LAS VEGAS -- Thickly put together like the weight-training enthusiast he is, Dr. John Pierce is a feisty character who finds himself in the crosshairs on the TRT issue with the Nevada athletic commission, particularly its medical consultant Dr. Timothy Trainor, himself an ex-amateur boxer. The two trade prickly barbs, from a distance, like a couple of cranky teenagers.

Recently, Trainor championed the fight to remove Pierce - medical director of the Ageless Forever clinic -- and what he deemed other non-traditional practitioners from the commission application process for a testosterone exemption. As commissioner Pat Lundvall explained, applications were coming from "age-management clinics -- or somebody that advertises everything from Botox to hormone replacement therapy to delivering your baby and fixing your foot."

Nevada athletic commission medical consultant Dr. Timothy Trainor. Mike Fish/ESPN.com

To that end, Nevada now requires that applications include a medical history performed by a physician board certified in internal or family practice medicine, endocrinology or urology -- none of which covers Pierce and his emergency medicine or anti-aging certifications. Also required is an annual letter from an endocrinologist affirming the fighter's need for TRT.

Trainor, an orthopedic surgeon, claims Pierce came on his radar after failing initially to submit proper lab work with fighter Frank Mir's application in 2012. In response, Trainor acknowledged recommending the fighter find another doctor. He also warned Jeff Davidson, his counterpart with the UFC, about Pierce, saying "I don't trust him."

If he had his druthers, Trainor said he'd turn down every testosterone request, if not for the fact it would invite potential lawsuits. Of the six approved by Nevada, most, if not all the fighters were already under a doctors care for TRT or had prior exemptions from other states."The point is they already have been on the stuff, so the normal hoops you would jump through to prove that you have it -- we can't do that unless we stop your medicine," Trainor said.

However, the major anti-doping agencies do exactly that in similar instances. Athletes on testosterone therapy and applying to USADA for an exemption, for instance, must discontinue use for up to two months before baseline testing, thus staging a tougher fight for hormone replacement advocates.

Perched behind his office desk, Pierce is staunchly convicted that he knows more about hormones than most endocrinologists, let alone his adversary who operates on knees and shoulders. He claims no referral relationship with the UFC, saying he's treated only a handful of fighters and some retired NFL players.

Yet he's a true believer in regenerative medicine, suggesting no damage is done allowing athletes to juice up their testosterone to normal, healthy levels -- maybe even an older fighter getting his levels back to where they were when he was 20 or 25. Nor does he see an issue granting such a pass to the likes of title contender Vitor Belfort, who previously failed a steroid test.

In his eyes, perking testosterone levels isn't breaking rules. "These guys that say testosterone is a bad thing, I think they all should be orchidectomized," said Pierce, agitated in particular by the anti-doping crowd. "They should all have their balls cut off and see how it feels not to have any testosterone. And then they'll see how beneficial testosterone is."

Without pause, Pierce broke into an unsolicited, personal rant, describing a respected anti-doping leader as "big and fat." He suggested the physician, who serves as a medical adviser to the federal government, "get on some testosterone and stop hanging out with your friend -- the king, the clown and the jack-in-the-box."

He further voiced disdain for professional colleagues he labels uneducated for not having read what he believes to be evidence-based literature, adding: "You cannot make blanket statements in medicine: 'Nobody needs this. It is all quackery.' Yeah, well, what you're saying is quackery -- I can show you the evidence-based medicine that actually proves that people actually do benefit from testosterone therapy and it is healthy for you."