two bouts of HIIT a week would be enough to induce adaption..i would think that would result in an increase in mitchondrial density and VO2 max increases

what I was thinking but its so hard to tell lol I guess only sure way to know is to experiment

Indeed
There was also a study on soccer players I recall, where in the off-season they showed one solid bout of HIIT/week was enough to at least sustain their level of CV endurance

if you do HIIT correctly, you will notice a difference from not doing any cardio, i assure you that haha



I'm not sure if that is the same one I saw when I was taking EXS classes or not, but I remember we had to dissect one that looked at using HIIT for maintenance, which sounds very similar to that

so far hiit has factioned into 30s bouts vs 1m bouts, and 10m sessions vs 20m sessions, mainly speaking. that's a matrix of 4 factions. where do you see yourself?

What do I personally do?
usually 20 mins & 30 sec bouts actually
that's if I do them on the stair-stepper, which is the most usual for me

If I just go run some sprints in my yard it's far different though.. I'll run 100% full out for about 50-60 yds, walk back calmly, not too slow/fast, then immediately turn around and do it again 6-10 times

i've done variances, which isn't true to any specific thing

have done them with given distances to be covered during a sprint such as working toward a total of ~400m covered in an actual sprint..so it could be:
sprint 20m, walk 10m x 20
sprint 40m, walk 20m x 10
sprint 60m, walk 30m x 7
sprint 100m, walk 50m x 4
etc, etc

have done bouts of 20s sprint/10s light on a stationary bike for varied time frames (usually did it in 4 minute bouts of that..so 4 min of that, 5 min rest, repeat 1-2 more times)

have also done 30s on, 30s off, 45s on 15s, and varied the total 'sprint' time

my favorite was the 20s sprint/10s light in the 4 minute sets though

yes its cardio