Now I know how Floyd Landis feels.

A few years back, I had an idea for a magazine article: I'd profile an ordinary weekend athlete who cheats by taking performance-enhancing drugs. Although I found evidence of what I call citizen doping, I could never pin down someone who both fit the bill and would cooperate, so I decided to cut out the middleman and do the cheating myself. Under medical supervision, I took testosterone for about a year, even as I continued to train and compete as an amateur bike racer. I chose T, as it's sometimes called, in part because it was the same stuff Landis apparently used to win the 2006 Tour de France.

My experiment evolved into a book project, and I soon learned plenty about doping and the facts and myths that surround it. For example, some scientists don't think that synthetic T, a lab-produced hormone that can be used to augment the human body's natural testosterone, benefits endurance athletes. (Could've fooled Landis.) But power­ful sports-policing federations like the World Anti-Doping Agency (WADA) have no doubt that it does, so synthetic T is forbidden in amateur and professional bike racing (as well as intercollegiate sports, Olympic competitions, and so on). The T, which WADA categorizes as an anabolic steroid (a type of hormone), unquestionably builds muscle mass and is thought to aid in recovery after rigorous exercise—like Tour stages.

As word about my book project spread, I was treated to a small-scale version of the wrath Landis experienced when it was announced, shortly after his Tour victory, that he'd tested positive for synthetic testosterone. When officials at USADA—WADA's U.S. affiliate—learned of my misdeeds (I told them), they let me know that I was in for swift retribution, probably a multi-year ban from amateur racing. I've also been getting ripped by bloggers and tweeters, including Joe Papp, an ex-pro who was busted for using performance enhancers in 2006, a saga I wrote about in Outside. Linking to an Amazon description of my book, Papp tweeted, "Wonder how aggressively @usanti­doping will come out against the author of this filth.... 'I doped b/c I could?' "

"About Tilin," one commenter said on a blog critical of my stunt, "if doping didn't vault [him] onto the podium ... then maybe it's no big deal. No big deal, because you'd still kick his 45-year-old hypocritical ass, clean."

Of course, any similarities between Landis and me end there. In 2006, Landis apparently used T after faltering badly in one Tour stage and before an epic victory in the next, and his performance triggered questions about how fast testosterone works. (Not that fast.) Subsequently, like the typical busted pro, he spent years denying what he'd done and didn't offer any insights about doping. In contrast, the whole point of my exercise was to experience testosterone and write about it. Over a nearly yearlong stretch that started in January 2008, I doped almost every day and kept records about the effects the drug had on my middle-aged body.

During that time, I competed in more than a dozen races, and in the end there was little doubt in my mind that testosterone provided performance boosts, though they weren't as obvious as many people assume. Take what happened during one of my early races as a doper, back in April 2008. It was a sunny, crisp Northern California Saturday, and I was struggling through the third of four laps in an obscure 51-mile contest called the Wards Ferry Road Race, pedaling against a bunch of thirty- and fortysomethings in a category reserved for non-elite amateurs. Sweat running down my back, I waited for the T to kick in—or at least to give me some sign that it was working. Why couldn't a light start blinking on my handlebars? Or my power meter play several notes of "Don't Stop Believin' "?

Near the end of the hilly course's third lap, however, something happened: I felt a subtle but unmistakable second wind. At the top of a rise, I turned around and realized that our original group of 30 riders was now a group of seven. Everyone else, as bike racers say, was off the back. I finished sixth, which for me was a great result.

Do I credit my training? Luck? The placebo effect? Those were factors, but so, I believe, was the testosterone. As usual, I had applied it, as a topical cream, to my inner thighs early that morning. I knew firsthand what any number of pros would tell you if they could: the stuff is strong medicine. Once you feel what it can do, it's hard to resist.

For several years before I embarked on my life of crime, I wondered—as many have—whether it was only the pros who were cheating, since it seemed logical that performance drugs would take hold among hypercompetitive athletes further down the food chain. Back in 2007, I was training and racing a lot with one of my best friends since childhood, a guy named Michael Piesco. (In recounting my tale, I've changed many people's names to protect their privacy.) Mike and I were getting schooled at nearly every masters bike race we entered, and we often grumbled—without any proof—that we were surrounded by dopers.

"What are these guys on?" Mike said to me one day, a bite of banana in his mouth. It was April, and we'd both just finished out of the running at the Wente Vineyards Classic Road Race in Livermore, California.

"Scumbags," I said. "Who can hold down a job and ride like these jerks?"

Before long I started a hunt for amateur dopers. I asked around locally and then did a nationwide search, calling scientists, sports governing bodies, bike-shop owners, coaches, and athletes to find out if they knew anything about also-rans taking drugs.

I got warm. I had a brief e-mail relationship with a guilt-ridden rider from the eastern U.S. who clearly implied he was doping but then backed off. "I don't need redemption," he wrote at one point. "What I need is for nobody to ever find out what I've done."

