Clamshells are great, but there’s a better option.
Why this matters:
A common way to strengthen the piriformis is to execute clamshells. That’s when you’re on your side and you raise your top knee up to the ceiling. It’s a great exercise especially when done correctly. However, the common compensations of this movement is trunk rotation (because the piriformis is weak). You can try really hard to not rotate, but in some cases it can be really hard. As a result, you’ll lose the benefit of the exercise.
If you would like to strengthen your hip in a better way, try out this modified fire hydrant. Being on your hands and knees allows you to stabilize your pelvis so you can emphasize hip motion. I like doing sets of 10-15 repetitions so I can truly feel the burn. This exercise is particularly good especially if you notice that your knees cave in when you squat as well if you notice that you have flat feet.
What other exercises do you do to strengthen your hips?