Join Date: May 2012
Location: Utrecht, the Netherlands
Hey, I'm not really here to comment on your 'system', just what I think is important.. Young horses are often full of energy and they will jump, turn and buck at their heart's whim. I don't think jumping at any height is necessarily bad for a young horse, if you consider that they do need muscle strength to jump high heights, which they will lack as young horses. What I think makes the difference is the amount of impact on the front legs.. A jump that is merely a hop, no biggie. A jump where they are completely off the ground and land with their full weight on just two legs, especially if more vertical, will be more strain on their legs. Therefore, not only the jump, but also the type will matter.. Oxers should be easier on young horses (and any horses learning to jump). And the next thing to consider is the breed of the horse and their own height. I think to determine when is a safe age to jump whatever you want, providing the horse has the strength thanks to good training, is when the growth plates of the bones in the leg close. Once this happens, the bones should be at their full strength. This differs for each bone in the body and also differs in different breeds.
And then there's the thing to consider about whether you're talking about loose jumping or ridden jumping.. A horse jumping loose should be fine with what he has the strength to do. A horse with a saddle and rider will not only have strain on the front legs, but also a hit in the back and on the back of the shoulders every jump he takes.. A good rider will diminish this, but the saddle will always lean on the shoulders at the landing and always push into the back at the take-off. Ask yourself whether you want your young developing horse to be subjected to this at a young age, when he barely even has the muscle strength to carry you and himself without hurting his body? The growth plates in the vertical spines on the vertebrae are the last to close in any breed, and will be the place that suffers most on horses worked too much too young, in any discipline.
And one more thing to consider if of course how often you jump them and how long at a time. Every day is a bad idea, with ANY horse, and especially a young horse, and obviously jumping for an hour straight also isn't smart.
So my advice is.. Don't look at the height per se. Look at your horse, his physical and mental strength, the theory you have of the development of their bones, their talent for jumping and the way they go over the fence, and the time you take training them for it. Then decide for yourself how much would be okay for your horse to jump.
Listen to your horse and he might just return the favour!