Active Isolated (AI) Stretching

What it is: Active isolated (AI) stretching involves tightening the muscle opposite to the one that you’re planning to stretch and then stretching the target muscle for two seconds. You repeat this process 8 to 12 times before going on to the next stretch. By stretching for such a brief period of time, you don’t give the muscle enough time to trigger its stretch reflex. What’s the purpose of tightening the muscle opposite the one you’re stretching?
When a muscle tightens, the opposing muscle has no choice but to relax. Although Active isolated stretching has been around since the 1950s, it’s just now gaining popularity — largely through the efforts of father-and-son physiologist team Phil and Jim Wharton, authors of The Whartons’ Book of Stretching (Times Books). Many sports teams and elite athletes, including one of the world’s fastest humans — sprinter and Olympic gold medalist, Michael Johnson — also favor the AI method. Researchers are currently studying this method and may soon offer more insight into its benefits.
AI stretching has its advantages:

• Many AI stretching exercises do a good job of isolating one muscle group at a time. For example, with an AI stretch, you can stretch the hamstrings without involving the lower back and hip muscles.
• If you’re particularly weak in one area or are rehabilitating a muscle from injury, the tightening may help strengthen that muscle.
• Many people find AI stretches less painful than traditional stretches.

This method of stretching also has disadvantages:

• The technique is harder to master than traditional stretching, and some of the positions are difficult to get into.
• AI stretching is time consuming. You need about 20 minutes to stretch your entire body, whereas you can do an adequate traditional stretch routine in 5 to 10 minutes.

Sample AI Stretch (see Figure): This move stretches your calf muscles.
Hold one end of a belt or towel in each hand. Sit on the floor, and lift your left leg a few inches off the floor, positioning your right leg in the most comfortable position. Loop the center of the belt around the instep of your left foot. Point your toes away from you to tighten your calf muscles and then pull your toes back to stretch your calf muscles. Hold the position for two seconds. Repeat 8 to 12 times and then stretch your right calf.