Anyone working with athletes suffering from patellofemoral pain syndrome (PFPS) will be interested in the results of this study. Strengthening the hip muscles first before working on the quadriceps (thigh) muscles speeds up the recovery process. Pain is less and function improved with this approach.
The study was done by a group of physical therapists, athletic trainers, and sports physicians at the University of Kentucky Musculoskeletal Lab. We've known for a long time that a weak, impaired, or imbalanced quadriceps muscle is a risk factor for patellofemoral pain syndrome (PFPS). But recent studies have shown that weak hip muscles (external rotators and abductors) are directly linked with PFPS.
The natural next step in research is to test the idea that strengthening just the hip muscles can positively affect PFPS. In this study, that's what they did -- they compared the results of hip strengthening exercises performed by one group of athletes with PFPS to a second group of similar athletes who did a quadriceps strengthening program instead.
All the participants in both groups were female. That was intentional because patellofemoral pain syndrome affects women twice as often as men in the general population and four times as often among athletes. So it's important to test a group of female athletes. And in a way, it's easier to test female athletes because there are so many around with this problem!
They carefully screened participants so that everyone had the same symptoms and clinical presentation. For example, everyone had pain underneath or along the front of the patella (knee cap). The knee pain was worse when climbing, hopping, running, squatting, kneeling, or sitting for a long time. There was no trauma or other knee problem causing the pain. No one in the study (either group) had ever had knee surgery. And everyone had knee pain for more than one month.
Results were measured using a couple of different outcomes. Pain intensity was one measure. Strength of hip and knee muscles was a second measurement used for comparison. They used a special handheld device called a dynamometer to test the muscles.
A third way to measure results was a test for functional strength. This test involved stepping down on one leg from a step, touching the heel to the floor, then returning back up to the step. The unit of measure used for comparison was the number of times each athlete could step down and back up in 30 seconds.
Before we look at the results, let's take a closer look at the exercise programs themselves. Each athlete performed flexibility exercises (performing each stretch three times for 30 seconds each) before doing strengthening exercises. Then they did their program of (quad or hip) exercises three times a week. During one of those three times, they were supervised by a physical therapist or athletic trainer. The other two sessions were done at home on their own.
There were two phases of the rehab program. Phase one (flexibility and strengthening as described) lasted four weeks. Everyone was retested at that point before progressing to phase two. Phase two consisted of weight-bearing resistance exercises, balance exercises, and a continuation of either the hip or quadriceps strengthening (the same exercise program done in phase one). Following phase two (four weeks), retesting was conducted and the results reported.
Here's what they found. Everyone in both groups gained in strength. Athletes in the hip strengthening group had less pain during the first four weeks compared with the knee group. The step-down test improved significantly for everyone in both groups.
They concluded that performing isolated hip strengthening helps decrease patellofemoral pain in female athletes faster than doing a traditional quadriceps strengthening program.
Doing either quadriceps strengthening or hip strengthening improved function as measured by the step-down test. The average healthy adult can perform 18 step downs in 30 seconds. Athletes in this study tested slightly below average (15 repetitions per 30 seconds) before rehab and improved to slightly above average (21 reps after rehab).
By the end of the study, the women in both groups had hip strength that measured close to normal. The authors noted the fact that they did not test a group with both sets of exercises at the same time or include a control group that did no exercise to compare the results.
Reference: Kimberly L. Dolak, MS, ATC, et al. Hip Strengthening Prior to Functional Exercises Reduces Pain Sooner Than Quadriceps Strengthening in Females with Patellofemoral Pain Syndrome: A Randomized Clinical Trial. In The Journal of Sports Physical Therapy. August 2011. Vol. 41. No. 8. Pp. 560-570.