Abstract
Runners are often categorized as forefoot, midfoot or rearfoot strikers, but how much and why do individuals vary in foot strike patterns when running on level terrain? This study used general linear mixed-effects models to explore both intra- and inter-individual variations in foot strike pattern among 48 Kalenjin-speaking participants from Kenya who varied in age, sex, body mass, height, running history, and habitual use of footwear. High speed video was used to measure lower extremity kinematics at ground contact in the sagittal plane while participants ran down 13 meter-long tracks with three variables independently controlled: speed, track stiffness, and step frequency. 72% of the habitually barefoot and 32% of the habitually shod participants used multiple strike types, with significantly higher levels of foot strike variation among individuals who ran less frequently and who used lower step frequencies. There was no effect of sex, age, height or weight on foot strike angle, but individuals were more likely to midfoot or forefoot strike when they ran on a stiff surface, had a high preferred stride frequency, were habitually barefoot, and had more experience running. It is hypothesized that strike type variation during running, including a more frequent use of forefoot and midfoot strikes, used to be greater before the introduction of cushioned shoes and paved surfaces.
Citation: Lieberman DE, Castillo ER, Otarola-Castillo E, Sang MK, Sigei TK, Ojiambo R, et al. (2015) Variation in Foot Strike Patterns among Habitually Barefoot and Shod Runners in Kenya. PLoS ONE 10(7):
e0131354.
https://doi.org/10.1371/journal.pone.0131354
Editor: Ramesh Balasubramaniam, University of California, Merced, UNITED STATES
Received: January 22, 2015; Accepted: June 1, 2015; Published: July 8, 2015
Copyright: © 2015 Lieberman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Data Availability: All relevant data are within the paper and its Supporting Information files. The raw data used to make all the analyses with the participants IDs removed has been uploaded on figshare.com at: http://dx.doi.org/10.6084/m9.figshare.1375654. Due to ethical considerations high speed videos are available upon request by contacting Daniel E. Lieberman, Department of Human Evolutionary Biology, Harvard University, Cambridge MA 02138; email: danlieb@fas.harvard.edu.
Funding: This work was supported by the American School of Prehistoric Research, Harvard University (DEL). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Description
The study investigates foot strike patterns in barefoot and shod runners.