How to Gently Release Tension Hiding in Your Psoas — the Most Important Muscle for Posture Start by lying down with your hands out to your sides. Place one leg at 90° on a chair or bench, while the other rests straight on a suitcase or bench. Hold for 10 minutes on each side. At first, you may notice a curve in your lower back — a sign of tight hip flexors. As your back plants into the floor, it’s a sign they’re settling in and realigning your pelvis. This is the position I show all the time — i