Medicine ball crunch ups are a great, fun way to strengthen and tone the muscles in your core and arms. Be aware that for best results, it is advisable to have a friend helping you out with the exercise. It is possible to perform it on your own, but the exercise is not as much fun.

Medicine ball crunch ups are a great exercise that strengthen, tone and stabilize the core. In addition, this exercise targets the muscles in the arms. While it can be done on your own, it makes it much more difficult and decreases your efficiency. Therefore, it is advisable to ask a friend or fellow gym member if they can spare a few minutes by helping you with the exercise. Be prepared the offer the same favor back to them.

Before you perform the medicine ball crunch up, it is important to position your body properly. Start by setting a yoga or exercise mat down flat on the ground, and lay back on the mat with your head and back pressed firmly to the floor, and your knees bent with your feet flat on the ground. Rest your arms by your sides. Instruct the person who will be helping you to stand at least five feet in front of you, holding a medicine ball. For beginners, be sure to use the lightest weight ball available. You can always move up in weight as you become stronger.

Now that you are positioned properly, you can go about performing the medicine ball crunch ups. Start by taking a deep breath. As you exhale, use the muscles in your core to lift your upper body to a sitting position. At the same time, instruct your assistant to gently toss you the medicine ball. Ideally, you should catch the ball right when you are approaching the height of the sit up. Once you catch the ball, slowly lower your upper body back down to the ground, still holding the ball. Perform another sit up, and toss the ball back quickly to your assistant as you approach the top of the sit up. Again, have your assistant quickly throw the ball back to you. Perform at least 10 repetitions of this exercise before taking a short break. Do another 2 sets of 10 repetitions of the medicine ball crunch ups.

This exercise is relatively challenging. However, once you notice that it has started to become too easy, you must increase the intensity of the exercise. The easiest way to do this is by choosing a larger medicine ball. This will not only make the sit up more difficult, but will also force your arms to work harder to throw the ball.