The 5 Hardest Ab Exercises Known to Man

The hanging knee raise is a regression of the move, but it’s still tough, says Ballantyne. It’ll engage the same muscles as toes to bar, but the load will feel lighter since your legs are closer to your body.

DO THIS: Grab a pullup bar with an overhand grip. Pull your shoulders down and away from your ears and hold them there. Create tension in your arms and throughout your core by pulling down on the bar as hard as possible. Bend your knees and curl them up toward your chest. Pace yourself: Lift for two seconds and lower for two seconds. Do 10 reps—or as many as you can—for 3 sets.

Once you master the hanging knee raise, try the hanging leg raise in an ab workout. Follow the directions above, but with only a slight bend in your knees. Take two seconds to raise your legs until they are parallel to the floor, and then two seconds to lower them. Perform as many reps as you can for 3 sets.

Follow this routine three times a week for two to four weeks, says Ballantyne. By that time, you should be able to do one or more reps of the toes to bar.