Active Isolated Stretching (AIS) is a muscle stretching and strengthening technique that allows for a gradual, gentle stretch of the specific muscles to maximize its length, flexibility and power. Also known as the Mattes Method, AIS was developed some 40 years ago by Aaron Mattes, a Florida kinesiologist. Mattes believes that a two-second, 10-repetition stretch to specific muscles avoids over-engaging the stretch reflex and allows maximum stretch of the muscle. This restores the greatest level of function to the muscles, tendons, vertebrae, ligaments, and joints. One of its most important benefits is that AIS promotes stronger superficial and deep muscle fascial structures, which can create greater overall power through increased flexibility and strength.

AIS has been described, as "assisted therapeutic stretching," since the trained practitioner coaches the patient to more effectively and gently stretch a muscle that he or she may have thought was inflexible. Once learned, these stretching skills can be used by the patient to stretch daily at home.