Lie on your back on a bench with your legs in a tuck position and your hands underneath your hips. Shoot your legs out straight, creating a reverse plank position. Quickly crunch up and pull your knees back into a tuck. Pause a moment, then shoot them out again. Repeat steadily.
Do this exercise with the best exercise equipment. We recommend using a bluetooth chest strap heart rate monitor or a smartwatch for more training optimization & performance tracking.