AIS is a method of muscle lengthening and fascial release, developed by Aaron Mattes. It uses active movement and Reciprocal Inhibition (RI), but not isometric work, to achieve greater flexibility.  The technique isolates the muscle to be stretched, and actively stretches it until the patient feels a ‘light irritation.’  After a hold for 2 seconds, the massage therapist then returns the limb to the start position. This action is repeated 8 to 10 times. Also see Reciprocal Inhibition (RI)