While prone on the floor, place a lacrosse ball 1 to 2 inches to the right or left side of the belly button. Put your forearms on the floor for support. Roll the lacrosse ball down towards your femur, using small movements. The psoas accelerates hip flexion and decreases hip extension. Its the most powerful hip flexor in the body, and is used in every running stride. It is often overactive with runners and people who sit at their jobs.

While prone on the floor, place a lacrosse ball 1 to 2 inches to the right or left side of the belly button. Put your forearms on the floor for support. Roll the lacrosse ball down towards your femur, using small movements. The psoas accelerates hip flexion and decreases hip extension. Its the most powerful hip flexor in the body, and is used in every running stride. It is often overactive with runners and people who sit at their jobs.

Original article and pictures take https://active.com site