How does jockey position impact a racehorse’s movement at the trot?
A recently published study found that when a jockey rode at a rising trot versus two-point seat, such as happens during pre-race warmups, there was a noted impact on both horse movement asymmetry and horse-jockey synchronization.
The study was led by Kate Horan, a postdoc at the Royal Veterinary College in the UK, and Thilo Pfau, a professor of veterinary medicine and kinesiology at the University of Calgary.
Pfau’s research group is focused on movement of quadrupedal animals – mainly horses, as well as dogs. One thing they’re looking at is stride parameters during racing, with the aim of improving existing models for predicting musculoskeletal injuries.
The latest study stemmed from a larger project which looked at how shoeing affected movement of horses, Pfau said, when Horan suggested they also look at how different surface conditions affect the interaction between the horse and jockey. That also led them to evaluating how the jockey’s position was impacting the horse.
Examining movement of horse and jockey
For this study, the researchers placed sensors on both the jockey and the horse, using inertial measurement units to calculate their acceleration and rotational movement – building a three-dimensional picture of how they were moving. On the horse, six sensors were placed at their poll, withers, left and right tuber coxae (the points of the hips), first lumbar vertebra, and sacrum. On the jockey, three sensors were placed at their pelvis, mid-back and upper back. The study used six retired Thoroughbred racehorses, who are still in regular work and used for jockey education at the British Racing School in Newmarket, UK; and one experienced jockey, who rode all six horses.
They looked at not only different surfaces, but also different riding styles, including a typical two-point seat, and a rising trot at both the left and right diagonal. They particularly looked at the relationship between the vertical (up-down) movements of both jockey and horse.
While they found that differences in riding surfaces had minimal effect, the jockey’s riding style could significantly affect movement – particularly weight-bearing capacities.
“For me, the most exciting findings that we have in this study relate more to the spatial movements, in particular, the asymmetries,” Pfau said. In a rising trot, as the jockey sits and rises, this affects how the horse moves, and weight bearing capacity of the front legs, he said.
It may be easier to detect movement abnormalities of a lameness when their horses are warming at lower speeds.
When jockeys were getting out of the saddle into the rising position, it affected how the horse pushed off with that diagonal, particularly from the front leg, with asymmetries noted in the withers and sacrum.
When jockeys were sitting down in the rising trot, it affected both the front and hind legs of that diagonal. “When you’re going into this seated diagonal, the horse needs to put more weight onto those two legs.”
“The biggest takeaway here, for me, is that this sort of rising trot that jockeys are doing affect both the weight bearing of the front limbs and also the push capacity of the horse for both the front and hind limbs,” Pfau said.
The study notes that this change in weight-bearing and push capacity might also be an effect of the horse lowering its head more to counteract the impact of the jockey, in turn helping to flex the back.
Uneven movement of the jockey’s hands could also have an impact – a previous study looking at dressage rider position found that at a rising trot, the horse’s head went higher, and noted that it “could be due to the rider interfering with the normal movement by raising the hand and thus encouraging the horse’s head in an upward direction through the bit as the rider rises.” Differences in riding styles, with jockeys keeping their hands closer to the horse’s neck and shorter stirrups that change their centre of mass, could also have an impact on how the jockey’s position impacts horse movement.
Along with this asymmetry, the researchers also noted increased time offsets between the movements of the horse and jockey – implying reduced synchronisation, compared to when the jockey was at two-point seat. Though movement wasn’t perfectly symmetrical at a two-point seat, either, which the jockey’s movement still possibly impacting the horse’s movement, it was closer.
Evaluating asymmetries and putting knowledge into practice
According to the study, some of their findings also implied that “underlying asymmetries are more apparent at lower speeds and is suggestive of reduced weight-bearing asymmetry with increasing speed.”
For riders and trainers who are trying to evaluate asymmetries, that could be particularly important to keep in mind, as it may be “easier to detect movement abnormalities of a lameness when their horses are warming up during ridden exercise at lower speeds,” the study notes. Evaluating asymmetries in their gait at this point could also allow for earlier intervention, and the opportunity to remove a horse from further training or competition before sustaining a more serious injury.
Pfau also notes that “we have previously established that horses that predominantly race in one direction seem to develop a bias towards one direction, and put more weight on what is typically the inside leg.” Bearing in mind the findings of the study, he said, “maybe there’s a little bit that the jockeys can do here… when they’re using the rising trot that would actually counterbalance that asymmetry that might be induced by the horses constantly racing in the same direction.”
By better understanding ranges of horse asymmetry, and the coordination between jockeys and horses, the study notes, it could allow race training programs to “offer feedback to jockeys on how they should adjust their body movements to influence and stabilise their horse’s movement.”
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