Looking for an edge, however slim, when you're stepping into a cage to fight seems inevitable. The gruelling training in advance of a mixed martial arts bout also takes a toll, prompting some to take shortcuts. And given fighters only get paid for competing, there is incentive to roll the dice and do what's needed to make it to fight night.
Still the latest doping scandal is a body blow to the MMA juggernaut given the star quality of the offender.
The UFC revealed Tuesday night that former middleweight champion Anderson Silva, one of the sport's icons, had tested positive for steroids on a Jan. 9 out-of-competition drug test. Adding to the scandal was the news that Nick Diaz, the man Silva beat in the main event of UFC 183 last Saturday, had tested positive for marijuana for a third time.
The news comes on the heels of a positive cocaine test prior to UFC 182 for light-heavyweight champion Jon (Bones) Jones, who succeeded Silva as the sport's pound-for-pound best fighter.
"Does anyone in the UFC actually follow the rules?" former Olympic and world wrestling champion Jordan Burroughs tweeted after the latest drug tests.
The rules are enforced by bodies like the Nevada State Athletic Commission, which tests boxers and MMA fighters alike in regulating their sports.
So-called social drugs are not considered performance-enhancing. But they are subject to sanction if detected fight night given the concern that fighters could suffer unnecessary damage if dulled or anesthetized by such drugs.
While Silva issued a statement denying doping and Diaz has yet to tell his side of the story, a thin doping line runs through the sport. Other organizations are not exempt from cheating but the spotlight shines on the UFC as the sport's major player.
Welterweight Thiago Alves, who beat Canadian Jordan Mein on Saturday's card, was suspended and fined in 2007 when a UFC 66 drug test showed traces of a diuretic.
German bantamweight Dennis Siver, who lost to Irish star Conor McGregor in the main event of a Boston card last month, tested positive for human chorionic gonadotropin at UFC 168.
Ashlee Evans-Smith tested positive for a diuretic at UFC 181 in December. The list goes on, with a nine-month ban and fine the usual punishment for a first offence.
With 45 shows planned for 2015, the UFC conveyor belt never stops. The organization currently has 575 fighters under contract.
Most need to fight to pay the bills.
Lightweight Donald (Cowboy) Cerrone, one of the UFC's busiest fighters, says he spent US$20,000 alone just to bring in sparring partners to help him train for Myles Jury at UFC 182.
Brazilian light-heavyweight Thiago Silva admitted to doping and tampering with his urine at a UFC 125 drug test in January 2011. He said his slide into doping started with a severe back injury shortly before facing Rashad Evans in the main event of UFC 108 in January 2010.
"It was the biggest fight of my career and there was no way I was going to pull out of it,'' he revealed in 2011. "I fought and lost and was out of action for a year rehabilitating the injury and getting ready to fight again.
"I reinjured my back 45 days before the (UFC 125) fight with Brandon Vera. After not fighting for a year, I made the decision to not pull out of the fight."
The only way to continue, he decided, was cheating — injections of a prohibited substance in his back and spine.
James (The Sandman) Irvin battled prescription drugs during his fighting career. He says he just has to look in the mirror to see the scars they left.
The light-heavyweight was knocked out brutally in 61 seconds when matched against Anderson Silva, then middleweight champion, in July 2008. Two weeks later Irvin was told he had tested positive for two unapproved painkillers: methadone and oxymorphone.
"The Anderson Silva fight, I have 25 stitches across my cheek from when he blasted me,'' Irvin said in a 2011 interview with The Canadian Press. "Every day when I look in the mirror, I have a clear reminder of what those drugs did to me and what lies ahead of me if I was ever to start using that garbage ever again.''
The painkillers dated back to knee surgery following a 2007 fight with Thiago Silva. He was prescribed Vicodin and said he had no trouble stopping taking the pills after three months.
But he kept getting injured. And Irvin, who at one point was training with a broken bone in his foot, kept taking the pills.
"It wasn't until a time that I just stopped taking them that I realized I needed them just to keep on functioning,'' he said. "At that time I had become an addict and I was hooked on them."
The UFC has also stretched itself by taking over testing duties itself when venturing into countries that do not have the framework in place to do it themselves.
Things came to a head last August when Cung Le's post-fight blood test in Macau showed elevated levels of growth hormone. Le's camp subsequently protested both the suspension and testing procedure.
UFC president Dana White said prior to UFC 182 that his organization, rather than launch its own full-time drug-testing program, would probably give athletic commissions more money for them to conduct testing.
White said the UFC's legal team subsequently "screwed it up." And he said he feared further mistakes.
"We have no business doing drug testing ... that's what the commission is there to do," he said.
"We'll help fund it so that they can do better drug testing, more drug testing. They're the regulators," he added.
Asked what the UFC will do in the future in commission-free zones, he directed the questions to Marc Ratner, the UFC's vice-president of regulatory affairs. Ratner did not offer an immediate answer.
Given the sport's makeup, there may not be one.
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