It has stood the test of time and is a staple in just about every physical therapy clinic. It is the beloved “clamshell” exercise.
This exercise is relatively simple, portable, safe, and effective in regards to recruiting the often-neglected gluteal muscles. Let’s take a quick look at the start and finish positions of this exercise.
As you can see with our starting position, the knees and the hips are flexed as the subject is lying on his side. A recent article from the Journal of Orthopedic and Sports Physical Therapy (July, 2013) suggests that the gluteal muscles are better recruited when the hips are flexed to about sixty (60) degrees as seen in the photo.
The movement involved with this exercise is simple. Lift one knee off of the other knee and hold the elevated knee in the raised position for three to five seconds.
Beware of the path of least resistance! Most patients will unknowingly cheat in order to more easily move into the end position. The most common cheat involves turning the “top side” of the pelvis backwards. To correct yourself, keep your pelvis straight up, or perpendicular to the floor. Some patients will have to back themselves up against a wall in order to keep the spine and pelvis aligned.
How do you know if you are doing it correctly? If you feel a prominent fatigue or burn in the gluteal muscles along the side and posterior aspects of the hip, you are doing a good job. Even the most conditioned athletes are often surprised at just how difficult this exercise is when performed correctly.