|Two very different footstrikes captured on high-speed video|
This post is a bit behind the times, but I thought I'd get it out there regardless. This post is a short analysis which takes a look at the latest research from Daniel Lieberman's lab at Harvard University. Lieberman is, of course, famous for his paper on foot strike in habitually shod and unshod runners which made the cover of Nature magazine and sparked a fierce controversy in the world of biomechanics. This latest paper, which is available as an "epub" online (it has been accepted and reviewed, but has yet to be printed), turns its attention to foot strike styles and injury rates on the Harvard track and cross country team. Its title is "Foot Strike and Injury Rates in Endurance Runners: a retrospective study," and I'll reproduce the abstract below for your convenience.
Purpose: This retrospective study tests if runners who habitually forefoot strike have different rates of injury than runners who habitually rearfoot strike.Methods: 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.Results: 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.Conclusions: 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.