Physiologists at Simon Fraser University in British Columbia asked adult volunteers to walk on a treadmill at an easy pace. Using motion capture technology, the scientists determined how many steps each person was taking per minute at this speed. A person’s pace depends, of course, on both step length and step frequency. But because the two are inextricably entwined — lengthen your stride and you’ll take fewer steps over a given distance — studying one provides sufficient information about the other, and frequency is easier to enumerate.

After establishing each volunteer’s preferred step frequency, the scientists then sped up or slowed the treadmill, and the researchers measured how quickly people’s legs responded.

The body, remember, wants things to be easy. When you increase or decrease the speed of your walking or running, various physiological changes occur; the amount of oxygen in your blood rises or falls, for instance, because your muscles start requiring more or less of the stuff. Other biochemical changes also occur within muscle cells. Sensing those changes, the body realizes that, at this new speed, your cadence isn’t ideal; you’re taking too few or too many steps to use the least possible amount of energy. Your body adjusts.

Read it at NY Times.