Study: Running Form Of The Tarahumara Indians
Harvard professor Daniel Lieberman turns from the Kenyans to the fabled ultrarunners of Copper Canyon.
By Amby Burfoot (Google+)Published May 12, 2014
Harvard evolutionary biologist and running-form expert Daniel Lieberman doesn’t mess around when it comes to studying the most fascinating running cultures. Several years ago he published a widely-heralded paper about the forefoot-strike employed by many Kenyan runners. Now he has reported from Mexico’s vast Copper Canyon where the fabled Tarahumara Indians live and run.
Copper Canyon and the Tarahumara formed the framework of Chris McDougall’s best-selling Born To Run, the book that launched barefoot running and minimalist running. Copper Canyon is larger and deeper than the Grand Canyon, and the huarache-shod Tarahumara have practiced long-distance-running contests for eons. Huaraches are rawhide- or car-tire-soled sandals. The Tarahumara have raced well on occasion in U.S. ultra races, and more than hold their own when U.S. runners travel to Copper Canyon for races. This despite the fact that they don’t “train” in any conventional fashion—an important point that Lieberman notes several times.
In his new paper [see below for free, full-text link], Lieberman compares the running style of huarache-wearing Tarahumara men and women with the style of slightly younger Tarahumara who have grown up mostly in western-style shoes. Many of the shy, wary Tarahumara refused to participate, not wishing to be videotaped. In the end, Lieberman was able to film 12 runners who were minimally shod (MS, grew up wearing huaraches most of the time) and eight who were conventionally shod (CS, grew up mostly in western shoes).
As usual, Lieberman was interested in footstrike (forefoot/midfoot v. rearfoot) and other stride variables such as stride length, hip/knee/ankle movements, and arch structure. The Tarahumara in the study ran at a range of easy paces, with many clustering around 7:30 per mile. The two groups did not differ in height, leg length, or body mass.
The CS runners were nearly eight years younger than the MS runners. More importantly, 75 percent of the CS runners landed on their heels, roughly the same percentage found in lab and road-race studies of western runners. Only 30 percent of the MS runners landed on their heels, a significant difference.
The MS runners were also significantly less likely to “overstride” than the CS runners. In other words, they were much less likely to reach their front foot beyond the knee at touchdown. Many running form experts believe this is a central tenet of good running form. There was no significant difference between groups for stride frequency. The MS runners hit the road with significantly more-flexed knees and hips, and significantly more plantarflexion at the ankles (toes pointed downward v. upward). These differences all disappeared at mid-stride.
Lieberman appears to be growing ever more interested in arch structure. In the new study, he found no significant difference in arch height between groups, but “arch stiffness” was almost twice as great in the MS group, and two of the CS runners actually had flat feet.
This finding, Lieberman writes, “suggests that the Tarahumara who wear huaraches had stronger intrinsic muscles that lead to a stiffer longitudinal arch.” In theory, this could lead to fewer injuries and more energy-return, although Lieberman himself makes no such claims.
That’s because he has grown weary of the way some runners interpret his studies, jumping to simple and unjustified conclusions. His new paper could not be more cautionary in tone. It includes many sentences such as the following. “There is much more to running form than strike type.” And, “Many limitations caution against over interpreting the results of this study.”
And this classic: “Finally, it is worth considering the relevance of these results for the majority of runners who grow up wearing shoes, rarely if ever run ultramarathons, and are habituated to conventional running shoes. Evidence that traditional Tarahumara who wear huaraches mostly avoid rearfoot landings on flat surfaces at moderate speeds is hardly justification for someone to switch to minimal shoes and stop heel striking.”
It's statements like these that lend credence to Lieberman's running research. He's first and foremost a scientist and evolutionary biologist. He knows how we got here, and knows there is infinite variation within our shared heritage. We’re the same, but different. Evolution hasn’t stopped; it’s continuous, with all the good and bad that implies.
The paper, “Strike type variation among Tarahumara Indians in minimal sandals versus contentional running shoes” is published in the open-access Journal of Sport and Health Science. Free full text.
http://www.runnersworld.com/minimali...humara-indians
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