Some coaches, trainers and textbooks recommend stretching before and after your workout because it can help your performance and reduce the risk of injuries. However, numerous research studies has shown that some types of stretching can enhance your workout while others do not improve or reduce your athletic capabilities. Exercise physiologist Len Kravitz recommends that you perform dynamic stretching before your workout and static stretching afterward.
Dynamic Vs. Static
Dynamic flexibility is often used as a warmup to stimulate your nervous system and muscles to be better prepared for the upcoming activity. It involves moving your muscles and joints repetitively within your range of motion. The movement is usually specific to the exercise or sport that you're going to play. For example, soccer players warm up by doing leg and hip swings in different directions, and boxers do a couple of standing torso and shoulder twists while working on their footwork and punches. Static stretching, which involves stretching a muscle for 20 to 30 seconds, decreases neural stimulation to the muscles and enhances relaxation. This type of stretching is usually non-sports specific, working on fixed muscle groups instead of movement like dynamic stretching. Therefore, static stretching should be performed after a workout.
Effects of Stretching
Dynamic stretching has been shown to improve athletic performance before training. A study performed at the University of North Carolina at Chapel Hill showed that subjects who performed dynamic stretching had significantly improved their strength and power during the vertical jump test. The other two groups in which one group performed static stretching and the other group performed no stretching showed no positive or negative effects in the test. Static stretching can decrease athletes' sprinting ability. In a study performed at Middle Tennessee State University, soccer players who performed static stretching before a bout of 30-meter sprints resulted in slower performance than those who didn't perform static stretching. Researchers concluded that athletes who are in sports that require sprinting should avoid static stretching as part of their warmups.
Dynamic stretching emphasizes full-body movements that can be performed with just your body weight or with certain tools. These include clockwork lunges, yoga series such as Sun Salutation, martial art katas, medicine ball swings and chops and standing butt kicks. Simpler dynamic stretching can also include neck rolls, shoulder rolls and jumping jacks. Static stretching include all kinds of stretches that you may recall from your middle-school physical education classes, including the seated groin stretch, standing toe touch, standing thigh stretch and lateral neck stretch. Always maintain a steady breathing rhythm in all your stretches.
Stretching too quickly and too far -- and sometimes too eagerly -- can cause your muscle fibers to contract and shorten reflexively. This reaction is called a stretch reflex, which is your body's defense to avoid tearing of your own joints and muscles. This can cause the muscle to be less responsive to length change and more sensitive to pressure and touch.