Both the crunch and the pike (shown on the next page) are great for targeting your abs. "It's hard to find a better belly flattener or core strengthener than these," Randy says.
- Start in a TRX plank position: face the floor and place your feet in the foot cradles with your straps under the anchor point. Point your toes to help secure your feet. Lie on your stomach and place your hands, palms flat, under your shoulders, then exhale and lift up your torso while engaging your butt and core muscles. Make sure your lower back doesn't droop, and keep a straight spine. Inhale and stay for a beat.
- As you exhale, pull your knees toward your chest while engaging your abs. Inhale and return to starting position.
- Repeat for 15 reps or for 30-60 seconds.