How much energy do we expend while walking?

WASHINGTON - Why do children tire more quickly than adults when out on a walk? Walkers use the same amount of energy per stride, but it becomes less economical for people of shorter height as they have to take more steps, researchers say.

Peter Weyand from Southern Methodist University, US, teamed up with Maurice Puyau and Nancy Butte, from Children’s Nutrition Research Centre at Baylor College of Medicine, and Bethany Smith, to find out if kids and small adults walk differently from taller people or do they tire faster for some other reason?

They decided to measure the metabolic rates of children and adults, ranging from five to 32 years old, weighing between 15.9 kg and 88.7 kg and ranging in height from 1.07 metres to 1.83 metres, to figure out why larger people expend less energy than smaller people

Weyand and colleagues discovered that walkers of all heights use the same amount of energy per stride, making short people less economical because they take more steps, reports The Journal of Experimental Biology.

First Weyand and colleagues filmed male and female volunteers as they walked on a treadmill at various speeds, according to a Southern Methodist University statement.

They also simultaneously measured the walkers’ oxygen consumption and carbon dioxide production rates to obtain their total metabolic rate.

Next the team calculated the amount of energy that each person used for walking.

Finally, the team compared the way each person walked, measuring the walkers’ stride lengths, stride durations and the proportion of each stride they spent in contact with the ground (duty factor) to find out if large and small people walk differently.

The team found that all of them moved in exactly the same way regardless of their height.