UK Edition
Flat-footedness may not be as debilitating as originally thought after a study showed that the arch which spans the width of the foot, rather than the length, is more important for strength and stability.
Currently a person is said to be flat-footed if their longitudinal arch - which runs from the heel to the ball, is not curved sufficiently upwards.
But new research from Warwick University and Yale has found that it is actually the transverse arch - which sits behind the toe mounds - that is most important for walking.
In the the Second World War, recruiting officers viewed flat-footedness as so severe that sufferers were deemed unfit to serve.
Yet, in recent decades it has been noticed that many people with a flat longitudinal arch have no difficulty walking at all.
To investigate whether the transverse arch creates stiffness, a team of engineers, performed bending tests on human feet and examined fossil samples of human ancestors.
They also created computer simulations and plastic models of the midfoot and measured how much force was required to bend them.
Results showed the transverse arch to be responsible for more than 40 per cent of foot stiffness.
Professor Mahesh Bandi said: “We found that the plastic models and simulations with more pronounced transverse arches were stiffer and less susceptible to bending than flatter ones.
“In contrast, on these models, an increase in the curvature of the longitudinal arch had little effect on the stiffness.”
The research also clears up a mystery about how our hominin ancestors managed to stand upright despite not having a longitudinal arch for two million years.
Paleontologists have found foot fossil bones of Australopithecus afarensis which date from 3.66 million years ago, and also footprints suggesting the tiny primates walked on two feet even though they only had a transverse arch.
Madhusudhan Venkadesan, an assistant professor at the Yale School of Engineering and Applied Science in the US, and one of the lead authors on the study, said: “Our evidence suggests that a human-like transverse arch may have evolved over 3.5 million years ago, a whole 1.5 million years before the emergence of the genus Homo, and was a key step in the evolution of modern humans.”
Scientists are hoping the findings will help robotics engineers design androids which are better able to stand upright.
The research was published in the journal Nature.