Yeah, it was an eye opener for me when he told me, but having cut me open and operated on me several times I figured he knew what he was talking about. It's very easy to get carried away in the gym, but it's essential to protect your greatest asset, which is of course your health. Everything must be done correctly to avoid injury. That link I posted earlier has a good safety conscious instructor, who calls himself Scooby, who has quite a following.