Machine Curls
Muscles Targeted To do these, you must be Ninja-like. Helps with stealth tactics.

Since Dave has been Joe Bodybuilder, he has been training by himself. He will train at odd hours of the day. I assumed it was business oriented or he structured it around meetings,etc.

I don't think so.

He trains alone because he knows he's going to be doing exercises like these. And these are best done when no one is around. It's like masturbating; you really don't want anyone to catch you unless you're a sick individual.