Tabata Intervals by Workload Instead of Time

I just tried a minor Tabata interval tweak:

First I set up the pull-up bar and then warmed up on my NordicTrack. For the first set, I cranked as hard as humanly possible on the NT for 20 seconds. I know you're supposed to go that hard whenever you do these, but this set really needs to be super-hard, like it's the only 20 seconds you're going to do, and you're going for the world record. Take note of how many calories you burn in that 20 seconds (so yeah, you'll need a machine with some kind of monitor for this flavor of Tabata interval). Now, during your 10 seconds of "rest" go immediately to the pull-up bar and do as many as you can, keeping count. You now have two numbers. Calories burned and pull-ups pulled. For your remaining Tabata sets, continue to go as hard as you can, but instead of doing them for time, do them for work. So in the second set, you stay on the machine until you've burned the same number of calories as in your first set, then you hop on the pull-up bar until you've done the same number of pull-ups as in your first set. Repeat for a total of eight to ten sets (four to five minutes of total work). Race against the clock, trying to stay within the time constraints defined by straight Tabata intervals. Do not dawdle as you transition from machine to bar and back.

The NT is slightly limiting in terms of how hard you can crank, so doing pull-ups during the "rest" really ups the intensity to a level I hadn't experienced doing unadulterated Tabatas on that machine.