Category Archives: Acclimation

What happens to your body’s physiology when you move between low and high elevations?

Aconcagua: an Athlete/Medical Scientist’s Narrative in Symptoms

“Day 10: I walked for maybe an hour up to Camp 3 (19,258’/5870 m) from Camp 2 (18,200’/5547 m). I became the slowest person. I had tunnel vision. It was bad. It took a lot of willpower. I do a good job of not telling people how bad I really feel. After about a mile, I told them I had to stop, and me and Logan turned around. We had that conversation,

‘I don’t think I should go up anymore. It’s not safe for me, and it’s not safe for the group.’

Barely able to move, about an hour above Camp 2.

“The others didn’t go all the way to Camp 3, but continue on a bit more. Angela said she got a headache really bad and couldn’t see out of her right eye. I had already pretty much decided — I was devastated — after two nights and two days of not acclimating. Alejo had a stethoscope and said my left lung was crackling. We thought I might develop some really serious pulmonary edema.”

Keshari Thakali, PhD is an Assistant Professor in the Department of Pediatrics at the University of Arkansas for Medical Sciences in Little Rock, AR. She is a cardiovascular pharmacologist by training and her research laboratory studies how maternal obesity during pregnancy programs cardiovascular disease in offspring. When not at work, you can find her mountain biking, rock climbing, hiking or paddling somewhere in The Natural State. She has a long-term career goal of merging her interests in mountaineering with studying cardiovascular adaptations at high altitude. She has climbed to some of the most extreme elevations in the Rocky Mountains, Andes and Himalayas. Last December, she flew down to Mendoza in Argentina for an ascent up Aconcagua.

Sacred in ancient and contemporary Incan culture, and the highest peak in the Americas, Aconcagua summits at 22,837′ (6960 m). Current statistics show only 30 – 40% of attempted climbs reach the top of this massive mountain in the Andes, in Principal Cordillera in the Mendoza Province of Argentina.

Sunset on Aconcagua from Base Camp.

The day following Keshari’s decision not to summit, she hiked back down to Plaza de Mulas (14,337’/4370 m) from Camp 2, carrying some of her colleague’s gear that he didn’t want to take up to the summit as he continued to ascend. Plaza de Mulas is a large base camp area with plenty of room for tents, available water, and large rocks that provide some protection from the wind as climbers take time to acclimate before continuing their ascent.

“Even though my oxygen [saturation] was low, I was functional. As you go down, everything gets better. The others continued up to Camp 3. They spent one night there, then summited the next day. It took them 12 hours.

“The day the others came back to Plaza de Mulas, I think that’s when everything hit me. I felt like a zombie. I did some bouldering and got so tired I had to sit down and catch my breath often, probably because I had been hypoxic and we were at over 14,000′.

“[The next day] we did the really long hike from Plaza de Mulas all the way to the entrance of the park. It probably took about 8 hours to walk all the way to the park entrance.

“We drove to Mendoza that night. I felt like my body was tired, but my muscles were functioning just fine. It’s hard to describe.”

They had done everything right and had taken every precaution. Each of Keshari’s colleagues boasted significant backgrounds in climbing and mountaineering, their cumulative accomplishments including Mt. Elbrus (18,510’/5642 m), Cotopaxi (19,347’/5897 m) and Denali (20,335’/6198 m), their ages 30 to 65. They weren’t initially planning to hire porters, “but they ended up carrying a lot of our stuff. In the end, it just makes sense to hire these porters to increase your chance of success.”

They gave themselves about two weeks to make the ascent and return. There was ample time for them to stop at each camp and spend time acclimatizing, including day hikes to the nearby peaks of Bonete and Mirador.

“Day 4 [we did an] acclimatization hike to Bonete (16,647’/5074 m), pretty much the same elevation of Camp 1. You look at the mountain and it looks pretty close, but … in mountaineering, you don’t do distances, you do time. Did the hike in mountaineering boots, which were heavy and clunky, but I learned how my boots actually work. You walk differently in these than a shoe with a flexible sole. The last part of the mountain is pretty rocky and it looks like you’re almost to the top, but you still have to walk an hour to the summit. It took about five hours to go up. We were walking slow, I felt fine. From the top of that mountain, looking away from Aconcagua, you can really see Chile and the Chilean Andes.”

Summit of Bonete.

All the way through their first week of climbing, including a day of resting and eating after their hike up Bonete, Keshari was feeling fine.

“Day 8, we made the push to Camp 2 (18,200’/5547 m). None of these hikes made me tired. I was plenty trained. We were carrying packs, but they were still pretty light, packed with stuff for the day. We spent the night at Camp 2, took oxygen mostly at night. [My] first reading at Camp 2 was low. We were at over 18,000′. I thought maybe I’ll just go to sleep and it’ll get better.

Looking down on Camp 2 covered in snow.

“Day 9 was a rest day at Camp 2 because the weather was really bad. All I did was sleep that day. If you’re gonna go to Camp 3, that means you’re gonna do a summit push the next day, because Camp 3 is so high. You’re just struggling to stay healthy. I felt really bad in the tent, but if I went outside to pee or walk around, I felt better. My pulse ox was still pretty low that day. That night, a snow storm blew in and it snowed a lot.” And it was the following day of their ascent to Camp 3 that Keshari made the decision not to summit.

Since returning from her expedition, she’s reflected on some other variables. “I swear I was hyponatremic (an abnormally low concentration of sodium in the blood). We went through four liters of water a day with no salt in the food. I was having these crazy cramps in my abs and my lats and places I don’t typically get them. To me, that has to do with electrolyte imbalance. Next time, I’m taking electrolyte tablets, not just stuff to mix in my water.

“I’m not very structured in my diet. In general I eat pretty clean, but I don’t count calories. I eat vegetables, but I also hate going grocery shopping. I feel like I eat a pretty balanced diet. If I buy meat, I’ll buy a pack of chicken and that’s my meat for a week or two.

