Active isolated stretching (AIS) is used to lengthen the muscles and fascia in the body. This form of stretching involves holding a stretch for two seconds, and stretching each muscle at least 10 times. AIS is used by a number of professional athletes and can be helpful for people who have back or postural problems.
There are two types of stretching: static and dynamic. Static stretching involves holding the stretch for a long period of time, whereas dynamic stretching involves short stretches that are repeated several times. Active isolated stretching is considered a form of dynamic stretching. Both static and dynamic stretching increase muscle and tissue flexibility, and play a role in helping repair tissue after a workout, but each one differs in its affect on performance. Static stretching significantly decreases muscle strength for about 60 minutes and decreases performance during a workout, whereas dynamic stretching typically will not decrease performance.
Active isolated stretching methods have been developed to stretch all the major muscles of the body using two main mechanisms. The first mechanism, called reciprocal inhibition, involves stretching of complimentary sets of muscles to promote proper posture. There are sets of muscles on the body that perform opposite functions; for example, the muscles along the front of the thigh, called the quadriceps, perform the opposite function to the muscles along the back of the thigh, called the hamstrings. Reciprocal inhibition in active isolated stretching would stretch the quadriceps to relax the hamstrings, and then immediately stretch the hamstrings to relax the quadriceps. This process helps ensure that the muscle is relaxed before stretching to help maximize the benefits of the stretch.
The second mechanism in active isolated stretching is designed to prevent activation of protective reflexes, which abolish relaxation of the stretching muscle and diminish the overall effectiveness of stretching. Preventative mechanisms are initiated after stretches are held for longer than 2.5 seconds, as a way to protect the muscle from what the body perceives as overstretching. Because each stretch in AIS is held for less than two seconds, it prevents the activation of protective reflexes and allows the stretching muscle to remain relaxed. This ensures maximum elongation of the muscle during stretching for increased flexibility.
Dynamic stretching in AIS also allows for warming of the muscles during stretching as a result of their movement. This pumps blood into the muscle, thereby providing the muscle with oxygen while flushing toxins out of the cells. As a result, isolated active stretching can relieve muscle soreness, prevents injury, and reduces chronic muscle pain.
Active isolated stretching can be done at home, with no equipment needed other than a rope or a towel. The rope or towel can be used to gently push or pull the body into a momentarily deeper stretch and then relaxed. Stretching should be done as part of a dynamic warm-up before exercise, and after a workout to release muscle tension. When practiced daily, active isolated stretching can quickly improve flexibility, improve posture, and prevent future injury.