When you exercise, your muscles contract and relax, contract and relax. The repeated contraction can lead to shortening up of the muscles. Stretching will prevent this and help you avoid injury while exercising.
Take action: When you stretch, ease your body into position until you feel the stretch. Hold it for about 25 seconds. Breathe deeply to help your body move oxygen-rich blood to those sore muscles. Don't bounce or force yourself into an uncomfortable position.