The way you stated your question makes no sense, you are making it sound as if you are too weak to mount a horse, but the muscles you strengthen when you ride a horse are, if you ride properly, thighs, back, abs, calves, arms and neck. But if you ride horribly and do not position your self right and have terrible posture you stregthen absolutely nothing.
if you sit properly in the saddle, and do a substantial amount of time in each gait, then yes!
(Strengthen your muscles)
The best exercises to strengthen the muscles around the ribs are planks, side planks, and dumbbell pullovers. These exercises help improve core stability and strengthen the muscles that support the rib cage.
Exercises such as deadlifts, back extensions, and supermans can help strengthen the back extensor muscles.
Any muscle group in the legs or abdominal areas. Also it wouldn't hurt to strengthen your arms.
Strengthen your abdominal muscles.
Exercises such as planks, leg raises, and bicycle crunches can help strengthen the muscles of the lower abdomen.
To get your legs to strengthen by running and running because this is using your muscles and that helps your legs to strengthen.
The functions of the back rib muscles include supporting the spine and aiding in breathing. To strengthen these muscles, exercises like rows, pull-ups, and deadlifts can be effective.
The exercise ball will strengthen different muscles depending on how you use it. It's probably most popular and frequently used for an abdominal work out.
Some exercises to strengthen the muscles in your hip include hip bridges, clamshells, hip abductions, and hip flexor stretches.
When exercise is done the muscles are broken down. The muscles are then repared back stronger.