The kinematics and kinetics of riding a racehorse: A quantitative comparison of a training simulator and real horses

A.M Walker,C Applegate,T Pfau,E.L Sparkes,A.M Wilson,T.H Witte

doi:10.1016/j.jbiomech.2016.08.031

Abstract

Movement of a racehorse simulator differs to that of a real horse, but the effects of these differences on jockey technique have not been evaluated. We quantified and compared the kinematics and kinetics of jockeys during gallop riding on a simulator and real horses. Inertial measurement units were attached mid-shaft to the long bones of six jockeys and the sacrum of the horse or simulator. Instrumented stirrups were used to measure force. Data were collected during galloping on a synthetic gallop or while riding a racehorse simulator. Jockey kinematics varied more on a real horse compared to the simulator. Greater than double the peak stirrup force was recorded during gallop on real horses compared to the simulator. On the simulator stirrup forces were symmetrical, whereas on a real horse peak forces were higher on the opposite side to the lead limb. Asymmetric forces and lateral movement of the horse and jockey occurs away from the side of the lead leg, likely a result of horse trunk roll. Jockeys maintained a more upright trunk position on a real horse compared to simulator, with no change in pitch. The feet move in phase with the horse and simulator exhibiting similar magnitude displacements in all directions. In contrast the pelvis was in phase with the horse and simulator in the dorso-ventral and medio-lateral axes while a phase shift of 180° was seen in the cranio-caudal direction indicating an inverted pendulum action of the jockey.

Highlights

The modern ‘martini glass’ jockey position was introduced in the 19th century and has been credited with a 5-7% reduction in race times (Pfau et al, 2009)
The combined cranio-caudal and dorso-ventral displacement trajectory of the real horse when being viewed from a left lateral angle was clockwise in direction while that of the simulator was in the opposite anticlockwise direction
A racehorse simulator exhibits smaller and more consistent dorso-ventral and medio-lateral but larger, still consistent, cranio-caudal displacements when compared to those recorded in real horses

Summary

Introduction

The modern ‘martini glass’ jockey position was introduced in the 19th century and has been credited with a 5-7% reduction in race times (Pfau et al, 2009) In this position, 90% of the jockeys’ mass is distributed over the withers (Fruehwirth et al, 2004), it has been proposed that jockeys are able to mitigate any deleterious effects by isolating their centre of mass (COM) movement from that of the horse (Pfau et al, 2009). Optimal stability in riding is traditionally ascribed to perfectly synchronous movement of horse and rider This suggests that the traditional sitting trot and canter are the most stable scenarios (Wolframm et al, 2013; Viry et al, 2013) and the modern jockey position with its isolated centre of mass (COM)(Pfau et al, 2009) the least stable. In some cases racehorse simulators are used during assessment of jockey competency prior to licensing

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