It’s a familiar feeling for newcomers and tourists: huffing and puffing up a mountain, feeling like reaching the summit is impossible or close to it.
Physical fitness aside, there’s a very real reason people not acclimated to altitude feel physiological changes, like difficulty breathing, when exerting themselves in a new alpine environment.
A continuous supply of oxygen is essential for physical and mental functioning. Your heart, muscles and brain all need better oxygen delivery, especially when they’re working harder. At higher altitudes, there’s less oxygen, resulting in a condition called hypoxia.
The lack of oxygen at high altitude can cause acute mountain sickness. People experience dizziness, thirst, fatigue, nausea, sleeplessness and swelling of the brain and sometimes even die as their respiratory system works harder to supply the same levels of oxygen to the bloodstream.
“High-altitude environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes,” states a paper on the effects of high altitude on sleep and respiratory systems in The Scientific World Journal.
Sustained exposure to hypoxia, scientists explain, has adverse effects on body weight, muscle structure and exercise capacity, mental functioning and sleep quality.
Altitude sickness can feel a lot like a hangover, which is why experts suggest drinking lots of water, limiting alcohol and transitioning slowly from the valley floor to higher peaks during the acclimation process.
But there’s much more to it. Researchers at the University of Colorado’s School of Medicine’s Altitude Research Center are taking a closer look at hypoxia, and for good reason: Altitude illness impacts 25 percent of tourists to Colorado’s many mountains and can set in at as low as 8,000 feet.
On the cutting edge of altitude
Understanding how altitude affects the body is important to mountainous states, like our neighbors to the south.
“Because millions of visitors travel to high-altitude locations each year, acute mountain sickness is a public health problem and has economic consequences, especially for the ski industry,” wrote Robert Roach, the director of the Altitude Research Center, in a paper in the New England Journal of Medicine in 2012.
His colleague Andrew Subudhi focuses on studying cerebral blood flow and exercise performance related issues related to altitude.
“The big picture we’re really chasing is how we can mitigate or lessen the effects of altitude for everybody who comes to altitude,” Subudhi said.
While Subudhi and his team are making strides, that hasn’t always been the case in altitude research. Drugs like acetazolamide and dexamethasone, the most commonly prescribed treatments, have risks and negative side effects.
“The field has really been stuck for the last 50 years,” Subudhi said. “We haven’t had any new ways to help people with mountain sickness.”
A subset of the population tends to get extra attention, thanks to funding by the Department of Defense.
“We’re sending troops to high-altitude locations, and they get sick, just like the rest of us,” Subudhi said. “They don’t perform well physically, just like the rest of us. They’re no different. They’re not immune, but the military would like to make them.”
In 2011 the Pentagon awarded a $4 million grant to the Altitude Research Center to develop ways to combat high-altitude sickness in soldiers and sailors.
One of the challenges Subudhi and other face in their altitude research is not being able to tell how quickly, if at all, people acclimatize to altitude.
“Believe it or not, we don’t know,” Subudhi said.
There’s no test. Instead scientists can ask how people feel — Does your stomach hurt? Does your head hurt? Do you feel dizzy? — and monitor how they’re performing physically.
“Are you performing better than you were when you first came to this altitude? That’s how we judge acclimatization,” Subudhi said. “There’s no real objective standard there. So what we’re trying to do is create more objective standards.”
Strides are being made, albeit in a one-step-forward, two-steps-back fashion. Years ago the team at the Altitude Research Center developed a blood test that can sometimes identify those who will get AMS.
“The science is evolving so fast,” Subudhi said. “Every year there are new and more sophisticated tests. Will it come to pass? Maybe. I don’t think it’s really ready for prime time yet. These are integrated problems that are complex. Sometimes the blood tests are very good, and sometimes they’re not so good.”
The team is also studying how people acclimate to hypoxia, hoping to use the results of the study to develop drugs that improve human performance when oxygen is limited.
