Four Dimensional Power Focus:
The very first Sufferfest video ever made (although it's since been remastered a couple of times)! Sigh. Both sets of intervals are designed to have equal work to rest ratios, so the longer intervals have longer recovery time afterwards. This first set will begin to deplete your AC, and by the end your aerobic system will have to work overtime to help keep the power up. And keep the power up you will, since as the intervals get shorter, they also get harder.
The second interval set follows the same pattern as the first, ensuring both your AC and MAP are pushed towards their limit. To give it that extra kick we added in a couple of 30 second efforts with 30 seconds of recovery (having flashbacks to Pain Shakes from Blender are we?). These final efforts are just hard enough—with just enough rest—that you will fully deplete your AC, forcing your MAP to pick up the slack.