A University of Southern California study of female runners adds support to the theory that decreased hip muscle strength underlies patellofemoral pain.

During running tests, 19 runners with patellofemoral paindemonstrated significantly greater average hip internal rotation,lower scores on eight of 10 hip strength measures, and more femoralinclination than 19 pain-free runners. Further analysis revealed thatisotonic hip extension endurance was the only predictor of average hip internal rotation.

The findings, published online Dec. 19 by the American Journalof Sports Medicine, suggest that hip strengthening exercises might en-able athletes to correct their hip kinematics during running and inturn alleviate their patellofemoral pain.

Similarly, an August study from the University of Delaware foundthat hip abduction and external rotation strengths were significant-ly lower in 20 recreational runners with patellofemoral pain than in 20 uninjured runners. At the end of a run, hip abduction strengthwas significantly related to peak hip adduction angle in the runners with patellofemoral pain.

Those findings were published in the Journal of Orthopaedic & Sports Physical Therapy.