[Rev]

Concerning chest flye's, here is some grade A info on the exercise in general taken from a different thread, posted by Lou.

Originally posted by Lou Schuler:
My guess -- and I'm sure Craig and the others who've actually been educated in this subject will let me know if I'm wrong -- is that you're sore near the shoulder joint because you've strained some connective tissue, not because of anything to do with the way the muscle fibers fired or didn't fire.

If it were truly delayed-onset muscle soreness, you should feel that right in the middle of the muscle.

A slightly different scenario:

Let's say you haven't done dips in a while, but for some reason you decide to do some heavy weighted dips. Chances are, you're going to feel extremely sore right in the middle of your chest, along the sides of your sternum.

Is that because the exercise somehow worked your "inner" chest? No. It's because you did something your body wasn't prepared to do
, and you damned near ripped your muscle fibers away from their attachments.

As for the fly, try this experiment:

Put your right hand on your left pectoral. Now pretend you're doing a bench press with your left arm. Feel the way your left pec contracts.

Now pretend you're doing a fly. Does it feel any different?

It shouldn't.

That's because the only difference between a bench press and fly is the position of your lower arm. But your lower arm has nothing to do with the action of your pectoral muscles. Their job in both exercises is horizontal flexion, or adduction, meaning they bring your upper arm in toward your torso.

All a fly does is increase the lever arm, which in my view means it puts your shoulder at greater risk without doing anything for your pectorals that a bench press couldn't do.

Just one man's opinion, but I've always felt that was one of the highest-risk, lowest-reward exercises in the gym. You know, if you can't fully work your pectorals with heavy sets of bench presses, you're doing something wrong.

(And yes, I know Ian has chest flys in the early stages of the programs of Book of Muscle. He likes isolating muscles at the beginning of a program, and then working up to the heavy, multi-joint exercises. But I assume you aren't in the beginning stages of a program.)