An excellent question posed by one of my clients recently, which I thought was worthy of a blog post.
For her school work, she wanted to know why we have trot diagonals and why we lay so much importance on them.
Firstly, it’s my biggest bug bear I think, when riders are ignorant of their trot diagonals – the ability to rise with unconscious autonomy and their age or ability to understand are the only exceptions. I just feel that by taking note of the little details of riding, such as trot diagonals, leads to a better learning focus and eye for details which can make all the difference in a dressage test. For example, if you overlook the incorrect diagonal, are you going to ride accurate school movements and strive to improve them?
The legs move in diagonal pairs in trot, so when you are on the correct diagonal the outside foreleg and inside hindleg are stepping forwards as you rise out of the saddle. Before I continue, I should clarify that this is the UK trot diagonals, and shouldn’t be confused with other countries (e.g. France, Russia) standards, which is reverse to ours … I won’t complicate matters!
For novice riders, who are yet to develop their feel I teach them to look at the movement of the forelegs. I use the outside limb because I think it’s easier to see the leg stepping forwards, but I know some instructors get riders to look for the inside foreleg moving forwards when the rider is sitting. I’ve not yet discovered the benefit of teaching this method but if someone would care to enlighten me that would be lovely. Once riders have developed their feel I introduce the idea of feeling what the legs are doing, in particular the inside hindleg so they no longer have to look down to check their trot diagonal.
Back to the original question.
As I said earlier, when on the correct diagonal the rider is rising when the inside hindleg and outside foreleg are stepping forwards. This means their weight is off the horse’s back with enables the horse to bring their inside hindleg further under their body, so increasing impulsion and encouraging the horse to engage their abdominals and lift their back, which all helps the horse work efficiently and correctly. The inside hind leg also bears more weight on a turn, so enabling it to step further under the horse’s body and relieving it of the rider’s weight until the leg hits the ground will allow the inside hip to drop slightly and for weight to be transferred into that limb.
Riding on the correct diagonal also helps the horse balance, and I find it helps them find the correct bend. In part, I think the upward swing of the rise by the rider helps the rider turn their body in the direction of the bend or turn. But whether that’s because the rider is using the propulsion from the inside hindleg, I’m not sure. Either way, there is a noticeable difference between a horse’s bend and balance when ridden on a circle on the correct and incorrect diagonal. I’ve heard that research has been done into the biomechanics of the effect of trot diagonals, which found that the stride length of a horse is longer when ridden on the correct diagonal, which would fit in with the improved balance theory.
It’s important to use the trot diagonals evenly – which is easier in the arena when you work evenly on both reins, but even happy hackers should be aware of changing their diagonals frequently on their hacks. If a horse is always ridden on the left diagonal – left foreleg and right hindleg stepping forwards in the rise phase – then the back muscles, particularly behind the saddle will develop asymmetrically. The left hindleg has to work harder to push forwards because the rider is in the sit phase, therefore the muscles become stronger and less supple. Have you ever ridden a horse in a straight line, and started off in sitting trot and found that the horse always “pushes” you up on one diagonal? This is because the horse has asymmetric muscles and gait, so needs work to correct the imbalance.