Reddit mentions of Tapped Out: Rear Naked Chokes, the Octagon, and the Last Emperor: An Odyssey in Mixed Martia l Arts

It's impact is obviously significantly less pronounced, but it's substantial enough that in various forms of competition nobody really feels free not to take it.

I don't know most of what goes into the blends of supplements that pro athletes get, but the effects can be pretty marked. Matthew Polly, the author of Tapped Out, described his experience of getting the same supplements provided to pro fighters at an MMA gym, starting from no supplements, saying that it felt like he'd gotten ten years younger, that his blood was fizzing, that there was a night and day difference in energy.

Of course, steroids have an even more pronounced impact than that. And a lot of supplement mixes apparently do contain small amounts of steroids (urine tests and the like don't really definitively test whether you're on steroids, they test whether your hormone balance is far enough outside the norm that you can be decisively flagged as being on steroids.) But it's a long way from nothing. And it's not surprising if the most performance enhancing substances carry health drawbacks, because otherwise we'd probably have evolved to take advantage of the easy performance gains by incorporating them or something like them naturally.

There are a number of books like that. American Shaolin and Tapped Out by Matthew Polly are both entertaining reads about martial arts training. Iron and Silk by Mark Salzman is another. Zen in the Martial Arts by Joe Hyams.