For those who have ever wondered if elephants can run, the answer is yes and no, according to a new study by researchers at four institutions, including the University of Colorado at Boulder.
Even at fast speeds, the "footfall pattern" remains the same as that in walking, and never do all four feet leave the ground at the same time -- a hallmark of running. But researchers are finding that an elephant's center of mass appears to bounce at high speeds. If that turns out to be true, an elephant's gait meets the biomechanical definition of running, said lead study author John Hutchinson of Stanford University.
A paper on the subject by Hutchinson, Dan Famini of the University of California, Richard Lair of the Thai Elephant Conservation Center in Thailand and Rodger Kram of the University of Colorado at Boulder will be published in the April 3 issue of Nature.
"The biomechanical definition of running indicates they are running," said Kram, an associate professor in CU-Boulder's kinesiology and applied psychology department. "Although all four feet never leave the ground at the same time, they 'bounce' up and down using the springy tendons in their legs."
The classic definition of running requires all four feet to be off the ground, Kram said. "An elephant at a fast speed always has at least one foot on the ground, and any kid on a playground will tell you that is not really running."
But in the footfall pattern of a gallop, the two hind limbs touch the ground one after the other, followed by a pause, after which the two forelimbs touch the ground one at a time. If an animal's feet are on the ground less than half of the time, Hutchinson said, it meets the biomechanical definition of running.
The research team calls this gait ``Groucho running`` after the silly, crouched walk of Groucho Marx. The members say the elephants seem to flex their limbs substantially in order to move their bodies more smoothly.
In 1997, Hutchinson, Kram and Famini all were at the University of California, Berkeley. Kram had noted that elephants preferred to walk at a slow but efficient speed that gave them what he called the "best gas mileage."Ìý
Hutchinson solved a longstanding mystery about elephant speeds by clocking the animals at more than 15 miles per hour in Thailand. "When I saw the speed-trap times and videos I was convinced," said CU-Boulder's Kram. "I ran the mile in 4:30 when I was in high school and I am still a competitive Master's runner. I can just barely sprint as fast as the fastest elephants we measured."
The average walking speed was 4.5 mph. But 32 of the elephants moved faster than previously documented -- up to 15 mph. Three were especially fleet of foot, exceeding 15 mph-- 50 percent faster than anyone had ever reliably recorded, Hutchinson said.
For their experiments, Hutchinson palpated the animals' limbs to find their joints, and then marked the joints with large dots of water-soluble, nontoxic paint. They videotaped 188 trials of 42 Asian elephants walking and running through a 100-foot course and measured their speed with photo sensors and video analysis.
Kram is planning to build a large force platform in the CU physics machine shop this summer. A force platform is a chassis-like frame embedded with strain gauges and placed under a platform. It will measure the forces exerted by the elephants as they walk and run over the device. He is looking for several CU undergraduate engineering students to help him build them, and hopes to ship them to Thailand and travel there later this year.
"Understanding the gait of an elephant can give us insight into physical stresses on overweight people," said Kram. "We may be the last generation of researchers to be able to study the locomotion of wild or active Asian elephants. Not only are they endangered, but more and more of the active ones that formerly hauled logs for the timber industry are unemployed due to a Thai ban on logging and as the habitat is destroyed."
Videos by Hutchinson of an Asian elephant walking and running are available at and .