Yahoo Sports Arched feet didn't evolve to give us a spring in our step – but to keep us upright, scientists say
The raised arch under the human foot evolved to help people stay upright and run, scientists have concluded.
Previously, experts thought that the arch acted as a lever to help propel the body forward to the next step, but now researchers believe it developed to help humans walk on two feet.
A global team of scientists has found that the arch helps reposition the ankle into an upright position for more efficient running and walking.
“We thought originally that the spring-like arch helped to lift the body into the next step,” said Dr Lauren Welte, first author of the study in Frontiers in Bioengineering and Biotechnology, who conducted the research while at Queen's University Belfast and is now affiliated with the University of Wisconsin-Madison.
“It turns out that instead, the spring-like arch recoils to help the ankle lift the body.”
Trait may have evolved to help humans run more efficiently
To investigate the role of the arch, the team studied seven people with different kinds of arches, some higher and more arched and some people with flat-feet who had more rigid arches, providing less spring.
The participants were asked to walk and run while their feet were being filmed by high-speed X-ray motion capture cameras.
They found that a more rigid arch caused the ankle to lean too far forward, creating a posture similar to that of walking chimpanzees, rather than the upright stance of the human gait.
In contrast, the flexible arch helped reposition the ankle upright, allowing the leg to push off the ground more effectively.
This effect is even greater when running, suggesting that the trait may have evolved originally to help humans run more efficiently.
“The mobility of our feet seems to allow us to walk and run upright instead of either crouching forward or pushing off into the next step too soon,” said Dr Michael Rainbow of Queen’s University, senior author.
The findings also suggest new treatments for people whose arches have fallen because of injury or illness. By increasing the flexibility of the arch it could improve overall mobility.
“Our work suggests that allowing the arch to move during propulsion makes movement more efficient,” added Dr Welte.
“If we restrict arch motion, it’s likely that there are corresponding changes in how the other joints function.”
The research was published in the journal Frontiers in Bioengineering and Biotechnology.
