Science puts silly walks to the test

LONDON - The mystery of why people swing their arms while walking rather than holding them still and rigid appears to have been solved.

An experiment involving making a group of volunteers take equally silly walks in a laboratory setting has confirmed that arm swinging makes walking more efficient and easier.

Although it may seem obvious why people swing each of their arms in opposition to their legs, scientists have puzzled over the practice for many decades because it seemed to serve no mechanical function given that the arms do not touch the ground.

One extreme theory even proposed that arm swinging while walking was hard-wired into the human nervous system and served no modern purpose because it was a vestigial relic left over from when our animal ancestors walked on all fours.

Scientists at Delft University of Technology in The Netherlands set up an experiment where people were studied as they walked in a variety of poses - normally with the arms swinging in opposition to each leg, with their arms at their sides either tied or held there voluntarily, or with each arm unnaturally forced to move in synchrony with each leg.

The scientists found that "normal arm swinging made walking much easier. Holding the arms at one's sides increased the effort of walking - measured by metabolic rate - by 12 per cent, which is quite a lot of walking, about the same as walking 20 per cent faster or carrying a 10kg backpack".

The study, published in the journal Proceedings of the Royal Society B, also found that the natural swinging motion of the arms tended to counteract the twisting motion or "torque" of the body, created by the movement of the two legs along a straight path.

- INDEPENDENT