I've had good results following the standard Tabata Protocol (20s "max" and 10s rest).
I do this protocol 5 days a week and mt bike pretty hard the 6th day. In the "work" cycle on the Tabata protocol I can reach "max" in about 15s.
But I got to the point where it takes me 15s or so to reach max This is on an exercise bike "out of the saddle". I could probably go a little harder by "running" rather than "jumping" onto each pedal but I find that tough to coordinate on a bike.
(I am not meaning to humblebrag here: I'm the slowest person on my weekly group Mt. Bike rides. I cardio is my limitation).
I'm currently on 25s /12s rest x 12 Reps. But.... I'm not completely wiped at the end (super tired for sure). And on each work rep I don't reach the "poop my pants" point . And I think I should be. On my mt. bike rides I find that I can now go "all out" for longer (maybe 1-2 minutes before reaching that "poop point", up from about 30 s or so). But the guys I'm riding with can just keep at that speed for 10 minutes. (I just want to keep up so I'm not slowing everyone down :)
What is the best way to increase it?
- Increase the work length?
- Decrease the rest?
- Increase the # of Reps?
And let me know whether you've measured positive results for yourself or if there is some citation of someone else who has measured it.
The Gibala Regimen and others I've seen which are designed to be less intensive increase the Work and rest cycle and reps to: 60 w/ 75 r x 8-12 Reps. So maybe that's my answer.