What are abs?

The abdominal muscles are the four big ones that shape the outer appearance of your stomach. 

> the rectus abdominis links the trunk to your lower limbs. This is the muscle we work through traditional stomach exercises. A well-defined rectus abdominis is also known as a six-pack! 
> the internal and external obliques are located to the side of the centre of your stomach and define your waist.
> the transverse muscle is the deepest lying muscle. It wraps around the centre of the trunk from front to back, and it contains and supports the abdominal organs. You use your transverse when you breathe in.