I think these are a bit like steroids though. They don't work on their own; you still have to train.

See this graph from [1] http://myzone-strengtheory.netdna-ssl.com/wp-content/uploads...

> Yes, you’re reading that chart correctly. The group that took a placebo and worked out only gained slightly more strength than the group that took testosterone and sat on the couch for 10 weeks. The group that took testosterone without exercise gained just as much, if not more, muscle mass than the people taking a placebo and actually working out.

[1]: http://strengtheory.com/the-science-of-steroids/