Dr. Laskowski: The lunge is a body resistance exercise that works the leg muscles. Specifically, the lunge targets the quadriceps and the hamstring muscles in the thigh, the gluteal muscles in the buttock, and to a lesser extent, the lower leg muscles. The lunge is a great conditioning exercise for many sports, especially those that involve lunging movements, such as tennis, basketball or soccer.
Nicole Campbell: To do a stationary lunge, start by standing up comfortably. Step ahead with one foot and lean forward until your knee reaches a 90-degree angle and your rear knee is parallel to the ground. Then return to the starting position. You'll feel some tension in your legs.
When you're doing lunges, keep your back in a neutral position, but don't flatten the curve of your lower back, and don't arch your back in the other direction. Make sure that your knee doesn't go beyond your toes and that your knee stays centered over your foot. Don't let your knee roll inward or outward.
If you can't lower your knee to a 90-degree angle, simply go as low as you can. Do as many repetitions as you can, depending on your fitness level. Stop when you're fatigued or your form begins to suffer.
For a variety, try a traveling lunge. Simply step ahead with the opposite foot rather than return to the starting position.
Remember, for best results, keep your back in a neutral position and let your knee follow your foot on the way down. Keep your movements smooth and controlled.