The Science of Landing on Your Feet

Researchers found that when we fall from different heights, our bodies move differently to absorb the impact.

(Inside Science) — In the name of science, researchers yanked footstools from underneath volunteers and observed how the victims stumbled and landed on their feet. They found that when we fall from different heights, our bodies tend to respond differently to absorb the impact.

In a series of experiments, scientists from the University of Queensland in Brisbane, Australia, asked healthy volunteers in their 20s and 30s to stand on wooden boxes that were either 5, 10, or 20 centimeters high (2-8 inches). Then, the researchers would tilt the boxes forward without warning, causing their study subjects to fall forward.

The researchers analyzed the volunteers’ body motions and the impact when they hit the ground. They found that people responded differently to drops with a difference of just a few inches. When the participants fell from a 5 cm tall platform, most just used their ankle joints to absorb the impact. In contrast, when dropped from 20 cm — roughly the height of a stair step — the participants absorbed most of the impact at the knee and hip joints.

They also found that we tend to push down against the ground more than necessary as we land after a sudden fall, probably to make sure that we won’t end up flat on our faces. This often leads us to hop a few times to dissipate the extra energy before stabilizing ourselves.

According to the authors, a better understanding of how our body naturally responds to falls may help engineers design better technology such as exoskeletons and prostheses.

Their paper was published last month in the Journal of the Royal Society Interface.

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