A pilot study has highlighted the risks to horses when riders are too heavy, paving the way toward development of guidelines to help all riders assess if they are the right weight for their mount.
The results show that a high rider-to-horse bodyweight ratio can induce temporary lameness and discomfort in the horse.
In simple terms, if the rider is excessively heavy for the horse in question, it can have a negative impact on the performance of the horse.
Researchers says the findings should help in developing suitable guidelines for riders which should enhance equine welfare, rider comfort and enjoyment.
The findings of the research, led by Dr Sue Dyson, head of clinical orthopaedics at the Animal Health Trust’s Centre for Equine Studies in Newmarket, were presented at this week’s National Equine Forum in Britain.
The study assessed gait and behavioural responses in six horses ridden by four riders of similar ability but different sizes. The riders were all weighed in their riding kit and were subsequently categorised as being light, moderate, heavy and very heavy.
Their body mass index (BMI) was also calculated. The BMI calculation divides an adult’s weight by their height squared and the score is used to assess healthy weight.
Each rider rode each horse in its usual tack and performed a set pattern of exercises comprising mainly trot and canter.
Gait, horse behaviour, forces under the saddle, the response to palpation of the back, alterations in back dimensions in response to exercise, heart and respiratory rates, salivary cortisol levels and blink rate were assessed for each combination.
The riding tests for the heavy and very heavy riders were all abandoned, predominantly because of temporary horse lameness. This was likely to have been induced by bodyweight rather than BMI, given that the heavy and moderate riders had similar BMIs, both being classified as overweight, yet only one of the moderate rider’s tests had to be abandoned.
A catalogue of behaviours developed by Dyson specifically to assess behavioural markers which may reflect pain in ridden horses, was applied.
The scores which may reflect pain were significantly higher in the horses when ridden by the heavy and very heavy riders.
The study also raised the issue of rider height and saddle fit. The owner of one of the test horses had a similar bodyweight: horse bodyweight ratio to the heavy rider and was of similar weight, but significantly different in height (157 and 185.5 centimetres, respectively).
This large difference in height has major potential implications for saddle fit for the rider and consequently the rider’s position and weight distribution. The taller rider sat on the back of the cantle, overloading the back of the saddle and making it more difficult to ride in balance, with the heel being in front of a vertical line between the shoulder and “hip”.
“While all the horses finished the study moving as well as when they started, the results showed a substantial temporary effect of rider weight as a proportion of horse weight,” Dyson said.
“The results do not mean that heavy riders should not ride, but suggest that if they do they should ride a horse of appropriate size and fitness, with a saddle that is correctly fitted for both horse and rider.”
Dyson stressed that it was a pilot study. “Further work is required to determine if horse fitness, adaptation to heavier weights and more ideal saddle fit will increase the weight an individual horse can carry.
“This should help us further in our quest to develop guidelines for optimum rider: horse bodyweight ratios.”
As the average weight and height of humans continues to increase, there is growing debate about relative rider-horse sizes, with riding school horses epitomising the variety of rider weights to which a single horse may be exposed.
Many inter-related aspects are involved with the horse-and-rider combination, including the age of the horse, its fitness and muscle development, the length of its back and the presence or absence of lameness.
The rider’s skill, fitness, balance and coordination are important factors, as is the fit of the saddle to both the horse and rider. The type, speed and duration of work and the terrain over which the horse is ridden must also be considered.
To date, little research has been conducted on the effects of rider weight on equine welfare and performance, leading to World Horse Welfare, the Saddle Research Trust, the British Equestrian Federation and several other organisations helping to fund the pilot study last northern summer.
World Horse Welfare chief executive Roly Owers said the results were not surprising but were very significant in adding vital evidence to inform an appropriate rider: horse weight ratio.
“It is common sense that rider weight impacts equine welfare. However, many might not fully understand or recognise this. What is desperately needed is basic guidance to help riders identify a horse or pony that is right for them and this research is a vital step in that direction.”
The study was supported by World Horse Welfare, the Saddle Research Trust, Frank Dyson, British Equestrian Federation, British Horse Society, Pony Club, Polocross, The Showing Council, The Showing Register, The Society of Master Saddlers, Riding for the Disabled, British Eventing, British Dressage, the British Horse Foundation, the Worshipful Company of Saddlers and Endurance GB.