If you are looking for an effective gut burning ab exercise, try the medicine ball V-ups. The exercise can be used as part of an abdominal training exercise program and is executed on the floor or mat with a medicine ball for added resistance.
The benefits of the V-ups include effectively working both the upper and lower abdominal muscles in a crunching motion. It will also use the core muscles as you must stabilize the low back, hips and abs while extending away from the crunch.
Holding the medicine ball in your hands, use a 2lb, 4lb, or 6lb ball and simultaneously raise your legs and hands until the ball touches the toes, then slowly extend both arms and legs toward the floor, hold and repeat. Draw in your naval toward your spine for added support and effectiveness.
You can find many core exercises used with a medicine ball complete with video and audio instruction at liveleantoday.com. Your online personal trainer will build a fitness routine for you and customize it to meet your specific needs.