WindWarrior loves these
and sees better performance improvements versus hammering out threshold intervals.
Another variation
where you do 2 minutes RPE vo2 and the last minute is all-out. On the road I usually push the tempo at 85-90%.
All kinds of interesting over/under variations that are not the same as Tom Bells. Those above are from my coach, I’ve got several Cusick plans (two older, a new BaseCamp Road Build to Peak) and don’t recall seeing anything like those in his plans.