Home Exercises for Fit Abs

The Ab Circle Pro is a piece of home exercise equipment that is touted as "the treadmill for your abs." The advertisements claim that the machine is better than a normal stomach crunch and that spending three minutes on it is the equivalent of doing 100 situps. The fact is, the Ab Circle Pro is neither better nor worse than doing normal crunches, just different. Both exercises are effective at strengthening your abdominal muscles and challenge them in different ways.
Abdominal Muscles
The abdominal muscles of the human body are the rectus abdominus, transverse abdominus and obliques. The word abs is a misleading one because it is not a scientific term. Many people will use the word abs to describe a single abdominal muscle even though the word itself is plural. When you say that someone has "six pack abs," what you're really referring to is their rectus abdominus, which is a single, paired muscle. The Ab Circle Pro claims to work your upper, middle and lower abs, but this is also misleading because they are all the same muscle.
Rectus Abdominus
The rectus abdominus is the muscle many people are thinking of when they talk about abs. It is the muscle that helps you maintain your posture and move your torso in a curling motion, such as doing a crunch or a situp. A regular crunch is more effective at working your rectus abdominus than the Ab Circle Pro because when you do a crunch the primary muscles used are the rectus and transverse abdominus. When you use the Ab Circle Pro, the primary muscles used are the obliques and transverse abdominus.
Transverse Abdominus
The transverse abdominus is called the corset muscle because it is located deep within your abdominal wall and is the muscle you use to suck in your stomach. Aside from pulling in your abdominal wall, your transverse abdominus is also responsible for supporting your posture and lateral flexion, wich is moving your torso from side to side. When you do a regular crunch, you are exercising your transverse abdominus. However, when you swing side to side or back and forth on the Ab Circle Pro, you are also exercising your transverse abdominus, so regular crunches and the Ab Circle Pro are both good at working your transverse abdominus in different ways.
Obliques
Your obliques are the muscles on each side of your abdominal wall. You use your obliques whenever you twist your torso or move your torso side to side. They are the primary muscles being used when you workout on the Ab Circle Pro. They are the secondary muscles you use when you do a regular crunch, so the Ab Circle Pro is better than a regular crunch when you are trying to target your obliques.