Riders representing 20 percent of a horse’s body weight induce greater body temperatures in key areas and higher heart rates than a lighter counterpart, researchers have found.
These differences were observed in a study at a level of exercise that might be comparable to a routine warm-up before a core training session.
Izabela Wilk and her colleagues at the University of Life Sciences in Lublin, Poland, are the latest to weigh in with research on the sensitive issue of rider weight.
“There are currently no strict weight limits for riders,” Wilk and her fellow researchers wrote.
“However, we believe that horse riders should pay more attention to this problem.
“As shown in this study, a horse’s load above 20% of his body weight, even with little effort, affects changes in surface temperature and the activity of the autonomic nervous system.”
The team set out in their study to analyze the differences in body temperature and selected heart rate parameters in horses in response to physical exercise.
They used 12 leisure horses, Warmblood geldings aged from 10 to 15 years old, each of whom weighed about 470kg.
Two equally qualified professional female dressage riders were used, whose body weights were about 20% and 10% of the average body weight of the animals.
Each rider rode each of the 12 horses in properly fitting saddles for 13 minutes at the walk and 20 minutes at the trot. Each rode six of the horses on one day, and then swapped mounts for the next day.
An infrared thermography camera was used to take images of the horses before they did the work, and immediately after the exercise session, as soon as they were unsaddled. This was repeated 10 minutes after unsaddling, during the recovery phase.
Temperatures of selected body parts were noted on the surface of the head, neck, front, middle, and back (croup) parts of the trunk, forelimb, and hind limb.
Immediately after the infrared thermography images were taken, the rectal temperature of each horse was measured.
Heart rate parameters were measured at rest for 10 minutes directly before, during, and 10 minutes after the end of each training session.
The researchers found that a rider body-weight load of about 20% of the horse’s weight led to a substantial increase in the surface temperatures of the neck, front, middle, and back parts of the trunk, when compared to the results from the rider at 10% of the body weight.
In fact, the lighter rider significantly influenced only the temperature of the back.
The head and limb average temperatures were not significantly affected by the load on the exercised horse. The expected rise in rectal temperature seen after exercise also appeared unaffected by rider weight.
Heart-rate values were significantly higher after work with the heavier rider, in both the post-exercise and recovery phases.
The authors said studies on the optimal rider’s body weight load on a horse should be explored in a multifaceted manner.
“For now, it is worth emphasizing that a load of 20% significantly influences the horse’s body, which is demonstrated by the increased temperature of the neck and back, accompanied with the predominance of sympathetic nervous system activity, as compared to less loaded horses.”
The study team comprised Wilk, Elżbieta Wnuk-Pawlak, Iwona Janczarek, Beata Kaczmarek, Marta Dybczyńska and Monika Przetacznik.
Wilk, I.; Wnuk-Pawlak, E.; Janczarek, I.; Kaczmarek, B.; Dybczyńska, M.; Przetacznik, M. Distribution of Superficial Body Temperature in Horses Ridden by Two Riders with Varied Body Weights. Animals 2020, 10, 340.