• A great set of abs can be a sign of fitness.sexy man with washboard abs image by MAXFX from Fotolia.com
  
  Working on your abdominal muscles can help increase flexibility, core strength and overall strength. While "six-pack" abs might be aesthetically pleasing, there are also fundamental health gains from working to have a flatter stomach. Decreased weight and fat in the abdominal region takes stress off the lower back.
  
  

Captain's Chair Crunches

• These are done while your body is suspended by the forearms, with your back against a cushion, using a machine found in any gym. Alternatively, straps can be used that serve the same function by suspending the body.
  
  With the legs hanging beneath, draw the knees toward the torso. Use your ab muscles. For increased difficulty, lift the legs while they're extended out from your body through the movement.
  
  

Plank

• Assume the top of a push-up position with the torso supported on your forearms and toes. Stabilizing the body by contracting the abdominals, hold the position for a few or several seconds.
  
  

Exercise Ball Leg Lifts

• Lying on your back, hold an exercise ball between your legs. Lifting the legs, make sure to hold the ball between your legs for the entire movement. Never lift your legs high enough for your lower back to come off the floor.
  
  

Traditional Crunches

• Sometimes there is no substitute for a classic. Lying flat on your back, support your head with your hands and lift with the abdominals until the abs are contracted to their highest point. It is important to not pull the head with the hands, but instead engage the abs to lift the upper torso.
  
  

Exercise Ball Crunches

• Performing a traditional crunch while balancing the torso on an exercise ball is an effective way to target the abdominals. The movement remains the same as a traditional crunch. However, it's important to not allow the lower back to come off of exercise ball at any point during the exercise.