‘Ankle is more efficient than other muscles’

April 24th, 2008 - 3:30 pm ICT by admin  

Washington, April 24 (IANS) The spring in your step is very real and helps you move efficiently, thanks to the ankle, a muscle that does thrice the work for the same amount of energy compared to other muscles. Scientists made the discovery while trying out a bionic ankle to measure the efficiency of individual muscles, in this case the ankle, said Daniel Ferris, of University of Michigan and the project’s lead researcher.

The results are likely to prompt manufacturers to rethink prosthesis design so the ankle part can do more of the work, said Ferris.

It also sheds light on why rehabilitation and mobility is so exhausting among people with unhealthy ankles or neurological problems.

Greg Sawicki of Brown University, working with Ferris built the bionic ankle equipped with fake muscles that mimic real muscle activity in the ankle, Ferris said.

Healthy subjects wore two of the boots, which were attached to the nervous system by electrodes.

Sawicki measured the amount of oxygen consumed when walking with or without the boot and compared the two. Muscles use oxygen when they burn fuel, which means the more oxygen used the more energy expended, Ferris said.

“The ankle is incredibly efficient at working so the amount of energy you burn with the ankle is much lower than what would be predicted with just isolated muscle studies,” Ferris said.

Researchers suspect this is largely because the Achilles tendon is so long and compliant, and is able to store and return energy during the stride cycle.

Amputees and people with neurological disorders don’t have the “bounce” of the stored energy in the ankle, Ferris said.

“For amputees, we need to come up with a better way for them to have a powered push off at the ankle,” Ferris said.

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