Why are Hip Muscles so Important in Preventing Knee Pain and Injuries?

How about the Plantar Fascitis at your Heel?

When your foot hits the ground, your center of gravity is normally to the outside of the foot.  This causes a stress along the outside of your leg which is handled by your IT band and lateral collateral ligament at the knee.  As you increase running distance during training, the stress is naturally increased, but hopefully you have planned enough recovery for these tissues to appropriately strengthen.

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(Note that women with shorter legs and wider hips or increased weight will naturally have increased stresses along these lines.  This coupled with the fact that some female hormones cyclically weaken connective tissue strength accounts for why many more women than men have repetitive stress problems.)

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If your lateral hip muscles are weak (gluteus medius and minimus), your pelvis is unstable and your body has two options to compensate.

1. It can shift to the outside slightly dropping your opposite hip while shifting your center of gravity even farther outside your foot.  This increases the stress on your IT band and lateral collateral ligament as well as increasing compression on the medial meniscus and knee cartilage.  

2. You may instead shift the other direction, over your foot by buckling your knee inward.  This produces stress on your ACL and medial collateral ligament as well as lateral meniscus and cartilage. It also stresses your hip external rotators such as the piriformis muscle producing butt pain.

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The most likely people to develop IT band syndrome are those with this pattern of excessive adduction and internal rotation of the hip which produces internal rotation of the femur on the tibia as well.

If you watch your knee as you buckle it inward, you will notice that it rotates inward as well.  Then, if you look at your foot and ankle, you will see the ankle pronate, your arch fall and your big toe forced laterally.  This is one reason some runners obtain knee and hip relief with supportive shoes and orthotics, however unless the hip muscle weakness is corrected, that source of the problem remains.

Deep buttock/posterior hip pain in runners is often piriformis pain. When it is bad it can radiate into the posterior thigh and even your lower leg. The piriformis muscle is an external rotator and is most stressed, as are most of your running muscles, during eccentric contractions. Eccentric contraction is when a muscle is lengthening while under tension which is precisely what is occurring when your piriformis is trying to slow the internal rotation of your hip. Occasionally piriformis syndrome includes entrapment of the sciatic nerve if it penetrates the muscle.

Your gluteus maximus is your strongest hip extensor but it is your strongest external rotator as well and if it is weak it will not be able to resist the above internal rotation stress.

People with patellofemoral pain syndrome (pain under your knee cap) often are treated with IT band stretching or surgical release of the lateral retinaculum and strengthening exercises for the medial medialis (the portion of the quadriceps near your medial patella).

These techniques ignore the fact that the main cause of patellar displacement during running is the above knee adduction and internal rotation of the femur under the patella. Females with patellofemoral pain syndrome (PFP) have twice the internal hip rotation as those without the problem. In addition, as their knees move medially, their quadriceps and IT band pull the patella even harder laterally increasing the patellofemoral joint pressure by more than 50%.

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Doesn’t it make sense to strengthen the hip muscles before resorting to surgery or before your joints wear out?

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If you observe a number of people performing 90 degree squats, you will notice that they vary as to how far they are able to sit back, keeping their knees behind their toes.  If their gluteus maximus is weak they have to shift their knees forward over their toes to substitute the quadriceps.  When the gluteus maximus is weak, you have to use your hamstrings more for hip extension during running.  Your low back muscles then, become overworked balancing your pelvis against the hamstring torque creating low back pain.  When you use your hamstrings this way they become fatigued early which lengthens your stride, producing anterior tibialis shin splints and slows your turn over rate.

As your hip changes angle as in hill running or stairs it changes in its ability to provide external rotation as does the piriformis muscle so that other rotators are needed to be strong at those angles. As the angle increases you use the adductor magnus as a major hip extensor so your abductors need to be strong at these angles for control.  This is a major reason for using a variety of hip exercises and hill training for runners. Watch your form during raining and don’t let your knees buckle inward when the going is steep or the lunge is deep.

One of the most common compensations for weak gluteus maximus is a shift of the weight to the rear on the stance leg. This increases stress on the quadriceps producing quad strains, patellofemoral pain, patellar tendinitis or ACL sprain.

Your hip flexors which oppose the gluteus maximus can shorten or become overactive, worsening the problem as well as altering your running gait, creating groin pain and damaging your hip joint capsule. Your abdominals which stabilize the front of your pelvis and balance your hip flexors are opposed by your back extensors and often inhibited in the above imbalance pattern. At the same time their weakness makes it worse.

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(Occasionally you may read about lower crossed syndrome. This is simply the pattern of short hip flexors, weak glutes and weakened substituted hamstrings, tight low back extensors and weak abdominal muscles. These produce a standing posture with the center of gravity moved posterior, hips flexed and low back arched with protruding stomach. Notice how similar this concept is to the above described imbalance patterns.)

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Functional tests for hip muscle strength include performing an overhead squat, single leg squat, stepping down from an 8 to 12 inch high step or jumping from an18 inch or so high box, landing on both feet.  In all cases the reaction of knees, pelvis and ankles are observed.

Another approach is to carefully try the various corrective rehabilitation, stabilization and strengthening exercises to see how many you can do with proper form. If you are unable to properly perform any repetitions without pain, you need to identify and correct the problem. This may be a simple as performing a lighter version until you are strong and stable enough to progress or you may have a problem in need of expert advice or diagnosis.

 You may read about eccentric training or have eccentric exercises prescribed for the prevention or correction of chronic tendon problems.  There is a significant body of evidence supporting this. 

You may read about lateral hip pain and trochanteric bursitis. This diagnosis is often in error in that many of the bursitis noted on MRI are on the pain-free hip. Also, as many as ½ of the bursitis diagnosed cases may actually have gluteus medius tendinopathy as the actual pain generator.