I've come across so many threads that touch on, in some way, the weight a horse should carry. So I'm going to put out some information that may be useful (or not) to anyone who really wants to know.
You may often here people talk about a horse carrying 20%, 25%, 30% of it's weight. There are different reasons for these % being used.
20% is probably from the old US Cav (when they rode horses). They went by a 20% rule, although it was probably more like 18%-23%.
People have competed in endurance races with their horses carrying 30% of it's body weight and so they will argue that 30% is correct. (25% is just in-between so I won't address if
Actually, both can be argued as correct depending on what you are requiring from you horse.
Can a horse carry 30% of it's body weight? Yes, but it's not obtimal. There are physical and chemical effects.
Several years ago a study was done, but I don't keep copies of everything I read
. However, in this case I was able to locate the study and result thanks to the to wonders of the internet.
Ohio State University Agricultural Technical Institute did a study.
To read about it check out: http://www.ker.com/library/EquineRev...pdate/SU41.pdf
It was an interesting study and certainly worth reading for those who really want to know the effects of what happens with their horse when they ride.
Now, don't read this and think that a persons weight should keep them from ever being able to ride. While it's true that heavy people shouldn't ride lighter horses, I can assure you that there are horses out there that could carry virtually anyone who has the ability to pull themself into the saddle on it's back. Most of the draft horse of today originated as war horses for armor clad knights. A 2,000 lb Shire can have a 350 lb rider on a 35 lb saddle (girth, etc...) and still have 15 lbs to spare before even reaching the 20%.
And before you think that sounds stupid looking (for those who have never seen it). The sight (and sound) of seeing or riding a large Percheron (I never saw a Shire do it, so I'm sticking with first hand knowledge) galloping across a field is like nothing else with the power that it conveys and that you feel when you're the rider. No light riding horse can match that, althought the light horse will be faster and more agile. Both are fun to ride.