Today’s Wonder of the Day was inspired by Bethany and Emma. Bethany and Emma Wonders, “Why do you swing your arms when you walk?” Thanks for WONDERing with us, Bethany and Emma!

Do you get enough exercise? In today's technology-driven society, it's quite easy to spend hours and hours every day lounging on the couch watching television or sitting in a recliner playing video games or texting your friends.

To maintain a healthy lifestyle, it's important to get up and get moving on a regular basis. One of the easiest ways to get a little exercise is to go for a stroll. That's right! Just walking around can boost your heart rate and improve your mood.

As you walk, your legs are getting a good workout. But did you realize there's another part of your body that gets a bit of a workout? Would you believe it's your arms? It's true!

Go for a short walk and pay attention to how much your arms swing while you walk. Most people never think about how their arms swing when they walk, but they do. So why exactly do they do that?

For a long time, scientists thought that swinging your arms while walking served no purpose whatsoever. Their best guess was that it was just some sort of evolutionary afterthought that we just never got rid of. After all, you don't have to move your arms to move your legs. So why do it?

Recently, scientists have completed more advanced research on the issue and discovered that swinging your arms while walking definitely does have a purpose. Like many other bodily functions, it occurs because it's the most natural and efficient way to walk. In other words, swinging your arms while you walk helps to reduce the total amount of energy it takes to walk.

Don't believe it's natural? Try walking without moving your arms. Better yet, try walking while swinging your left arm when you step with your left foot and vice versa. Both of these practices are unlike the natural method of arm swinging while walking, which is for your left arm to swing forward as you step forward with your right foot.

Scientists used those two alternative methods to test whether the natural method of arm swinging while walking was the most efficient. To their surprise, they discovered that people who hold their arms still while walking use 12% more energy than people who swing their arms normally.

Even more surprising was what they found when they had people walk with their arms in sync with their legs (left arm swing forward when stepping forward with the left leg). Those people used 26% more energy compared to normal walking.

Researchers found that normal arm swinging actually doesn't use much energy from the arm muscles. Simply walking causes the body to sway in a way that makes the arms move naturally, like a pendulum.

So when you walk, your arms begin to swing naturally without much effort from your arm muscles. The natural movement of your arms also helps to offset a part of the force caused by your legs hitting the ground, keeping your torso and hips from wobbling and twisting too much. This results in your legs using less energy!

Wonder What's Next?

Tomorrow’s Wonder of the Day comes in really handy in case of a fire!