Developed by scientists at the University of Udine in Italy, Descending Intervals are proven to increase the amount of time an athlete is able to spend above 90% of VO2max intensity within a single session. This makes the workout a potent way to boost aerobic capacity (aka VO2max).

The heart of the workout is a set of short, fast efforts of decreasing length that target Maximal Aerobic Speed (MAS), which is the fastest pace a runner can sustain for about 6 minutes and falls at the high end of Zone 4. Each MAS effort is followed by a Zone 1 active recovery that's two-thirds the duration of the preceding effort.

Athletes have a natural tendency to adjust their effort to the duration of a segment, automatically doing shorter segments at a higher effort level than longer ones. In Descending Intervals Rides like this one, though, you should do each Zone 5 segment at the same effort level even though they get shorter.