“On the mountain, in general, I felt like they fed us way more fiber. In Argentina, they eat a lot of meat. They’re meat-eaters. They didn’t feed us steak on the mountain, but … at Base Camp, I felt like they were overfeeding us. We had pork chops one night, but on the mountain, I felt like it was mainly lentils and noodles. Even though you’re burning calories, how your body absorbs them is different. They really try to limit your salt intake because they’re concerned about having too high blood pressure. At Base Camp, breakfast was always scrambled eggs with bacon and toast. Lunch and dinner were always three course meals starting with a veggie broth soup. They fed us like kings … I brought Clif blocks with caffeine in them for hiking snacks, Lara bars.”

I ask about her main takeaway from it all:

“I think I need more time to acclimate. I don’t know how much more time, but maybe more time at about 16,000′. Maybe take Diamox. Someone suggested I should have been on an inhaled steroid, especially because my asthma is worse in the cold. If I were to go next time, I would want a couple more days at 15,000 – 16,000′. Maybe the Diamox is something I would need to use next time.

“The nerd in me wants to measure pulmonary wedge pressures (via very invasive catheters; you could go through the jugular), nothing practical,” she laughs. “The pulse oximeter is the easiest tool.”

One last thing she’d do differently? One of her colleagues bought a hypoxic generating system from Hypoxico, “which I think puts CO2 back into your system; sleeping high, training low. That might have been the best thing.”

Keshari went sky-diving back in Mendoza the day after returning from their descent. “I was expecting a lot of adrenaline jumping out of an airplane, but there was none. I enjoyed the freefall, but when the parachute went up, I got really nauseous. Maybe I had just been stressed for so long, there was no more adrenaline left. I was like, ‘Where’s the risk involved in this?'”

An illustrated oxy-journey.

Keshari also summited Cotopaxi earlier the same year. Read her own account here.

robert-ebert-santos

Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not developing applications and graphics, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.

Oxygen

It has everything to do with how well the body functions at increasing elevation. In Summit County, Colorado, we live at an average elevation of 9000′ (2743 m). Most bodies start a significant physiological response to 8000′ (2438 m). Even healthy athletes experience shortness of breath during certain activities that wouldn’t be noticeable at lower elevations. The body compensates by circulating more oxygen-carrying red blood cells, because there isn’t as much oxygen packed into each breath you take. Heart rate increases, you take quicker breaths, speeding up your ventilation. You are hyperventilating. If you manage well enough for a couple weeks, your body will eventually start creating more red blood cells to circulate more oxygen throughout your body at all times. This process will peak at about three months.

We often get questions about the canisters of oxygen sold at convenience stores, souvenir shops and gas stations across Colorado and whether or not they make any difference. There is a 100% consensus among every physician, athlete, EMT and ski patroller we have ever interviewed that they do not.

Why not? Dr. Chris has been practicing medicine at 9000′ for 20 years in Frisco, CO, so I asked her a couple of the questions that have come up at our clinic and on our blog recently and frequently.

How much oxygen is needed to actually mitigate symptoms of altitude sickness?

For someone with low blood oxygen saturation, our target would be 90% . They should be put on a concentrator or a large tank [of oxygen]. The adult dose is 2 to 4 liters per minute, the pediatric dose can be between 1/4 L per minute and 1 L per minute, 24 hours a day, for up to a week, or until their oxygen saturation can maintain at 90%. Less than that, and usually, it will drop again after 10 minutes off oxygen; and it’ll often be lower when you sleep, too.

What if I bought ten of these canisters of oxygen available at the gas station and breathed all of them in, one after the other. Would that make a difference?

You might get three hours worth of oxygen if you bought ten of those store-bought cans, which might help an altitude sickness-induced headache. But again, your oxygen would likely drop shortly thereafter, and you would be experiencing the same symptoms.

What happens if someone struggling with acclimatization also contracts COVID-19 or another disease with associated respiratory complications?

We don’t know. Their oxygen requirement might be higher. All of us at altitude might be at greater risk than someone living at sea level.

When do you make the decision to send someone to a lower elevation? How low?

If they are having trouble breathing in spite of being on 4 L of oxygen per minute. If they need more than that, we would send them to a lower elevation. Most people are fine going to Denver. By Georgetown (8530’/2600 m, a town between Summit County and Denver), they’ll experience an improvement. It’s above 2500 m where altitude issues become problematic.

Research in recent years, including our own, is revealing many other different variables that may affect an individual’s ability to acclimatize to high elevations, including different hormones, genetics, and muscle mass. We continue to advise anyone traveling to the Colorado mountain region above 7000′ from lower elevations to stay hydrated and well-rested, and time a slow ascent, planning to spend at least 24 hours in Denver, or another comparable lower elevation, before arriving at your final destination.

robert-ebert-santos

Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not developing applications and graphics, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.

Medicine Man: Ski Patroller & EMT Jonathan Sinclair’s Elevated Experience

“I’ve been here 25 years,” Sinclair shares with me over coffee at the Red Buffalo in Silverthorne, Colorado (9035’/2754 m). “Born and raised on the East Coast in Philadelphia.” The software company he had been working for moved him out to Colorado Springs. He hadn’t ever skied in his life until then. Shortly after, “on a whim”, he moved up to Summit County and started working on the mountain as what we used to call “Slope Watch”, the mountain staff often in yellow uniforms monitoring safe skiing and riding on the mountain. After a month, he got really bored, “and I said, ‘How do I get to be a patroller?'”

Sinclair then went to paramedic school to get qualified as an Emergency Medical Technician, then spent 19 years as an EMT and 9 years as a Medic. For the last six years, he’s worked for the ambulance service in Summit County, one of Colorado’s highest counties, with towns at above 9000′. He has also worked as a ski patroller at Copper Mountain, Keystone, and Park City (Utah). This year is the first he hasn’t been patrolling in 18 years. During the summer, he is a wildland fire medic, where he often works with crews that are shipped in from lower elevations, including sea level.

