How do my muscles work?

Muscles work by moving in harmony with one another. When one muscle gets a message to tighten, its opposite muscle gets told to relax. This means that muscles work in harmony when they move. The brain tells muscles which ones should tighten and which ones should relax. The brain sorts out the messages that go to the muscles. Once they’re sorted, the messages go from the brain to the muscles telling them what to do.

Dr. Mehmet Oz, MD
Cardiologist (Heart Specialist)

Muscles are made up of tissues that contract and relax. They’re kind of like an extendable ladder that snaps together and shortens when you pull or apply tension at one end. When you release that tension on the muscle or ladder, it relaxes and extends. Your energy intake (healthy food, not flaming nacho cheesy fries) provides the power for your muscles to contract and relax. Work them and feed them right, and they grow. Starve yourself long enough, and you start breaking down those muscles to fuel the rest of your body and little by little you will get weaker.

Muscles grow after they’re used. Lifting weights, doing push-ups, or performing any kind of exercise that requires you to push or pull damages the muscle fibers; the soreness you may feel afterward comes from toxins released by muscle tissue when it is damaged. When you’re done, the muscles say, “Forget this, we’re not going to be damaged again. We’re going to build up to be even stronger than before,” which is why they get larger. For those who are overweight or looking to maintain weight loss, the great thing is that muscle actually helps you burn calories much faster than fat or other tissue. So if you’re looking to lose weight, in addition to watching your calorie intake, build some muscle to increase the fat-burning engines in your body.

YOU: The Owner's Manual for Teens: A Guide to a Healthy Body and Happy Life

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YOU: The Owner's Manual for Teens: A Guide to a Healthy Body and Happy Life

A few years ago, we wrote YOU: The Owner’s Manual, which taught people about the inner workings of their bodies—and how to keep them running strong. But you know what? There’s a big difference...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.