Ankle Joint Dynamic Stiffness in Long-Distance Runners: Effect of Foot Strike and Shoes Features

Alessandro Garofolini,Simon Taylor,Carlo Albino Frigo,Patrick Mclaughlin,Karen J Mickle

doi:10.3390/app9194100

Alessandro Garofolini, Simon Taylor + Show 3 more

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https://doi.org/10.3390/app9194100

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Journal: Applied sciences	Publication Date: Oct 1, 2019
Citations: 12	License type: CC BY 4.0

Affiliation: Victoria University, Politecnico di Milano

Abstract

Foot strike mode and footwear features are known to affect ankle joint kinematics and loading patterns, but how those factors are related to the ankle dynamic properties is less clear. In our study, two distinct samples of experienced long-distance runners: habitual rearfoot strikers (n = 10) and habitual forefoot strikers (n = 10), were analysed while running at constant speed on an instrumented treadmill in three footwear conditions. The joint dynamic stiffness was analysed for three subphases of the moment–angle plot: early rising, late rising and descending. Habitual rearfoot strikers displayed a statistically (p < 0.05) higher ankle dynamic stiffness in all combinations of shoes and subphases, except in early stance in supportive shoes. In minimal-supportive shoes, both groups had the lowest dynamic stiffness values for early and late rising (initial contact through mid-stance), whilst the highest stiffness values were at late rising in minimal shoes for both rearfoot and forefoot strikers (0.21 ± 0.04, 0.24 ± 0.06 (Nm/kg/°∙100), respectively). In conclusion, habitual forefoot strikers may have access to a wider physiological range of the muscle torque and joint angle. This increased potential may allow forefoot strikers to adapt to different footwear by regulating ankle dynamic stiffness depending upon the motor task.

Highlights

There is an ongoing debate on whether the foot strike pattern of long-distance runners plays a role in defining performance and injury risk in this population [1,2,3]
Posthoc analysis revealed that Kankle was 12% higher in med-minimalist indexes (MI) compared with high-MI shoes (p = 0.007; g = 0.706)
Significant differences were found among all subphases: early rising phase (ERP)–late rising phase (LRP) (0.176 ± 0.01; 0.215 ± 0.01 Nm/kg/◦ ·100) p = 0.001; g = 3.9; ERP–during the unloading phase (DP) (0.176 ± 0.01; 0.091 ± 0.01 Nm/kg/◦ ·100) p < 0.001; g = 9.5; LRP–DP (0.215 ± 0.01; 0.091 ± 0.01 Nm/kg/◦ ·100) p = 0.001; g = 12.4

Summary

Introduction

There is an ongoing debate on whether the foot strike pattern of long-distance runners plays a role in defining performance and injury risk in this population [1,2,3]. Experienced long-distance runners are able to change their foot strike pattern during a competition [4] or if they are asked to [5]. Their ability to adopt a different foot strike pattern has been often interpreted as a sign of adaptability. The ability to adopt different execution patterns refers to the ability to change joint kinematics (and kinetics) without necessarily meeting the task-goal. It is unknown if runners who adopt different execution patterns (i.e., rearfoot strikers versus forefoot strikers) have developed a different level of adaptability

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