Bellevue Club member Dr. Todd Freudenberger knows a thing or two about the lungs and how they function during challenging physical feats. He is a specialist in pulmonary medicine and critical care at Overlake Medical Center & Clinic. And he spends his off-time mountaineering on Mount Rainier, mountain biking, trail running and more. As peak climbing season is upon us, he fielded a few questions about what happens to the body during high elevation exercise.
At what elevation does acute mountain sickness become a risk?
After you reach about 9,000 feet or so, the problems associated with low oxygen environments are magnified.
What is actually happening in the body when you reach higher elevations?
At sea level, the inspired oxygen pressure in the air is about 150 millimeters of mercury,
and in your body it’s about 90 millimeters of mercury. Oxygen is transported to muscles and organs by hemoglobin in red blood cells, which is 95 percent full or saturated at this altitude. The amount of oxyg
en you’re carrying is about 89 percent. When you’re at the top of Mount Rainier, your body is at about 50 to 60 millimeters of mercury and your oxygen levels are about 85 percent.
How does this manifest?
You can become very short of breath, especially if
you reach high elevation quickly. Your body has mechanisms it uses to try and compensate for that, and one is to increase ventilation so you start taking bigger and more breaths per minute.
Anything else going on?
Yes, your body becomes alkaline because you’re breathing more and more and your carbon dioxid
e levels drop. When that happens, the kidneys have to eliminate all that alkaline as another compensatory mechanism, which can be tough on some people. There are medications you can take for this though.
What are the symptoms of acute mountain sickness?
Dizziness, nausea, confusion, headache, lack of desire to eat and general malaise. It occurs most often when people attempt to ascend quickly. To treat it, you need to rest, take a non-steroidal an
ti-inflammatory like Tylenol or Ibuprofen, and hydrate.
How can you tell if you are going to be susceptible to acute mountain sickness?
It’s genetic, and there is no way to predict if someone will do well at high altitude for the first time. It isn’t affected by ability or your athletic prowess or even training. I have a friend
who could destroy me cycling at sea level and we ended up pulling him up the mountain.
Can it be life-threatening?
It’s very rare, but something called High-Altitude Pulmonary Edema or HAPE can develop. It usually occurs within two to fours day after being at 8,000 feet or higher, and it’s when fluid is escaping from the blood vessels in the lungs. It is accompanied by extreme shortness of breath and develops quickly. It is life-threatening and those people have to get taken off the mountain immediately.
What are your recommendations if you know you are at risk for acute mountain sickness?
Take the time to acclimatize. Take two days to get to 8,000 or 9,000 feet. The rec
ommendation for susceptible people is don’t ascend 1,500 feet or more per sleep. Also, sleep at lower elevations if possible and then climb high during the day. There’s a mantra: climb high and sleep low. Other than that, there are medications that help a great deal called Acetazolamide (brand name Diamox). Also, alcohol should be avoided when your climbing because is has a depressive effect on the body.
What about those elevation training masks? Do they help?
I don’t recommend them. Others say sleeping in a sealed tent helps. I saw one series of literature that suggests if you slept in a tent for two weeks it can help a little, but I don’t think it’s worth it when there are other more effective ways to help.
Are there conditions where people should not attempt high altitude activity at all?
Any kind of serious lung condition, like chronic obstructive pulmonary disease, or people with underlying heart conditions. It’s important to speak with your doctor if you are worried at all.
What about asthma?
People with asthma can actually do better up high because there are less things in the air that can trigger reactions. And for most people with asthma, exercise can help with airway dilation but the exertion should be moderate. And again, talk with your doctor first.
Anything else you want to let people know?
Just that the classic thing is for the young, very fit athlete to push themselves, go too fast, too rapidly, and ignore warning signs. Take your time. Also, if you’re with a guided group, don’t hesitate to speak up if something is wrong. Sometimes you don’t know the other people and don’t want to slow down the group, but talk to your guide immediately if you feel unwell.