Although he’s decided to take this season off, he still maintains a very active relationship with the outdoors, travelling around the backcountry on expeditions to remote mountain cabins, and has made a recent trip to Taos, New Mexico (6969’/2124 m). He’s witnessed his share of altitude complications.

What are the most common altitude-related complications you see?

You see the families coming up to go skiing … Usually 90% of them are fine. Altitude doesn’t seem to bother them at all – they’re either healthy enough or lucky enough. They get in, they ski, they get out. But there’s that one family or that one couple that just don’t acclimatize. They don’t realize that they don’t acclimatize, and the rest of their group doesn’t realize. A couple of days go by and they think, ‘Geez, I feel awful,’ then they go ski, or do something active, and their condition is exacerbated. Or ‘Geez, I haven’t slept,’. you get that story over and over.

And you’re having this conversation on the hill as a patroller?

Or they’ve called 911 on their way [up to the mountains]. They have no idea. Just no idea. I ask them what they’d had to eat. They had a donut or a pastry or just coffee before the plane ride. I ask them when was the last time they peed. You’re trying to find the physiology of what’s happened.

I tell them, ‘You need to sit down or go back to your condo. You need liters of water. You need liters of Gatorade. No fried foods, no alcohol, no coffee. No marijuana. Let your body catch up. Wherever you’re staying, tell them you need a humidifier. Put it in every bedroom, crank it up and leave it on. You’re gonna have trouble sleeping.’

And they never wanna hear it. They never wanna take a day off, but by the time you see them, they’ve taken the day off anyway, because there’s no way they’re getting back up there!

Sinclair also expresses some frustration with the lack of resources provided by the ski industry itself:

How do you educate them? The marketing people don’t want to. Because if they have to spend a day in Denver [to acclimate], that’s one less day up here [at the ski resort]. They don’t want to publicize that [altitude sickness] can happen, that it’s common. People ask, ‘How often does this happen?’ Easily, at any resort in a day, Patrol probably sees 20 – 25 people, whether they called, they walked in, you skied by them and started talking to them. ‘You’re dehydrated. You’re at altitude. It means this …’ The resorts don’t want that many to know, otherwise, you’re gonna go to Utah or California, where it’s lower.

You get such misinformation. ‘At 5000 ft., you have 30% less oxygen.’ No, the partial pressure is less, there is still 21% O2 in the air. You just have to work harder to get the same volume. The real physiology of what’s going on is systemic. [People experiencing altitude sickness] don’t know why they feel like crap. They think it’s because they’ve been drinking too hard.

How do you mitigate their symptoms on the mountain?

We do a lot, but it’s reactive, not proactive. I hate to bash the oxygen canisters, but it’s not doing anything for you. It’s not gonna make you feel better, other than what you’re sucking up. At 10,000′, it’s questionable. We’ll be at the top of Copper [Mountain] giving them two to four liters of oxygen, then they’ll ski down and feel great.

Sinclair refers to the Summit County Stress Test, which was the first I’d heard of it:

You’re 55, you’re 40 – 50 lbs. overweight, and you come up for your daughter’s wedding. You walk over to Keystone [Ski Resort], you take the gondola over, then all of a sudden, you find out you have a heart condition. You find out whatever else you have going on. We’ve done it over and over and over. They go ski, they call us at 3 in the morning, we find out they’ve got a cardiac issue, or they’ve irritated the pulmonary embolism they’ve had for years.

I had a guy last year, at the Stube at Keystone for lunch.

Keystone’s Alpenglow Stube is a reputable restaurant that sits in the resort’s backcountry at 11,444′ (3488 m).

He had some food, alcohol, he’s having a great day. Ski patrol gets a call, ‘Hey, my husband doesn’t feel well.’ This guy looks bad, sitting on the couch, sweating profusely, and he can hardly tell what’s going on. It’s the classic presentation of an inferior heart attack.

‘I don’t have any heart conditions. I saw my cardiologist.’ You saw a cardiologist, but you don’t have any heart conditions?!

And there are a lot we don’t see. People who go home because they think they have the flu.

Have you seen any rare or surprising complications?

We see HAPE (High Altitude Pulmonary Edema) now and again. That seems to be a walk into the hospital where [their blood oxygen saturation is] at 50 – 52. We’re not in the zone to see HACE (High Altitude Cerebral Edema). We’re just not at the altitude.

HACE is more typical above more extreme elevations, above 11,000′. Colorado’s highest peaks are just above 14,000′. Most ski resorts in Colorado are below 12,000′.

I’ve only seen one HAPE case on the hill. In their 50s. You listen to their lungs, and they’re getting wonky. A guy who was reasonably fit, but you look at him and go, ‘Hm, this is bad.’ But he was responsive and talking. Then you start seeing the things like the swaying, getting focused on something else [in the distance]. One of those [situations] where you’re like, ‘Let’s get out of here.’ [We need] tons of oxygen. Again, ‘I didn’t feel good yesterday, but I decided to go skiing today.’ He was sitting at the restaurant at the top of Copper [Mountain].

People do not realize that their diabetes, their asthma, their high blood pressure, things that they commonly manage at home, are exacerbated at 9000′. By the time they realize it, they’re calling 911. At that point, your best bet is to get out of here.

What tools or instruments do you use the most as a paramedic and ski patroller?

Cardiac monitor. It’s got a pulse oximeter. [Also] simple things you ask. ‘Hey, do you know what your blood pressure is?’ I use a stethoscope all the time. Sight and sound. Are they talking to me? Are they having a conversation with me? Are they distracted by what’s happening to them? When was the last time they peed? Was it regular color? Did it smell stronger than usual?

People ask, ‘How much water do I need?’ How much water do you drink in a day? If I’m outside and I’m moving, I probably have 10 liters. If I’m on a roof laying shingles, I probably have 4 or 5 liters before lunch. It’s those little tools. You don’t even have to touch somebody.

Do you have any personal recommendations for facilitating acclimatization at altitude?

