Many people tout the benefits of high intensity interval training (HIIT). According to a recent study published in the Journal of Strength and Conditioning Research, it might work well enough to only need to be performed as little as once every two weeks.
The HIIT program was of the longer variety, not like, say, a Tabata workout. The sessions consisted of five rounds of four minutes at 87%-97% of maximum heart rate, which is a grueling pace for that amount of time. The researchers did not designate the length of the rest periods between the rounds. HIIT rest intervals tend to be short, but with such an intense pace they may have been several minutes long.
Both groups maintained their VO2 max with HIIT. Not only that, but surprisingly, there was no difference between groups who performed HIIT training only once every other week and those who did it once per week, at least over the course of a six-week break from soccer training. That’s pretty good, especially for people looking to maintain VO2 max while saving time for work on sport-specific skills.
By contrast, both groups reduced performance in the twenty-meter shuttle run. The researchers speculated that this is because shuttle runs are more specific to soccer than HIIT training. As a result, ceasing intense soccer practice caused a decline in the shuttle run performance. This probably means that spending time doing shuttle runs instead of HIIT when not in season might be prudent for soccer players, but perhaps doing both is the safer bet.
One oddity of this study design was that the soccer players did other workouts during the six-week period. It’s certainly not odd for this to be the case in life, especially since these players were semi-pro and probably would have been unable to participate in a study if normal training couldn’t be followed. The study did take place during a low training period. Specifically, the group that did HIIT every two weeks averaged 2.2 hours of training weekly, and the other group averaged five hours. Strength training accounted for most of the difference between the two, but both groups had a substantial amount of running included outside of the study.
In research like this, a control group is a must. This would be a group who didn’t do HIIT at all, but still had statistically similar workouts elsewhere. It’s possible that such a control group would have also experienced no decline in VO2 max. With only eighteen participants, this group might have been too small to have a control, but it’s a glaring hole in the study design.
What we do know is that performing five intense intervals once every other week, along with two to five hours per week of additional training is sufficient for maintaining your VO2 max. However, it’s important to note that this might not be enough to maintain more skill-specific endurance, speed, and strength. If you have an off-season in your sport, keep practicing.
References:
1. Gunnar Slettaløkken, et. al., “High intensity interval training every second week maintains VO2max in soccer players during off-season,” Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000356
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