Look at the way opposing players stumble at Ball Arena.
It isn’t just Nathan MacKinnon skating past them.
It’s the air itself.
Denver sits at 5,280 feet. A geography that hurts the lungs before it hits the legs.
The Colorado Avalanche finished the 2025-2026 regular season with the NHL’s best record. Everyone expects them to take the Stanley Cup.
Why?
Partly skill. Mostly altitude.
Air is 20.9% oxygen everywhere.
But density changes.
At sea level, pressure crushes those molecules together. You get a full breath. Up in the Mile High City?
Pressure drops. Molecules spread out.
Every breath in Denver contains roughly 17% usable oxygen.
A noticeable dip.
The human body hates being suffocated.
Or at least, it panics a little.
Martin MacInnis, a kinesiology professor at the University of Calgary, notes that tissue starving for oxygen triggers hypoxia. The body compensates. It makes more hemoglobin. The red stuff that carries oxygen around.
“Your body signals to increase red blood cells,” MacInnis explains.
This boosts VO2 max. A fancy metric for how much oxygen your muscles can process in a minute. More processing power means you can sustain higher intensity without gasping.
The Avalanche do most of their work in the thin air. Forty-one home games. Daily practices. Gym sessions where every squat burns twice as hard.
Randy Wilber, a physiologist for the US Olympic Training Center (which sits in Colorado Springs, coincidentally), sees it as an upgrade.
“They get a ‘five-gear’ engine,” Wilber says, compared to the “four-gear” standard sea-level opponents.
It’s a double whammy. The home team builds their engine while the visitors struggle to turn theirs over.
Data from strength coaches backs this up.
Visitors lose 5 to 10% performance in the first ten minutes of a Denver game. Their blood oxygen saturation drops below 90%. They are effectively drowning in air.
Aerobic metabolism delays. The body struggles to kick in.
But here’s the catch.
Altitude helps distance runners immensely. It doesn’t help a powerlifter nearly as much. Hockey lives somewhere in the middle.
Sprints. Bursts. Then stop. Then go again.
MacInnis points to the gaps.
“You skate hard. You stop. You recover.”
High altitude players bounce back faster between shifts. They are fresh when the visitors are still wiping sweat from their eyes.
This matters for the upcoming third-round series.
The Las Vegas Golden Knights play at 2,000 feet. That’s high.
But Denver is higher.
Effective oxygen in Vegas? Around 19.4%.
Still thin. But Denver is thinner.
The Avalanche didn’t win because they figured out how to breathe.
Ten years ago, they had the worst record in hockey. Altitude was the same. Players were not.
They won in 2022. Vegas won in 2023.
Cale Makar wins trophies on skates. James Norris awards don’t come from extra red blood cells.
“It’s the players they have right now,” MacInnis says.
They swept the first round. Lost only one game in the second.
The altitude advantage?
Maybe a fifth gear.
Or maybe just noise while they skate circles around everyone else.
