Nancy and I present the BOSU jackknife, an ab exercise that uses both a BOSU (a sort of Swiss Ball chopped in half) and a medicine ball. If you're a fan of Blaine Moore's series on bridge exercises, then this exercise might be a nice next step up the ladder of difficulty.
In this video analysis (Quicktime, 7.6 MB; Google video, no download), Nancy and I (Bud) present the BOSU jackknife, an ab exercise that uses both a BOSU (a sort of Swiss Ball chopped in half) and a medicine ball. The exercise keeps constant tension on the abs and like our Swiss Ball jackknife has a significant stabilization component that works the obliques. If you're a fan of Blaine Moore's series on bridge exercises, then this exercise might be a nice next step up the ladder of difficulty.
To perform this exercise, position your back on the center of the BOSU as Nancy and I illustrate in Photos 1 and 3 on the left. Then grasp the medicine ball directly over your head. Nancy and I both use a 9 lb. medicine ball. Choose a light one to start. It adds difficulty to the exercise by lengthening the torso (i.e., the length of the lever you are exerting force on) and adding weight to boot.
To execute the exercise, place one of your feet on the ground for stability and stretch the other out flat. This second foot should be close to the floor but not touching. Then, as Nancy and I illustrate in Pictures 2 and 4, simultaneously perform a crunch with your upper torso (holding the ball over your head) and lift the knee of your extended leg to touch your elbows. Next, reverse the movement to return to the start position. Make sure the extended leg does not touch the floor. Repeat 15 times for one leg extended before switching to the other.
If executed properly, this exercise will keep constant tension on the abs and give you a real abs workout. Cheating in this exercise involves removing tension from the abs. One way to do that is to touch your extended foot to the floor. When you first try this exercise, you may find yourself having to touch your extended foot to the floor out of necessity, but you should try to avoid it. Another way to cheat is to let your arms do some of the work in moving the ball up and down. If you carefully examine the strip of photos on the left, you will notice that Nancy and I keep the ball in a constant position relative to our heads.