This method of stretching was developed by a pair of exercise physiologists, who are a father and son team that trained Olympic athletes during the Barcelona games. Their names are Jim and Phil Wharton. It's proven to be very effective in increasing flexibility without the kind of difficulty that some people who are very tight experience with other forms of stretching. One of the great qualities of it is that it can be done without a warm up. Like strength training, stretching can be rather traumatic to the muscles, which is why a warm up should be done beforehand. Since Active Isolated Stretching (AI-Stretch) is done actively by holding for just 2 seconds while exhaling and then releasing while inhaling, it can be done without a warm up. In fact, in many cases it is a crucial component to a good warm up. If a person has tight facilitated muscles, then it is incredibly important to stretch those muscles before doing strength training, because those tight muscles can rob neurological energy from the opposite muscles, which will keep muscular imbalances in place. If this happens, then any attempt to correct muscle and postural imbalances through a strength program will be in vain. The tight muscles must be relaxed beforehand so that the opposite muscles can be well trained.

The Wharton's have developed a total of 59 AI-Stretches for the entire body. We need only use the ones that apply to our tight muscles or to muscles that need to be stretched for athletic or rehab purposes.