You'll read a lot this week about 44-year-old Dan Henderson, a throwback to a simpler time in the sport of mixed martial arts. In the days before biological passports and year-round random drug testing, before, MMA fighting was even a full-time profession, Henderson carved out a legacy as one of MMA's most enduring legends.

Henderson's career is perhaps most remarkable for its longevity. After all, when he made his first UFC appearance way back in 1998, his 28th birthday was creeping up on him. His physical prime was spent only occasionally in the cage, the dream of Olympic glory dying hard.

By the time he really had things figured out, a period that culminated with a 2007 knockout of Wanderlei Silva, he was already in his late 30s. It had been a good run, but it had to be coming to an end. Athletes, after all, don't excel into their 40s.

That's just science.

Henderson, however, had a secret. He was, we would later find out, an early adapter of testosterone replacement therapy, a since-banned medical procedure that allowed older fighters the benefits of a younger man's hormones into their dotage.

Many fighters who used TRT, claimed to be suffering from hypogonadism, a condition in which a male's body does not produce enough testosterone. Among world class professional athletes, actual medical need is almost unheard of. The most common reasons for reduced levels of testosterone and the need for TRT, at least among professional fighters, are previous anabolic steroid abuse, painkiller usage and concussions.

Despite known risks, including enlarged prostates, potential blood clots, congestive heart failure and sleep apnea, fighters like Henderson were willing to take whatever chances necessary to excel.

"I knew what I was doing. I knew that what I was doing is bad for my body in the long run," former TRT user and UFC Hall of Famer Forrest Griffin told the Boston Herald. "But to me, being a better fighter was worth it. It was worth even shortening your lifespan to be good at something."

Once known as "Decision Dan," Henderson's career-changing knockout win over Silva was accomplished with the help of synthetic testosterone. So were his legendary knockouts against Michael Bisping and Fedor Emelianenko and his fight-of-the-decade bout with Mauricio Rua at UFC 139.

In fact, almost every moment that would make up a Dan Henderson highlight reel was the product of a chemical boost.

Henderson, for whatever reasons, has escaped the scrutiny and vitriol fellow aging legend Vitor Belfort faced for his TRT use. Belfort, who like Henderson, saw dramatic results from his own drug usage, became a target for scorn and recrimination, even from fellow fighters.

But the fact we've mostly ignored it doesn't change anything. Henderson's is a legacy built on the power of synthetic testosterone. To make matters worse, when TRT was finally outlawed in 2014, Henderson's surging late career comeback hit the skids.

He's lost four of his last five, his lone win coming in a rematch with a declining Rua last year in a fight where the Brazilian Commission allowed him to return to the drug. More damning, still, is how bad he's looked doing it. Dan Henderson without TRT is a very different beast than Dan Henderson on TRT.

Despite it all, Henderson fights on. His bout this weekend against Tim Boetsch seems like the kind of entertaining bout capable of making fans forget his past and reminisce about the time their two drunk uncles scrapped over the final can of Pabst Blue Ribbon at the family barbecue.

Henderson discussed his upcoming fight with Bleacher Report's Duane Finley.

I think this fight has a lot of potential to be very exciting for the fans. We both move forward and are aggressive. We are both wrestlers who have a lot of power in our hands. I think there are some holes in his game I should be able to exploit, but he’s a tough fighter. He's not going to be easy to beat, but I’m excited to get out there and bang with him.

As Henderson fights out the final bouts of his UFC contract, mechanisms are in place to assure he will be the last of his kind. The UFC's new PED program will incorporate random, unannounced testing of every fighter on the roster year-round. A minimum of 2,750 tests will take place each year, a staggering number which averages out to about five random tests per fighter, per year. 

“Our goal is to have the best anti-doping program in all of professional sport,” Jeff Novitzky, UFC's vice president of athlete health and performance, told Bleacher Report's Jeremy Botter.

That is obviously good news for those who dream of a clean sport. But it's bad for anyone hoping against hope to be the next Dan Henderson.

If fighters need a needle or a patch to compete, they no longer belong in the cage. That, more than any of his iconic knockouts, is Henderson's true and lasting legacy in this sport.

Jonathan Snowden covers combat sports for Bleacher Report.