Does body build make a difference in having a better seat when riding horses?

It might have to do with build, but I personally think that her not being able to sit the trot comes from riding bareback. (I saw your previous question.) If all she is used to is bareback, then she's learned, by feeling through her seat, how the horse moves and how to follow its movement. When a saddle is thrown into the mix, she loses that direct contact with the horse, which could through her balance/coordination off.

For example, I have a hunter jumper pony I'm training and I decided to ride bareback yesterday. We started with the basic walk-trot-canter, and then jumped a few small cross rails, all bareback. Then I put a saddle on and got her ready for a short informal lesson. I tried her again with the saddle over the same jumps just for fun, and I dropped my stirrups for a few of them. Everything was a lot different with the saddle, and I felt like the movement was more interrupted over the jumps, even with my stirrups.

In short, I think having a saddle underneath her makes a big difference. Lots of muscle will help a lot, but it'll take a little while for her to redevelop that balance using a saddle. To help her, try telling her to put most of her weight in her heels and to try to wrap her legs around the horse's belly, along with imagining that her seat is glued to the saddle.

Hope that helps at least a little!

Not necessarily body building, but yeah, exercise in general CAN help a lot. That said, I know riders who don't really exercise and are of a bigger build, and they can ride as well as the rest of us. So build doesn't determine anything, but in my in my experience, being in shape helps a lot. As far as her being not good at sitting the trot compared to people of less experience, well, we all have our weak areas. Maybe she's fantastic at something else, when other people aren't. It's just part of being an individual... We all learn at different rates, and we all have different areas of natural skill. I'd just recommend getting her lessons with a qualified instructor, and ask her to focus particularly on the sitting trot.

Body build can make things easier. The "ideal" body type for a rider is a person with long legs and a fairly short torso and a slim build. This lowers your center of gravity and makes it easier to balance on a horse.

That said, one of the best riders I know has a thick build and short arms and short legs. She has to use her athleticism to keep her balance and ride well.

i could say artwork together with her somewhat on the floor first. Like, walk her in the process the rocks and poles. Get her used to noises, at the same time with: canines barking plastic bags branches snapping birds squawking Then, whilst driving start up with much less rocky places and be sure you shop your thighs squeezed against the saddle. Then, slowly artwork into the rockier places.

not necessarily. I've seen skinny riders with an awful seat and heavier riders with an awesome seat and vice verse. It's a matter of talent and practice.