The side plank is an excellent body weight exercise which helps to develop the core muscles. This exericse is beneficial because it has low risk of injury and is very safe to do, plus you can generally do it from anywhere and without equipment. To help make the exercise a bit more challenging, you can incorporate a bosu into it as well.
A bosu is akin to the top portion of an exercise ball that has been affixed to a flat base. It adds in an element of balance to any exercise that you would normally do without a bosu and makes it slightly more difficult. Thus, a bosu side plank is a more advanced version of a standard side plank. To further augment the benefits to your core muscles and to your leg muscles as well, you can add in a leg raise to make this exercise even one step more difficult.
The basic positioning of this exercise is oftentimes the most difficult portion of the exercise itself. Place the bosu in an open and flat area. Rest so that your feet are next to the bosu. Lay on your right side such that your right elbow is underneath your body and your left arm is resting along the top of your left side. Your legs should be together and the outside of your right foot should be in contact with the ground. Lift your legs up onto the bosu so that your right foot is touching the bosu with your left foot on top of it. This is the resting position for this exercise.
When you're reading to begin, lift up your midsection and hips so that the only points of contact that you have with the ground are the right foot on the bosu and your right shoulder. While you hold yourself in this position, lift your left leg up directly above your right leg and hold it there as well. Ideally, you should rest in this position for about 10 to 20 seconds. Repeat the side plank with leg raise between two and four more times throughout the course of your workout.
Safety and Injury Prevention
It's best to practice this exercise without a bosu first. Because there is naturally some balancing work involved in the exercise, it's important that you be careful as you work out to avoid having any chance of falling over. Only when you're completely comfortable should you move to include the bosu as well. Always continue to breathe deeply as you workout.
This exercise is already a highly modified version of the standard side plank. There are few additional things that you can do to modify it. You can, however, strap a small weight to your free leg to increase the difficulty of raising it up. Also, be sure to flip over onto your other side to do the bosu side plank with leg raise in that position as well.