After doing a sprint interval workout, my running buddy complained that sprinting often made her low back feel tight. I had a notion that her psoas might be tight. This muscle is a major hip flexor and it attaches to the low spinal vertebrae. When the psoas gets short and tight from activities like sprinting, it can yank on the vertebrae, creating a sensation of tightness. The good news is that stretching out the hip flexors can alleviate a lot of lower back pain. Once you are warm, and especially after a run or sprinting session, you should stretch your psoas.

Learn two ways to stretch your psoas.

For the kneeling hip flexor stretch you only need a wall.

• Fold up a towel and place it about eight inches away from a wall.
• Kneel down and place your left knee on the towel and your toes against the wall.
• Now place your right foot on the ground in front of you, and lower your hips down until you feel a stretch in the front of your left hip. Make sure your right knee is directly above your ankle.
• Place your hands on your front knee to help keep your torso straight. Stay here for at least 30 seconds. Then slowly release and do this stretch on the other side.

If you have a foam roller, this passive psoas stretch feels relaxing.

• Place the roller perpendicular to your spine and lie with your sacrum, the back of your pelvis — not your spine — on the roller.
• Pull your right knee toward your chest, keeping your left heel on the ground. You should feel a stretch on the front of your left hip.
• To increase the stretch reach your left arm over your head and open your knee out to the right.
• Hold for 30 seconds, then switch legs.