Training in a single leg stance is an important practice. It ensures symmetry and proper functioning, but to be able to train in a single leg stance you need to first be able to stabilize your self over on leg. This means we need to make sure the dynamic stabilizers of the hip are strong. Second poor strength of these dynamic stabilizers, especially the hip abductors and external rotators can lead to injuries and things like patellofemoral pain. This is due to the fact that the weakness of these muscles will lead to excessive adduction and internal rotation of the hip (Valgus Collapse) while the foot is planted causing the femur to move improperly on the patella. This is probably one of the biggest causes for wear and tear on the joint.
In addition excessive internal rotation and adduction of the hip (Valgus Collapse), which would be otherwise prevented through sufficient hip external rotator and abductor strength, can lead to ACL injury, knee pain, and ankle problems.
But we never effectively strengthen these hip stabilizers because we are so sagittal plane dominant and spend very little time working the coronal and transverse planes. This increased the biomechanical disadvantage that is already occurring. This means we need to spend time outside of the sagittal plane on a regular basis.
To prevent all these catastrophic accidents from occurring it is important to maintain sufficient strength in the hip external rotators and hip abductors. This can be done by directly training the hip to abduct and externally rotate or by training the hip abductors and external rotators to isometrically stabilize during movements in the sagittal plane and control the amount of hip adduction and internal rotation during eccentric motion.
One of these important hip abductors and external rotators is the gluteus medius and it is one of the most commonly weak muscles. Which means it is important for most people to include an exercise that both activates and strengthens the gluteus medius so that it can help prevent the catastrophes we discussed above.
Side Note: The gluteus medius is also important for stabilizing the pelvis in a neutral position during the single leg stance. If one gluteus medius is weak it will cause the opposite side hip to drop.
EMG studies have told us that the Clamshell is a great exercise for facilitating this strengthening. So consider involving this activation drill in your warm-up or prior to a heavy session of squatting or single leg training. It also makes a great isolation resistance exercise for the gluteus medius if a thera band is wrapped about the top of your knees.
How To Perform the Clamshell
- Lie on your side with your knees bent.
- Flex your hips to between 30 to 60 degrees
- Place your top hand on the top of your hip so that you can palpate your iliac crest.
- Make sure your hips and shoulders stay square.
- Keep your feet together.
- Raise your top knee causing your hip to externally rotate. Keep your bottom knee and leg driven into the ground. Be sure your hips do not open up allowing your back to become overly involved in the motion.
- Lower your top knee back to start and repeat for repetitions then switch sides.
Below is a video of me demonstrating the entire movement.
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