If you have a client who loves to run but is stymied by hip or pelvis problems,
Pilates might help.

A functionally based Pilates intervention program that focused on restoring
correct lower-extremity alignment returned running ability to an experienced
high-level female runner. In the case study, health professionals at the University
of Connecticut School of Allied Health in Storrs, Connecticut, described how a Pilates-evolved exercise program resolved a long-term runner’s inability to run
because of dysfunction of the hip, spine and pelvic stabilizers. Other traditional treatment approaches had already failed. The Pilates program focused on functional and progressive resistance exercises designed to dynamically stabilize the spine, pelvis and hip through all planes of motion.

The case study was published in Current Sports Medical Reporter (2006; 5 [3], 137–40).