The Side-Plank Up ab exercise works your rectus and transversus abdominis, obliques, and inner thighs.
-Cinch-It Secret: Side Plank-Up. Get into side plank position and place a rolled up towel between your thighs. Then, lift your hips off the floor so your body forms a straight line. Squeeze the towel throughout the move to tone your inner thighs. Do 10 reps, then switch sides and repeat. Do 3 sets total.