Influence of sports background on the bouncing mechanism of running

ABSTRACT

During running, the mechanical energy of the centre of mass of the body (COM) oscillates throughout the step like a spring-mass system, where part of its mechanical energy is stored during negative phases to be released during the following positive phases. This storage-release of energy improves muscle-tendon efficiency, which is related to lower-limb stiffness. This study explores the effect of sports background on the bouncing mechanism, by examining differences in stiffness and step spatiotemporal parameters between swimmers and football athletes. All athletes performed three consecutive running bouts on an instrumented treadmill at three different speeds (3.9, 4.4 and 5.0 m·s⁻¹). The ground reaction forces were recorded. Vertical stiffness and step spatiotemporal parameters were analysed and compared using a two-way ANOVA. Vertical stiffness of football players was on average 21.0 ± 1.1% higher than swimmers. The modification of step spatiotemporal parameters also suggests a more elastic rebound by increasing the stretch of tendons relative to muscle within muscle–tendon units in football players. Compared to swimmers, they (1) decrease the effective contact time by 9.7 ± 2.4% and (2) decrease the duration of the push by 15.0 ± 6.4%, suggesting that background training adaptations influence spring-mass behaviour during running.

KEYWORDS:

• Spring-mass system
• muscle-tendon efficiency
• biomechanics
• training experience
• running economy

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Correction

List of Abbreviations

af, vf	=	fore-aft acceleration and velocity of the COM
av, vv, Sv	=	vertical acceleration, velocity and displacement of the COM
BW	=	body weight
COM	=	centre of mass
Ek, Ep, ECOM	=	kinetic, potential and total mechanical energy of the COM
Ff, Fv	=	fore-aft and vertical component of the GRF
GRF	=	ground reaction force
kvert	=	vertical stiffness
MTU	=	muscle-tendon unit
Fmax	=	maximum of Fv
tce,tae	=	effective contact and aerial time
tpush, tbrake	=	duration of the COM positive and negative work
∆y	=	range of Sv during tce
MTU	=	efficiency the ability to transform chemical energy into muscle work

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Correction Statement

This article was originally published with errors. This version has been corrected. Please see Correction notice (https://doi.org/10.1080/14763141.2021.1923225).