Effect of the Construction of Carbon Fiber Plate Insert to Midsole on Running Performance.

Fengqin Fu,Zhihao Xie,Gusztáv Fekete,Ievgen Levadnyi,Jiayu Wang,Yaodong Gu,Yuhui Cai

doi:10.3390/ma14185156

Fengqin Fu, Zhihao Xie + Show 5 more

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https://doi.org/10.3390/ma14185156

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Abstract

In this paper, to investigate the independent effect of the construction of the forefoot carbon-fiber plate inserted to the midsole on running biomechanics and finite element simulation, fifteen male marathon runners were arranged to run across a runway with embedded force plates at two specific running speeds (fast-speed: 4.81 ± 0.32 m/s, slow-speed: 3.97 ± 0.19 m/s) with two different experimental shoes (a segmented forefoot plate construction (SFC), and a full forefoot plate construction (FFC)), simulating the different pressure distributions, energy return, and stiffness during bending in the forefoot region between the SFC and FFC inserted to midsole. Kinetics and joint mechanics were analyzed. The results showed that the footwear with SFC significantly increased the peak metatarsophalangeal joint (MTPJ) plantarflexion velocity and positive work at the knee joint compared to the footwear with FFC. The results about finite element simulation showed a reduced maximum pressure on the midsole; meanwhile, not significantly affected was the longitudinal bending stiffness and energy return with the SFC compared to the FFC. The results can be used for the design of marathon running shoes, because changing the full carbon fiber plate to segment carbon fiber plate induced some biomechanical transformation but did not significantly affect the running performance, what is more, reducing the peak pressure of the carbon plate to the midsole by cutting the forefoot area of the carbon fiber plate could be beneficial from a long-distance running perspective for manufacturers.

Highlights

It was notable that track shoes such as the Nike Vaporfly 4% (VF) shoe combine both advances in midsole thickness and longitudinal bending stiffness (LBS) to reduce energy loss by about 4% for runners [1,2,3,4], which contributes to an improved running performance [4]
The finite element (FE) simulation showed that the maximum pressure on the forefoot of segmented forefoot plate construction (SFC) (0.307 MP) was lower than that on the forefoot plate construction (FFC) (0.435 MPa) (Figure 3), but the results from the forefoot flexion scores and bending simulation indicated that there were no effects between SFC and FFC in LBS and energy return (Table 1)
In contrast to our first hypothesis, differences in the construction of the carbon fiber plate did not induce differences in shoe LBS during bending (Tables 1 and 2). This is inconsistent with the previous result which has shown that cutting the carbon fiber plate would reduce the shoe LBS due to the mechanical behavior-changing of the shoe midsole [18]

Summary

Introduction

It was notable that track shoes such as the Nike Vaporfly 4% (VF) shoe combine both advances in midsole thickness and longitudinal bending stiffness (LBS) to reduce energy loss by about 4% for runners [1,2,3,4], which contributes to an improved running performance [4]. Runners wearing the VF shoe broke world records in the full-marathon, half-marathon, and 100 km distances, and so on [5]. It was not yet understood whether the midsole material [3,6], midsole construction [5], or shape of carbon-fiber plate [7,8] contribute more to these ‘racing running shoes’. The full-length embedded carbon fiber plate to midsole would increase the LBS of the shoe [9,10], reducing running economy by about 1% [6]. The energy loss might be caused by the MTPJ changes on account of an increased LBS [12,15,16,17], and increased peak plantarflexion moment [12,15]

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