I asked Papp, who wouldn't give me names of amateur dopers but assured me they existed. There was good reason to believe him: while I researched Papp's story, the U.S. Drug Enforcement Administration went public with details of Operation Raw Deal, the largest steroid-policing effort in U.S. history. During a series of sweeps directed against dealers here and abroad, 11.4 million dosages of banned substances were confiscated, including anabolic steroids, human growth hormone (HGH), and insulin growth factor. Not all of that could have been going into the bodies of pro athletes and bulging barbell junkies.

Citizen dopers ultimately did bubble up here and there. A Florida cop and bike racer guaranteed me that he rode with a number of aging amateurs who used performance enhancers. One racer in Michigan was caught taking erythropoietin (EPO), a drug that boosts the blood's oxygen-carrying capacity. There was a similar case in Colo­rado, and in New Jersey nearly 250 police and firefighters were found to be taking steroids and HGH.

For all the action around me, though, I still didn't have my profile subject, and in the summer of 2007 it occurred to me to do it myself. "The amateur doper doesn't have to be someone I hope to meet," I told my wife. We were in bed. Our seven-year-old son and five-year-old daughter were finally asleep. "He can be me."

"Take drugs for a story?" she said, shaking her head no. My graceful spouse, who's understanding about most things, has her limits. This sounded dangerous and dumb.

But I kept wondering about testosterone—not just about the athletic boost it could give me but also about the general health effects it might bestow. Testosterone is the primary male sex hormone—healthy young men produce eight times as much of it as young women—and unlike with EPO and HGH, doctors regularly prescribe it to aging men. You're considered T-worthy if you have low levels of the natural hormone—as judged by doctors, whose opinions vary as to what "low" means—or if you suffer from symptoms that include diminished sex drive, wither­ing muscles, sapped energy, and erectile dysfunction. I've dodged the E.D. bullet, but I can identify to varying degrees with the other symptoms.

My urologist agreed to put me on a modest amount of T, but I wanted to go whole hog, so I Googled physicians in my area who might prescribe it more liberally as an anti-aging medication—a use that's legal and increasingly condoned by doctors. In January 2008, I walked into the offices of an internist near my Bay Area home. She had a solid professional background and an interest in alternative therapies.

"I'll put you on the Wiley Protocol," she said, referring to a specific anti-aging program that involves a fluctuating schedule of testosterone use. Using no-needle syringes that measure out precise dosages of a custom-mixed cream, I would apply anywhere from zero to 200 milligrams of T daily. The urologist would have started me on 50-milligram dosages. The Wiley amounts, though greater, would probably spare me from testosterone's reputed side effects: mood problems, shrinking testicles, and body acne, among other things.

The office visit cost $250, with a few more appointments and blood tests coming down the road. The drugs cost about $75 a month. Juicing was going to be easier, and cheaper, than I expected.

Four months after starting my program, in May 2008, I found myself lining up with some 50 other riders for the Berkeley Hills Road Race, a three-lap, 52-mile event.

By this point, I felt far more vital and virile than I had at the Wards Ferry race. Around the house, the T's presence had been palpable. The kids wondered why Daddy wanted to hug Mommy all the time. What I couldn't tell them was that testosterone fuels libido in the brain and facilitates the production of chemicals required for sexual arousal.

Other body parts were affected, too: I'd already seen new feats of strength from my jockey-slight, 145-pound frame. Over a span of six sets, I could do 210 partial squats with a 125-pound barbell. I pushed approximately 400 pounds during leg presses. I could see new muscle definition in my shoulders, triceps, calves, and quads. I was almost buff.

Meanwhile, on the bike, I recovered from hard workouts amazingly fast. I felt fresh the day after a training session that included multiple, intense ten-minute intervals. I could generate 310 watts of sustained pedaling power—up from 260 at the start of the year.

Still, as I'd noticed at Wards Ferry, the effects of T weren't instantaneous. During the first two laps of the Berkeley Hills race, my legs felt heavy. On the second lap, I nearly lost contact with the main group as we crested the loop's longest climb, Papa Bear.

All of which was consistent with what I was hearing from some hormone experts. Doping with any drug won't turn a screen-loving blob into an elite athlete, and even with my 13 hours a week of training factored in, it's not entirely clear to scientists whether T can help someone like me. Some researchers believe that the increased power it delivers will be offset by added bulk. (Thanks partly to the burn of intense cycling, I didn't add any pounds.) These scientists also doubt that bigger muscles necessarily aid recovery.

"It's confusing to me why a cyclist would take it," says John Amory, a former consultant for USADA and an internist (specializing in testosterone) at the University of Washington Medical Center in Seattle. "The studies don't support it."

Others argue that an endurance athlete on testosterone will unquestionably have an edge over his rule-abiding peers. Don Catlin, a former professor and physician at UCLA who founded what is now the world's largest testing facility for performance-enhancing drugs, testified during Floyd Landis's doping hearing that testosterone definitely helps a distance athlete snap back faster. Michael Bahrke, a fellow at the American College of Sports Medicine and author of Performance-Enhancing Substances in Sport and Exercise, agrees. Joe Papp told me long ago that supplemental T is used widely in the pro peloton, and he had a quick response to Amory's assessment: "Bullshit."

