Xu, Y. Z., Tsuji, K., Iemitsu, M., & Tabata. I.(2013). Effects of 2 days/w high-intensity intermittent cross training on maximal oxygen uptake. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2144.

This study explored the effects of non-exhaustive high-intensity intermittent cross training (HIICT) on maximal oxygen uptake (VO2max).

For Experiment 1, the HIICT exercise consists of seven intermittent 20-second exercise bouts with 10 seconds of rest between the bouts. Ss (N = 8) rode a bicycle ergometer for the first, third, fifth, and seventh bouts, and ran on a treadmill the second, fourth, and sixth bouts. Exercise intensity (170% VO2max) for both bicycle and running of the HIICT exercise was similar to high intensity intermittent exercise (HIIE) which exhausts Ss after they exercise intermittently for all seven 20-second bouts of running or bicycling with 10-second rest intervals. The peak oxygen uptake, rating of perceived exertion, and peak blood lactate concentration were measured for both HIICT exercise and HIIEs (running and bicycling).

For Experiment 2, healthy males (N = 16) were randomly assigned to either a training group (N = 8) or a control group (N = 8). The training group underwent the HIICT for 2 days per week for six weeks.

In Experiment 1, oxygen uptake during the last bout of bicycling and running of HIICT exercise was statistically similar to VO2max. Rating of Perceived exertion of HIICT exercise (15±2) was significantly lower than observed for both HIIE running (20) and HIIE bicycling (20). Peak blood lactate for the HIICT exercise (12.8±1.0 mmol/L) was also significantly less than both HIIE running (16.7±1.3 mmol/L) and HIIE bicycling (16.6±1.4 mmol/L). In Experiment 2, the HIICT increased the training group's VO2max for both running (13.1%) and cycling (10.4%). There were noVO2max changes in the control group.

Implication. The non-exhaustive high-intensity intermittent cross-training, which maximally taxes the aerobic energy releasing system, elevates maximal aerobic power when performed two days per week.

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