Walking involves a repeated process referred to by scientists as 'crash, vault, push' – landing ('crashing') on the heel, vaulting over the stationary leg and then pushing off with the toes. This is the most economical way of walking and, as research published today in the Journal of the Royal Society Interface shows, the force exerted on the ground is the same for people walking normally or in high heels and for ostriches.
Dr Tatjana Hubel from the Royal Veterinary College explains: "Despite vastly differing arrangements of joints and hip wiggles, humans walking normally, women in extremely high heels and ostriches all produce strikingly similar forces when walking. This is the most mechanically economical way of walking. We do everything we can to make the forces follow the same pattern, which is why for example women wiggle their bottoms when they're in high heels. The question for us is, why is the human foot shaped the way that it is and not, say, like an ostrich's?"
When scientists model how the leg moves, they tend to simplify the movement and view the leg as a stick with a block on top (the body) which moves in an inverted pendulum motion. In this simplified model, the shape of the human foot does not make sense. But in fact, the human leg is more complicated than this; it contains muscles that likely evolved out of a tension between being optimised for walking and being more efficient at running. As humans are intelligent and able to plan and use tools, being able to move quickly to catch a prey or to evade a predator is not essential.
The shape of the human foot means that when the foot is flat on the ground, all the force goes through the ankles, allowing the muscles to support the weight of the body whilst being largely unloaded during the 'vault' stage. When muscles bear a load, they get tired easily, even if they are doing no work. For example, if we hold our arms outstretched, after a few minutes they will grow tired; by comparison, a JCB digger can extend its arm indefinitely.
The researchers believe this finding may have implications for the design of better prosthetic limbs for above-knee amputees and for the legs of humanoid robots. These might be improved by bearing more resemblance to an ostrich leg than that of a human.
Dr Jim Usherwood, a Wellcome Trust Senior Research Fellow at the Royal Veterinary College, explains: "If you want to make a good prosthetic foot but don't care what it looks like, you should put the motor – in this case, the ankle – as far up the leg as possible, where it can provide the power without making the feet heavy and hard to swing backwards and forwards. There's no point in putting the motor at the end of the foot, where it makes the leg more difficult to swing forwards – important in both walking and running.
"Some clever prosthetics copy the ankle and are very human-like, which is fine for prosthetics to replace the foot, but for above-knee amputee, a typical prosthetic leg which is very human-like is heavy and hard to move around. It's much better to have an ostrich foot at the end of a very lightweight leg.
An example of this kind of prosthetic already in use are the blades used by Paralympic athlete Oscar Pistorius – the 'Blade Runner'. These blades are light, springy and without a heel, similar to an ostrich's legs, which are optimised for running from predators rather than for walking.
Jen Middleton | Source: EurekAlert!
Further information: www.wellcome.ac.uk
More articles from Interdisciplinary Research:
Autonomous energy-scavenging micro devices will test water quality, monitor bridges, more
14.06.2013 | SPIE--International Society for Optics and Photonics
New tasks become as simple as waving a hand with brain-computer interfaces
12.06.2013 | University of Washington
- Biological fermentation process converts CO and CO2 into bioethanol and platform chemicals
- Process uses energy contained in steel plant off-gases
- Ten-year co-operation to develop and market integrated environmental solutions for the steel industry worldwide
Siemens Metals Technologies and LanzaTech have signed a ten-year co-operation agreement to develop and market integrated environmental solutions for the steel industry worldwide. The collaboration will utilize the ground-breaking fermentation technology developed by LanzaTech transforming carbon-rich off-gases generated by the steel industry into low carbon bioethanol and other platform chemicals. ...
Novel application of 3D printing could enable the development of miniaturized medical implants, compact electronics, tiny robots, and more
3D printing can now be used to print lithium-ion microbatteries the size of a grain of sand. The printed microbatteries could supply electricity to tiny devices in fields from medicine to communications, including many that have lingered on lab benches for lack of a battery small enough to fit the ...
... two engines aircraft project “Elektro E6”.
The countdown has been started for opening the gates again for the worldwide leading aviation and space event in Le Bourget, Paris from June 17th - 23rd, 2013.
EADCO & PC-Aero will present at the Paris Air Show in Hall H4 booth F-7 their new future aircraft and innovative project: ...
Siemens scientists have developed new kinds of ceramics in which they can embed transformers.
The new development allows power supply transformers to be reduced to one fifth of their current size so that the normally separate switched-mode power supply units of light-emitting diodes can be integrated into the module's heat sink.
The new technology was developed in cooperation with industrial and research partners who ...
Cheaper clean-energy technologies could be made possible thanks to a new discovery.
Led by Raymond Schaak, a professor of chemistry at Penn State University, research team members have found that an important chemical reaction that generates hydrogen from water is effectively triggered -- or catalyzed -- by a nanoparticle composed of nickel and phosphorus, two inexpensive elements that are abundant on Earth. ...
19.06.2013 | Life Sciences
19.06.2013 | Agricultural and Forestry Science
19.06.2013 | Studies and Analyses
14.06.2013 | Event News
13.06.2013 | Event News
10.06.2013 | Event News