More Realistic Biomechanics In New Computer Locomotion Model

(PhysOrg.com) -- No one has ever won a race on peg legs if they were running against others with flexible legs. But, until now, mathematical locomotion models predicted that stiff legs were the most efficient.

Observation alone tells us those locomotion models cannot be right, particularly because humans, and many animals known for their running skills, have legs and bodies that bounce - an elastic energy.

An integrative physiologist, Monica Daley, at the Royal Veterinary College in Hatfield, U.K., noticed the agility of the African guinea fowl and how it was able to maneuver difficult terrains, like sudden drops and other obstacles with such grace. Certainly the guinea fowl, with its ‘crouched, compliant motion,’ has a more efficient style of movement than stiff-legged animals would have.

Daley and her colleague, James Usherwood, designed a new kind of locomotion model, one that took the complexities of movement, like the shape of an animal’s body, its 'seesawing guts,' the spring in its steps, and the nature of the terrain into consideration.

Daley and Usherwood found through their model that even in animals whose bodies were not efficient for running, compliant legs offset the bounce of their bodies and helped them conserve energy. Additionally, those legs protected them from falling or injury when hitting rough terrain.

Next, Daley will be testing the new model, published in Biology Letters, on a wide spectrum of running birds in the wild.