It was the morning of a 2010 playoff game, and one of the Nuggets had just smoked some nuggets. As the team practiced, the player was so high that Rex Chapman, a team executive at the time, had to pull him aside to get him to focus.

“Across all walks of life and in every profession, people smoke (marijuana). This is no secret, and pro sports are not exempt,” said Chapman, who played 12 years in the NBA. “But employers deserve and pay for A-plus employees. There is a time and place for everything. As a member of a team, guys owe it to their teammates to put their best foot forward.”

Marijuana use has long been a part of sports’ subculture, especially and fittingly in a place nicknamed the Mile High City. It soon may become part of the mainstream. New laws taking effect Wednesday in Colorado allow the retail sale of recreational marijuana.

But as much as society often mirrors changes in sports culture, to most of the ruling bodies of sports, weed remains a four-letter word. Fiercely protective of their image, they don’t want athletes openly smoking marijuana, regardless of what Colorado voters might say. There is evidence in recent surveys, however, that society’s changing views toward marijuana, specifically widespread acceptance of the medicinal benefits in alleviating pain, are thawing previous hard-line stances.

Winter Olympic athletes, for example, are all but given a free pass for smoking marijuana while out of competition. And the World Anti-Doping Agency this past May increased the threshold for a positive marijuana test tenfold. The NHL, meanwhile, alone among the big four North American professional sports, does not include marijuana among its banned substances.

Nevertheless, advocates for the use of marijuana know they face an uphill challenge making cannabis legal for athletes.

“It’s going to be a hard row to hoe,” said Allen St. Pierre, the executive director of NORML, the National Organization for the Reform of Marijuana Laws. “It’s a sexy topic because it shows a clear conflict with law and holding athletes to a double standard. … But now that those legal mores are changing, one should hope these athletes should enjoy the benefits of what’s been a 50-year civil justice movement.”

Asked if legal marijuana would alter the NBA as we know it, Nuggets coach Brian Shaw said, “Just like people got accustomed to alcohol, I don’t think it’s so far out there that it would change anything.”

He pointed out that the NBA didn’t officially start testing for marijuana until 1999. “So the NBA has already had a time where marijuana was a big part of the league and wasn’t being tested for,” he said. “I do understand that the league is trying to market and portray a certain image, and all of these players are commodities and entities.”

Former Broncos receiver Nate Jackson describes the clash between NFL teams and its players as the new reefer madness.

“(Marijuana) is part of the culture of 20-something kids. But the people of the older generation have a different idea about what marijuana is and does,” he said. “It’s weird, because the perception is: We can’t let these guys smoke weed because they are going to be ‘stoners.’ But the thing is, these guys are at the very, very top of their profession. They are not burned-out stoners on grandma’s couch watching movies. They are the best in the world at what they do, so if they become so enamored with weed that it affects their job performance, they are going to get cut. (Most players) are not stupid enough to let it come between them and their jobs.”

Banned by NFL, MLB, NBA

In 1970, when NORML was founded, a Gallup poll showed that only 12 percent of the public supported legalization of marijuana. Over time, the public slowly changed its perception of cannabis. According to a nationwide Gallup poll conducted in October, for the first time a clear majority of Americans, 58 percent, supported legalizing marijuana. Medicinal marijuana is legal in 20 states and in the District of Columbia, eight of which are home to NFL teams.

“When (these laws) happened, we knew a professional athlete somewhere would run afoul of the law and make the argument, ‘I should be a legal recipient of this, and if I’m legally receiving, I shouldn’t be held to some standard like I’m a criminal,’ ” said NORML’s St. Pierre.

But, as of now, athletes in Major League Baseball, the NFL and the NBA are punished if they test positive for marijuana. The NHL tests for recreational drugs, such as marijuana and cocaine, but only to monitor use. Multiple failed tests will result in the NHL and its players union reaching out to offer help for the player, according to Avalanche player representative John Mitchell. The only banned substances in the NHL are performance-enhancing drugs. Mitchell said although the NHL doesn’t punish the use of recreational drugs, “there are rules within the team” that will lead to in-house penalties for its use.

The NFL, famously protective of its image, has no plans to re- assess its view on marijuana. When asked whether the NFL has any plans to change its policy toward marijuana, league spokesman Greg Aiello released a statement saying: “The NFL’s policy is collectively bargained (with the NFLPA) and will continue to apply in the same manner it has for decades. Marijuana remains prohibited under the NFL substance abuse program.”

And so, there’s a stigma. Numerous athletes interviewed for this story, including four Broncos, wouldn’t go on the record when asked about their view of legalization. Use of marijuana is believed to be widespread among pro football players. Last year, former Detroit Lions lineman Lomas Brown made news by saying at least 50 percent of NFL players probably smoke marijuana. An ESPN survey this year found that 70 percent of the prospects at the NFL scouting combine admitted to using marijuana in college.

