It's a placebo if you're not putting close to 100% into it, some will make a difference if you really push yourself, i.e. getting yourself so worn and have done so much muscle damage that you have trouble getting out of a chair or dressing the next couple of days, and doing that every lifting day for weeks. The people that do that are who the supplements are for. If you don't push yourself like that, you're probably better off spending that money on eating better. That said, I usually try to get some after workout protein since it seems to keep the hurt level down the next day or two.