Hi Garret and Dada,
Thanks for getting a good conversation going on 30-30s; I’m (obviously) a huge fan of this intensity format so am psyched whenever folks add them to their routine.
For target intensity I would suggest aiming for max VO2 (by HR) for the “on-time” and only allowing a 5bpm drop for the off-time. Max VO2 *typically* occurs somewhere around 90-95% of max HR, so you can make an estimate accordingly. For instance, if your max HR is around 190 then your max VO2 lies somewhere in the mid to high 170s. Use the first few repeats of your 30-30s workout to move into that range, and make sure the rest interval sees that 5bpm drop.
While you’re right, Dada, that the workout shouldn’t involve an ever-rising LA accumulation, you will be operating the entire time at and above your AnT (by HR) and probably maintaining a moderate but steady state of LA in the blood. The perception of that, however, is one of less effort than a traditional max VO2 workout (4x 4min, etc) because of the more frequent (but short) rest intervals, so you’re able to push a higher speed in the on-time, benefiting overall economy of the muscles to operate at higher rates against fatigue.
Garret: with regard to your above-mentioned strategy for finding your max HR in the 30-30s, I would be careful about pushing the upper (on-time) HR too high, as that will make it difficult to extend the workout to longer durations and to keep your speed high throughout. Start your progression by using AnT+5bpm as your “on-time” target HR (use the first few intervals to ramp up to this effort), and then simply drop to AnT HR during the rest period. If you find that you’re able to confidently bump that on-time HR a few beats higher after a few workouts, go for it, but make sure that you’re able to sustain that effort and speed throughout the whole session.