When you leave the office and head to the playing field, dance studio or gym, you've got to prepare your body for action. If you've been sitting hunched over a desk, your leg muscles are probably shorter and tighter than they should be, which increases your risk of injury. That's where dynamic stretching -- which involves continuous, repetitive, flowing movement -- comes into play. As part of a general warm-up routine, dynamic stretching, such as deep knee bends, can increase flexibility, enhance your performance and help prevent injury.
Warm up with five to 10 minutes of general physical activity to raise your core body temperature and increase circulation to your lower body. Take a brisk walk around the block, use an elliptical machine or do jumping jacks. When you break a light sweat, it's probably safe to progress to knee bends.
Start with the most basic version of the deep knee bend. Stand with your back straight, your feet shoulder-width apart and your shoulders down and slightly back. Extend your arms in front of you at shoulder height to help you maintain your balance. Focus in front of you and keep your head centered over your spine throughout the exercise.
Inhale and lower your hips as if to sit on a chair, letting your buttocks jut back. Keep your torso long and your knees over the second and third toes of each foot. Avoid rounding or arching your lower back. Continue lowering your hips until your thighs are parallel, or almost parallel, to the floor. Hold for one count.
Exhale and rise from the bent-knee position, fully straightening your legs. Hold for one count. That's one rep.
Repeat the deep knee bend 10 to 15 times if you can do so with impeccable form. Maintain control and keep your movements smooth and rhythmical.
Add an overhead reach to warm up your shoulders, chest and upper-back area. Start with your arms near your sides. During the down-phase of the knee bend, let your arms swing slightly back. During the up-phase, swing your arms to the front and overhead.
Add a toe rise to warm up your ankles and increase the balance challenge. Bend your knees and lower your hips as you would for the basic exercise. When you straighten your knees, rise onto the balls of your feet. Hold briefly and then lower your heels before returning to the bent-knee position.