The iliopsoas is the muscle that quietly runs your entire operation while getting absolutely no credit. It’s actually two muscles, the psoas major and iliacus, fused into one system. It connects your lumbar spine to your femur. Translation: it links your spine to your legs. Every step you take, every kick, squat, sprint, or sit-up runs through it. When the iliopsoas works well, movement feels light and coordinated. The hips flex cleanly, the spine stays organised, and the pelvis stays neutral. W