The decline sit-up is a bodyweight core exercise that works the rectus abdominis or "six pack" muscles. Sit-up variations are usually performed for moderate to high reps, such as 10-15 reps per set or more, as part of the core-focused portion of a workout.
Develops strength in the abdominal muscles and hip flexors
Benefits both aesthetic and functional goals
Can be progressed by increasing the decline angle over time or adding weight