When pulling together active stretching routines, there's one key point to keep in mind: these stretches should only be held for a second or two. In gym classes, you were probably taught that stretches are only effective if you hold them for a long time and bounce into the stretch to gain the most flex. This sort of stretching has fallen out of favor, and most active stretching enthusiasts would say that bouncing into long stretches can actually damage and shorten your muscles instead of helping lengthen them. An active stretching routine is designed to reduce damage to your muscles by allowing some of them to do the work while others simply stretch. This might sound complicated, but in reality, it's quite easy.
Your body is made up of pairs of muscles. One set performs an action, and the other stands in line to do the reverse of that motion. To give a bit of a simplified example, to extend your elbow, your triceps flexes and your biceps relaxes. When you bend the elbow again, the biceps flexes and the triceps relaxes. The muscles work in tandem. Understanding this concept is key to understanding active stretching. In this process, you use your active muscles to hold a passive muscle in place for a stretch. You don't use any other mechanism (such as a band or unrelated muscles) to perform the stretch.
Active stretches are particularly useful for the large muscle groups of the legs. While standing, extend your leg straight in front of you until you feel a stretch, and don't hold the leg in any way for support. Hold for a second or two, and slowly lower the leg to the floor; don't let gravity do the work for you here. Continue the stretch all the way to the floor by keeping your muscles tight. You can perform the opposite of this stretch by lying on the floor. Lie down with one leg flat and the other leg bent so your knee is pointed at the ceiling. Extend your leg with just your muscles until you feel a stretch, and then slowly bend your knee until you’re back in your starting position. Stretching your back with these techniques may be a bit more complicated, but you'll feel a great stretch in return for your hard work. Sit with your knees bent and spread, with your toes pointing to the ceiling. Tuck your chin under and using your abdominal muscles, curl your body until your head is bent to your knees. You can grasp your calves for added support, but don't use your arms to pull your body in. Each stretch you perform should be repeated 5 to 10 times.
Active stretching routines are often incorporated into yoga classes. Holding a position for a specified period of time is a form of active stretching, and taking a few classes in yoga can help you pick up new active stretches you hadn't considered before.
One final word of caution: don't do these stretches before a run or an athletic event. Stretching your muscles in this extreme way and then subjecting those muscles to strenuous activity could lead to injury.