Balance and Center of Gravity

Vertigo: the sensation of spinning or whirling. The sensation can be associated with balance problems. A friend of mine woke up dizzy several nights ago. “I had trouble walking without feeling like I was going to fall down,” she said. Her doctor had diagnosed vertigo and given her some exercises to do. “Boring! Boring!” she complained with a chuckle.

“Maybe boring, but helpful,” said her husband who came in with his cellphone buzzing. It was an alarm to remind him when it was time for her to do her exercises. Calcium crystals in her inner ear had likely become dislodged somehow. They are critical in maintaining balance. Always ready with a joke, I shook my head rapidly back and forth: “Is this the exercise?” I asked. “Close,” her husband said. My friend demonstrated the real exercises, turning her head to the side and holding it in position for 30 seconds before turning it even further and repeating. “Just boring!” she groaned.

This started me thinking about balance and some experiments. These are geared with children in mind, but adults have fun doing them, too.

Are you in balance?

  1. Stand with feet slightly apart. Are you in balance now? How can you tell? (you feel solid and fixed in position) Now stand on one leg. Are you still balanced? Perhaps, but not immediately. How can you tell you’re not in balance? What can you do, to help become safely balanced on one leg? You need to re-center yourself so that you are standing over your center of gravity or center of balance. Sometimes it helps to throw an arm to the side. Where is your center of gravity when you’re standing on two feet? (right down the midpoint of your body). Where is it when you stand on one leg? Why can it help to hold an arm out to the side?
  2. Now try this (good party trick, too!). Tell a friend you’ll give them a sack full of gold if they can only pick it up without falling. Put the “gold” or other treasure on the floor and demonstrate picking it up. Simple! Can you do it, if you keep your knees straight and your feet unmoving? Yes. Now position them against a wall as shown, with the treasure in front of them. Ask them to pick up the treasure without bending their knees or moving their feet – or falling. It is impossible. Why? To discover the answer, watch a person carefully as they bend to pick up an object without the constraint of staying against the wall. What do you notice? How does your body change so that you keep your balance?

Image courtesy of Scientific American

I led the previous experiment with a group of giggling Afghan students in Kabul. I offered them an American penny if they could pick it up. How they tried to cheat, laughing uproariously: moving away from the wall, using their arms against the wall to stabilize themselves. I let them each have the penny afterward.

Tight Ropers

Consider how type rope walkers balance themselves. Examine these photos to see how they do it.

Struggling to place himself over his center of gravity
This long bar has weights on end
The bar has weights and. is drooping

In the lower two photographs, professional tight ropers use bars to broaden their mass and/or to lower it. Broadening your mass (spreading it out) makes you less likely to tip or rotate off your center of balance. Lowering your mass lowers your center of gravity, which is another method stabilizing yourself. When I was learning to roller blade down hills, I found myself naturally bending my knees to keep low to the ground. Lowering my center of gravity helped stabilize me. Weights on the end of tight rope bars aid in spreading and lowering the mass of the tight rope walker.

A caterpillar and balancing butterfly

Image adapted from ThinkingFountain.org
  1. Cut two of these patterns from medium weight cardboard. Shoebox cardboard is perfect but others will work, too. From one of the butterflies, cut out the center portion and decorate it to look like a caterpillar. Find its center of gravity and balance it on your finger. Then try balancing it by placing only its nose on your finger.
  2. Color the remaining butterfly as you wish, or use a photo to color a butterfly you’d like to study. Find its center of gravity and balance it on your finger. It should be easier to balance than the caterpillar. Why? Then try to balance the butterfly by its nose on your finger tip. Can’t do it.
  3. Tape a penny on the underside of each wing in the position shown. Now you should be able to balance the butterfly by its nose on your fingertip…your nose…your toe…your ear…a pencil tip. Why?
  4. NOTE: It might be easier to download the pattern directly from: https://www.thinkingfountain.org/s/symmetry/butterflypattern.gif

Your built-in balance tools

We’ve discussed how distributing weight can help tight rope walkers balance. But of course those aren’t necessary for humans to run, jump, walk, stand, or even walk on tight ropes. Our hearing, sight, sense of touch and air movements all send messages to the brain. The inner ear sends its own messages. The inner ear has three canals, lined with hairs and containing fluid and calcium crystals. As you move, the crystals brush against the hairs. Get this: (amazing, I think!) One canal senses up and down movement of your head, one senses tilt, and the other senses sideways movement. How glorious is that?

So, back to my friend with vertigo. After a day or two, the condition went away. She had done her exercises as asked. Did the exercises get her inner ear crystals in the proper condition, or did time just do its healing work? I don’t know but I’m glad she’s feeling better. Now I’ll see if I can get her to undertake tight rope lessons.

Update: African long distance runners and center of gravity

Kalenjin runners from west Kenya, tend to have tall lean bodies which may help them win marathons. Their ankles, far from their center of gravity, are thin. It has been theorized that thin ankles make it easier for them to move their legs…as opposed to stockier body types that have thicker ankles. Allen’s Rule is a scientific theory that suggests people who live in warmer climates, such as the Kalenjin, have long thin bodies. People who live in colder climates, such as Inuit, have developed stockier bodies.

2 thoughts on “Balance and Center of Gravity

  1. on line. Causality is an interesting issue. Was I getting over the vertigo as a matter of course or did the exercises help? Either way, if I contracted the malfunction again, I would immediately try the exercises. I sure did seem to perk up quickly when doing the exercises…

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  2. The doctor diagnosed the problem as vertigo. My husband found the exercises on line. Causality is an interesting issue. Was I getting over the vertigo as a matter of course or did the exercises help? Either way, if I contracted the malfunction again, I would immediately try the exercises. I sure did seem to perk up quickly when doing the exercises…

    Like

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