High-Intensive Interval Training or Supramaximal Interval Training - What to Choose When the Goal is to Improve VO2max and Aerobic Endurance Performance in Females

Aim: The present study aims to compare the effects of high-intensive interval training (HIIT) and all-out supramaximal intensity interval training (SIT) on maximal oxygen uptake (VO2max), work economy (WE), lactate threshold (LT), anaerobic capacity (maximal accumulated oxygen deficit (MAOD)), and 300- and 3000-meter running performance in moderately endurance-trained females. Methods: 11 healthy, non-smoking, and recreationally active to moderately endurance-trained females were randomized to perform HIIT or SIT three times per week over 8 weeks. HIIT was performed as 4 x 4-minute treadmill running intervals at 90-95 % of maximal heart rate (HRmax) interspersed with 3-minute active recovery at 70 % of HRmax between intervals. SIT was performed as 10 x 30-second all-out treadmill running intervals interspersed with 3.5-minute active recovery at 70 % of HRmax between intervals. Results: The VO2max and oxygen (O2) pulse increased significantly more after HIIT compared to SIT (p < 0.01 and p < 0.05, respectively). VO2max increased by 8.9 % after HIIT (54.1 to 58.9 ml·kg-1·min-1) and by 3.3 % after SIT (54.1 to 55.8 ml·kg-1·min-1). The VO2max improvements were closely followed by O2 pulse improvements of 9.3 % after HIIT and by 3.5 % after SIT. MAOD increased significantly more after SIT compared to HIIT. The SIT group improved MAOD by 32 % (60.6 to 79.8 ml·kg-1), while the changes were not significant after HIIT. The 300- and 3000-meter running performance changes were not significantly different between groups. The 3000-meter running performance improved by 5.7 % after HIIT (843 to 794 seconds) and by 5.7 % after SIT (845 to 797 seconds). The 300- meter running performance improved by 5.1 % after HIIT (57.5 to 54.6 seconds) and by 5.7 % after SIT (54.3 to 50.8 seconds). Conclusion: HIIT was significantly more effective in improving VO2max and O2 pulse compared to SIT. SIT was significantly more effective in improving MAOD compared to HIIT. There was no significant difference in WE, LT, 300- and 3000-meter running performance changes between groups