Specific riding exercises?

Tense your stomach muscles for a correct and straight posture. It is not about the back, keep your shoulders in line with your hip and ankle, keep your shoulders back, square and relaxed. Allow your hips to go with the movement in the working canter. Keep your lower leg still but relaxed. Also, try half seat when jumping. It can help improve personal balance and keep those stomach muscles tensed. It allows fluidity of movement. On the ground, try some stomach muscle building excercises. Wearing a body protector can also help you to keep your back nice and straight.

Also, if you have a rubbish saddle, this can majorly affect your posture. Find a saddle that you can maintain an accurate posture in. It might take time, effort and work to find the correct one but sitting in a decent dressage saddle for flatwork makes all the difference. I remember during lessons I used a rubbish saddle, I could not sit on my seatbones, I kept slipping back, therefore my lower back was hunched, I was constantly propping myself back onto my fork, my back began to hurt, my lower leg was everywhere and I was horribly uncomfortable!

I dont have any specific riding exercises but it does sound like you have the wrong position. When you ride you need to be sitting back on your butt. Your butt needs to be touching the saddle not out behind you. Doing this will also straighten your back and help with your balance.

It's not really exercises you need, but someone to show you how to re-adjust your weight. If you're sticking your bum out, you're sitting on your crotch.

There are three parts of your seat you can sit on: Pelvis, front of your seatbones, backs of your seatbones. You want to be in the middle (front of seatbones). So, humor me and find a chair you can sit backwards on. Sit so that your weight is over your crotch (pelvis, zipper... pick your term). Then, without moving your spine, move your weight back to be centered over your seatbones. Then shift farther back so that you're sitting on your tailbone.

The first position (over your crotch) is going to force you to do one or all of the following:

1.) Pinch with your knee,

2.) Tip forward,

3.) Stick your bum out

4.) Use your knee as a fulcrum, which makes your upper body AND leg swing in the canter

The last position (over your tailbone or on your pockets) will do one or all of the following:

1.) Put you in a chair seat,

2.) Make your bum act as a driving aide, which will drive your horse heavily into your hand, which results in...

3.) Shutting your horse down, or...

4.) Pulling your horse behind the vertical

Not only that, but sitting on your pelvis and tipping forward blocks off all sorts of muscles in the horse making it more difficult for him to carry the rider.

So you can see that you want to be centred on the front of your seatbones and not ahead of or behind them.

If you want exercises to strengthen your back and legs, though, working in a half-seat (NOT a two-point) will help with your back/thighs. Working without stirrups with help strengthen your core and legs.

Any core strengthening exercise will help... things like pilates, kettlebells, or just general back-strengthening exercises (like superman). You can find all sorts of things on google and youtube.

ETA: I agree about the saddle fit. Not all saddles are created equal, and even if it fits you almost everywhere, a saddle can still tip you forward (usually when the stirrup bars are too far forward).

Hey I ride too.! Ermm practice sitting in trot and put your weight in your heels. That's what I do also make sure ur sitting with square hips that's what's effecting your seat/position

There is a riders fitness program book that will help. i just got it and there are tons of exercies for your arms legs and back.

try yoga