DENVER >> Joking around before the start of the NBA Finals, Charles Barkley and Grant Hill took hits from oxygen masks they brought onto the set for a pregame TV show.

But the thin air in Denver is no joke. There’s a reason it’s known as the Mile High City.

The city sits 5,280 feet above sea level and there’s plenty of science that shows just how altitude impacts any athlete — including basketball players. The Denver Nuggets have been using the lung-searing elevation to their advantage for years — especially during these playoffs.

With their 104-93 win over the Miami Heat on Thursday, the Nuggets improved to 9-0 at home during their postseason run. Yes, Nikola Jokic, Jamal Murray and friends have a lot to do with it. But altitude deserves an assist. The Nuggets try to push the pace to make the Heat feel the burn coming in from sea level.

“So there’s just as much as oxygen in Denver as there is in Miami,” explained Randy Wilber, a senior sports physiologist for the U.S. Olympic & Paralympic Committee. “What’s different is the barometric pressure in Denver is significantly lower than in Miami. ... So ultimately, yes, you’re getting less oxygen to your working muscles.

“That’s a fact. That’s not a wives’ tale. That’s not a myth.”

The Nuggets know it. And they remind opponents of it. There’s a sign that greets visiting teams entering Ball Arena listing the elevation. Before games, the stadium announcer proclaims the challenges of playing at altitude. On the floor, “5280” is stenciled at each free throw line — just to provide another reminder.

The Heat, though, aren’t letting it get into their heads.

“I don’t think that was part of the game,” Heat center Bam Adebayo said of the role of elevation after Game 1. “I didn’t even think about the altitude until you just said it.”

To the Heat, the adjustments for Game 2 on Sunday night have more to do with shot making than altitude concerns. The Miami trio of Caleb Martin, Max Strus and Duncan Robinson went a combined 2 for 23 from the floor.