Want to Know What a Core-quake Feels Like? Try Jordan Chiles's and Simone Biles's Ab Workout

This circuit should be done without stopping, moving through a Superman with different arm positions demonstrated here:

• Hold 10 seconds of a regular Superman with your arms and legs out long, followed by 10 reps of rocking back and forth.
• Hold 10 seconds of a Superman with your hands by your ears and elbows out wide, followed by 10 reps of rocking back and forth.
• Hold 10 seconds of a Superman with your arms raised behind you and against your sides, followed by 10 reps of rocking back and forth.

The above video shows a modified version, where your feet are not lifted, only your chest.