Extra weight added to riders carrying out a dressage test did not appear to adversely affect the horses, based on a range of tested parameters.
While the initial findings may be encouraging for heavier riders, the researchers stress that the riders, even with the weight added to their vest, still fell within horse-weight ratios of between 15 and 23%.
Previous studies have found that physiological responses and gait symmetry parameters are negatively affected when horses carry heavy riders, for example when the rider-horse weight ratio increases from 20% to 35%, as found in a 2017 study involving Icelandic horses.
New research should help shed more light on how increased rider weight may affect a horse during exercise under saddle, looking at lower rider-horse weight ratios which are more common for warmblood horses.
Janne Winther Christensen, from Aarhus University in Denmark, and her research team looked at the impacts of an acute increase in rider weight on horse behaviour, physiological responses, and gait symmetry.
The initial results were presented at the recent International Society for Equitation Science conference in Canada.
“The effect of rider weight on horse welfare is much debated and is likely affected by a number of factors including horse type, work intensity, horse training level, and rider skills,” Christensen said.
The study included 20 rider-horse combinations. The researchers asked riders to complete a standard dressage test in a balanced cross-over study.
The riders rode with no additional weight, or with an extra 15% or 25% of their body weight added to a vest.
The horses’ heart rate, salivary cortisol levels (an indicator of stress), gait symmetry and behaviours, such as head tossing, tail swishing and mouth opening, were measured during the test.
The study team found that the increased rider weights did not significantly affect any of the assessed parameters.
It should be noted, however, that the maximum rider-horse weight ratios fell between 15 and 23%, and the exercise intensity was relatively low.
“Thus, within this weight ratio range and during light to moderate exercise, acute increases in rider weight did not induce changes in the parameters analysed so far.”
The study also compared rider symmetry measured on the ground with their symmetry on horseback when riding with and without additional weight.
On-ground symmetry was measured as weight on the left and right leg respectively, while standing on two identical bathroom scales. In addition, their mobility and balance when sitting on a gymnastic ball was scored based on their ability to perform standardized exercises.
Poor mobility on the gymnastic ball was associated with weight asymmetry — that is, the poorer the mobility the larger the weight asymmetry.
Rider crookedness in the saddle was measured using a saddle pressure mat. Almost all riders — 19 of the 20 — had more weight on the right side of the saddle. Crookedness correlated significantly with weight asymmetry on the ground, but only in the 0% weight treatment, and not when the riders rode with an additional 15% and 25% of weight, suggesting that artificial addition of weight might make some riders less crooked as they become more aware of their relative asymmetry.
Thus, a simple weight symmetry test with two ordinary bathroom scale weights reflects rider crookedness in the saddle and can help riders become aware of their imbalance. Lack of mobility of the pelvis on a gymnastic ball also reflects this imbalance.
Kate Fenner, a member of the International Society for Equitation Science council, was pleased that Christensen attended this year’s conference to share the results.
“We know that there is a great deal of interest in the potential effects of rider weight on equine welfare,” Fenner said.
“We’re happy that we are able to provide a meeting area for researchers to share new findings like these each year, and hopefully spark more collaborations and research in these areas.”