“Ban the Clam?” Rethinking the clamshell exercise in post hip arthroplasty rehab
What is The Clamshell Exercise?
The “clam” or “clamshell” is a well-known exercise commonly performed for Gluteus Medius strengthening. The exercise is done in side-lying with the hips and knees flexed and the ankles together. The top leg is then abducted and externally rotated so that the knee moves upward while the ankles remain together, and the hips stacked. Many health and exercise professionals prescribe this exercise for hip and glute strengthening; however, the clamshell exercise may be counter-productive for those with hip pain, or for patients recovering from hip surgery because it places the hip joint in a disadvantageous position both anatomically and biomechanically ultimately resulting in compression of the structures in and around the hip joint, pain, weakness, and immobility (1).
Clamshells, Compressive Load, and Gluteal Tendinopathies:
Many of the most common Gluteus Medius exercises, including the clamshell, are not ideal as they involve positions that result in compressive load of the tendon. Clamshells are done in a side lying position, which allows the hip to cross the midline, with gravity and the added resistance of a band pulling the hip into adduction, creating compressive load on the gluteal tendons (2). During the clamshell exercise, the iliotibial (IT) band moves forwards and backwards over the greater trochanter (a protrusion of the upper thigh bone) as the knees move apart and back together. When the knees are brought together the hip is brought into hyperadduction. When the hip is in this adducted position, the IT band is wrapped firmly around the superior femur which causes compression of the gluteal tendons and bursae against the underlying greater trochanter (3). It is thought that this increased compressive load on the gluteal tendons during the clamshell exercise may contribute to the development or exasperation of gluteal tendinopathies (1) similar to the way that walking with poor lumbopelvic stability or sleeping on the side of a hip tendinopathy creates es a compressive load on the tendons and often provokes a painful response (2).
Clamshells Post Hip Arthroplasty:
Following hip arthroplasty (hip replacement surgery), it is common for patients to exhibit markedly decreased strength of Gluteus Medius (3). Iliopsoas is a deep muscle group which acts to flex and externally rotate the hip. Pain or tendinitis of iliopsoas is common during postoperative rehabilitation for the hip (4). Although there is limited evidence, it is thought that rehabilitation exercises addressing Gluteus Medius weakness may also aggravate an inflamed iliopsoas muscle after hip surgery (3). Therefore, selecting exercises which strengthen Gluteus Medius while reducing activation of the iliopsoas muscle is important to prevent iliopsoas tendinitis following hip arthroplasty (3). The clamshell exercise has been shown to have high relative activation of Iliopsoas compared to Gluteus Medius, and consequently, should not be used in the early phases of rehabilitation following hip arthroplasty (3). Additionally, due to the degree of hip external rotation occurring at the end of the concentric phase of the clamshell, this exercise also places high amounts of stress on the anterior hip capsule which can be problematic if there is any degree of anterior instability following hip surgery (5).
Summary:
While the clamshell can be a useful exercise to strengthen the hip abductors, there are certain cases in which it may be contraindicated. One example of a scenario when the clamshell exercise may be counterproductive is in patients with lateral hip pain caused by gluteal tendinopathies. This is because the position of hip adduction that occurs when the knees are brought together in the side-lying position causes the gluteal tendons to be compressed between the greater trochanter of the femur and the IT band. This compressive load on the tendons can aggravate gluteal tendinopathies and cause pain. A second scenario in which the clamshell exercise is not ideal, is for patients rehabilitating from hip replacement surgery. Since iliopsoas pain and tendinitis is common after hip arthroplasty, it is recommended that the clamshell exercise be avoided to minimize the activation of the iliopsoas muscle group.
Alternate Exercises to Strengthen Glute Med:
1. Lateral step ups
- Stand up straight, sideways to a step.
- Your working leg should be closest to the step, and your feet close together.
- You may use a handrail or chair for support if required.
- Step your closer leg onto the step.
- Step up, pushing through your working leg, and stand tall, hovering your other leg above the floor.
- Return your other leg to the floor, while keeping your working leg on the step.
2. Hip Hikes and kneeling hip hikes
- Stand with your working leg on a stair or step.
- Let your other foot drop slowly to the floor sideways, do not flex your knee or hip in the movement.
- Move in a slow and controlled pace during this exercise.
- Move your leg back into the starting position and repeat.
- If you are unable to balance on one leg, the same exercise can be done from a tall kneeling position
3. Supine lying isometric hip abduction
- Lie down next to a wall with the leg closest to the wall bent and the foot planted on the floor
- Place a medicine ball or foam roller between your knee and the wall
- Press your knee outward into the ball/foam roller without rotating at the hips or arching your lower back
- Can increase difficulty by performing glute bridges in this position
4. Seated clamshells from a neutral hip position
- Sit with a resistance band tied around your knees.
- Keeping one leg still, turn the thigh of your other leg out as far as you can without twisting the body and then steadily return to the start position.
- Don’t allow the moving knee to adduct inward past neutral (keep the knee in line with the hip and the femur pointing straight in front)
- You should feel this down the side of your hip.
5. Side-lying clamshells performed with relative hip abduction
- Lie on your side with your feet, ankles, and knees apart so that the hips are in an abducted position
- Bend the legs slightly and engage your core
- Keeping the feet apart, lift the top knee up.
- Make sure you don't roll your body back with the movement.
- Control the movement as you bring the knee back down to the starting position, do not lower the knee below neutral
If you are looking to strengthen your glutes and hips without exasperating symptoms of lateral hip pain or tendinitis, there are plenty of other exercises you can try. The physiotherapists at Elios Health are knowledgeable and experienced with exercise prescription and will help select the most appropriate exercises to help you reach your goals. We might prescribe the clam - or we might not!
In addition to exercise prescription, our practitioners will use a variety of manual therapy techniques, active and passive range of motion, and modalities such as IMS or acupuncture to help reduce your symptoms and mitigate any pain you may be experiencing so that you can get back to feeling your best and engaging in the activities you enjoy. To check for availability, click here.
References:
1. https://www.jospt.org/doi/pdf/10.2519/jospt.2015.5829
4. Stalzer S, Wahoff M, Scanlan M. Rehabilitation following hip arthroscopy. Clin Sports Med. 2006;25(2):337-357, x
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425631/
Original Article by Rachel Rubin-Sarganis
Cover Photo by Charlota Blunarova