Workout, be in shape, go harder than you normally do that month before you get here. Get the cardiovascular system more efficient before you get here. If you have any kind of medical concerns, make an appointment with your doctor and say you’ll be at 10,000′ to sleep. Just ask, ‘What do I need to do?’ The day before you get on the plane, stop drinking coffee and start drinking water. Hydrate before you get here. They humidifier thing. Make sure the place you’re going has one. Find out. Go to Walmart and spend $15 to buy one.

Watch your diet. Just so your body’s not fighting to get rid of fat and crap.

When we’re getting ready for a hut trip, we are mostly vegetarian (although we do eat meat), but we ramp protein up a week prior, pushing more chicken, more red meat. We tend to eat fish normally, but there’s always at least one fish meal at the hut. We don’t do crappy food at the hut. I don’t care if I have to carry another 10 lbs. In addition to going to the gym, go for a skin, go to 11,000 – 12,000′ for a couple hours. Ramp up the altitude work.

What do you eat on the trail?

Pre-cooked sausage, usually some kind of chicken sausage. Cheese. Whole grain tortillas, and if we’re feeling spunky, some kind of hot sauce or pico [de gallo]. For me, it’s just a handful of nuts and raisins. If I feel like something else, I’ll throw in some chocolate or white chocolate. I hate the packaging, the processed foods, the bars. Somebody usually makes granola for on-the-way-out food. And I tend to carry dried fruits. Lots of peaches during Palisade peach season. I used to take a lot of jerky.

A recent topic that comes up alot in altitude research at our clinic is Aging.

I have to work harder to stay at the same place. I’m sitting here and I can feel my right knee. I was at a 15″ [of snow] day in Taos, and I caught something [skiing]. It’s been weeks, and it’s not weak or anything, but I just know. It takes longer. I find I need more sleep. I was a 4 or 5 hour a day guy for a long time. Now I’m at 7. The days I get 8 are awesome. Luckily enough, I’m still healthy, fit. If I’m up at night, it doesn’t shatter my day. Haven’t slept on oxygen yet. Don’t want to find out.

He laughs.

As I get older, I’m adding more supplements: fish oil, glucosamine, glutine (for eye health). My eyes are bad anyway, and I’m constantly standing outside against a big, white mirror (the snow). And I’m cautious of the bill of a hat vs. a full-on brim during the summer. Other than my face, everything’s covered during the winter. The color of the bill on your hat can be way more reflective. A black bill will cut the reflection. Little things.

I’ve rounded out my workouts. They’re more whole-body. I concentrate on cardio. I’m conscious that I’m not as flexible as I was. I’d like to say we’re regularly going to yoga, but at least we’re going.

The gauge for me is you go on a hut trip with our friends in the middle-age category, but we’ll take some younger folks [too]. I kinda monitor who’s doing what – chopping firewood, who’s sitting more than who. It’s not out of pride. I need to realize.

I’m colder. You start to notice. It’s not that your feet are cold, it’s that your calves are cold. I succumbed to boot heaters a few years ago.

Year after year, in every season, visitors from all over the state and all over the world come to Colorado’s high country. For many of them, it’s the highest elevation they’ve ever visited, and often ever will. The dryness, the elevation, the air pressure, the intense sun exposure and the lack of oxygen demand a lot of compensation from the body. Sinclair’s experiences at altitude are consistent across every conversation I’ve had with physicians, athletes and other professionals when it comes to preparing your body to be active at altitude, from getting plenty of water to controlling the speed of your ascent to any elevation above 7000′ to consulting with a specialist regarding any pre-existing cardiac or respiratory conditions to how much oxygen one needs to mitigate symptoms of altitude sickness to decreasing elevation in case of an emergency. Any one of these experts will also tell you that the best ways to prepare your body for altitude is to get plenty of sleep, exercise regularly, and limit foods containing a lot of oil, grease and fat that will demand more from your body.

robert-ebert-santos

Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not developing applications and graphics, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.

Understanding the effects of nocturnal hypoxemia in healthy individuals at high altitude: A chance to further our understanding of the physiological effects on residents in Colorado’s mountain communities

The population of Summit County, Colorado is projected to grow by 56% between 2010 and 2030. Along with adjacent Park and Lake Counties there are now over 40,000 people living above 2800 meters elevation. This is the largest high altitude population in North America. As opposed to native populations in South America, Africa and Asia who have been residing above 2800 m for centuries, the North American residents are acclimatized but not adapted. Symptoms related to hypobaric hypoxemia are notable above 2500 m.  Recognized conditions associated with altitude include central sleep apnea leading to hypoxemia (abnormally low oxygen level in the blood) which activates the sympathetic nervous system. In susceptible persons this can cause systemic and pulmonary hypertension. The incidence of this potentially devastating side effect of mountain living is unknown.  In order to better understand the potential side effects of nocturnal oxygen desaturation in healthy individuals, it is beneficial to investigate the normal physiological changes that occur during sleep, which leads to low oxygen levels in all individuals.

When the body enters the sleep state, many of the behavioral mechanisms that are active during wakefulness are blunted, and it’s been found that different sleep stages have varying effects as well.  One of the major changes is a diminished response to hypercapnia (high carbon dioxide levels in the blood) and hypoxia.  During sleep, the CO2 set point is elevated from 40 mmHg to 45 mmHg, which results in reduced alveolar ventilation.   It’s also observed that minute ventilation is reduced, which is due to decreased tidal volumes that is normally compensated for with an increase in breathing frequency during wakefulness.  Also, during sleep, there tends to be upper airway narrowing that is normal and there is reduced reflex muscle activation of the pharyngeal dilator muscle.  All of the above factors contribute to decreased ventilation during sleep. 

