Popsugar Fitness Workouts 15-Minute Ab Workout I'm a Trainer, and This Is the Ab Workout I Do For a 6-Pack December 6, 2018 by Tamara Pridgett View On One Page Photo 5 of 8 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 5 Reverse Crunch Lying on your back, lift your legs in the air with your knees bent. Place your hands on the floor beside you. Without momentum, use your lower abs to slowly curl the hips off the floor and into your chest. Slowly lower them back to the starting position. This counts as one rep. Complete 15 reps. Previous Next Start Slideshow WorkoutsStrength TrainingBodyweight ExercisesBodyweight WorkoutsAb WorkoutsCore ExercisesTrainer Tips15-Minute WorkoutsAb Exercises