Different types of abdominal crunches use different patterns of movement or equipment that activate your muscles in various ways. You can modify many types of abdominal crunches by performing them on inclined and declined surfaces, or holding a weighted plate across your chest. Exercise variation helps keep your body in an adaptive state -- and you have a wide variety of abdominal crunches to choose from.
The standard crunch is a body weight exercise that isolates the rectus abdominis muscle. Lie face up with your knees bent and feet flat on the floor, or with your lower legs elevated and resting on a bench. Place your hands lightly behind your neck or head. Flex at your waist to raise your upper torso off the floor as high as possible, while keeping your lower back on the floor. Reverse the motion until the back of your shoulders hit the floor, and then repeat.
The cable crunch adds resistance to the crunch motion. Kneel below a high pulley equipped with a rope attachment. Grasp the cable rope attachment with both hands and pull the cable down behind your neck until your hands are near your chin. Flex your hips slightly and allow the weight to straighten your lower back. Bend forward at the waist to contract your abdominal muscles, and pull your elbows out over your thighs. Keep your hips stationary and maintain constant tension in your abs throughout the movement.
You can perform push crunches with dumbbells or a barbell. Lie face up with your head on the lower end of a steep incline bench. Secure your feet under the foot pad, and grasp the barbell or dumbbells with an overhand grip. Extend your arms straight up, and position the weight over your chest with your hands approximately shoulder-width apart. Bend forward at the waist to lift your upper torso off the bench as high as possible, while pressing your lower back firmly against the bench. Reverse the motion until the back of your shoulders hits the surface of the bench.
Stability Ball Crunch
The stability ball crunch is a top exercise for activating the rectus abdominis, and builds core strength by activating stabilizer muscles that help your abs perform each repetition. Sit on an exercise ball. Walk forward on the ball to roll the ball under your back. Bend your knees and hips, and let your head and shoulders hang off the ball. Extend your back along the curved contour of the ball, and place your hands lightly behind your head or neck. Bend forward at the waist to raise your upper torso while keeping your lower back against the ball.
Reverse crunches isolate your abs while emphasizing activity in the lower rectus abdominis muscle fibers. Lie down on the floor with your legs fully extended and arms outstretched along the side of your body with palms flat on the floor. Elevate your legs and position your thighs perpendicular to the floor to get into the starting position. Put your feet together with the bottom of your feet parallel to the floor. Contract your abs by pulling your legs toward your torso, rolling your pelvis back and lifting your hips off the floor. Bring your knees all the way to your chest, then move back to the starting position with your thighs perpendicular to the floor.
The tuck crunch combines elements of the standard crunch and reverse crunch. Lie down face up on the floor with your back pressed against the floor. Get into the starting position by crossing one ankle over the other and raising your legs to bring your thighs perpendicular to the floor with your knees slightly bent. Cross your arms on top of your chest, and slowly lift your torso while keeping your lower back firmly pressed against the floor. Slowly reverse the motion while keeping your legs stationary throughout the movement.
Twisting crunches emphasize your abdominal obliques. Lie face up on the floor with your knees bent and feet flat on the floor, or with your lower legs elevated and resting on a bench. Lightly place your hands behind neck or head. Bend at the waist to raise your upper torso off the floor as high as possible while twisting to one side. Reverse the motion until the back of your shoulders hits the floor, then repeat the motion twisting in the opposite direction. Continue alternating the direction of each repetition.