Originally Posted by
MSchott
Intervals at or near VO2 max is one thing but is it humanly possible to do this for 30 minutes?
Interval workouts have little to do with a specific intensity; they're just a set amount of time/distance at a different (usually) harder intensity.
You do longer efforts (hour plus) at sub threshold, 3-6 min efforts at vo2 max, 1-2 mins near max efforts, 10-15 secs sprints, and anything in between.
All have their purpose and place depending on fitness goals.