The hip anatomical alignment and flexibility
There are very few scientific proofs about the reliability and validity of hip and pelvic alignment measures. A longer or shorter leg has often been pointed out as having an impact on biomechanics and joint injury.
From the literature, a leg length discrepancy - LLD - has to be over 20mm, measured on an X-ray. In reality, we do not see many LLD over 15mm. The association with the injury-rate remains unclear to this day.
The important movement for a runner’s hip is internal rotation. It requires enough motion to avoid stress on the different downstream joints.
Unfortunately, few studies have investigated the role of hip rotators' strength on musculoskeletal injuries.
Hypermobility of the hip rotators can sometimes be associated with knee pain, because of atypical biomechanical motion.
The IT-band, on the outside part of our thigh, seems to be influenced by both over-pronation at the foot, as well as reduced hip abductors' strength.