You may be wondering why training out of the saddle helps you become a better rider and saddle time is not enough. In two words, muscle memory. Muscle memory occurs when your body has repeated a movement so many times that you no longer need to think consciously about how to make it happen. Your muscles simply know what they need to do. We build muscle memory by repetition. This can work for and against a rider depending on the situation. this type of movement and unless you break the pattern it will continue.
Prescribing a set of floor exercises that introduces lack of stability across the body forces you to maintain a neutral spine and squared-up shoulders and hips in spite of disturbances. Now, the next time you climb in the saddle, your body is used to staying stable in an unstable environment and you are quieter and able to keep your balance without much movement. You have trained your muscles through repetition on the ground to improve your riding in the saddle.