Listen to what I read!
Yeah, at least 95 percent of that "pot lowers testosterone" stuff is bullshit. I about shit when "Dr. Drew" told some guy on a Loveline call in that his gyno came from him smoking pot when he was younger. What is he a doctor of? Voodoo? I have never seen any study verifying any of these myths and I've kept my eyes open.
But, on to the tagline: a while back I was reading in MD that there is evidence that Marijuana increases metabolism! Think about, it's got to be true- look at all these potheads that eat tons of junkfood and stay rail thin. I know I was like that when I used to smoke. Does that mean it's a performance enhancer? Not necessarily. But is there a possibility that marijuana would basically be a wash, and not hurt your training at all? All indications are yes.
As far as losing motivation, yeah, it can happen. But I know a few ironworkers who work like sum'bitches when they toke. Honestly, on a high rep day a little Mary Jane could be just what the doctor ordered, especially if you take some ephedrine and caffeine along with it.
Think about it, besides just getting high, might there be a reason that some pros use it? Imagine you were going to be doing high reps for your arms on the cables, trying to induce a heavy lactic acid burn. Some people would actually do more reps in that situation if they were stoned, it's that simple.
Personally my main problem with weed is it makes me paranoid, so I'm a little skittish about going to the gym stoned.