The modified V-sit is an intermediate level abdominal exercise that requires balancing on your sit bones while your torso and legs are lifted in the air. This is very effective abdominal exercise when performed correctly. The key is to fully engage your abdominal and upper back muscles for stability rather than relying on momentum.

Some people incorporate a medicine ball into the V-sit. A modified V-sit ab exercise will help you build form and core strength if the full version is too challenging. Instead of the legs being straight throughout the movement, the knees bend at a 90-degree angle and are brought toward the chest as you lift.

The modified V sit works on your internal obliques, external obliques, rectus abdominis, and hip flexors (2). This results in core strength, as it simultaneously hits multiple areas of your torso. The modified V sit can also slightly activate your shoulder muscles, depending on which variation you choose.