If you remember high-school gym class, you probably remember three things about it: a) changing clothes in front of adolescent peers is no fun; b) proper stretching is essential before any physical activity; and c) the meek may inherit the earth, but not before a few dodgeballs ricochet off their foreheads.
It now seems that the weight of modern science contradicts the second rule—in other words, stretching before exercise doesn’t do much for your joints or muscles. In fact, static stretching (where you hold a stretched position for 20 or 30 seconds) temporarily weakens the muscle, and may even make injuries more likely when you stretch at the beginning of a workout. That’s because resting muscle is stiff. It’s just not ready to meet the demands of vigorous exercise or deep stretches. In fact, static stretching may simply increase your stretch tolerance, which is a fancy way of saying that your brain will allow you to extend stretched muscles a little bit more, even though they aren’t yet warmed up and really ready for it.
That doesn’t mean that you should leap straight from the couch onto the treadmill. Before any sort of exercise, you should perform a short 5- or 10-minute warm-up. This stimulates blood flow to your muscles and literally warms up your body. It also gently loosens muscles and tendons, increasing the range of motion in your joints. Your warm-up should match the exercise you’re doing. If you’re getting ready to run down the street, start by jogging in place. If you’re lifting weights, start with a little light jogging (just enough to break a sweat) and then perform a set of your chosen exercises with a much lighter weight. Once you finish, you can begin the real muscle-straining workout. And after your workout? Recent studies suggest that just as pre-exercise stretching doesn’t prevent injury, post-workout stretching does little for muscle soreness. At one time, experts thought that stretching reduced the buildup of lactic acid in muscles, reducing the stiffness and soreness you feel the next day. However, the theory didn’t fit the facts. Although lactic acid causes the burning feeling you experience while you strain your muscles, it quickly disappears after exercise. Muscle soreness usually appears much later (after a day or two), when there’s little lactic acid left in the muscles. Today, biologists believe that the soreness is caused by inflammation, which sometimes follows the microscopic muscle-tearing that stimulates muscle growth.
More important than stretching after a workout is carrying out a proper cool down—gradually stepping down your exertion until your heart rate is just 10 to 15 beats above normal. Stopping too abruptly can cause a sudden drop in blood pressure and muscle cramping.
Finally, none of this is to say that stretching isn’t worthwhile—many experts believe stretching is very important for preserving flexibility and maintaining health. Good stretching regimens include yoga and tai chi, and may also involve meditation and breathing techniques that reduce stress.
The best ways to avoid muscle soreness are to keep up a regular exercise routine, avoid abruptly increasing the intensity of your workout, and give tired muscles sufficient time to recover (a day or two, depending on how much you exercise).
Source of Information : Oreilly - Your Body Missing Manual