This exercise develops core function, strength, and control in a manner similar to various tricks with Freeskiing. Very similar to a mute grab while hanging from a pull-up bar, the exercise requires contraction of the core for stability, combined with hip flexion and a vertical body position to bring the legs up to the upper body, which contrasts from many supine/ground core exercises.
To start: find a vertical bench at your gym. (You can also do this exercise on a pull-up bar.).
Contract your abdominal muscles and tuck your feet up towards your butt, with your knees pointing up and to the right. Return to the starting position.
Contract your core, lift and twist your legs to the right.
Contract your core, and lift your legs straight out in front of you, parallel to the floor.
Control your movements—try not to let your body weight swing when you lower or raise your legs.