Form

• Crunches are meant to work your abs and should never cause pain in your neck or back. To do a proper crunch, lie on your back with your knees bent and your feet flat on the floor. You can do them with your legs straight on the floor or in the air, but it is best to bend your knees first, as it is less risky. Fingertips should be placed behind the ears, not hands to head. It is too easy to pull on your neck if your hands are behind your head.
  
  Your chin is lifted from your chest as if a tennis ball was between your chin and chest. Your neck is straight in line with your spine. This is easy when you are lying on the flat ground, but be sure to keep this alignment as you crunch. Contract your abs by pulling in your belly button and pushing your low back into the floor.
  
  Crunch up to 30 degrees from the floor, which is just enough to clear your shoulders. Do this with a controlled speed so no momentum is being used. Keep the elbows open wide. Exhale as you lift, hold the crunch for 2 seconds, and then slowly lower yourself to the floor as you inhale.
  
  

Frequency

• The abs are hard muscles to fatigue or injure. You can therefore do crunches safely 3 to 5 days a week, as long as you are doing them correctly. Start with 2 days a week and take days off in-between to recover. Add a day every 2 weeks until you get to 5 days a week. Beginners may only be able to do 10 crunches at a time. Do two sets of 10 at first and work up to three sets of 20 or more.
  
  

Ball Bicycle Crunches

• The abdominal muscle group comprises the rectus abdominus, obliques and transverse abdominus muscles. Standard crunches target only the rectus abdominus, which is the muscle that makes up a "six pack," but all of these ab muscles should be worked. Once you can easily do standard crunches because you have built up ab strength and muscle memory, try ball bicycle crunches. Ball bicycle crunches strengthen all the ab muscles.
  
  To do them, lie on your back and extend your legs straight at a 90 degree angle to the floor. Hold a stability ball between your shins and squeeze it tightly. Place your fingertips behind your ears. Crunch your shoulders up off the floor by contracting your abs and exhaling. Twist your shoulders to the left, and simultaneously twist your hips to the right. Return to the mat as you inhale. Crunch up again and twist in the opposite directions. Do five reps per side and work up to 10.