Exercises / Hip & gluteal

Clamshell

Strength
Hip & gluteal
Mat, Elastic band (optional)

Opening the top knee with the feet together. Low intensity but the best gluteal-to-TFL ratio in fine-wire EMG.

Also called clam, clams, side-lying hip external rotation.

Log this in Hazumo

Where you stand

No published distribution for this exercise yet. We add one only from a peer-reviewed study.

Muscles worked

Filled: primary. Outlined: secondary.

How much

Typical strength dose: 2-3 sets of 8-12 repetitions at a load that is hard by the last repetition, 2-3 days per week (ACSM novice guideline). Adjust to symptoms.

Start: Side-lying, hips about 30-45° flexed, knees bent

Steps

Lie on the side with hips and knees bent, feet together, pelvis stacked.
Keeping the feet together, lift the top knee without rolling the pelvis back.
Lower slowly. Add a band around the thighs to progress.

Cues

Keep the pelvis neutral and stacked
Small, controlled range

Common mistakes

Rolling the pelvis backward
Flexing or extending the lumbar spine

Used for

Early hip abductor/external rotator training
Patellofemoral pain
Knee valgus control

Evidence (3)

The clam had the highest gluteal-to-TFL activation index (115) of 11 exercises.5
A neutral pelvis gave greater gluteus maximus and medius activity than a flexed or extended pelvis.3
Clams produced about 40% MVIC of gluteus medius, less than side-lying abduction.1

Harder

References (5)

Distefano LJ, Blackburn JT, Marshall SW, Padua DA. J Orthop Sports Phys Ther. 2009;39(7):532-540. Gluteal muscle activation during common therapeutic exercises
Boren K, Conrey C, Le Coguic J, Paprocki L, Voight M, Robinson TK. Int J Sports Phys Ther. 2011;6(3):206-223. Electromyographic analysis of gluteus medius and gluteus maximus during rehabilitation exercises
Willcox EL, Burden AM. J Orthop Sports Phys Ther. 2013;43(5):325-331. The influence of varying hip angle and pelvis position on muscle recruitment patterns of the hip abductor muscles during the clam exercise
Neumann DA. Elsevier. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed.
Selkowitz DM, Beneck GJ, Powers CM. J Orthop Sports Phys Ther. 2013;43(2):54-64. Which exercises target the gluteal muscles while minimizing activation of the tensor fascia lata? Electromyographic assessment using fine-wire electrodes