Wearable Technology May Assist in Retraining Foot Strike Patterns in Previously Injured Military Service Members: A Prospective Case Series

Donald L Goss,Daniel J Watson,Gregory M Freisinger,Eliza B Szymanek,Amy N Weart,Erin M Miller

doi:10.3389/fspor.2021.630937

Abstract

A rearfoot strike (RFS) pattern with increased average vertical loading rates (AVLR) while running has been associated with injury. This study evaluated the ability of an instrumented sock, which provides real-time foot strike and cadence audio biofeedback, to transition previously injured military service members from a RFS to a non-rearfoot strike (NRFS) running pattern. Nineteen RFS runners (10 males, 9 females) were instructed to wear the instrumented socks to facilitate a change in foot strike while completing an independent walk-to-run progression and lower extremity exercise program. Kinetic data were collected during treadmill running while foot strike was determined using video analysis at initial (T1), post-intervention (T2), and follow-up (T3) data collections. Nearly all runners (18/19) transitioned to a NRFS pattern following intervention (8 ± 2.4 weeks after the initial visit). Most participants (16/18) maintained the transition at follow-up (5 ± 0.8 weeks after the post-intervention visit). AVLR of the involved and uninvolved limb decreased 29% from initial [54.7 ± 13.2 bodyweights per sec (BW/s) and 55.1 ± 12.7 BW/s] to post-intervention (38.7 ± 10.1 BW/s and 38.9 ± 10.0 BW/s), respectively. This effect persisted 5-weeks later at follow-up, representing an overall 30% reduction on the involved limb and 24% reduction on the uninvolved limb. Cadence increased from the initial to the post-intervention time-point (p = 0.045); however, this effect did not persist at follow-up (p = 0.08). With technology provided feedback from instrumented socks, approximately 90% of participants transitioned to a NRFS pattern, decreased AVLR, reduced stance time and maintained these running adaptations 5-weeks later.

Highlights

Running is a popular form of exercise among all military service branches, and it is associated with a high rate of injuries (van Gent et al, 2007; Hauret et al, 2015; Molloy, 2016)
Foot strike pattern (FSP) have been suggested to affect important loading biomechanical variables related to running injury risk to include average vertical loading rate (AVLR), the rate at which force is applied to the body during loading response
It is well documented that AVLRs are greater in individuals who run with a RFS pattern versus a non-rearfoot strike pattern (NRFS) (Lieberman et al, 2010; Zadpoor and Nikooyan, 2011; Goss and Gross, 2013; Almeida et al, 2015; Goss et al, 2015; Miller et al, 2020; Xu et al, 2020)

Summary

Introduction

Running is a popular form of exercise among all military service branches, and it is associated with a high rate of injuries (van Gent et al, 2007; Hauret et al, 2015; Molloy, 2016). 80% of shod runners, those who run with a shoe on, use a rearfoot strike (RFS) pattern (Hasegawa et al, 2007; Lieberman et al, 2010; Almeida et al, 2015). It is well documented that AVLRs are greater in individuals who run with a RFS pattern versus a non-rearfoot strike pattern (NRFS) (Lieberman et al, 2010; Zadpoor and Nikooyan, 2011; Goss and Gross, 2013; Almeida et al, 2015; Goss et al, 2015; Miller et al, 2020; Xu et al, 2020). It is plausible that altering running biomechanics to reduce AVLR, and thereby improving shock attenuation, may be beneficial in the treatment and prevention of injuries (van der Worp et al, 2016)

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