Contribution of Plantar Fascia and Intrinsic Foot Muscles in a Single-Leg Drop Landing and Repetitive Rebound Jumps: An Ultrasound-Based Study.

Makoto Komiya,Rami Mizuta,Masanori Morikawa,Yukio Urabe,Arisu Hirota,Yuichi Nishikawa,Toshiki Kobayashi,Noriaki Maeda,Kazuki Kaneda

doi:10.3390/ijerph18094511

Abstract

The plantar fascia and intrinsic foot muscles (IFM) modulate foot stiffness. However, it is unclear whether the corresponding ultrasonography findings reflect it. This study aimed to examine the effect of the plantar fascia and IFM morphologies on force attenuation during landing and reactivity when jumping in healthy adults (n = 21; age, 21–27 years). Thickness, cross-sectional area (CSA), and hardness of the plantar fascia, abductor hallucis (AbH), and flexor hallucis brevis (FHB) muscles were measured using ultrasonography. Single-leg drop landing and repetitive rebound jumping tests assessed the ground reaction force (GRF) and reactive jump index (RJI), respectively. The CSA of FHB was negatively correlated with maximum vertical GRF (r = −0.472, p = 0.031) in the single-leg drop landing test. The CSA of AbH was negatively correlated with contact time (r = −0.478, p = 0.028), and the plantar fascia thickness was positively correlated with jump height (r = 0.615, p = 0.003) and RJI (r = 0.645, p = 0.002) in the repetitive bound jump test. In multivariate regression analysis, only the plantar fascia thickness was associated with RJI (β = 0.152, 95% confidence interval: 7.219–38.743, p = 0.007). The CSA of FHB may contribute to force attenuation during landing. The thickness of the plantar fascia and CSA of AbH may facilitate jumping high with minimal contact time.

Highlights

The human foot comprises 28 bones that form three flexible arch structures
This study aimed to examine the relationship between the plantar fascia and intrinsic foot muscles (IFM) morphologies, and force attenuation during landing and reactivity when jumping among healthy adults
This study has demonstrated an association between the thicker plantar fascia and greater reactive jump index (RJI)

Summary

Introduction

The human foot comprises 28 bones that form three flexible arch structures. The stiffness of these foot arches is passively and actively modulated by the plantar fascia and the intrinsic foot muscles (IFM), respectively [1]. The plantar fascia and IFM decrease or increase foot stiffness to attenuate external forces or transmit the internal force of the extrinsic foot muscle to the foot, respectively [2]. IFM can protect the plantar fascia from excessive strain or modulate foot stiffness in response to increased postural and loading demands [4]. Force attenuation while landing is necessary to prevent injury [5]; lower-limb stiffness at the time of jumping contributes to the ability to jump higher with minimal ground contact time [6].

Objectives

Methods

Conclusion