You’ve seen it in sports, and likely experienced it yourself. Lingering tightness in your hamstrings is a nuisance. The cause of it, however, might surprise you.

Tight hamstrings are not actually due to a lack of flexibility. Instead, the muscles are tensed up due to instability in other muscles or joints.

Think about your pelvis. Your hamstrings run down the back of your thighs, connecting your pelvis to your knees. Chronic hamstring tension can originate from tightness in another muscle group: your hip flexors. Your hip flexors connect your thighs to your pelvis, so tight hip flexors will thrust your pelvis forward, putting stress on your hamstrings to keep you upright.

Your hamstrings’ connection to your glutes can have the same impact. Glutes are crucial for pelvic stability. Without sufficient strength in them, your tight hamstrings become a symptom of their weakness.

Thankfully, you can turn to several at-home exercises for some relief.

Try a supine bridge with a hip lift. All you need to do is lie on your back with your knees bent and feet on the floor. Then, you hip thrust into the air, moving your glutes off the ground by 3 to 9 inches. These gentle hip lifts build muscular strength and even restore alignment.

If you’re at the gym, grab a dumbbell or kettlebell and try a single-leg deadlift. Keeping your core engaged with a small bend in your knee, hinge forward from your hips while lifting your left leg straight behind you. Your torso and lifted leg should be together as you push your hips back and maintain a neutral spine.

Stop when you feel a stretch in your hamstrings — but keep doing the exercise a few times a week to see results.