Not all of them, most do it IM as far as I know, but some of them definitely do. These people are using human grade gear tho... Who knows whats in some of the UG stuff. So I wouldn't really recommend it for someone cycling. Plus they use much smaller amounts than someone on a cycle. I personally wouldn't want to pump 2cc's into my fat lol. You can check out some other HRT forums, there are guys all over them doing it that way.