Foot Structure and Muscle Reaction Time to a Simulated Ankle Sprain

Abstract

Context: Foot structure has been shown to effect aspects of neuromuscular control including postural stability and proprioception, however to our knowledge, no previous study has measured muscle reaction time to a simulated ankle sprain mechanism on participants with different foot structures. This is despite an association between pronated and supinated foot structures and the incidence of lateral ankle sprains. Objective: To determine whether pronated and supinated foot structures contribute to neuromuscular deficits as measured by muscle reaction time to a simulated ankle sprain mechanism.Design: Cross-Sectional Study Setting: University Biomechanics Laboratory. Patients or Other Participants: Thirty volunteers were categorised into three group’s dependant on navicular drop height measures. Ten participants had neutral feet (navicular drop height 5-9mm), ten participants had pronated feet (navicular drop height ≥10mm), and ten participants had supinated feet (navicular drop height ≤4mm). Intervention(s): Three perturbations on a standing tilt platform simulating the mechanics of an inversion and plantar flexion ankle sprain. Main Outcome Measure(s): Muscle reaction time (ms) of the peroneus longus, tibialis anterior, and gluteus medius to the tilt platform perturbation. Results: Those with pronated and supinated foot structures had significantly slower peroneus longus reaction times than those with neutral feet (P = .01 and P = .04 respectively). No significant differences were found for the tibialis anterior or gluteus medius. Conclusions: Peroneus longus reaction time is influenced by foot structure. Further research is required to establish the consequences of slower peroneal reaction times in pronated and supinated foot structures. In future, researchers investigating lower limb muscle reaction time should control for foot structure as it may influence results.