Clamshell exercises are a wonderful tool for warming up the glutes, protecting the knees, and strengthening the hips.
Start sidelying with pelvis in neutral (relaxed) with the hip slightly flexed and knees bent at 45 degrees. The bottom arm may curl under and support the head while the top arm rests comfortably across your abdomen.
Begin the movement with knees and feet together.
Bring some awareness to the core as you tighten your glutes and raise your top knee toward the ceiling.
The feet stay in contact throughout.
Hold the movement at the top for a second before lowering the knee back down.
Return to starting posture.
Both the knees and feet are once again in contact.