Originally Posted by
TexMac
Seems like the 30 seconds intervals with 15 sec rest time increases VO2 max power more thatn 4-5 min intervals. 10 week sturdy on trained athletes
Joe Friel - High-Intensity Interval Duration
I like to do 5-20 minutes 90% interval one day and either 30s-3minute VO2 another day with a day off between
It's generally accepted that vo2 max isn't even reached until at least 2.5 mins into an effort, thus intervals should be a minimum of that to elicit the most amount of time possible at vo2max.
Just going 30s-3min at a time is going to leave so much down time that you're only going to be reaching vo2 max at the very end of each interval, and not maximizing the amount of time spent there.
But whatever works for you. Many ways to skin the cat. I like bang for the buck myself, though.