Ab Workout for a Flat, Tighter, Toned, Tummy If you're looking for a fun, effective ab workout, that will tighten your tummy, you're in the right place. This ab workout helps tighten abdominal muscles, improves core strength, and burns fat. The best part? This ab workout burns, only uses dumbbells and can be done in 20 minutes. It's perfect for busy women that want to exercise their tummy quickly at home or the gym. Here's the ab workout we're doing - Keep reading for tips on how to get a flat, toned, tummy! Why this ab workout works well