Your problem is that you're trying to sprint for a minute: physiologically, that's impossible. The sprint period should be no more than 15, *possibly* 20 seconds in general (and can be as low as 10 seconds if you're truly pushing yourself) if you're attempting true HIIT, with another 30-60 seconds in recovery, depending on your conditioning. 10-15 cycles are all you should be able to accomplish before you're spent if you're doing it "correctly."