A lot of what is understood about the effects of nocturnal hypoxemia is due to extensive studies in individuals with underlying diseases, and these studies are not always conducted at higher altitudes.  One such study investigated the effects of nocturnal desaturation (SaO2 < 90% occurring for > 30% of the sleep study) in chronic obstructive pulmonary disease (COPD) patients without a diagnosis of sleep apnea.  The authors found higher rates of dyspnea, increasing rates of worsening COPD symptoms, poorer quality of sleep and health-related quality of life.  Another such study found that some patients with COPD experience increased transient arterial hypoxemia (TAH) during rapid eye movement (REM) sleep.   In this study, the authors observed that the study subjects experienced increased pulmonary vascular resistance (which can lead to pulmonary hypertension) and a few subjects experienced an increase in their cardiac output. The authors found that individuals could experience a decrease in this phenomena by using nighttime oxygen therapy.

Studies, such as above, do not assist in identifying healthy individuals that may need early intervention due to nocturnal hypoxemia at altitude.  What about the healthy individuals without underlying diseases?  In the study conducted by Gries and Brooks in 1996, the authors collected data from 350 patients.  Their recorded average low saturation in the study of 350 subjects was a reported 90.4% lasting an average 2 seconds.  This study was conducted at the Rainbow Babies and Children’s Hospital located in Cleveland Ohio, at an elevation of 653 feet (198 m). This is one of the largest studies done to assess normal oxygen levels observed during sleep, and the results, along with results from other studies are displayed in Table 1.  As of right now, there is no equivolent study for subjects at elevations like that of Summit County, CO, which is at an average of 9110 feet (2777 m). Aside from the normal physiological changes noted above, the rates of developing underlying central sleep apnea leading to systemic and pulmonary hypertension is unknown.  Further, there are no guidelines as to initiating treatment in patients that may be experiencing adverse effects of high altitude nocturnal hypoxemia, because there is a lack of data to establish baseline normal values observed at this elevation.  This leads to unnecessary sleep studies, and further involvement of a myriad of healthcare professionals that have no specific guideline to reference when approached by one of these patients. 

In order to further our understanding of the effects of high altitude and nocturnal hypoxemia in healthy individuals, like that of Summit County, there has to be preliminary and ongoing research in these individuals.  Dr. Chris Ebert-Santos is currently conducting an overnight pulse oximetry study, which aims to recognize which symptoms they may or may not be experiencing, that are related to high altitude or sleep disorders, so that they may receive treatment, feel better, and remain active. 

At this moment, initial study results reveal a decreased average low night oxygen saturation from that of the study conducted by Gries and Brooks.  In a sample of just 14 individuals, the average low SpOs recorded overnight is at 81.3%, which is 9% lower than that recorded by Gries and Brooks (Graph 1).  The study is also revealing a trend in lower night oxygen saturations in individuals that have lived at elevation for a longer period of time (Graph 2). These findings suggest the need to expand and build on the current study being conducted by Dr. Chris and her team at Ebert Family Clinic. If interested, you may apply in-person at Ebert Family Clinic, where you will be required to fill out a health questionnaire on your length of residence at altitude, medical history, and possible symptoms related to high altitude.  Your basic vitals will be logged at the appointment.  After the first study, you will then be rescheduled in 12 months for a follow-up overnight study to monitor for any changes.  Overall, this study is designed to help with an understanding on the potential impact of high altitude on healthy individuals that are acclimated, but not necessarily adapted, to this environment.

Robert Clower is a second year physician assistant student at Red Rocks Community College in Arvada, CO.  His undergraduate degree was in Biology, which incorporated both medical health science courses as well as independent research courses in general biology and ecology.  While attending school at the University of North Georgia, Robert served in the Army National Guard for a cumulative time in service of 8 years.  After completing his undergraduate degree, Robert gained medical experience as an operating room assistant, which included assisting support staff with surgical preparation and patient transport throughout the hospital for surgical appointments.  Outside of his studies, Robert enjoys snowboarding, hiking, snowshoeing, exercising and spending time with family and friends. 

Sources

Summit County Population Projections: Summit County, CO – Official Website. Summit County Population Projections | Summit County, CO – Official Website. http://www.co.summit.co.us/519/Population-Projections. Accessed March 3, 2020.

Tintinalli JE, Ma OJ, Yealy DM, et al. Tintinallis Emergency Medicine: a Comprehensive Study Guide. New York: McGraw Hill Education; 2020.

Gupta P, Chhabra S. Prevalence, predictors and impact of nocturnal hypoxemia in non-apnoeic patients with COPD. 52 Monitoring Airway Disease. 2015.

Lemos VA, Antunes HKM, Santos RVT, Lira FS, Tufik S, Mello MT. High altitude exposure impairs sleep patterns, mood, and cognitive functions. Psychophysiology. 2012; 49 (9): 1298-1306.

Cingi C, Erkan AN, Rettinger G. Ear, nose, and throat effects of high altitude. European Archives of Oto-Rhino-Laryngology. 2009; 267 (3): 467-471.

Altitude Training 101

High elevation prompts physiologic changes in the body. As elevation increases, oxygen concentration in the air decreases; this is why some people suffer from altitude sickness when travelling to high altitude environments like Summit County, Colorado from a lower elevation. Training and/or living at elevation increases our red blood cell mass in order to compensate for the lower oxygen concentration, thus increasing our oxygen-carrying capacity. Red blood cells are like microscopic rafts that flow down the rivers of our blood vessels, picking up oxygen from our lungs when we breathe and then transporting it to all the muscles and organs that need it to function properly. For athletes, this physiologic concept can be used to their advantage in order to improve their performance. If they can train their blood cells to carry more oxygen by forcing them to grow in a more hypoxic (low-oxygen) environment, then they can have more oxygen available to their muscles to perform in any activity.

