title: Loading rate increases during barefoot running in habitually shod runners: Individual responses to an unfamiliar condition.
abstract: The purpose of this study was to examine the effect of barefoot running on initial loading rate (LR), lower extremity joint kinematics and kinetics, and neuromuscular control in habitually shod runners with an emphasis on the individual response to this unfamiliar condition. Kinematics and ground reaction force data were collected from 51 habitually shod runners during overground running in a barefoot and shod condition. Joint kinetics and stiffness were calculated with inverse dynamics. Inter-individual initial LR variability was explored by separating individuals by a barefoot/shod ratio to determine acute responders/non-responders. Mean initial LR was 54.1% greater in the barefoot when compared to the shod condition. Differences between acute responders/non-responders were found at peak and initial contact sagittal ankle angle and at initial ground contact. Correlations were found between barefoot sagittal ankle angle at initial ground contact and barefoot initial LR. A large variability in biomechanical responses to an acute exposure to barefoot running was found. A large intra-individual variability was found in initial LR but not ankle plantar-dorsiflexion between footwear conditions. A majority of habitually shod runners do not exhibit previously reported benefits in terms of reduced initial LRs when barefoot. Lastly, runners who increased LR when barefoot reduced LRs when wearing shoes to levels similar seen in habitually barefoot runners who do adopt a forefoot-landing pattern, despite increased dorsiflexion.
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, Western Cape, South Africa. Electronic address: nicholas.tam@uct.ac.za.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Tam
authors.affiliation: Dynamics of Human Motion Laboratory, School of Biomedical Engineering, Faculties of Engineering and Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Janie L
authors.initials: JL
authors.lastname: Astephen Wilson
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, Western Cape, South Africa.
authors.forename: Devon R
authors.initials: DR
authors.lastname: Coetzee
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, Western Cape, South Africa.
authors.forename: Leanri
authors.initials: L
authors.lastname: van Pletsen
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, Western Cape, South Africa; School of Medicine, University of the Free State, Bloemfontein, Free State, South Africa.
authors.forename: Ross
authors.initials: R
authors.lastname: Tucker
mesh_terms: D000842:Ankle; D001696:Biomechanical Phenomena; D005528:Foot; D006801:Humans; D012420:Running; D012775:Shoes
keywords: Biomechanics; Exercise; Footwear; Injury; Shoes