Flex Your Muscle IQ

It’s enough to make your skin crawl. “Mus” means “mouse” in Latin. Word-makers thought some muscles looked like tiny mice moving around under the skin.

If you’re a lean man, your body is about 45% muscle, 15% bone, and 15% fat. If you’re a woman, you have around 30% muscle, 12% bone, and 30% fat. The other 25% of your weight comes from your organs.

It may not do any heavy lifting, but your heart is a muscle your body uses constantly. From the minute it forms while you’re in the womb until you die, it beats without stopping, helping move blood through your body. 

You need muscles for everything you do, from running and lifting to digesting, breathing, and even getting goosebumps! It’s no wonder you have more than 600 of them to keep your body in working order.

It’s been a rumor for a long time that frowning uses more muscles than smiling. But scientists tested it and put an end to the myth. You use about 11 muscles to frown, and a mere 12 to turn it upside down.

Your fingers are like puppets and your hands are the puppeteers. There’s no muscle on your finger bones -- only tendons that hold them to the muscles in your palm and wrist.

Looks like Popeye was really on to something. Spinach is a rich source of iron, which your body needs to carry oxygen through your blood. Without enough of it, your muscles would be too tired to work. Spinach alone won’t make you a champion bodybuilder, but the iron in it is a key player in muscle health.

Scientists found that when you build muscle, it forms new structures, called nuclei, which can make more muscle later on. Even when you stop using these muscles, the nuclei stick around. That gives you a head start when you start training again.

A workout will set the tone for strong muscles, but sleep is when you really get pumped up. Your body strengthens and repairs tissues during your deepest sleep cycles. So get your ZZZs -- you need a full night’s rest for optimal muscle mending and growth.

It’s called the stapedius, and it’s in your middle ear. It’s connected to the smallest bone in your body, the stapes. This little muscle keeps the stapes from vibrating too much when loud noises hit your ear -- including the sound of your own voice.