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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 15 November, 2000 Next Week's Question
Moving arms helps balance in walking
Question
Why is it normal to move your arms when you walk or run?

Question
I think that while people walk and run their motions are chosen to reduce effort, increase speed, and keep stable. If someone walked or ran with their arms hanging straight down instead of swinging them, they would get more tired. They couldn't run as fast. And they might fall down more. How does swinging your arms make walking and running easier and faster?

I don't think anyone really knows, but here are a few ideas.

1) If you hang from a rope and swing your legs as if you were walking your body will twist back and forth. When you walk, that twisting tendency is still there. Swinging your arms opposite to your legs, like most people do, twists you the opposite way so its easier to walk straight.

2) If you just relax your arms, they will swing because your shoulders move when you walk. It takes effort to stop them from swinging. People are lazy so they let their arms swing.

3) Swinging arms can help push you forward. Each time you swing your arm you throw your fist forward like a ball. At the end of the forward swing your fist pulls your body to catch up. Why doesn't the 'throwing' effect cancel the 'catching' effect? That's the kind of thing we are still trying to figure out.