Sit on the floor with your knees bent and lean back slightly until you feel your lower abs engage. Hold the ends of the foam roller with both hands.
Lift both feet off the ground, balancing on your tailbone. Try not to round the back by keeping your abs engaged and lifting your chest up.
Rotate your torso to the right using your obliques (the muscles on the sides of your belly) to power the movement. The end of the foam roller will be a few inches off the ground to the right of your belly.
Rotate your torso back to center and perform the same twist on the left side.
This completes one rep.
Perform three sets of 24 reps, followed by a 30- to 60-second rest.