4 x 4 Minute VO2 Max intervals

These are going to hurt a bit :) Luckily they are over quickly. 20 minutes warmup in Zone 2, then 4 minutes at Zone 5 wattage or HR. 4 minutes recovery, then repeat. This is one set.
Rest (spin easy) for 8 minutes, then a second set.
Cool down for at least 20 minutes. DON'T make the mistake of starting these off too hard and tapering off - the last should be just as intense as the first. Enjoy :)