm, Weight: 77.7±7.3 Kg, VO2max: 66.7±4.4 mL.Kg-1.min-1) participated in the study. Volunteers performed a graded exercise test (GXT) on the cycle ergometer at 35 W.min-1 to volition fatigue. The highest power output at the beginning of the plateau in VO2max was defined as the pVO2max. Following a rest period of 30 minutes subjects performed an endurance test at pVO2max (Tmax). Within seven days volunteers returned to the laboratory to perform an interval session (INT). The interval sessions required volunteers to cycle at 60% of Tmax during the interval and then recover between intervals at an equal duration (20W). Intervals were repeated four times. HR and expired air were measured continuously throughout the interval bout. One-way ANOVA with repeated measures and Tukey’s post hoc procedure was used to assess the results. RESULTS: The percentage of time to achieve VO2max decreased significantly from INT1 to INT2 (63.8±11.3 vs 43.8±9.3%Tmax) and again from INT2 to INT4 (34.9%). VO2max was not significantly different between GXT and Tmax test (67.4±4.0 vs. 65.7±5.6 ml.kg-1.min-1) Peak VO2 during INT1 was significantly lower than GXT (62.9±4.0 ml.kg-1.min-1) Peak VO2 during INT2-4 were not significantly different from GXT. O2 pulse was not significantly different across trials. HR during INT1 was significantly lower than GXT (173±10 vs 181±11 bpm). HR during INT 2-4 was not significantly different than GXT. VE was significantly lower during INT1 than GXT (168.7±24.9 vs. 147.6±15.9 L.min-1) VE during INT2-3 were not significantly different than GXT, but during INT4 VE increased significantly from INT2 (176.6±27.1 L.min-1). CONCLUSION: We conclude that the time to achieve VO2max decreases significantly with consecutive intervals. Further, INT 1 primes the HR and VE, while late in the bout the preceding intervals prime VE.