Descending intervals (DIs) train your body to buffer lactic acid, produce anaerobic power, and sustain the repeated hard efforts that often occur in a race.
This is a very intense workout that should only be performed once or twice a month. You can perform DIs on your stationary trainer or on a long flat section of road.
Start out with a high cadence (110) at a maximum effort. Your first effort can be two or three minutes in length. Recovery time between efforts should be the same as the effort. So if your effort is two minutes, your recovery time will also be two minutes.
After each effort, cut the length of the next effort in half. For example, a typical DI workout would be two minutes, one minute, 30 seconds, 15 seconds. I recommend two or three sets of DIs with at least 10 minutes recovery between sets. All efforts are performed at maximum effort with a sustained high cadence.