Written by Stephen E. Alway, Ph.D.
Slice & Dice Your Lower Abs with the Reverse Crunch
The muscle fibers in the lower abdominal wall are pretty hard to isolate and very difficult to tighten. Although the lower abdomen is activated to some degree by regular crunches and incline sit-ups, typically the muscle fibers in this region do not get a lot of direct stimulation from these exercises. This is because maximal activation demands that the anterior part of the pelvic bones is rotated slightly upward. This is achieved in a very strong fashion by the reverse crunch.
The reverse crunch is so effective, because it shortens the fibers of the lower regions of the abdomen, as it invokes an upward pelvic tilt at the beginning of each lift. Furthermore, this exercise maintains near constant tension in these muscle fibers throughout the exercise. The reverse crunch will transform your lower abdomen better than that which can be achieved by traditional crunches or leg raises.
What You’re Working
Both the external and internal oblique muscles on each side of the waist are activated by reverse crunches, but they primarily act to stabilize the trunk. The external oblique muscle runs from the lower ribs by small bundles of muscle fibers from lateral to medial. The external oblique fibers anchor on the iliac bones of the pelvis, the hip structure and the linea alba. When both the left and right sides of the external oblique muscles work together, they flex, which helps the trunk move the thighs toward the head during reverse crunches.
Get It Done
As the name of this exercise suggests, reverse crunches will take the normal crunch and do it backward. Instead of crunching your head and torso toward your thighs as in a normal crunch, the reverse crunch will raise your thighs, hips/pelvis, and legs toward your face.
1 - Lie supine (face up) on flat bench. Grab the edge of the bench next to your head with both hands.
2 - Flex your knees and hips so that your thighs become perpendicular to floor.
3 - Curl your pelvis toward your head (this is only a few degrees of movement). Next, lift your pelvis and lower back upward, and move your knees toward your head by lifting the lower back off the bench. Try to concentrate on feeling your lower abdominal fibers contract as you lift your hips and legs upward.
4 - Keep your knees flexed and your thighs parallel to the floor as you slowly return your legs and hips to starting position.
5 - As soon as your sacrum and coccyx (tailbone) of your posterior pelvis hits the bench, start upward for the next rep.
6 - Repeat for 20-25 reps in a slow and deliberate fashion. This should take about 2 seconds to lift the thighs and 2-3 seconds to come down. Work up to 3 sets.
*If you can get 3 sets done without too much effort, it is time to progress to a decline bench. This is done in the same way as the flat bench, but the head is at the high end of the decline bench and the feet start at the low end of the bench and this increases the effort needed to move the legs upward.
Note: You should not hold your breath during the reverse crunch, because this would elevate your intra-abdominal pressure and prevent the abdominal fibers from shortening properly when you lift your legs. Instead, you should either exhale as you are crunching your feet toward your head.
Reverse crunches have a rather small range of motion, but it delivers big results for the lower abdomen. If you do the exercise correctly, the fibers in your lower abdominal wall should feel as though they have been through a shredder. If this is the sensation that you are experiencing about midway through your first set, then you will know that the transformation from your old waist to a sliced lower abdomen has begun. The best news of all is that if you start today, you still have time to get your abs in outstanding shape for this summer.