“Yeah, guys smoke marijuana. That’s the way it is,” said former Nuggets guard Earl Boykins, who said he has never smoked cannabis. “It has nothing to do with the team, or the legality. If you want to smoke, you’re going to smoke. If you get caught, you release a statement.”

Professional painkillers

He once tore his groin off the bone. He dislocated his shoulder, broke his tibia, broke a rib, tore the medial collateral ligament in his knee and dislocated his shoulder, again.

“My body would start to break down, and it would feel like (expletive) on a daily basis,” said Jackson, the former Bronco. “And those days were long.”

Jackson’s NFL injury history is similar to most of the modern-day gladiators who throw their bodies into on-coming traffic every Sunday during the season. So, what’s the big deal if a player relaxes with a little marijuana on Sunday night to help with the pain?

“I think in the NFL, in particular, players have a legitimate and substantial claim to use medical marijuana,” Jackson said. “They live in a great deal of pain on a daily basis, and marijuana helps with that. … I think it’s the most innocuous of the pain medicines that players can use.

“Teams pass out opioid painkillers, which are highly addictive — they are a derivative of the poppy plant — so it is basically heroin, pharmaceutical heroin, which can be physically addicting,” he said. “And that can affect a player long after they are done playing. Marijuana doesn’t have those types of effects. Players get shots to play because it is a very violent game, and for the NFL not to be compassionate about the pain those players are going through is kind of cruel.”

But, according to the NFLPA, no player has received an exemption to use cannabis for medicinal purposes. And beyond the stigma of its players using a drug that is illegal in most states, the NFL continues to label marijuana as a banned substance.

But, increasingly, the key issue in this debate is turning toward allowing the use of cannabis for recovery from pain and injuries.

St. Pierre pointed to Mark Stepnoski, a Dallas Cowboys center who played in the 1990s. He was a big proponent of marijuana when he played. “When everyone was self-medicating with alcohol, he was using cannabinoids, which is a natural and very effective anti-inflammatory,” St. Pierre said.

“So now, I think there’s actually a legitimate argument to be made — maybe those who are using cannabinoids have an edge against those who don’t. That makes it so we have to have a serious discussion about the science and pharmacology of cannabis.”

What is a cannabinoid?

As St. Pierre explained, it’s a range of a drug molecule, and a type of it, called CBD, “is like the new green gold in Colorado, because the argument is, you can deliver the product without a head high and still get all of those good body effects. So people in Colorado, particularly Dixie Elixir in Denver, one of their claims to fames is they’re developing high CBD-rich product.

“So, these athletes could really benefit. I’m sure when these lawyers and labor folks negotiate these contracts, it adds another onion layer to this, about what do they want to do in the future.”

Leafs lighting up leaves

So what’s next? Leagues aren’t about to change their rules, at least overnight. Players will continue to be penalized for smoking marijuana, such as Broncos linebacker Von Miller, who tested positive for cannabis as a rookie and served a six-game suspension this season for violating terms of the NFL drug policy. Broncos fans, at least in Denver, can smoke marijuana legally if old enough.

The fear of some coaches and teams is that allowing players to smoke marijuana would affect their daily behavior.

“We make a lot of money to perform at a high level, so if guys were coming into the locker room stoned out of their mind, they won’t perform at a high level,” said Broncos defensive tackle Terrance Knighton. “There has to be some type of governing.

“But you’d rather a guy drive stoned than drive drunk. So there’s a double standard there. And if you watch television, all you see is beer commercials. Everybody and their mother is watching the Super Bowl, and it’s either a Doritos commercial or a Bud Light commercial.”

Maybe by 2043, marijuana will be as much a part of sports culture as it’s a part of Colorado culture in 2013. Advertisements for cannabis will cover outfield walls in ballparks like the ivy does at Wrigley Field. The NBA’s Blazers will truly be blazers. And joints will help hockey players rest their sore joints, Leafs lighting up leaves.

Will all this be a bad thing? A good thing? And, really, how much of this is any different than what athletes do now?

“If we advance the clock 30 years from now, and marijuana is purely blasé, nonplus — just like tea and coffee consumption, and alcohol to be sure — then think about how does an athlete deal with this stuff now?” St. Pierre asked. “It’s kind of a social contract, when they sign these huge contracts, they agree to all kinds of behavior they’re not going to do, largely not to embarrass the team.”

Benjamin Hochman: bhochman@denverpost.com, www.twitter.com/hochman Patrick Saunders: psaunders@denverpost.com, www.twitter.com/psaunders

Staff writers Mike Chambers and Jason Blevins contributed to this report.