Almost a year ago I had a couple of posts (here and here) about a Harvard Professor who was doing research into barefoot running. The research continues, and Wired Magazine had a feature on his two latest studies which have been published just this month. Their piece is called More Evidence Supports Barefoot Running and points to Daniel Lieberman's latest work:
If you’re a runner, start striking with your forefoot. And wear those goofy minimalist shoes while you’re at it. Your body will thank you.The two studies are:
Those are the findings of a pair of studies by Daniel Lieberman, a professor of human evolutionary biology at Harvard University. He found runners who use a forefoot strike face a significantly lower risk of repetitive stress injuries, and barely there running shoes produce more efficient movement than conventional kicks.
Foot Strike and Injury Rates in Endurance Runners: a retrospective study.
PURPOSE:(interesting that cross country running seems risky whatever you do!)
This retrospective study tests if runners who habitually forefoot strike have different rates of injury than runners who habitually rearfoot strike.
We measured the strike characteristics of middle and long distance runners from a collegiate cross country team and quantified their history of injury, including the incidence and rate of specific injuries, the severity of each injury, and the rate of mild, moderate and severe injuries per mile run.
Of the 52 runners studied, 36 (59%) primarily used a rearfoot strike and 16 (31%) primarily used a forefoot strike. Approximately 74% of runners experienced a moderate or severe injury each year, but those who habitually rearfoot strike had approximately twice the rate of repetitive stress injuries than individuals who habitually forefoot strike. Traumatic injury rates were not significantly different between the two groups. A generalized linear model showed that strike type, sex, race distance, and average miles per week each correlate significantly (p<0.01) with repetitive injury rates.
Competitive cross country runners on a college team incur high injury rates, but runners who habitually rearfoot strike have significantly higher rates of repetitive stress injury than those who mostly forefoot strike. This study does not test the causal bases for this general difference. One hypothesis, which requires further research, is that the absence of a marked impact peak in the ground reaction force during a forefoot strike compared to a rearfoot strike may contribute to lower rates of injuries in habitual forefoot strikers.
Effects of Footwear and Strike Type on Running Economy.
This study tests if running economy differs in minimal shoes versus standard running shoes with cushioned, elevated heels and arch supports, and in forefoot versus rearfoot strike gaits.
We measured the cost of transport (mlO2/kg/m) in subjects who habitually run in minimal shoes or barefoot while they were running at 3.0 m/s on a treadmill during forefoot and rearfoot striking while wearing minimal and standard shoes, controlling for shoe mass and stride frequency. Force and kinematic data were collected when shod and barefoot to quantify differences in knee flexion, arch strain, plantarflexor force production, and Achilles tendon-triceps surae strain.
After controlling for stride frequency and shoe mass, runners were 2.41% more economical in the minimal shoe condition when forefoot striking and 3.32% more economical in the minimal shoe condition when rearfoot striking (p<0.05). In contrast, forefoot and rearfoot striking did not differ significantly in cost for either minimal or standard shoe running. Arch strain was not measured in shoes condition but was significantly greater during forefoot than rearfoot striking when barefoot. Plantarflexor force output was significantly higher in forefoot than rearfoot striking, and in barefoot than shod running. Achilles tendon-triceps surae strain and knee flexion were also lower in barefoot than standard shoe running.
Minimally shod runners are modestly but significantly more economical than traditionally shod runners regardless of strike type, after controlling for shoe mass and stride frequency. The likely cause of this difference is more elastic energy storage and release in the lower extremity during minimal shoe running.