One by one, they entered a nondescript building on the eastern edge of town, 18,000 square feet with no signage out front. They came looking for relief. These nine former professional football players are part of the Denver Broncos Alumni Association. They played in nearly 700 NFL games combined and have enough aches and pains to keep an entire hospital staff busy.

“Every day, I wake up in pain, from my ankles to my neck,” said Ebenezer Ekuban, 40, who played defensive end for nine NFL seasons. “It’s part of the territory. I know what I signed up for.”

Retirement is a daily exercise in managing pain, which is what brought the men to the unmarked CW Hemp offices on a recent Friday for a tour and a firsthand lesson on the potential benefits of the marijuana plant. As the country’s discussion on the drug broadens, state laws change and public perception shifts, there’s a movement in football circles to change the way marijuana is viewed and regulated within the NFL, which still includes cannabis on its list of banned substances.

For decades, football players have treated pain with postgame beers, over-the-counter anti-inflammatories and powerful prescription painkillers. The sport’s overreliance on drugs for pain management is the subject of a federal lawsuit and has sparked an investigation by the Drug Enforcement Administration. Retired NFL players use opioids at four times the rate of the general population, according to one study, and marijuana advocates say there’s a safer, healthier alternative available.

No professional sport has so many outspoken proponents of marijuana’s medicinal qualities, but then again no sport is as closely associated with pain and injury.

“This pain is never going away. My body is damaged,” said Eugene Monroe, 30, who was released by the Baltimore Ravens last year three weeks after becoming the first active player to publicly call on the league to permit medical marijuana. “I have to manage it somehow. Managing it with pills was slowly killing me. Now I’m able to function and be extremely efficient by figuring out how to use different formulations of cannabis.”

There’s still no shortage of opposition to marijuana, and many on both sides of the debate agree that further research is needed. While many states have rolled back laws in recent years, early signs from the Trump administration suggest that the Justice Department isn’t ready to soften its stance. Attorney General Jeff Sessions said last month that marijuana is “only slightly less awful” than heroin.

NFL Commissioner Roger Goodell speaks with the media during a press conference for Super Bowl 51 at the George R. Brown Convention Center on February 1, 2017 in Houston, Texas. (Photo by Tim Bradbury/Getty Images)

NFL Commissioner Roger Goodell said last week that he opposes players using the drug recreationally but is willing to listen to the league’s medical advisers on the potential value of medicinal marijuana. “To date, they haven’t said this is a change we think you should make that’s in the best interests of the health and safety of our players,” he said. “If they do, we’re certainly going to consider that.”

Most of the former Broncos on the tour in Boulder had been skeptics not long ago. But the more they learned, the more they’d come to think that some form of marijuana could be the alternative they’d been looking for, the answer for their sore backs, balky knees, pounding headaches and sleepless nights.

“Hey, everybody. Thank you so much for being here,” said Del Jolly, CW Hemp’s business development manager. “We’re excited to tell you about who we are, how much care is put into this product, and how it’s incredibly legit, incredibly safe and incredibly high-quality, something we need to get the NFL to start understanding.”

The former players put on protective glasses and prepared to tour the facility. “You all got a grow house in here?” asked one player. Another inquired about a free sample before the tour began, and another asked, “Will we be able to drive home when we’re finished?”

The room laughed. “It depends on what you had before this,” Jolly explained.

‘Let me give this a shot’

CW Hemp specializes in cannabis that is rich in cannabidiol (CBD) that the ex-players were told acts acts much differently than marijuana as most people know it. The company’s roots are in helping cancer patients undergoing radiation and chemotherapy, and it began making headlines when children with epilepsy saw a dramatic drop in the number of seizures they experienced after taking CBD.

The plant used to be called “hippie’s disappointment,” Vijay Bachus, the company’s site director, told the former players, “because it wouldn’t get you high.”

“It had high levels of CBD but low levels of THC. Nobody would be smoking it for recreational purposes,” he said, likening the THC levels to the amount of alcohol found in an O’Doul’s.

