I see it as further evidence that HIIT is very effective. I've been wondering lately what the actual number of all out intervals required in each session really is? I know some do 6, some 8, some 10 or 12. Could it be possible that only a few intervals, perhaps done a little more often could be just as effective if not more and maybe safer as well. For now I do 6-8 intervals about once a week. I haven't felt this good in a long long time. It has most definitely improved my cardio conditioning. Just my breathing while at rest is noticeably easier.