This piece appeared in the May issue of Competitor Magazine.
Written by: Matt FitzgeraldIt now appears that the most common cause of PFPS is a genu valgum, or “knock knee” effect that is linked to weakness in the hip musculature.
Does your knee hurt? If so, you’re in good (painful) company. The knee is the single most common site of injury among runners. And the most common knee injury among runners is patellofemoral pain syndrome (PFPS), whose main symptom is pain below the kneecap during and after running.
Experts have speculated that the most common cause of PFPS is weakness in the hip abductor muscles. Based on this speculation, strengthening exercises for the hip abductors have become a standard treatment for PFPS. But how well do they work?
Researchers at the University of Calgary sought to find out in a new study involving 25 runners, 15 of whom had ongoing cases of PFPS. The injured runners performed strengthening exercises for the hip abductors for three weeks, while the uninjured runners did not.
Both before and after this intervention, the researchers measured peak strength of the hip abductor muscles on both sides, plus a couple of relevant biomechanical factors during running, and pain ratings. Before the intervention, the injured runners exhibited less strength and some noteworthy differences in biomechanics. After the intervention, the injured runners exhibited improved hip abductor strength, reported less pain, and ran more like the uninjured runners.
Lessening pain is the main goal, of course, but it’s impossible to say from this study that the hip strengthening exercises were responsible for the pain reduction. This would have required that injured runners who did not perform strengthening exercises be included in the study. Still, the study provides an encouraging sign that strengthening exercises for the hip abductors can alter knee joint kinematics in a way that reduces strain on the knee during running.
The Hip Hiker
There are a number of good strengthening exercises for the hip stabilizers. One of the best is the hip hiker. Stand with the instep of your right foot along the edge of a raised surface such as an aerobics step and your left foot elevated above the floor. Without bending the knee of either leg, relax the muscles of your right hip and allow your left foot to drop a few inches toward the floor. Now contract the muscles of your right hip and “hike” your left hip, lifting your left foot as high as you can without leaning or bending your left knee. This is a small movement. Repeat 20 times and then switch legs.