look up registration statistics on steroid forums, subreddits, and ask some guys who workout and juice at gyms; ask dealers.
you can find out a lot just by talking to the right people.
Look; back a few years ago when guys like me were saying that guys like Nick Bare were juicing, some of you guys resisted.
Now, it's apparent and without a shadow of a doubt that we were right. Everybody is juicing.
Obviously there are exceptions, but the fact is, some of the most competitive-spirited folk who are some of the most successful folk are also some of the best at keeping a secret and trying their damnedest to hide it.
And for some of them? Getting a prescription for inhaled albuterol, pinning gh from a doctor, pinning insulin after a hard workout, and taking TRT prescribed by a doctor and keeping them under 1200ng/dl will allow them to pass tests and perform at their highest without issues.
And on top of that, they're using PEMF, red light devices, acoustic wave therapy (Gainswave basically), and something like DSIP to enhance sleep, perhaps other peptides, too. Maybe BPC and TB-500. Doctors can prescribe those, too, and I doubt the athletes get tested for them regularly