Selected Psoas Stretches
1) THOMAS STRETCH
Sit tall at the end of a table, with your thighs halfway off . Pull one knee to your chest and lean back. Your lower back and sacrum should be flat on the table. If there's any rounding in your back, or tipping of your pelvis, then you're pulling the knee too far, so loosen your hold. The other leg should hang free off the table. Hold for 30 to 60 seconds for each side, and complete at least two or three repetitions.
NOTE: Physical therapists often use this stretch as a flexibility test for the hip flexor. To pass, the posterior thigh should touch the table, and the knee should passively flex at an angle of at least 80 degrees.