One of the more common arguments for barefoot running (or at least transitioning to minimalist shoes or just a forefoot/midfoot strike) is that it is easier to more lightly contact the ground and eliminate the magnitude of impacts associated with a heel strike. Now we have this study that looked at the magnitude of reduction in the ground reaction forces following a transition to barefoot running:
Reduction in ground reaction force variables with instructed barefoot running
Cynthia D. Samaan, Michael J. Rainbow, Irene S. Davis
Journal of Sport and Health Science; in press
Barefoot (BF) running has recently increased in popularity with claims that it is more natural and may result in fewer injuries due to a reduction in impact loading. However, novice BF runners do not necessarily immediately switch to a forefoot strike pattern. This may increase mechanical parameters such as loading rate, which has been associated with certain running-related injuries, specifically, tibial stress fractures, patellofemoral pain, and plantar fasciitis. The purpose of this study was to examine changes in loading parameters between typical shod running and instructed BF running with real-time force feedback.
Forty-nine patients seeking treatment for a lower extremity injury ran on a force-sensing treadmill in their typical shod condition and then BF at the same speed. While BF they received verbal instruction and real-time feedback of vertical ground reaction forces.
While 92% of subjects (n = 45) demonstrated a rearfoot strike pattern when shod, only 2% (n = 1) did during the instructed BF run. Additionally, while BF 47% (n = 23) eliminated the vertical impact transient in all eight steps analyzed. All loading variables of interest were significantly reduced from the shod to instructed BF condition. These included maximum instantaneous and average vertical loading rates of the ground reaction force (p < 0.0001), stiffness during initial loading (p < 0.0001), and peak medial (p = 0.001) and lateral ground reaction forces (p < 0.0001) and impulses in the vertical (p < 0.0001), medial (p = 0.047), and lateral (p < 0.0001) directions.
As impact loading has been asociated with certain running-related injuries, instruction and feedback on the proper forefoot strike pattern may help reduce the injury risk associated with transitioning to BF running.
I have only two things to say about the implications of study¹:
1. It based on the assumption that reducing the ground reaction forces is a good thing and a desirable goal. As we know, the evidence supporting that is far from compelling (see: Just How Significant are Heel Impacts at Causing Injury When Running?).
2. To achieve that reduction in impact forces, you have to increase the load in some other tissue(s) and that carries an injury risk with it. The authors did not look at this, so did not report it (see: Its six of one and half a dozen of the other: Rearfoot vs Forefoot striking when running).
As always, I go where the evidence takes me until convinced otherwise and this study shows that instruction in the barefoot running technique can be used to reduce the impact forces associated with running …. if that is what you want to do.
1. I have no comments on the methodology and analysis of the results as they all appear fine to me and I can see no issues.
Samaan, C., Rainbow, M., & Davis, I. (2014). Reduction in ground reaction force variables with instructed barefoot running Journal of Sport and Health Science DOI: 10.1016/j.jshs.2014.03.006