Based on my experiences, I have to agree with Papp, and as I neared the end of the third and final lap at Berkeley Hills, I found myself near the front of a group that had winnowed to 35 riders. As we approached the base of a climb called Mama Bear, the first of the course's final three uphill portions, a fabulously sinister feeling washed over me. I experienced a surge of energy.

I slowly accelerated past a rainbow of jersey-wearing riders. When I neared the front, I kept going. Halfway up the climb, there was nobody ahead of me. One hundred feet from the top, I looked over my shoulder and saw 20 guys in a line, strung out down the hill. I had destroyed the field. Me and my buddy T.

I eased up at the top only long enough for the first ten racers to catch me. Then, hoping to demoralize them, I accelerated again. I lost five of them on the first of two short climbs. I dropped four on the second.

"We're clear!" a voice called behind me. I glanced back and saw one rider in red and yellow. Nobody else.

"Take that, you motherfuckers," I muttered to myself. "There's more."

I wasn't surprised by my aggro disposition. For weeks, I'd sensed that the T was making me edgy. Small things ticked me off, and my family sometimes incurred my verbal wrath.

Sociologists and psychologists agree that testosterone and behavior are linked, although the connections aren't fully understood. Some experts believe high levels of supplemental testosterone don't by themselves cause irritability. Others question the very existence of so-called 'roid rage, or violent behavior stemming from anabolics.

"'Roid rage may be a popular term," says Harrison Pope, an expert on steroid abuse and a professor at Harvard Medical School. "But even with high doses of testosterone, the majority of subjects show little or no change—although occasional subjects do show pronounced behavioral reactions."

Approaching the base of Papa Bear in first place, I was sure I could tolerate T-driven moodiness for a long time: hard as it is to admit, I could see the benefits I was feeling on the bike outweighing the guilt I felt about cheating. As for the long-term health effects of supplemental testosterone on a healthy man? They're unknown. Some researchers now say that changes in testosterone concentrations, once widely believed to contribute to prostate cancer, do no such thing. Some doctors even theorize that low T increases one's risk for prostate cancer.

In short, T is becoming harder to dislike.

Clean racers will be glad to know that I didn't win at Berkeley Hills, though the drugs did their part. Basically, I was strong enough but not smart enough. I used up my energy too early. Sixteen other racers passed me on the hill leading to the finish line.

Afterwards, I called my friend Mike and gave him a race report. He had been aware from the start that I was using testosterone. "Maybe you were passed by better dopers than you," he laughed.

Cheating isn't right. Now that my story is in the open, I'll tell people that I'm human. I'll say that my body is now T-free and that my year on drugs was an opportunity to learn something interesting. Still, many inside and outside of racing will be angry.

I've already had glimpses of the mixed feelings to come, starting as far back as July 2008, when I was racing in all my doping glory. I was at the Cascade Cycling Classic in Bend, Oregon, with Mike. Usually, he's a stronger rider than me, and he competes in a superior category. We both thought of Cascade—a stage race that attracts top pro cyclists—as one of the season's target races. We both wanted to do well, and we were scheduled to compete in four events: a time trial, a criterium (a short, turn-filled course), a road race, and a circuit race.

By the start of the road race, in which Mike's and my categories would compete together, I was in 11th overall in my group. For me, a top-10 finish would be insane.

The 71-mile road race wound through the Deschutes National Forest and past a reservoir before ending at the Mount Bachelor Ski Resort. The course tilted upward, pretty much for good, near the 50-mile mark. Mike and I arrived there together. A few miles before reaching Mount Bachelor's parking lot and the finish line, I felt strong, and I accelerated when other riders increased the pace.

Then I felt that same buzz and boost that I felt almost every time I competed as a doper. It was naughty and fun.

I turned around and Mike wasn't there. I crossed the line 12th in my category. Mike arrived nearly 90 seconds later. I ultimately finished the Cascade Classic 10th overall in my category and received $25 in winnings. I never cashed the check. "What am I supposed to say?" Mike said to me, doubled over his handlebars, soon after he finished the road race. "Congratulations?"

Mike let go of his anger, but others won't. A few months ago, I admitted what I'd done during an interview with Travis Tygart, USADA's chief executive. USADA doesn't have the bandwidth to test at every race, so if I hadn't confessed I probably could've ridden under the radar forever.

Tygart wasn't moved by my admission. "What do you expect us to do when you admit lying and cheating under our jurisdiction?" he said, laughing incredulously.

"Whatever is appropriate."

More laughter. "You won't be given any special treatment or immunity." Tygart quickly had his lawyers call me, and I've been banned from racing for two years. If I'd cashed the Cascade check, USADA would have strong-armed me to pay it back.

I'm not saying that what I did is smart or cool, or that my kids should someday be proud of me. But I discovered a few things, like how accessible performance-enhancing drugs really are. They're so easy to acquire and safely use that I still wonder how many other graybeards dope.

While I offer sincere apologies and would never again betray my fellow racers, cycling's organizers, or its governing bodies, I'll be honest: If you threw out the rules and put a doctor in front of me holding syringes? The temptation would be hard to resist.