Why do children tire faster than adults walking in a mall? A new study says they tire because they need more steps to cover the same distance than adults. The results appear in the Journal of Experimental.

The study analyzed and measured the stride and metabolism of a set of walkers of different ages and sizes. It included a three-foot tall kindergartner to a six-foot adult. The results could throw new light on how metabolic rates influence the physiological status of soldiers on the battlefront.

The researchers found that people walk the same way irrespective of their height and spend the same energy per step. It is just that adults need to spend less energy because they need fewer strides to cover the same distance as against children. If the five-year-old kid is scaled up to a six and half feet tall adult, the child will walk and spend the same energy as an adult, according to the study led by Peter Weyand from Southern Methodist University.

“This goes back to Max Kleiber's work on resting metabolic rates for different sized animals. He found that the bigger you are the slower each gram of tissue uses energy,” said Weyand. ‘It's interesting to know how and why metabolism is regulated that way.”

“The equation allows you to take your height and weight and plug it in and say if I walk this far and I'm this tall and I weigh this much here's how many calories I burn,” said Weyand. “This has clinical applications, weight balance applications and the military is interested too because metabolic rates influence the physiological status of soldiers in the field,” he added.