Muscles cause movement. Muscle movement is initiated by nerves from the spine. Many times an owner or trainer will tell me the horse does not move well. It is important to know that specific muscles are responsible for forward movement and all too often I find muscle and spinal imbalance which will inhibit the horse.
Two main muscles are often at fault and these are the Lats as well as the medial gluts and tensor fascia latae {TFL}. The first muscle namely the Lats control backward humerus {front leg bone above the elbow} movement. If there are saddle issues or alignment problems in the mid back, the Lats will be weakened and inhibit front leg movement.
The Medial Gluts need to relax and allow the TFL to pull the rear leg forward for engagement. If a pelvic subluxation{alignment fault} or lumbar{low back vertebrae} exists then there will be power loss and your horse may even through the head or buck.
Chiropractic can often evaluate and correct these problems.