Relationship between Connective Tissue Morphology and Lower-Limb Stiffness in Endurance Runners. A Prospective Study

Felipe García-Pinillos,Ferrán Abat,Alberto Rubio-Peirotén,Luis E Roche-Seruendo,Antonio Cartón-Llorente,Diego Jaén-Carrillo

doi:10.3390/ijerph18168453

Abstract

Background: The lower limb behaves like a spring compressing and decompressing during running, where lower-limb stiffness is one of the most influential factors. This prospective observational study is aimed at examining the relationship between the connective tissue morphology and lower-limb stiffness and investigating whether the barefoot/shod condition influences on such relationship. Methods: 14 male amateur runners (10-km time trial <50′) were included. Data were recorded over one session, where participants ran 2 trials (i.e., barefoot and shod conditions) of 3 minutes at 12 km/h, where running spatiotemporal parameters and vertical (Kvert) and leg stiffness (Kleg) were obtained. Prior to testing trials, thickness and cross-sectional area (CSA) were recorded for Achilles (AT) and patellar tendons (PT) and plantar fascia (PF) with ultrasound. Results: Under barefoot condition, a positive correlation was found between Kleg and AT-thickness and CSA and PF-thickness; and between Kvert and AT-thickness and PF thickness. Under shod condition, a positive correlation was found between Kleg and PT-CSA and PT-thickness, and between Kvert and PT-CSA and PT-thickness. Conclusions: The results reveal a specificity of the relationship between the lower-limb stiffness and the morphology of the connective tissue. Greater tendon shows higher lower-limb stiffness when that tendon is specially demanded by the function.

Highlights

During running, the lower limb behaves like a spring, which compresses and decompresses over the different gait phases [1,2]
An excellent intra-rater reliability was reported for the measures related to the morphology of the connective tissue (ICC > 0.989, 95% confidence interval (CI): 0.913–0.996)
In the light of these results, the specificity of the task determines the relation between the morphologic characteristics of the connective tissue and the lower-limb stiffness during running

Summary

Introduction

The lower limb behaves like a spring, which compresses and decompresses over the different gait phases [1,2]. The release of that energy occurs during the concentric phase of stance facilitating the subsequent movements [3,4] The behavior of such leg-spring function can be influenced by several factors such as the foot strike pattern (FSP) [5], footwear condition [6], sex difference [7], velocity [8], fatigue [9] or surface type [10]. It has been shown that two of the most important elements of the spring-like behavior of the leg while running are the stretch-shortening cycle (SSC) [11] and the lower-limb stiffness [12]. The relation between tendon and lower-limb stiffness has

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