Clamshells

The clamshell exercise works the hips and glutes. It particularly targets and tones the gluteus medius, which forms the upper and outer part of the butt. This muscle gives your glutes shape and helps to stabilize the pelvis and hips, as well as moving the thigh away from the midline of your body (hip abduction) and rotating it outwards (hip external rotation).

If your glutes medius is weak, other muscles jump in to help out, which can lead to a cascade of problems including instability of the hips, knee and low back pain, injury, and poor movement mechanics.

Clamshells strengthen the gluteus medius and are one of the most effective exercises for injury treatment and prevention. It’s a classic exercise that often part of rehab programs. Clamshells can improve athletic performance in running-based sports, as it will strengthen the hips and improve running form and efficiency, helping you to run stronger and better.

The clamshell exercise is also simply called the clam or more technically – side-lying hip external rotation.

How to Do
Clamshells

Starting position: Lie on your side with your hips slightly bent and your knees bent about 90 degrees. Stack your feet, knees, and hips on top of each other. Rest you head with your lower arm. Your neck should long and in line with your body.

• Engage your core and squeeze your glutes. Slowly lift your top knee, hinging at the hip while keeping your heels together. 
• Pause, then slowly and with control lower your knee to return to the starting position.

Breath: Exhale as you raise your knee, inhale as your lower it.

Some people feel their glutes working harder when their knees are closer to their torso, while others when their knees are only slightly bent. Therefore, adjust how much you bend your knees for maximum glute activation.

Keep you torso and pelvis steady as you raise your knee. It’s a common mistake to tilt the torso forward or for the hips to roll backward as you execute the movement. Keeping your core engaged will help keep your upper body stable.

Variations: You can make clamshells more challenging by looping a resistance band around your thighs, just above the knees. Another way to increase difficulty is to progress to the side plank clamshell, where you’re in a similar position except the bottom arm is bent and your elbow is directly underneath the shoulder.