Meet Your Abs - Your abdominal muscles are a lot like a skilled group of employees

The harder your abs work, the better they make you look, and vice versa.

This is because you use your abs in virtually every movement that matters. Lifting. Running. Jumping. Reproducing. (It takes a lot of midsection stability to stand over that copy machine. Especially when it's printing on both sides of the page.) So the stronger they are, the harder and longer you'll be able to play. Here's a quick course in the anatomy of your abs.

Rectus Abdominis
This is the six-pack muscle that helps your upper body bend (like in a crunch) and also helps keep good posture. It's what people think of when they think of abs.

External Obliques
These muscles start on the ribs and extend diagonally down the sides of your waist. If a movement happens at your waist, the external obliques are involved. The torso rotation that's key to golf, tennis, and hockey is mostly a function of the external obliques. Even the basic crunching motion, attributed to the rectus abdominis (the six-pack muscle), wouldn't be possible without a strong contraction of the external obliques to stabilize the torso.

Internal Obliques
These lie between the rib cage and the external obliques, and also extend diagonally down the sides of your waist. Similar to the externals, the internal obliques are involved in torso rotation. You use these muscles when you breathe deeply.

Transverse Abdominis
It's a thin muscle that runs horizontally, surrounding your abdomen. It's also known as "the girdle" because it functions as a compressor for the abdomen, keeping everything in place.