Why: Helps the range of motion at the hip, which can increase running-stride length (and speed) and prevent hip flexor tendonitis.
Who: Runners, cyclists, and swimmers.
How: Lie with the roller under the front of your hip. Keep your opposite leg extended, with the hip rotated outward and the instep of the foot on the floor. Lift the other foot an inch or two and roll the hip back and forth.