It is all too common that core building routines can cause excessive shortness and tightening in your body. Cultivate length and strength in your centrally-located psoas muscle, without creating excessive contraction. Practice a series of poses that can help strengthen and provide more stability for your ilio-lumbar region. As you move through each posture, tune inward and focus on the importance of your psoas muscle throughout your practice. Props Needed: A block, a blanket, a bolster and a strap.