If you are looking for related equestrian concepts involving a horse's belly or core, you may be interested in:
Instructors sometimes use metaphors like "belly dancing" to help riders understand how the pelvis must move independently of the shoulders to absorb the horse's motion. adilia horse belly riding
Given the lack of evidence, “Adilia horse belly riding” may arise from non-equestrian contexts: If you are looking for related equestrian concepts