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A note on the linear and temporal stride kinematics of Olympic show jumping horses between two fences

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Abstract

The aims of this study were to describe the temporal and linear stride kinematics of horses within a two-stride combination of fences and to make comparisons between the first and second intermediate strides. Video recordings (60 Hz) were made of eight horses jumping two vertical fences that were 1.47 and 1.51 m high. The fences were separated by a distance of 10.96 m, which was sufficient for two non-jumping strides. The video images were digitised using a computerised gait analysis system and custom software. The following kinematic variables were measured: stride length (m), step lengths (m), stride duration (s), step durations (s) and velocity (m/s). The results showed that the two intermediate strides had similar velocities, but the second intermediate stride had significantly shorter stride length and stride duration. Compared with published descriptions of horses jumping a single fence of similar size, the first intermediate stride resembled the first departure stride and the second intermediate stride resembled the final approach stride. The stride lengths of the two intermediate strides showed low inter-horse variability, but the step lengths were much more variable indicating that different horses achieved similar stride lengths using different combinations of step lengths.

Introduction

Equine jumping kinematics are described with reference to the approach strides, the jump stride and the departure strides (Clayton, 1989, Leach, 1993). The jump stride is the stride in which the horse jumps the fence. It begins with ground contact of the trailing hind limb prior to the fence and finishes at contact of the trailing hind limb after the fence (Clayton, 1989). The approach strides precede the jump stride and the departure strides follow the jump stride. The approach and departure strides are numbered consecutively from the fence in either direction, with the strides closest to the fence being approach stride 1 and departure stride 1 (Clayton, 1989).

Previous studies of the linear and temporal kinematics of show jumping horses have focused on terminology (Clayton, 1989), the phases of the jump stride (Clayton, 1990, Leach, 1993), and the stride characteristics during the approach and departure over single fences (Clayton and Barlow, 1989, Clayton and Barlow, 1991, Deuel and Park, 1991, Clayton et al., 1995). During the approach strides, the kinematics are adjusted in preparation for take-off. The final approach stride (A1) has a shorter stride length, a shorter stride duration, and a slower velocity than preceding approach strides (Clayton and Barlow, 1989, Deuel and Park, 1991, Clayton et al., 1995). During the departure strides, the horse must re-establish balance and forward motion. Compared with A1, the first departure stride (D1) is characterised by having a longer stride length and longer stride duration, but similar velocity (Clayton and Barlow, 1991).

In show jumping competitions, combinations of fences are used as further tests of the horse’s athletic ability. Within these combinations, the distances between fences determine the number of strides taken by the horse. The departure strides from one fence in a combination are also the approach strides for the subsequent fence. These intermediate strides are numbered sequentially from landing over one fence to take-off over the next fence. Riders and trainers believe that the ability to adjust the intermediate strides has an important influence on a horse’s success in the sport of show jumping. We are not aware of any previous studies describing the kinematics of the intermediate strides within a combination of fences.

The objective of this study was to describe the linear and temporal kinematics within a two-stride combination and to make comparisons between the two intermediate strides. The hypothesis to be tested is that there are significant differences in stride kinematics between intermediate stride 1 (IM1) and intermediate stride 2 (IM2) in a two-stride combination.

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Materials and methods

Data were collected during the warm-up show jumping competition at the Real Polo Club, Barcelona, during the 1992 Olympic games. Eight horses were analysed jumping the second and third fences of a combination (fences 4b and c). Fence 4a was a spread fence (height 1.48 m; width 1.66 m) located 7.57 m from fence 4b, which allowed one non-jumping stride. Fence 4b was a vertical fence 1.47 m high and fence 4c was a vertical fence 1.51 m high. They were separated by a distance of 10.96 m, which was

Results

The Shipiro–Wilks test showed that all variables had a normal distribution so parametric statistical tests were used. IM2 had a significantly shorter stride length and stride duration than IM1, but the velocity did not differ between strides (Table 1). The difference in stride length between IM1 and IM2 was a result of significantly shorter step lengths from LdH to TrF (diagonal distance) and from TrF to LdF (fore step) in IM2 (Table 2). The shorter stride duration in IM2 compared with IM1 was

Discussion

When a horse jumps a single fence the approach and departure strides have clearly different functional responsibilities. During the approach, the stride is gathered in preparation for take off, whereas the landing strides are concerned with re-establishing the horse’s balance and forward motion. The intermediate strides within a combination must fulfil the roles of departure and approach strides simultaneously. The results of this study show that there are clear differences between IM1 and IM2,

Conclusions

The results of this study support the experimental hypothesis that there are significant differences in the linear and temporal kinematics of the intermediate strides IM1 and IM2 within a combination. Stride IM2 achieves the same velocity as stride IM1 using a shorter stride length and shorter stride duration. Comparisons with published studies of horses jumping single fences of similar size suggest that IM1 resembles the first departure stride and IM2 resembles the final approach stride. The

Acknowledgements

The authors thank Richard Curle and Connie Argue for assistance with data collection at the 1992 Olympic games. This study was supported by Sport Canada and the McPhail endowment.

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