Originally Posted by Rickson
Cal, I never met Purvis in person, but I met guys who trained directly under him at NASM and I'm not talking about his clients. Purvis was the inventor of the 6 steps to exercise utilized by NASM. You probably saw this guy in those bowflex commercials. He's the guy who points at the exercisers' bodyparts and says
"look at those muscles working!". Purvis left NASM to work with Bowflex. I'd suspect Purvis is promoting some Bowflex exercise if he says dips are bad for you. Purvis is known as Mr. alterior motive.
No, it wasn't related to bowflex. He had his owns series of videos about his theories of safe and effective lifting technique and training. I think I have some of them around. If I recall, the exercises he thought were bad for you were dips, behind the neck pulldowns, maybe sled leg press -- incline leg press was ok, though -- and possibly decline presses. Also some other machines or exercises that I can't recall now that he believed made your muscles/joints move in unhealthy ways.
I talked to him on the phone once years ago. He seemed like a enthusiastic guy who was passionate about encouraging safe and effective training. He may be wrong in his beliefs, or a shyster of some sort, but he seemed geniune.