If you want a core that can handle anything, the hollow body position  is where it starts. This hollow body HIIT workout  develops total-body tension, teaching your abs to stay braced against movement — the foundation of real strength. The Workout Format: 35 seconds work per move 15 seconds rest between moves 3 rounds total Rest 1 minute between rounds Moves: Hollow Body Hold Hollow Body Rock Bent Hollow Hold Benefits of This Hollow Body HIIT Workout Hollow Body Hold:  Streng