We investigated the effects of high-intensity intermittent cross-training (HIICT) on maximal oxygen uptake ( Omax). The HIICT consisted of alternating intermittent 20-s treadmill running (1, 3, 5, and 7 bouts) and 20-s bicycle exercise (2, 4, and 6 bouts) with a 10-s rest period. Each intensity for running and bicycling of the HIICT corresponded to an oxygen demand of ���160% and ���170% of the Omax, respectively. Fifteen healthy young males (aged [24 ����� ���1] yrs) were randomly assigned to training (TG, ���= ���8) and non-training control (CG, ���= ���7) groups. The TG completed this HIICT daily 4 days/week for 6 weeks. Significant group ����� ���time interactions were observed for both the running and bicycling Omax ( ���< ���0.001 each). After the training, the Omax for both running ([57.4 ����� ���4.8] mL��kg��min) and bicycling ([50.6 ����� ���3.7] mL��kg��min) in the TG were significantly higher than those for running ([50.1 ����� ���3.1] mL��kg��min) and bicycling ([43.7 ����� ���3.6] mL��kg��min) in the CG, respectively ( ���< ���0.01 each). Post-hoc tests revealed a significant increase in Omax for running and bicycling in the TG after the HIICT ( ���< ���0.001 each) but no significant difference in the CG. These results demonstrated that the newly developed HIICT increases the Omax for both running and bicycling.
