Some riders lean forward. It’s not as bad as leaning backwards, but I’ll come to that later.
If you sit forward too much with your upper body, you can’t absorb the movement of the horse with your lower back which in turn will stiffen his back.
Sometimes it´s the saddle. A good dressage saddle is designed to help you to stay in a balanced vertical position. Jumping saddles have a different purpose, which is to support your knees when you are out of the saddle in a jumping position. So if you are serious about dressage, invest in a good saddle, that fits you and the horse.
Squeezing
Some riders are leaning forward because they are afraid. If you squeeze too much with your knees to stay in balance, you will actually push yourself out of the saddle a little, tipping your upper body forward and your lower legs back. The tension and the feeling are unsettling for a horse, so he might even speed up, making you even more unsure. If you are afraid, try to do something about it. Have lessons on the lunge line to work on your seat. Find a trainer that can help you with this. Gymnastics without reins and stirrups will help you to learn how to follow the movements of a horse with your seat, without clenching or gripping with your knees or upper thighs. Find a nice and quiet schoolmaster horse to work on, until you are more experienced.
Focus on your breathing. Stretch your core, without holding your breath. Take your legs away from the horse, really sitting on your backside. Feel your two seatbones evenly in the saddle. Try to stay on the backside of your leg muscles, not the front side.
Core stability
Some riders tip forward in a downward transition, when their back and belly muscles are weak. Don’t try to tighten your back to stay in position. You need core stability, but stiffening your spine prevents movement of your hips, which is necessary to follow the back of the horse. There are good fitness trainers that can help you develop your body. But make sure to find someone who’s familiar with horse riding. If you work the wrong muscles, it could get in the way.
Tipping forward can also happen if the horse is not reacting enough to the leg aids. If you are pushing him forward and therefor you are doing the work he should be doing, you are getting in front of him. Remember that about 70 percent of the horse has to be in front of you. More tips about how to get him off the leg later.
The weight should be transferred to the back
A lot of riders are leaning forward because the horse puts them there. Especially young horses tend to push the rider forward. If you are on a young horse, slightly leaning forward is not a bad thing. It means you are not that heavy on its back. But as they develop more, the weight should be transferred to the back.
If you look at a horse in the field, a substantial part of his bodyweight is on the forehand. It’s where the grass grows. Very inefficient, because his ‘engine’ is actually behind. You can see this when something spooks them and the start to run all of a sudden. They lower their hindquarters to catapult themselves forward, jumpstarting into a gallop.
When we sit on their back and add our weight, horses go on the forehand even more. So a horse that moves on the forehand pulls the rider forward, which makes the horse go more on the forehand and so on. It is an important task of a rider to get the weight transferred to the hindlegs over time. It saves the frontlegs from too much wear. Some vets are convinced that leg problems like navicular are caused by riding on the forehand too much. Transferring the weight to the back makes the horse easier to ride, as he will carry himself and not lean on your hands. If you manage to get him on his hindquarters, he will carry his own head and he´ll be able to lift his frontlegs more. Later on I’ll explain how you can work on this. But it all starts with realizing you tip forward. There is no point in doing exercises if you sit on the forehand. The horse might put you there, but you will have to be the one that changes the situation. You’ll have to work yourself into that vertical position again. Ask people around you to warn you if it happens. Problem is that we tend to get used to a certain way of going, so we don’t even realize what we are doing, unless we are told. Repeatedly. Even I need someone on the ground that reminds me all the time.