The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism

Jeffrey D Simpson; Hunter DeBusk; Christopher Hill; Adam Knight; Harish Chander

doi:10.1016/j.foot.2017.11.010

The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism

Foot (Edinb). 2018 Mar:34:53-57. doi: 10.1016/j.foot.2017.11.010. Epub 2017 Nov 22.

Authors

Jeffrey D Simpson¹, Hunter DeBusk², Christopher Hill³, Adam Knight⁴, Harish Chander⁴

Affiliations

¹ Neuromechanics Laboratory, Department of Kinesiology, Mississippi State University, P.O. Box 6186, Mississippi State, MS 39762, United States. Electronic address: jds1313@msstate.edu.
² Human Systems Engineering Laboratory, Department of Industrial and Systems Engineering, Mississippi State University, P.O. Box 9542, Mississippi State, MS 39762, United States.
³ Applied Biomechanics Laboratory, Department of Health, Exercise Science, and Recreation Management, University of Mississippi, 642 All-American Drive, University, MS, 38677, United States.
⁴ Neuromechanics Laboratory, Department of Kinesiology, Mississippi State University, P.O. Box 6186, Mississippi State, MS 39762, United States.

PMID: 29288908
DOI: 10.1016/j.foot.2017.11.010

Abstract

Background: Ankle sprains are a common orthopedic injury in military populations, which may be attributed to occupational demands and footwear. Minimalist military boots have become popular, but their influence on ground reaction force (GRF) attenuation capabilities during an ankle inversion perturbation are unknown. Therefore, the purpose of this study was to examine potential differences in GRFs during an ankle inversion perturbation in a standard issue (STN) and minimalist military boot (MIN) before and after a simulated military workload.

Methods: Twenty-one healthy adult males completed an ankle inversion perturbation protocol in each footwear condition before and after an incremental treadmill exercise protocol to volitional exhaustion while wearing a 16kg rucksack. The ankle inversion perturbation protocol consisted of stepping down from a 27cm box onto a force platform with a fulcrum (FUL), which created 25° of inversion upon landing, or flat (FLT) outer sole attached to the plantar aspect of the participants' footwear in random order. Peak vertical, anterior/posterior, and medial/lateral components of the GRF during FUL and FLT conditions were assessed, normalized to multiples of body weight in each footwear. Dependent variables were then analyzed using separate 2 (footwear)×2 (time) repeated measures ANOVA (p<0.05).

Results: The MIN footwear demonstrated significantly greater vertical GRF and significantly less medial GRF during the FUL condition.

Conclusions: These results indicate that various mechanical and design characteristics of military footwear may influence GRF attenuation capabilities and ankle joint loading when the foot/ankle complex is forced into inversion.

Keywords: Ankle stability; Lateral ankle sprain mechanics; Lower extremity injury; Military boots.

MeSH terms

Adult
Analysis of Variance
Ankle Injuries / prevention & control*
Biomechanical Phenomena
Computer Simulation
Healthy Volunteers
Humans
Male
Military Personnel
Sampling Studies
Shoes*
Sprains and Strains / physiopathology*
Stress, Mechanical
Workload*