One, Two, Three, Stretch!
To increase muscle flexibility with the active-isolated technique, you use the opposite muscle to do the work. You can do it as hard as you want and nothing bad will happen, because you can't injure the muscle unless you hold it for more than two seconds. If you hold it less than two seconds, you can get a nice stretch but a two-second stretch isn't going to be effective. So, do lots of them, 10, 20, 30 repetitions for one stretch. Over time, it has a profound effect in lenghthening muscles.
"At first it was kind of hard," admitted Elizabeth Robe, a University of Missouri track and field performer. "But then, when you started doing it more often, you start to see the improvements. It helps. It's helped me to become more flexible."
The confusing concept is, you don't feel it. There's no "burn," no tightening. If science didn't tell us differently, you wouldn't think you were doing anything. In this stretch, range of improvement is so small, day-to-day, session-by-session, you don't notice it. And, the new approach to stretching isn't just for athletes. It's proved to effectively treat chronic back pain and carpal tunnel syndrome, as well as knee, hip and ankle pain.