Often the pelvic stabilizing muscles are weak and the Hypaxial muscles [ the abdominal muscles ] are tight. By doing some specific rear leg extension exercises and having a chiropractor evaluate the spine and pelvis you can often improve stride length and flexability for dressage or jumping. The rectus abdominal muscles and psoas muscles are often the culprits that need attention.
Please contact me at Indekchiropractic@gmail.com or call me at 617-472-0661 with any questions.