Starting the position by getting into the top of the push-up position, keep your back in a straight line, bring your left knee toward your chest, then quickly bring it back to the starting position. Now, bring your right knee towards your chest and quickly return to starting position. As you’ve mastered the movement, alternating legs quickly as if you were running with your hands placing on the ground. To increase pressure on your abdominal muscles, placing the palms of your hands on sliding discs such as Valslides, paper plates, weight plates and the like.
Starting the position by lying on your back on the floor with legs widely extended and your heels touch the floor while stressing your arms straight above your head and your hands touch the floor. Slowly bend both legs while bring your knees to your chest at the same time wrapping your arms around your knees. Then, release your knees, your legs and extend arms, putting your heels back to the ground. To increase the difficulty, always keep your heels off the ground throughout the practice.
5. Oblique Crunch
Starting the position by lying on your back on the floor and keeping your legs bent in the air at a 90-degree angle while placing your hands behind your head with your elbows flared out to each side. Stimulating twist your torso to move your left shoulder toward your right thigh until your upper back is off the floor and your left elbow is close to or touching your right knee. Lower yourself gradually back down to the starting position. Repeat the movement by rotating your right shoulder toward your left knee. Alternate reps between your right and left sides. This is different from a bicycle crunch or air bike, where you keep your legs moving above the ground the entire time. Instead, as soon as your elbow and knee touch, back to the starting position before switching sides for the next rep. For a more intense exercise, kick one leg out straight while bringing your elbow to meet the other.