THC — tetrahydrocannabinol — is the cannabinoid that produces the high that most associate with marijuana. CBD has some similar properties but not the psychoactivity and mood-altering effects.

While researchers have found that THC might have some benefits — particularly with pain, anxiety or nausea — the science behind CBD is not as robust. But recent studies have found evidence that it can be effective treating everything from epilepsy and cancer to heart disease, diabetes, anxiety and schizophrenia. It can also act as an anti-inflammatory and a neuroprotectant, raising hopes it may be valuable in treating and preventing head injuries.

Related: The NFL punishes pot use, but a growing number of players say it’s better than painkillers

The group entered a room where two dozen 40-pound barrels were filled with ground-up cannabis plant.

“I can smell it now,” said Steve Foley, 63, who played defensive back for the Broncos from 1976 to 1986.

The scent is faint; more like a college dorm room after a vigorous cleaning. The quality control room is the first step of the process.

The NFL suspended Bills offensive tackle Seantrel Henderson for using marijuana to relieve Crohn’s disease. (AP Photo/Bill Wippert, File)

“Where does the oil come from?” asked one former player.

“Have some patience,” Le-Lo Lang said with a laugh.

A laboratory processing cannabis is about the last place Lang would ever have imagined himself. As a professional athlete — a defensive back for the Broncos from 1990 to 1993 — he never took drugs. He didn’t taste alcohol until a sip of champagne on his wedding day, and still today he rarely drinks. “It was never something that interested me, not even a little bit,” he said.

Lang, 50, has been away from the sport for nearly 25 years. Today he has headaches, difficulty sleeping, back pain, knee pain, shoulder pain “and everything else,” he said.

But for him, there was a stigma attached to marijuana and the people who use it. He lives in Colorado, which was a pioneer in relaxing state marijuana laws, but his feelings still took years to overcome.

The country has moved in a similar direction. In a recent poll, 72 percent of Americans said regular alcohol use posed more of a health risk than regular marijuana use. The same survey found that nearly one in five marijuana users rely on the drug to help manage pain.

That prospect is what helped Lang and his fellow ex-athletes open their minds. “I just felt like with all the pain and issues that I’m having, let me give this a shot,” he said.

The exact effects of CBD are mostly anecdotal. It’s not classified as medicinal marijuana and is currently regulated as a hemp product. Manufacturers, like CW Hemp, are careful not to make too many medical claims. But increasingly, researchers are finding a correlation between marijuana use and a decreased dependence on opioids. The National Institute on Drug Abuse cites a pair of government-funded studies in saying “that medical marijuana products may have a role in reducing the use of opioids needed to control pain.” The federal institute cautioned that more research is needed.

After a few weeks of using CBD, Lang noticed he was sleeping much better. He still had headaches, but they weren’t as bad. Some of his other pains were still present, though.

Bachus led the group into a lab. The cannabis had soaked in alcohol, and an employee was squeezing liquid out of a mesh bag into a pan. “Just like squeezing the juice out of a tomato,” one of the players observed.

The lab has hosted football players in the past, including Kyle Turley, a former offensive lineman who says his football career led to a painkiller addiction, and Jake Plummer, a former quarterback who has become a vocal proponent of CBD.

Ekuban played with Plummer for four seasons with the Broncos and had first heard about the potential benefits of cannabis from his former teammate. Ekuban retired in 2009 after nine seasons, and it wasn’t until five or six months had passed that he realized the aches weren’t going away.

“I thought I’d feel better getting away from all those hits,” he said, “but I was worse off.”

As a player, Ekuban had surgery on his lower back, knee, shoulder and Achilles’ tendon. Painkillers and anti-inflammatories were a regular part of his regimen, the drugs carrying him from one game into the next. “A couple blood tests showed elevated liver enzymes,” he said. “I knew they were from all those painkillers.”

The more he studied cannabis, the more he felt comfortable with it. He’s started using CBD in the mornings and at night. “It hasn’t taken everything away,” he said, “but I believe it’s helping significantly.”

