Works: Core
Lie faceup with hands behind head, elbows out to sides and legs extended on the ground. Lift head and shoulder blades as you pull knees toward chest [A].
Lower head and shoulder blades as you slowly extend legs 45 degrees off ground, keeping abs super-tight; repeat [B].
If moves that engage the lower abs like this one result in back pain, try these standing core exercises to target those difficult to reach muscles injury-free!