The artificial gaits are taught by the use of any type of device. The most used devices are the heavy shoes, chains around the fetlocks and pasterns, severe bits, trimming too much the hooves and the use of drugs.
The first point to think about this physical aggression is the pain and unsoundness caused to the horses. The second point is the lack of honesty not explained to buyers the way the horses are trained to be sold as gaited horses.