The Psoas Muscle: The Most Important Muscle for Posture Most people don’t even know where the psoas is—yet it’s one of the most powerful posture muscles in the body. It starts deep in the inner part of your thigh (femur), travels through your pelvis and abdominal wall, and attaches to the front of your spine at T12–L5. 
It’s the only muscle that connects your upper body to your lower body—and when it’s short or tight from sitting, it can pull your spine, pelvis, and posture completely out of balance. The position I’m showing here—one leg at 90°, the other straight, lying on your back—gently separates the hips and gives the psoas space to lengthen naturally. Breathe deeply into your stomach and let it release. Want to unlock your psoas and fix posture issues like forward head, rounded shoulders, and back pain? Click the link in my bio for a free 3-day trial on the Posture Guy Mike app. Full programs designed to realign your body from the inside out. Big thanks to @anatomy.of.motion for their awesome visual #psoas #psoasrelease #posturecorrection #posturefix #hipflexor #backpainrelief #forwardheadposture #roundedshoulders #postureexercises #postureguymike #hipmobility #corestability #alignmentiskey #deepcore