The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism. (March 2018)

• Record Type: Journal Article
• Authors: Simpson, Jeffrey D.; DeBusk, Hunter; Hill, Christopher; Knight, Adam; Chander, Harish
• Is Part Of: Foot. Volume 34(2018)
• Page Start: 53
• Page End: 57
• Publication Date: 2018-03
• Subjects: Ankle stability -- Lateral ankle sprain mechanics -- Lower extremity injury -- Military boots; Foot -- Diseases -- Periodicals; Foot -- Surgery -- Periodicals; Foot Diseases -- Periodicals; Foot -- surgery -- Periodicals; Pied -- Maladies -- Périodiques; Pied -- Chirurgie -- Périodiques; Pied -- Lésions et blessures -- Périodiques; Foot -- Diseases; Foot -- Surgery; Periodicals; Electronic journals; Electronic journals; 617.585005
• DOI: 10.1016/j.foot.2017.11.010
• Languages: English
• ISSNs: 0958-2592

Abstract

Highlights: Large vertical GRF can generate supination moments that damage the lateral ankle ligament complex. A potential link between footwear midsole stiffness and GRF attenuation capabilities has been suggested. The minimalist boot augmented the vertical GRF, but reduced medially directed GRFs during the inversion perturbation. GRFs were unaffected following the completion of the simulated workload in either footwear condition. A combination of various footwear properties may reduce GRFs, especially when the foot/ankle is forced into inversion. 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 16 kg rucksack. The ankle inversion perturbation protocol consisted of stepping down from a 27 cm 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.