In a new study, scientists have shed light on the role of our feet in maintaining our body's balance.
Researchers at the Ohio State University described a mathematical model that can explain over 80 percent of the apparent randomness in the location of a person's next step, based only on tiny variations in the movement of that person's pelvis.
Assistant professor, Manoj Srinivasan explained that every step a person takes is a balancing act as the body falls forward and sideways. They were able to show that the next foot position could be predicted way in advance of when the foot is placed, as early as the middle of the previous step, based on how the body is falling.
The scientists fitted 10 participants with motion capture markers and tracked them walking on a treadmill at various speeds, from a leisurely stroll to a moderate pace (from around 2 to 3 miles per hour).
If the researchers were trying to make a generic model of how humans walk, they would have disregarded the tiny variations in pelvis movement and foot placement as "noise" in the data. But in the experiment, the noise was what they were interested in, because that's when a slight change in the balance could be offset by a slight change in where we place our feet.
That is, our bodies initiated an almost imperceptible fall to the right before taking a step to the right, and a fall to the left before taking a step to the left. If our pelvis happened to move a millimeter differently one way or the other in a particular step, it created a tiny imbalance, which people seemed to compensate for by placing the next step in an appropriate position. This all happens without conscious thought on a person's part.
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The researchers said that a better understanding of the human gait could inform the design of assistive exoskeletons that help people with movement disorders walk naturally. It could also aid the design of humanoid or even four-legged walking robots.
The study is published in the journal Biology Letters.