Washington: Researchers at North Carolina State University have for the first time compared the role of hips, knees and ankles for human walking and running motions.
They found that hips generate more of the power when people walk, but the ankles generate more of the power when humans run.
Knees provide approximately one-fifth or less of walking or running power, according to the study.
NC State biomedical engineers Dominic Farris and Gregory Sawicki said the finding could help inform the best ways of building assistive or prosthetic devices for humans, or constructing next-generation robotics.
The study showed that hips generate 44 percent of the power when people walk at a rate of 2 meters per second, with ankles contributing 39 percent of the power.
When people start running at this 2-meter-per-second rate, the ankles really kick in, providing 47 percent of the power compared to 32 percent for the hips.
Ankles continue to provide the most power of the three lower limb joints as running speeds increase, although the hips begin closing the distance at faster speeds.
"There seems to be a tradeoff in power generation from hips to ankles as you make the transition from walking to running," said Sawicki.
The study has been published in the journal Interface, a Royal Society scientific journal.