Few people realize how important the abdominal muscles are. Not only do they give you a six-pack, but they also help support the spine and keep the internal organs in place. Unfortunately, they are also one of the most difficult muscle groups to train.
There are two types of abdominal muscles: the rectus abdominis, which runs down the center of the stomach, and the obliques, which are on the sides. The key to a good workout is to target both types of muscles.
There are a number of different exercises that can be done to work the abs. One of the most effective is the plank. To do a plank, you need to get into a push-up position, but rest on your elbows instead of your hands. Hold this position for as long as you can.
Another good exercise is the sit-up. This is a bit more traditional, but it is still effective. To do a sit-up, lie on your back with your knees bent and your feet flat on the ground. Place your hands behind your head and slowly sit up, making sure to not use your momentum to swing up.
There are many other exercises that can be done to work the abs, but these two are a good place to start. Remember to focus on both the rectus abdominis and the obliques for the best results.