Varying walking speed may burn more calories

A new research shows that changing walking speed can make a substantial difference to the number of calories burned.

Changing the pace of walking can burn up to 20% more calories compared with maintaining a constant speed, say the researchers.

Writing in the journal Biology Letters, two engineering researchers at Ohio State University (OSU) in Columbus describe how, compared with maintaining a steady pace, walking at a varying pace can burn up to 20% more calories.

They believe their study is among the first to measure the effect of changing walking pace on calories burned, or "metabolic cost." 

"Measuring the metabolic cost of changing speeds is very important because people don't live their lives on treadmills and do not walk at constant speeds. We found that changing speeds can increase the cost of walking substantially."

The study is significant because it suggests traditional methods of measuring calories burned while walking in daily life or playing sports may be underestimating them.

In fact,  just changing speed burns energy, but that is not usually taken into account in calorie-burning estimates.

The researchers stated that up to 8% of the calories we burn every day are spent just in starting and stopping walking.

Walking at any speed costs some energy, but when you're changing the speed, you're pressing the gas pedal, so to speak.

The researchers explain that changing pace, which effects a change in the kinetic energy of a person, requires the legs to work slightly harder, and that requires more energy.

Participants changed walking pace on steady treadmills

For their study, the researchers invited volunteers to walk on treadmills and change their walking pace without changing the speed of the treadmill. Thus, when walking more quickly, the participant moved to the front of the treadmill, and when walking more slowly, they moved to the back.

The following video shows a participant changing walking speed without changing the treadmill speed:

The researchers measured the cost of changing walking speeds as the participants changed their walking pace. They found that:

"The metabolic rate for oscillating-speed walking was significantly higher than that for constant-speed walking." The increase was between 6-20% for speed fluctuations ranging from +0.13-0.27 to -0.13-0.27 meters per second.

The researchers explain that usually in such experiments, the researchers change the treadmill speed. But this means the treadmill itself is doing some of the work, not the person walking.

"Just do weird things. Walk with a backpack, walk with weights on your legs. Walk for a while, then stop and repeat that. Walk in a curve as opposed to a straight line."

References:

1.  The metabolic cost of changing walking speeds is significant, implies lower optimal speeds for shorter distances, and increases daily energy estimates, Nidhi Seethapathi and Manoj Srinivasan, Biology Letters, doi:10.1098/rsbl.2015.0486, published online 16 September 2015, abstract.
2.  Ohio State University news release, accessed 9 October 2015.