WHAT IS OVERSPEED TRAINING?
Overspeed training can be classified as any system that enables the body to train at higher speeds than would be possible under normal conditions; likewise, underspeed training refers to adding resistance or weight to the athletic movement. An example of Underspeed/Overspeed combo training for a sprinter might be:
Running uphill into the wind/running uphill with no wind (both US)
Running downhill with no wind/then downhill with the wind (both OS)