AKA Ab wheel, evil wheel
The ab rollout is an exercise that strengthens the abs isometrically and the hip flexors dynamically.
Hold an ab-wheel or barbell with rotating sleeves with straight arms either kneeling or standing depending on your strength, the wheel close to the knees or feet. Roll the wheel out until your body is flat and roll back to the starting position. From the start, forcefully contract the abs to create a “hollow” position with the pelvis slightly posteriorly tilted (i.e. lower back flat) and do not allow this position to change—avoid hyperextension of the lower back.
The ab rollout is an exercise that strengthens the abs isometrically and the hip flexors dynamically to help train the ability of the lifter to stabilize the trunk and pelvis together and maintain their proper relationship during lifts.
Ab rollouts should be done for sets of 10-30+ reps.
Static holds in the extended position can be added, as can partial recoveries on each rep before recovering completely to the starting position.