If you want a balanced midsection, you can’t just train the six-pack muscles. Your obliques — the muscles down the side of your core — are essential for rotation, balance, and overall strength. This oblique HIIT workout  will challenge your side abs with three killer moves. The Workout Format: 35 seconds work per move 15 seconds rest between moves 3 rounds total Rest 1 minute between rounds Moves: Russian Twist Heel Touches Alternating Cross-Body V-Up Benefits of This Oblique