There is a modern training model that some athletes have adopted called “Live High, Train Low”. This means that the athlete performs high intensity training sessions at a lower elevation, but maintains general training and living at higher altitude. Your body begins making metabolic changes immediately when exposed to high altitude and hypoxia, but it can take a couple weeks for the maximum effect. Expert Dr. Gustavo Zubieta-Castillo, who spoke in La Paz, Bolivia at the 7th Annual Chronic Hypoxia Conference that Dr. Chris attended in 2019, claims that it takes him about 40 days to build up his hematocrit to be back to functional in La Paz which is situated at nearly 12,000 ft. All in all, the goal of living and/or training high, while including high intensity sessions at lower altitude, is to give your body enough time to build up some acclimatization to the hypoxic environment. Several studies in the last 25 years have taken various groups of athletes and placed them on different training regimens over 4 weeks. Some would live at low altitude and also train low, some trained low and lived high, and others trained high and low while living at high altitude. One study completed in 2008 concluded that athletes who either live high and train low, or live high while training low and high, showed about a 1.4% improvement in sea level endurance performance.

How high is too high, and how low is too low?

Snowshoeing above 9000 ft., Summit County, Colorado.

It was found in this same study, that there is in fact a “sweet spot” for implementing the “Live High, Train Low” paradigm. If subjects were living lower than 1800 m, there was not a significant improvement in athletic performance. On the other hand, if subjects were living too high, they could not adequately recover from training and therefore did not show improvement because their bodies struggled to keep up with the hypoxic environment. The best elevation to live and/or train at in order to increase RBC (red blood cell) production, RBC mass, and oxygen-carrying capacity is between 2100 m-2800 m, or about 7000 ft-9000 ft.

What does this mean for athletes in Summit County who live high and train high?

Great news! There are still major benefits to those who live and train in Summit Country, as well as for people who visit the mountains and train while they are in town. This is because of a physiologic process called autophagy. Autophagy is described as our cells’ process of degrading old proteins and damaged cell parts. This is a normal process that modulates cell survival, is important for cell renewal, and is also a promoting factor of exercise performance from altitude training.

When exposed to a hypoxic environment, our cells produce adaptive responses that ramp up autophagy and cell renewal elements. These responses include factors that promote skeletal muscle growth, boost skeletal muscle capillary concentration, and enhance coronary arteries (the arteries that feed your heart). Living and training at altitude is good for your heart and it can help build muscle while decreasing body fat mass. It also shows significant increase in cardiac output and strength of your heart stroke.

However, excessive exercise and especially excessive exercise at altitude can prove harmful to our skeletal muscle. It has been observed in male subjects running 20 km that the excessive exercise induces autophagy too much which leads to degradation of muscle protein, damage, and eventual loss of skeletal muscle all together. Therefore, just as there is a sweet spot for altitude training, it is also a good idea to monitor training in order to maximize the benefits of training in a place like beautiful Summit County.

So, how should I be training if I live in Summit County or if I am visiting for some time?

I had the pleasure of speaking with Mary Scheifley about this particular strategy. Mary is the owner of Peak One Fitness, a 24-hour gym in Frisco, Colorado (9000 ft.). She has over 20 years of experience in fitness and athletic training. She competed semi-professionally in mountain bike racing, and continues to bike today as well as cross-country ski, snowboard, weightlift, hike, and anything else that keeps her active. She loves Frisco and has found that being outside and active is almost spiritual. She is passionate about fitness and nutrition, and she works extremely hard to tailor her training regimens to each of her clients based on their individual needs or goals.

Cardio machines at Peak One Fitness, Frisco, Summit County, Colorado

When she trained people in Denver, she typically was running high-intensity aerobic classes. However, here in Frisco, she prefers to focus on strength and only include high-intensity interval training (HIIT) in short spurts. She believes that you don’t need to be over-exerting your body to see a positive response. She has a client who lives near sea level for most of the year where her main training regimen includes Cross Fit. When she comes to Frisco though, she can see a significant decrease in BMI and body fat index in just two months of lower-intensity training. Though frustrated that she cannot run on the treadmill as fast or as long as she can at home, by the end of her stay in Frisco, this client understands that difference of the elevation and appreciates the process that Mary provides for her.

Mary recognizes that fitness is not “one size fits all”. She typically likes to start people out at 80% of their maximum heart rate when exercising, but there are factors that may change this. Her clients that live in Summit County have already been acclimatized to the elevation so she can add a little to their 80% max heart rate because for them, 80% may feel like 70%. On the flip side, if you are visiting from sea level, she may have to decrease your 80% of maximum because of the hypoxia at elevation. Other factors that play a role in how Mary develops her training regimens include age, the client’s goals, their previous fitness level, and their overall reaction to altitude.

I also asked Mary about her experience with competition and professional athletes. Personally, she could tell that her endurance was superior to her competition when she raced at altitude against bikers from Denver. She also noticed that when she was in Denver, the racers there were stronger and bulkier than her. She also has experience training athletes who are preparing for competitions such as the Leadville 100 or who are professional skiers who tell her that it is more beneficial for them to come to altitude about 3 weeks prior to competition in order to prepare rather than just training at lower altitude. This is because their body will better adapt if they give it a little more time before competition while training.

At the end of the day, whether you are training for a competition, or just trying to stay healthy, being at altitude can pose challenges as well as benefits to our bodies. The following are some tips from Mary on maximizing your workouts at altitude without compromising your health and wellness.

Mary’s tips for athletic training and exercising at high altitude:

  • Increase water intake, even before you come to elevation. You should be drinking at least 3-4 liters of water per day.
  • Increase caloric intake. At altitude you are burning more calories than at sea level, and if you are wanting to train you need to fuel your body appropriately. Especially increase protein intake.
  • No alcohol. If you enjoy one drink here and there you should be fine, but if you are wanting to train at a high level alcohol should not be on the menu.
  • Add electrolytes. In addition to increasing water, you need to make sure you are replenishing your body with the salts it requires.
  • Take it slow. Maybe start with some yoga or moderate stretching before moving into running or HIIT classes. You may need to decrease your level of training by 20%.
  • Consider spending a night in Denver before heading up the mountain to Summit County. Dr. Chris has expressed this frequently to travelers and visitors of Frisco; it gives your body a chance to acclimatize prior to ascending to 9,000+ feet.
  • Don’t expect to be at your “home” level of endurance or fitness. Do not get discouraged if you cannot run your typical 7-minute mile, or you can’t easily warm up with a set of 10-15 squats. Your body needs to adjust, and you may need to just take it easy in the altitude. Ultimately, have fun and enjoy the beautiful outdoors!

