The psoas is a deep muscle of the core and hip flexors. It connects the lumbar region of your back to the front of your leg. When you run, this muscle is the initiator of the movement and can be responsible for your stride, whether good or bad. It can also lead to knee pain, back pain and hip flexor shortening, depending on whether it is weak or tight. All of these can deter your running abilities. Exercises can be done to strengthen or release your psoas and improve your running ability.
A weak psoas may be responsible for knee pain, hip flexor pain and back pain. When you run without sprinting, your knee stays below hip height. The psoas is strengthened and contracted when you lift your knee to hip height or higher. Long distance and routine runs often rely on the hip flexor at the front of the hip and the thigh to do the majority of the work. This causes the muscles to pull on the lower back and down into the knee, which can affect your ability to run. Strengthening your hip flexor, if it is weak, can help protect these areas and improve your run.
To strengthen your psoas, you'll need to perform exercises that draw your leg to hip height and either hold in a contraction or use the psoas to move in and out of the exercise. Try lying on your back on an exercise mat. Pull your right knee in to your chest and release your left leg down to the ground. Hold for 10 counts. Then lift both legs toward the ceiling, at a 90-degree angle with the hips. lower your right leg to 45 degrees and return to the start. Switch to the left side. Keep your navel pulled in to your spine and your lower back into the ground for support. Repeat this exercise 10 to 12 times.
A tight psoas can cause lower back pain, as well as not allow you to fully extend in your stride. The psoas can become tight from too much exercise but also from too much sitting. The psoas becomes tight when the knee is at hip height and it is contracted for too long. A tight psoas stays slightly contracted, which pulls on the pelvis and lower back, causing pain. Stretching exercises can release this pain and allow you to run without hurting your lower back or pelvis.
Stretches that lengthen the front of the hips and hip flexors also lengthen into the deep psoas muscle. This stretch can help to release the contraction in your psoas and relieve back tension. Try stretches such as a low half lunge or the yoga pigeon pose. Come to a kneeling position. Step your right foot forward and bend your knee over your ankle. Lengthen your left leg back until your hips are lower to the ground and press forward slightly. The left hip flexor will be open. Hold for five breaths. Then slide your right leg to the ground. Bring your right knee to the right wrist and your shin across to the left. Lower close to the ground and hold for five breaths. Switch sides and repeat.