Research has found that CBD increases a molecule called anandamide, which reduces pain and increases the production of neurons in the hippocampus region of the brain, which can impact mood and anxiety. Compared with a placebo, the National Academies of Science, Medicine and Engineering found “strong evidence” that marijuana is effective at dealing with chronic pain. Twenty-nine states plus the District of Columbia have legalized medical marijuana; 22 of the NFL’s 32 teams play their home games in those jurisdictions.

“I think in due time, the NFL is going to realize that CBD is not a performance-enhancing drug,” Ekuban said. “If anything, it helps with anxiety, helps with concentration, it helps with pain.”

‘Make a smart decision’

The NFL does not release the results of drug tests, so there’s no way to know the number of active players who use marijuana or the reasons they might use it. Players who have never violated the league’s drug policy are tested for recreational drugs only once a year — at some point between April and August.

Quarterback Jake Plummer of the Denver Broncos. Plummer has become an advocate of medical marijuana. (Photo by Mike Ehrmann/NFLPhotoLibrary)

“There is no doubt that players are using cannabis extensively, almost as a substitution therapy for other treatments that the NFL is offering that they perceive as more toxic or highly addictive,” said Sue Sisley, an Arizona-based physician who serves on the board of advisers for the Korey Stringer Institute, which has partnered with the NFL on health and safety issues. “For instance, these players obviously receive mega-dosages of opioids easily from their trainers and team docs. But when they want to seek out what they believe is a safer, less toxic alternative like cannabis, they’re fined and sanctioned.”

The NFL has indicated an interest in studying the issue but seems resistant to major changes. Goodell told ESPN Radio last week that marijuana is addictive and unhealthy and that he is not currently in favor of allowing players to use it recreationally.

“Listen, you’re ingesting smoke, so that’s not usually a very positive thing that people would say,” the league commissioner said. “It does have [an] addictive nature. There are a lot of compounds in marijuana that may not be healthy for the players long term. All of those things have to be considered. And it’s not as simple as someone just wants to feel better after a game.”

The NFL Players Association has formed a pain management committee to study the issue, and many expect marijuana to become a bigger discussion point in the near future. The union could urge the league to differentiate between recreational and medicinal use or push to lessen the penalties for a failed test. “We still think there can be a more therapeutic approach in the way we deal with marijuana in particular, and we’d like the league’s help with that, and we know owners feel that way, too,” said George Atallah, a union spokesman.

The current collective bargaining agreement is set to expire in 2020, and both sides have indicated they might be willing to address the issue — either the testing, the legality or the penalties levied.

“I would hope that the NFL stands by what it says it stands for — player health and safety, first and foremost,” said Monroe, who since his retirement has emerged as football’s most prominent marijuana proponent. “If that statement is true, there’s enough info out there right now for the NFL to make a smart decision.”

‘A young industry’

Stopping at CW Hemp’s research and development lab, Bachus explained to the former players that the company must be poised for regulatory changes. Marijuana is still classified as a Schedule 1 drug, which means the federal government sees a potential for abuse and no medical value. It also means researchers have a difficult time cutting through red tape to study the drug.

The Food and Drug Administration is considering how it classifies CBD, and if the extract gets approval as a medication, not only could doctors start prescribing it, the DEA could classify CBD differently than marijuana.

One of the players in the group, Justin Sandy, was more familiar with cannabis than his cohorts. Sandy, 35, was in the NFL for parts of four seasons — a career that lasted just long enough to break bones in both feet, require four knee surgeries and trigger daily pain in his back, knees and feet. He got into organic agriculture early in his retirement and recently began growing five acres of cannabis in nearby Boulder County.

“This is such a young industry,” he said. “I think the majority of the country still lumps hemp and marijuana together. It’s like a tomato plant with different varieties, that’s how I like to think about this.

The research is continuing. CW Hemp’s charitable partner, Realm of Caring, is working with researchers out of Johns Hopkins and the University of Pennsylvania on studies specific to football players. Several of the former Broncos players would sign up.

The tour was wrapping up, and the former players began removing their protective glasses.

“Any final questions?” Bachus asked.

“You all going to let us try some?” one of the former players deadpanned.