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Birds on treadmills

Guinea fowl are domesticated birds that are good for studying the science of walking and running. [Image courtesy of Richard L. Marsh]
Click here for a high resolution photograph.

The roadrunner cartoon (Beep, Beep!) never seems to get tired, but real animals do get tired when they run. A new study investigates what movements in walking and running use up energy. This is a long-standing mystery of exercise science.

After studying helmeted guinea fowl -- pheasant-sized birds -- running on treadmills, the authors report that leg swinging (when the foot is in the air) consumes one quarter of the total energy burned in leg and hip muscles.

These results do not fully agree with past research projects that predicted that legs use almost all the energy when the foot is on the ground.

To estimate the amount of energy the active leg and hip muscles consumed during leg swinging, Richard Marsh from Northeastern University in Boston, MA and his colleagues tracked the amount of blood going to particular muscles during guinea fowl walks and runs. The harder a muscle is working, the more oxygen it uses.

With more research, scientists hope to understand the exact job all the working muscles perform when animals, including humans, run.

The study appears in the 02 January, 2004 issue of the journal Science.


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