Low-back pain is plaguing the nation! And if you, bike, or sit too much, tight hips could be contributing to the ache around your spine. A major hip flexor muscle, the psoas, not only draws the thigh toward the abdomen, but is also attached to the five lowest vertebrae of the spine. When the psoas shortens and tightens from activities like sprinting or cycling, it can pull on the vertebrae, creating a sensation of tightness in the low back. The good news is that stretching out the hip flexors can alleviate a lot of lower back pain. Once you are warmed up, and after every workout, you should stretch your psoas.