Sarah Brzecezk is a 2nd year Physician Assistant student attending Midwestern University in Glendale, Arizona. She graduated from Northern Arizona University in Flagstaff, AZ with a Bachelor’s in Biomedical Sciences and then worked as a medical assistant in Internal Medicine prior to starting PA School. She is passionate about healthy eating and maintaining a physically active lifestyle, and she hopes to specialize in Orthopedics when she graduates this Fall. During her 6 weeks at elevation in Frisco, Colorado, she has enjoyed numerous hikes, two hut trips, yoga classes, and running in the gorgeous outdoors. Her goal as a provider is to help others overcome injury and illness in order to return to physical activity and athletics, enabling them to combat chronic illness and stay healthy for their future years.

References

Zhang, Y., & Chen, N. (2018). Autophagy Is a Promoter for Aerobic Exercise Performance during High Altitude Training. Oxidative medicine and cellular longevity, 2018, 3617508. doi:10.1155/2018/3617508

Brocherie, F., Millet, G. P., Hauser, A., Steiner, T., Rysman, J., Wehrlin, J. P. & Girard, O. (2015). “Live High–Train Low and High” Hypoxic Training Improves Team-Sport Performance. Medicine & Science in Sports & Exercise, 47(10), 2140–2149. doi: 10.1249/MSS.0000000000000630.

Stray‐Gundersen, J. and Levine, B.D. (2008), Live high, train low at natural altitude. Scandinavian Journal of Medicine & Science in Sports, 18: 21-28. doi:10.1111/j.1600-0838.2008.00829.x

High Altitude Hawai’i

Rising 13,803′ (4207 m) from the surface of the Pacific Ocean, Hawai’i’s tallest dormant volcano, Mauna Kea, reaches well into its own unique high altitude environment. Measured from its base on the ocean floor, it is the tallest mountain in the world, about 33,000′ (10,000 m) in height.

A frozen Haleakalā silversword. PC: Lyle Krannichfeld & Pueo Gallery

You may never have thought to find a high altitude environment on the tropical island chain, but Mauna Kea is just one of four peaks that summit over 8,000′. The next three are Mauna Loa (13,679′), Haleakalā (10,023′), and Hualālai (8,271′), with Haleakalā (“House of the Sun”) on the island of Maui and the other three on the Big Island. Each of these dormant volcanoes is home to species of plants and animals found only in Hawai’i, many of them only found around their respective peaks.

Sacred lands, whose access was once restricted to only the divine rulers of Hawaiian society, Mauna Kea now hosts 13 observatories and research staff in addition to its foreign and local visitors, many of whom make the historic pilgrimage to the summit from sea level in a matter of hours via an access road established in 1964.

Visitors to Mauna Kea are advised to acclimate at the Visitor Information Center which sits at 9,200′, although a particular length of time is not specified. In addition to the more intuitive precautions regarding pregnancy or heart and respiratory conditions, visitors in Hawaii are also warned against making an ascent within 24 hours of having been SCUBA diving, which may not be so obvious. You can find this and more helpful tips consistent with current high altitude research on their Public Safety brochure, which includes information about symptoms of HAPE (High Altitude Pulmonary Edema, featured in a previous article, and very common in the Colorado high country).

Poliahu visits Haleakalā. PC: Lyle Krannichfeld & Pueo Gallery

In addition to the hypoxic conditions, Mauna Kea and its aforementioned counterparts are also prone to the dryness and weather systems we see in Colorado, with snowfall above 10,000′ as recent as the past few days, a visit from Poliahu, Hawai’i’s own goddess of snow, and the subject of songs and hula dances in her honor.

Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not on a computer, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.

Dr. Chris’s HAPE Cheat Sheet

Inflammation and altitude can cause low oxygen. Inflammation is commonly caused by viral infections such as colds or influenza, but can occasionally occur with bacterial infections such as strep throat or pneumonia. Low oxygen, or hypoxia, is the result of fluid collecting in the air sacs of the lungs, called pulmonary edema.

There are three types of high altitude pulmonary edema (HAPE).

  1. Classic HAPE, recognized for over a century. occurs in visitors to altitudes above 8000 ft (2500m) beginning during the first 48 hours after arrival. Symptoms include cough, congestion, trouble breathing, and fatigue, all worse with activity.
  2. Re-entry HAPE occurs in people who are living at altitude, travel to lower altitude, and develop symptoms during the first 48 hours after returning home
  3. High Altitude Resident Pulmonary Edema (HARPE) is a recently recognized illness that occurs mostly in children who have an underlying respiratory illness and live at altitude, with no recent history of travel. They have oxygen levels below 89 and lower but do not appear toxic. They are fatigued but rarely have increased work of breathing.
Parents are often worried their children won’t wear a canula for oxygen, but they don’t typically mind.

Treatment of HAPE is oxygen. There may also be signs of asthma or pneumonia which are treated with bronchodilators and antibiotics. Most people with pneumonia at altitude do NOT have hypoxia. All three types of HAPE can reoccur, but typically not with every arrival at altitude or viral illness. Many of these patients are told they have pneumonia again and again, or severe asthma, and are treated with inhalers and steroids. Usually, this adds nothing to their recovery.

A chest x-ray may show typical infiltrates seen with pulmonary edema, but in mild or early cases, can look normal. There is no blood test for HAPE. Oxygen should be used continuously at a rate that raises the oxygen saturation into the 90’s. Length of treatment may be as short as 2 days or as long as ten days

Most importantly, owning a pulse oximeter and measuring oxygen levels in anyone at altitude with symptoms of cough, congestion, fatigue and trouble breathing with exertion can keep people out of the ER and ICU. HAPE can rapidly progress to respiratory failure and death if not recognized and treated expediently.

