June 21, 2013
The trend gained traction in popular media with the publication of the book Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen by Christopher McDougall, and boomed following the 2010 publication of “Foot strike patterns and collision forces in habitually barefoot versus shod runners” by Lieberman et al. in Nature, in which they gave credence to the idea that runners run more efficiently and are less prone to injury with a forefoot running pattern.
UMass Amherst postdoctoral research associate Allison Gruber, along with Kinesiology faculty members Joseph Hamill, Brian Umberger, and Barry Braun, set out to examine the claim that there are differences in running economy between these groups, and to see if running economy would change when they ran with the alternative footstrike pattern. Their findings were recently published online in the Journal of Applied Physiology.
The study examined 19 habitual rearfoot (RF) and 18 habitual forefoot (FF) runners performing RF and FF strike patterns on a treadmill at varying rates of speed (slow, medium, and fast). The lab group measured oxygen consumption and carbohydrate contribution to total energy expenditure rates for each footstrike pattern and speed condition.
The results ran counter to the common claim that the FF pattern is the more efficient running pattern. The RF pattern resulted in lower oxygen consumption and carbohydrate contributions compared to the FF pattern at the slow and medium speeds in the RF group but not in the FF group. At the fast speed, however, running economy improved when FF runners ran with RF patterns.
Also of significance, the study showed that RF running appeared to burn fewer carbohydrates than FF running, which is of particular significance to distance runners who need to conserve carbohydrates. FF running is likely to cause “hitting the wall” faster.
Popular media latched onto Gruber’s study, reporting her findings in such publications as Runner’s World and The New York Times and locally on WFCR(New England Public Radio). Online comments have ranged from support to outright hostility, as advocates of one style or another weighed in on her findings.
“I had no idea that the end result would generate any controversy when I first started the pilot data for my dissertation (in late 2008),” says Gruber. “At that time, there were only a few papers but a lot of speculation about the benefits of running on your toes. My motivation was to determine the empirical evidence to address the big picture claims regarding forefoot strike running.”
One common thread among online critics has been the claim that injury rate is not accounted for in Gruber’s study of running economy. Their belief that a RF running pattern leads to a higher rate of injury is not supported by the literature, notes Gruber.
“At my last count and to my knowledge, there are just as many papers that found no relationship between biomechanical characteristics and injury rates [as there are papers that found a relationship],” says Gruber. “Two different people can run with similar biomechanical characteristics and one of them will get injured but the other one will not. High running injury rates are determined from all causes…[and] include things that can be controlled (e.g., training errors).”
Adds Gruber, “Running economy and injury risk do not go hand-in-hand. Improving one does not improve the other and both parts cannot be answered in a single study. The study in the Journal of Applied Physiology took on the running economy side of things. The injury prevention side of things is in the works…”