'Whip from the hip': thigh angular motion, ground contact mechanics, and running speed.

David J. Stearne,Christopher R. Meng,Kenneth P. Clark

doi:10.1242/bio.053546

David J. Stearne, Christopher R. Meng

Open Access

https://doi.org/10.1242/bio.053546

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Journal: Biology open	Publication Date: Jan 1, 2020
Citations: 22	License type: CC BY 4.0

Affiliation: West Chester University, University of Notre Dame

Abstract

ABSTRACTDuring high-speed running, lower limb vertical velocity at touchdown has been cited as a critical factor needed to generate large vertical forces. Additionally, greater leg angular velocity has also been correlated with increased running speeds. However, the association between these factors has not been comprehensively investigated across faster running speeds. Therefore, this investigation aimed to evaluate the relationship between running speed, thigh angular motion and vertical force determinants. It was hypothesized that thigh angular velocity would demonstrate a positive linear relationship with both running speed and lower limb vertical velocity at touchdown. A total of 40 subjects (20 males, 20 females) from various athletic backgrounds volunteered and completed 40 m running trials across a range of sub-maximal and maximal running speeds during one test session. Linear and angular kinematic data were collected from 31–39 m. The results supported the hypotheses, as across all subjects and trials (range of speeds: 3.1–10.0 m s−1), measures of thigh angular velocity demonstrated a strong positive linear correlation to speed (all R2>0.70, P<0.0001) and lower limb vertical velocity at touchdown (all R2=0.75, P<0.001). These findings suggest thigh angular velocity is strongly related to running speed and lower limb impact kinematics associated with vertical force application.

Highlights

Whether at sub-maximal or maximal intensity, maintaining a constant forward running speed presents several mechanical challenges
We present a framework of thigh angular motion during the gait cycle
Representative data for thigh angular position versus time is presented in Fig. 1, with a male recreationally trained athlete at sub-maximal and maximal speeds displayed in Fig. 1A and C, and a male sprinter at sub-maximal and maximal speeds displayed in Fig. 1B and D

Summary

Introduction

Whether at sub-maximal or maximal intensity, maintaining a constant forward running speed presents several mechanical challenges. Among these requirements, steady-speed running necessitates that the net three-dimensional acceleration of the center of mass (COM) over an entire stride cycle is zero. A wealth of experimental research has investigated human locomotor performance (Blickhan, 1989; Farley et al, 1993; McMahon and Cheng, 1990; Nagahara et al, 2014; Rabita et al, 2015; Seyfarth et al, 2003; Weyand et al, 2000), a complete description of the mechanics that runners select to satisfy the demands of high-speed running has not yet been completely established.

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