How to Strengthen Your Thighs: A Fitness Myth Debunked

There's a lot of misinformation out there about exercise and nutrition. As an ongoing feature, I'll ask experts in those fields about their pet fitness peeves—commonly believed myths that are just plain wrong. This week, I asked Nicholas DiNubile, an orthopedic surgeon and author of FrameWork: Your 7-Step Program for Healthy Muscles, Bones , and Joints, about how to properly strengthen your legs. He offered the following explanation for a fitness myth he's heard all too often.

Myth: If I'm working on my feet all day, or am already on a walking program, I'm giving my quads and the rest of my leg muscles a sufficient workout.

Explanation: I'm a knee surgeon, and I talk to post-surgical patients about what they're doing for their thigh muscles. They say, "I'm fine; I'm on my feet all day," or "I walk a lot." I also see that misunderstanding in my patients who see me because they're into fitness, and in the aging population. People don't understand the specificity of exercise; when you are walking, you're strengthening the heart but not the thighs. It's almost like thinking your biceps will be worked by walking.

The thigh muscle is the biggest in the body. Once you get over 40, its mass starts to decline almost imperceptibly. Leg strength is clearly important to protect the knee, to avoid falls. [To sustain it,] do strength training, and try to work the entire leg, but at the very least please make sure you work the front of the thigh. You can use ankle weights, elastic bands, or just do lunges, squats, and wall-sits. Or use the stationary bike, adding interval training and resistance.

If you're a medical or sports professional and want to share your own favorite fitness myth, E-mail onfitness@usnews.com.