Everything is connected in riding. Rhythm, balance, self carriage, straightness, suppleness/stiffness, back movement, rein contact, impulsion, collection (i.e. flexion of the haunches) are all interrelated and influence each other. Rider balance and horse balance, rider crookedness and horse crookedness, rider stiffness and horse stiffness affect each other in very direct ways. Any improvement in one area leads to improvements in all the other areas. Unfortunately, it works the other way around, too: a problem in one area will also have negative repercussions throughout the entire system.