As kids, we discover that our two legs can manage many different gaits. After walking and running we figure out how to tiptoe, hop, and skip. (Personally, I decided at one point to become a better skipper than anyone I knew, practicing backward skipping and figure-eights in our driveway. I may have sensed that my competition in this pursuit was not very stiff.)
For basic getting around, we usually settle on walking and running. But why do we ignore so much of our bipedal repertoire in favor of locomotion that's more, well, pedestrian? Researchers in Belgium asked this question about one gait in particular: the gallop.
In case you missed this one as a kid, the human version of a gallop involves holding one leg always in front of the body and the other leg always behind. Bounding along, you create an uneven rhythm of footfalls: ba-DUM, ba-DUM, ba-DUM.
"Gallop is, though rarely used, a familiar gait for humans," the authors write in the Journal of Experimental Biology. People may start galloping spontaneously under certain (infrequent) circumstances, such as going quickly downhill.
For their study, lead author Pieter Fiers of the University of Antwerp and his colleagues had a dozen volunteers run and gallop down a hallway, then dissected their motion in great detail. Platforms that lined the hallway measured the force people produced in their steps. The subjects were covered in motion-capture markers, like Avatar actors. Finally, a separate group of subjects did their running and galloping on a treadmill while the researchers measured how much oxygen they used and carbon dioxide they gave off.
People preferred to gallop at pretty much the same speed they ran. But the length of a galloping stride was shorter than a running stride—so gallopers had to take more steps, and do more work, to travel at the same speed as runners.
Gallopers exerted that effort unevenly, with the front leg doing more work than the back leg. And the galloping stride, researchers saw, demanded more from the hips than running did. This tired people out quickly. Out of 12 treadmill gallopers in the study, 4 gave up before the end of their 4-minute session, complaining of fatigue and stress in their hips and thighs. (An intended 13th galloper couldn't figure out how to gallop on the treadmill belt in the first place.)
When researchers calculated their subjects' metabolic rates, they found that galloping was about 24% more costly than running at the same speed. In other words, galloping burns up more energy, takes more effort, and is less comfortable than running. It's no wonder we don't usually opt for it.
Still, the fact that we're not efficient at galloping means it would be a tougher workout than running. Maybe athletes should start mixing some alternative gaits into their usual exercise routines. Who knows—with practice, you might become the best galloper in the whole world.
Fiers P, De Clercq D, Segers V, & Aerts P (2012). Biomechanics of human bipedal gallop: asymmetry dictates leg functions. The Journal of experimental biology PMID: 23239890
Image: Devon D'Ewart (Flickr)