hello, I have a question regarding cardio. I pretty much avoid long bouts of med/low intensity cardio in favour of HIIT. I was wondering if it MUST be done BFL style.. or of any type of intervals are ok. For example, there are some stairs nearby - it takes me 10 seconds to sprint to the top. That does not do THAT much for my heart rate but if I sprint up, run down, and sprint up immediately my HR is waaaay up... then I take it easy for the next 30-60 seconds and repeat the double sprint and continue this for about 15-20 min. My other routine is on a mountainside and I sprint for 20-30 seconds, walk until my HR is no longer crazy and repeat. Is there some reason that BFL cardio should be done instead of these?

My other question is, I LOVE doing these cardio sessions. I sometimes do them 2x a day. Can I do them every day and still train my legs? Should I cut my legs training to 1x week and only 2 exercises high volume or?

thanks,
Meg