"I would definitely say somewhere in the percentage of 85 percent of guys are definitely using, especially the guys who can afford it are definitely using," said Soszynski. "I would even go as high as 95 to 96 percent of the top level athletes that are definitely using it. You can clearly see it."
Soszynski has been out of action with a knee injury since his decision victory over Mike Massenzio at UFC 131 in June, but the rehab process opened his eyes to the easy availability of performance-enhancers in MMA, he said.
"I even had someone talk to me about stem cell injections. You're looking at stuff like EPO, and at least five or six different counterfeit drugs out there that people are using and they're not even detectable in the body. It's just amazing to me how far athletes are willing to go to make their mark in this sport."
At the same time, Soszynski expressed a degree of empathy for PED users in MMA, and expressed doubt that the problem could ever be fully eradicated.
"If there's a substance you can take out there that's going to make you bigger, stronger, more explosive, going to help you train harder, going to help you train longer, and it's going to help with your recovery as well, and you know if you take it the right way and follow the right instructions, you'll never get caught for it, wouldn't you take it?"
Soszynski said the current system that most athletic commissions use of testing fighters just prior to fight night is completely ineffective, since that's when "you're only going to catch the dumb guys, who have no idea what they're doing."
Instead, he said, MMA needs random, out-of-competition drug-testing.
"I totally agree [with random testing]. Ten weeks out, eight weeks out, six weeks out -- that's when all the training happens. That's when you're training at your hardest, at your peak. Every athlete who knows how to train properly knows they're going to have to taper off two weeks, two and a half weeks out from their fight so they'll be in perfect condition for their fight. All the hard training happens eight, ten weeks [from the fight]. That's the time when everybody's doing their drug abuse and that's when they're taking their testosterone and their steroids. That's when I think fighters should be tested."
As for fighters like Nate Marquardt and Chael Sonnen, who have recently argued that they have a legitimate medical reason to undergo testosterone replacement therapy, Soszynski said that it creates an uneven playing field to allow some fighters to inject themselves with hormones but not others.
"My thought on that is very simple: either everybody does it, or nobody does it. If guys are doing it and the commissions are allowing these guys to do it as long as they get to a certain level within their bodies, then we all should be allowed to take it as long as we get our levels to a certain number. That's what I believe."
Soszynski, who's no stranger to a pro sports drug culture after experiences with pro wrestling and competitive bodybuilding, added that while most fighters might be on PEDs, he's among the small percentage that isn't.
"I haven't used [PEDs] for mixed martial arts," he said. "Back in the days when I was a bodybuilder, obviously it was a little different. But for mixed martial arts, I don't. I don't believe in it."
As for whether that puts him at a disadvantage, Soszynski said he knows of "a bunch of guys in the sport who don't [use PEDs] and who are very successful," but at the same time, "I feel like we should be on an even playing field."
Then again, just because Soszynski might want it that way -- and might fear for MMA's reputation in the long run if it doesn't address the PED issue -- that doesn't mean he's terribly optimistic about the chances of weeding it out completely.
"It's just part of guys trying to become the best," said Soszynski. "You want to become the best, you're going to do anything and everything you can to become the best, and this is one of those things."