AIS is a studied technique based on a thorough study of anatomy and physiology. The “A” or “Active” component of AIS is based in part on the understanding of antagonist muscles and understanding of the stretch reflex. Antagonist muscles
Antagonist muscles are muscles with opposite actions. For example, the Biceps, at the front of the arm, bends the elbow. Its antagonist, the Triceps (back of the arm), extends the elbow. Biceps and Triceps are antagonist muscles. If both muscles contract at the same time, the elbow is locked – this is essentially what happens in a plank position for instance, where the muscles contract on both sides to keep the elbow from moving. If only one muscle contracts, the opposite muscle needs to relax to allow the body part to move. In order to engage the Biceps and flex the elbow, the Triceps must relax. And in order to extend the elbow, the Biceps must relax.
Using antagonist knowledge in stretching
For effective stretching, the muscles being stretched ought to be relaxed. By using the principle of opposing muscles, one way to achieve this is to engage the antagonist muscle. Indeed, when a muscle is engaged, its antagonist has to relax. For example, to stretch the hamstrings, we need them to relax. Engaging the Hip Flexors and Quadriceps, the antagonist muscles of the Hamstrings, helps with the relaxation process of the hamstrings. This can be done by lying on the floor and lifting the leg – kept straight - (Hip Flexors and Quadriceps engaged) up and toward the head. By using a rope attached at the end of the foot, it is possible to enhance the stretching by pulling a little at the end of the stretch.
Another element to take into consideration is the stretch reflex. When a muscle is being stretched comfortably, it stays in a relaxed state. However, if the stretch is pushed over the comfort level the muscle reacts by contracting itself for protection from pain and injury. The stretch reflex takes about 2 seconds to kick in, so an effective stretch would be 2 seconds or less to avoid it. For the Hamstring stretch, that translates into: lifting the leg, pulling with the rope for no more than 2 seconds, then lowering the leg; the whole sequence is repeated approximately 10 times.
For more effective stretching, an AIS specialist will spend time at the end of a session to teach a series of at home stretching. Check out this video on self Hamstring stretching.
This article and/or video are for educational purposes only; do not attempt without your physician's clearance. If you are in pain or injured, see your physician.