The guidelines in Dr Randle’s research state that the “optimum” weight for a rider is less than 10 per cent the weight of their mount (US guidelines say 20 per cent). With the average stable horse weighing 500kg to 600kg (79 to 94 stone) this means a rider should weigh 60kg (9.4 stone).  But since horses have been lugging heavy loads for centuries – armour; carriages; caravans – you’d have thought they’d be used to it by now.  Not so, says Julian Marczak, chairman of the Association of British Riding Schools. “A horse’s back is precious,” he warns. “The combination of a heavy rider and an incorrect saddle fitting is enough to put a horse out of work, long-term. And, behaviourally, you can turn a very sweet-natured horse into a cranky horse overnight.”  There are now 4.3 million amateur riders in Britain. The number of horses in private households has increased from 900,000 to 1.2 million in a decade, with £732 million spent on riding schools every year. As the number of “happy hackers” increases, so, too, do the risks they bring to their mounts: limited experience, nervous handling and – often – excess weight.  Overweight amateurs particularly upset readers of Horse & Hound. “Don’t fat riders make your blood boil?” asks one on the magazine’s forum. News editor Flora Watkins says the furore was ignited last year when a US company started producing “extra large”, 18-inch saddles for obese riders. “A horse will find it hard to leave the ground, let alone leave the fence up, if its rider is too heavy,” she warns.  “Larger riders should look at heavier breeds – like a half-shire or a weight-carrying cob,” she continues. “The Household Cavalry horses, which are half-Irish draught and half-thoroughbred, must be able to carry a 13 to 14 stone man, plus four stone of armour, when they are on parade.”  Whatever the breed, a rider’s weight is a sensitive subject. “It’s one of the most embarrassing things to bring up,” says Marczak. “But what’s more important – saving someone’s blushes, or saving the horse’s back?” Food for thought for rotund riders.
It's not just humans who get bad backs. Now horses are feeling the strain as   overweight riders put the pressure on