Dressage riders put three times more tension on the reins than the horses themselves adopted when voluntarily allowed to set the pressure of side reins.
Lara Piccolo and Kathrin Kienapfel, writing in the journal Animals, point out that too much rein tension while riding may compromise horse welfare. But who generates the tension on the reins — the horse or the rider?
The pair, from Ruhr-University Bochum in Germany, described a pilot study in which they set out to evaluate the maximum rein tension that horses voluntarily adopt when wearing side reins set up so the horses adopted a good dressage position for their head and neck.
“We assumed that horses exercised in dressage frame with side reins without a rider will self-maintain a relatively comfortable rein tension,” they said.
Rein tension was measured by sensors on 13 horses, all of whom had completed basic dressage training, at the walk, trot, and canter in both directions in a round pen.
They then compared those results with the rein tensions used by riders in an open riding arena to keep the same horses with their head and neck in a dressage posture.
Without a rider, all horses maintained a rein tension force of about 1kg in all gaits.
For the same horses with a rider, rein tension force was significantly higher, at about 3kg on each side to maintain the dressage posture.
All phases of the study were videoed. Analysis of that footage revealed that conflict behaviour was higher with a rider than without.
Discussing their findings, the researchers said their results suggest it is possible to maintain the correct dressage position, with the nasal line on or slightly in front of the vertical, with relatively low rein tension.
“Since rein tension may be an aversive stimulus that can cause discomfort or pain, it is important to keep the strength of this stimulus as low as possible.
“It might therefore be assumed as ideal that, while riding, the horse’s self-selected rein tension when equipped with side reins should not be exceeded.”
They said the number of conflict behaviours per minute when ridden was about five times greater than without a rider.
“Higher numbers of conflict behaviours can indicate discomfort and/or stress, so being ridden could be perceived as stressful by the horses in this study.
“Since the head-neck position remained the same for both states, with the noseline at or slightly in front of the vertical, and only the rider was added, it is reasonable to assume that factors related to the rider are the key difference.
“It is reasonable to assume that rein tension greater than that which was adopted without a rider may be potentially painful.
“Of course, there are other aspects of carrying and interacting with a rider that could contribute to discomfort and/or stress.
“Nonetheless, an improvement of the level of rein tension while riding could lead to less discomfort and therefore fewer expressions of discomfort.”
The pair acknowledged that being a pilot study, there were limitations, including the small number of horses.
They said the study will be expanded with higher numbers and refinements in the study design to provide broader insights.
“A further goal is to make the next step into building a large database on finding the acceptable rein tension for most horses, which does not adversely affect their welfare.”
In conclusion, they said the findings indicate that higher rein tension may be primarily generated by the rider.
“The results suggest the potential to determine the amount of rein force exhibited by the horse and the rider, which provides interesting insights into the horse-rider interaction and may be a useful tool for the individual training of the rider.
“Understanding and lowering the peak forces acting on the mouth of the horse could enhance equine welfare in daily riding practice.”
Voluntary Rein Tension in Horses When Moving Unridden in a Dressage Frame Compared with Ridden Tests of the Same Horses — A Pilot Study
Lara Piccolo and Kathrin Kienapfel
Animals 2019, 9(6), 321; https://doi.org/10.3390/ani9060321