Horses are big, powerful animals, but they do have their limits when it comes to how much weight they can carry. Researchers have identified a suitable rider weight threshold of 20% a horse’s bodyweight, including the weight of the tack. Beyond this and a horse will be under strain, making injuries more likely and reducing the horse's ability to perform.

While most healthy horses will be able to carry a rider and saddle, when the load exceeds 20-25% of their bodyweight, a horse will start to show physical signs indicative of stress and soreness.

Researchers found that the horses in their study carrying 15-20% of their bodyweight managed it with ease and showed very little indication of stress. In contrast, those carrying 25% of their bodyweight seemed to struggle more, and those carrying 30% loads showed clear signs of strain.

These signs included faster, more laboured breathing, higher heart rates and muscle soreness following exercise. Horses with wider loins were less affected, but still struggled under 30% loads. It has been suggested that for optimal performance, horses should carry no more than 10-15% of their bodyweight.

Interestingly, while some people will say that weight is only part of the problem and that other factors affect a horse’s comfort while being ridden, this research concludes with the same guideline as the US Calvary Manuals of Horse Management published in 1920.

Therefore, the 20% rule has been an advisory, backed by a wealth of research, for nearly a hundred years. As the average weight of the population continues to increase, the capability of horses to saddle such weights has become a growing concern and something riding schools, shows, and other organisations have started taking notice of.

Of course, many horses will be able to carry heavier loads, and it will also depend on the fitness and muscle development of the horse, as well as the type, speed and duration of the work, and the terrain the horse is ridden on.

The experience, skill and fitness of the rider should not be overlooked as a huge contributing factor, as a lighter rider with poor balance and coordination will have more of a negative impact than a heavier rider with greater skill. Uneven weight distribution on the back and landing awkwardly in the saddle can lead to lameness and other problems, so it's important to focus on this as much as the weight of the rider.

Roly Owers, Chief Executive of World Horse Welfare, said "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."

[Note: calculating 20% of your horse's bodyweight should be based on the 'ideal weight' of your horse, rather than the current weight if a little on the heavy side.]

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Written by: Hannah