Contract your abs to lift and raise your glutes and lower back off the floor. Hold this position at the top, then lower back to the start and /511952-mad-muscles-reviews-by-android-users/ repeat. Flutter kicks hit the lower abs and hip flexor muscles, activating your lower back. The move also requires core stability to stay in a crunch Read more about 63 Bodyweight Abs Exercises to Simplify Your Fitness Routine[…]