About fourteen days a year the fog takes a vacation and the sun shines a few rays on Golden Gate Park. Besides forestalling a few diagnoses of seasonal affective disorder, this phenomenon triggers a veritable explosion of joggers that resembles emergence of the seventeen-year cicada in the eastern United States. Watching these curious creatures (the homo sapiens that is) burrowing out from under the rocks and desks where they were encased I was struck by the variety of methods by which bipedalism was being accomplished. Listening to the clank of knees and the shuffle of feet I wondered how many of them would survive longer than their cicada counterparts. Can the way you run increase your risk of injury?
To answer this question I found an article titled “Suspected Mechanisms in the Cause of Overuse Running Injuries: A Clinical Review” by Reed Ferber PhD, Alan Hreljac PhD and Karen Kendall MKin published in Sports Health: A Multidisciplinary Approach in June 2009. While many factors influence the likelihood of running injury here the focus is only on running biomechanics.
Most of the research on running biomechanics and injury risk focus on one of two regions: the foot and the hip. This might seem strange given the fact that over half of running injuries occur at the knee. But because the knee is stuck between the ankle and the hip it is the belief of many who study running injuries that the knee is merely the injured bystander.
Pronation occurs when the foot hits the ground and the arch collapses to some degree while pressure moves from the outside to the inside of the foot. This is a normal shock absorbing mechanism but rapid or prolonged pronation is thought to be a cause of injury because it causes more medial rotation of the tibia which might result in medial rotation of the femur and abnormal tracking of the patella. This is a tidy hypothesis but the only two methodologically sound prospective trials looking at foot pronation found opposite results. In one study, folks with more rapid and prolonged pronation were more likely to go on to sustain a running injury and in the other study they were less likely. More research and better standardization of measurement may clear this up in the future.
Incraesed adduction and internal rotation of the thigh during running, a pattern which some are calling “hip pronation” is another suspected culprit in running injuries such as patella-femoral pain “runner’s knee.” In hip pronation the knee moves toward midline while the foot is on the ground and in extreme cases the term “knock-kneed running” is an apt description. The task of limiting the amplitude and velocity of “hip pronation” falls mostly on gluteus maximus and medius. Unlike foot pronation, a large and growing body of evidence points towards rapid and excessive “hip pronation” is a cause of patellofemoral pain while preliminary research is linking it to other common running injuries including ilio-tibial band syndrome, Achilles tendonopathy and plantar fasciopathy.
The summarize, the failure of the gluteal muscles to stabilize the hip and prevent excessive hip adduction and internal rotation while running is the only biomechanical factor that has robust support from the literature as a cause of injury. Fortunately for us, training of these muscles has been shown to improve function and decrease pain in people with patella-femoral pain. “Hip pronation” shows up in jumping, stair climbing, squatting and walking so even if you are not running it is prudent to include some gluteal muscle training into your routine.
You can find out if you are a “hip pronator” with a step-down test.
Step Down Test
- Stand on a step facing a mirror and slowly step down counting to three and touch your opposite heel down to the ground.
- Watch your knee in the mirror, if it goes towards the middle of your body past the inside of border of your footprint, you are a hip pronator.
There are many different exercises to train you out of the pattern of hip pronation and you will be more likely to succeed if you have someone to guide you to the appropriate level of difficulty. An exercise in the middle of this progression is the reverse step down and I’ll show it here as an example.
Reverese Step Down Exercise
- Stand on one leg on a 4 inch step, leaning slightly forward at the hip with the other leg extended behind you and in line with your body.
- Step down and back slowly, touching the toe to the ground and never letting the knee of your stance leg move forward more than an inch past your toe or move at all towards midline and over the inside of your footprint.
- Rest between each repetition and focus on quality counting only the repetitions that meet the criteria on each side. Practice each side for five minutes and increase the difficulty when you can do 12 in a row perfectly without stopping.