A more recent finding of the Altitude Research Center, published in a 2016 article in the Journal of Proteome Research, found that even short exposures to high altitudes can trigger changes within red blood cells that make it easier for people to deal with low-oxygen conditions.
Scientists thought that red blood cells might be what cause that phenomenon, but they were wrong.
“There’s some memory of that acclimatization,” Subudhi said. “They don’t lose everything. That’s a really interesting finding that’s been supported by a bunch of anecdotal stuff. Mountaineers have been saying that for years. But nobody’s got the answer yet, so we’ve got to figure that out. And what we know is that it’s probably never going to be one single thing. There are thousands of changes that go on, and it’s probably some combination of these things that lead to acclimatization.”
Ways to be prepared
There are ways to prepare your body for exertion at high altitude. Depending how high you plan to go — the summit of Mount Glory, say, or the summit of Mount Everest — techniques vary.
Local cardiologist Ellen Gallant is an expert at how to prepare for altitude. Gallant trained for the past 15-plus years in hopes of summiting Everest. After two previous attempts, one ending in tragedy, Gallant reached the top of Everest last May.
While much of her training was physical, like bootpacking Mount Glory and Snow King with a 40-pound bag of cat litter on her back, Gallant also used sleep to her advantage. She slept for months with an altitude tent covering her bed, simulating a low-oxygen environment similar to that at 18,000 feet.
“It doesn’t negate the need to go to the gym or anything, but it certainly helps,” Gallant said. “I’m a believer.”
Subudhi agreed, no one should rely solely on the tents.
“It’s tough to really acclimatize in one of those small tents,” he said. “The data is pretty clear that you need to spend 12, 15 hours a day to get the same benefit of living at that real terrestrial altitude. That makes them pretty hard to use in that fashion. To say you’re going to do all your acclimatization in a tent, I don’t think there’s any data to suggest that’s your best strategy. Part of training is moving around.”
Gallant also used a mask that can simulate working out on a stationary bike at 18,000 to 20,000 feet. That’s much higher than Mount Whitney, which at 14,494 feet is the tallest mountain in the contiguous United States.
“I’d be on my bike, watching CNN for an hour and a half each evening, spinning at 20,000 feet,” she recalled.
For the comparatively mellower summits of the Tetons, trainer Crystal Wright knows firsthand how to get her clients up to snuff. Her methods include acclimating in the gym with training — strength training and working on raising heart rates with cardio — and then taking it outside.
“Fitness definitely helps with altitude, from my professional standpoint,” Wright said. “You’re going to acclimate faster if you train in a controlled environment in the gym.”
Muscles need oxygen to function, she said. And the more fit you are the more oxygen you can take in at high altitudes. Many studies of the benefits of moderate altitude training to improve competition performance at both altitude and sea level have found that training should include short-duration, high-intensity efforts at altitude.
“The quicker your heart rate can recover, the better as well,” Wright said.
Wright is just like us. At 12,000 feet she hits a wall. Even though her heart rate is lower than when she’s in the gym, she said, “I feel like I’m dying.”
Even fit people at lower altitudes shouldn’t underestimate the power of thinner air, she said. Many people travel to Jackson Hole to climb the Grand Teton. One of her clients, a triathlete, came in with an “I do Ironmans, this is no problem” attitude.
“I don’t think he made it to the top,” Wright said.
One tip she shared is to go to higher altitudes as frequently as possible.
“If you go up one of the Teton peaks once a week, that’s definitely going to make you a stronger athlete in general,” she said.
But training here, even at a base elevation of 6,237 feet in town, can be helpful.
“Super-good athletes come here for the summer, like pro bikers,” Wright said. “They get here and they’re like, ‘Whoa,’ just gasping for breath. I think it’s good for them to train here.”
Knowledge is power: No more blaming the pace of an ascent on the altitude in and of itself.
“A lot of people that move here will use altitude as an excuse for being de-conditioned,” Wright said. “I get that excuse a lot.”