Section House in December: Moose Country

Section House sits at 11,481′ (3499 m), on Boreas Pass, just south of Breckenridge, Colorado. It isn’t the highest hut in the Summit Huts system, but its unique location and history is what makes it one of the most challenging.

Many of the huts in the Summit and 10th Mountain Division systems sit on a hillside, below tree line, which provides a significant amount of weather mitigation. Section House is right at the tree line, on the pass, which means any wind and weather will likely be funneled right into you. And because you are in one of the highest counties in the United States, weather is highly variable.

I’ve done this hut in a blizzard before, arriving to find the padlock on the front door was frozen shut. That may have been the most I’d ever despaired in my life up until then.

Even in great weather, however, the temperature alone is a liability. When we set out from the trailhead this time, it was sunny and relatively balmy for December, in the 30’s (Fahrenheit). But the temperature in the shade can be several degrees lower, and as the sun sets below the Ten Mile Range, the temperature starts to drop by the tens of degrees really quickly.

The Stats

Distance: a little over 6 miles; GPS and some maps may differ by tenths of a mile. If you tell your friends 6, they may resent you.

Timing: the same hike has taken me a couple hours with no weight on my back besides water, on well-packed snow. This time, it took over an hour a mile, including frequent breaks, thanks to all the weight I was carrying and pulling. Additionally, we constantly had to redistribute weight among sleds and backpacks to relieve shoulders and keep sleds from tipping over. If you decide to pull a sled, keep the weight low and as evenly distributed as possible. The other very limiting factor was the last half of the trail was covered in at least a couple feet of unpacked, fresh powder. Our lead was breaking trail in snowshoes.

While the grade going back down to the trailhead isn’t steep enough to keep momentum without skating, it is significantly easier and faster, and took us half the time even after waiting for moose to safely cross our path.

Elevation gain: about 1100′.

Capacity: 12 people.

Packing

I’ve pulled a sled both times I’ve done this hut. I don’t regret it, but it is challenging at best in calm weather. Unless you are going for more than a couple nights, I’d recommend packing everything into a backpack.

Because the elevation gain is so gradual, the challenge with weight is the distance. Pack your weight so it will still be comfortable on your shoulders after three miles. The advantage of pulling a sled was having less weight on my shoulders, but after several miles, even minimal weight can dig into your muscles.

The only source of water around this hut is the snow you melt, which is why it isn’t open in the Summer season. Water purifying filters are the quickest way to refill all your containers at the hut, but you will want plenty of water for the hike in alone. Running out of water on the trail is dangerous. An added risk: when the sun went down on us after the first three hours in, the water in our CamelBak nozzles started freezing if we weren’t regularly sipping on them.

Bring a sleeping bag. Most huts I’ve been to have blankets and pillows on the mattresses, but this one does not. This is also one of the oldest and coldest cabins; built in 1882, it takes hours to heat up by wood stove, especially if no one has been in it recently.

Moose

Now forget all the advice I just gave you and center your whole packing strategy around how you plan to evade a charging moose.

This region is moose country: high, high meadows filled with willowy wetlands. They don’t care how cold it is. In the dead of night, one of us opened the front door to use the outhouse and a young bull was standing right in front. On the trail back, two different parties ran into a moose and her calf right on the trail. They are not in the way. You are on their trail.

But seriously, pack to be prepared for your comfort and sustenance on the trail and at the hut. The only thing you can do about the moose is give them a lot of space while avoiding any confrontational, jerky movements that may suggest any predatory intent. If moose perceive a threat, they are liable to charge, male or female. If they charge, drop everything weighing you down and pray-run (praying while running).

When we ran into the moose on the trail, we stayed over 50 meters away and just waited while the moose wandered further off our path. As soon as they were about 50 meters off our path, we proceeded with caution. But we waited for over 30 minutes, and would have waited longer if we needed to.

Skis vs. Skins vs. Snowshoes

This was the most highly contested logistical conversation among our party. In the end, four of us were on cross country skis (without skins), one was on skis with skins, one was on a split-board with skins, and one was on snowshoes.

This really depends on the conditions. Two weeks prior, three of us hiked the trail in boots, on well-packed snow after days of warm, dry weather. Days before we left for the trip, however, a series of storms blew several feet of snow in, which changed everything. Boots alone were definitely not an option.

Most people, who aren’t hiking to the hut, will stop and turn around at the halfway mark where historical Baker’s Tank stands. This means the trail up until that point will reliably be pretty packed down. Because of the recent snow, however, no one could be sure what conditions would be like for the second half of the trail.

Freshly-broken trail through fresh snow past the midway point to Section House.

Sure enough, Baker’s Tank to the hut was unbroken trail through deep, soft snow. Our lead, on snowshoes, was cursing all the way to the hut as he carved the path for the rest of us. But in deep snow, snowshoes are sometimes the most comfortable option for an ascent, especially if you are inexperienced on skis and skins.

The advantage to skinning up on a split-board or downhill skis is the width of the blades. They are wider than cross country skis, which makes balancing the extra weight more comfortable and stable.

On a packed track, cross country skis were relatively comfortable, if narrow. The boots are more similar to normal footwear, so are more flexible and comfortable than ski or snowboard boots. Price was also a determining factor: renting skis or a split-board can cost upwards of $45 per day at most rental shops. We found cross country skis for $10 per day at Wild Ernest Sports, above Silverthorne, and they worked well. One thing about cross country ski boots, however, is that they aren’t as well-insulated as downhill ski or snowboard boots. Trekking through deep snow in them requires much better waterproofing and insulation than we were prepared with.

Jupiter rising in the dusk on the way up to Section House.

As for skins, although the trail grade is very gradual, there is enough of a grade at times that you will be thankful for the traction that skins provide. So unless you’re on cross country blades, you’ll want some skins.

Altitude & Acclimatization

One advantage of carrying all the weight we did was that it forced us to make a slower ascent and take frequent breaks. These are two things you can do to minimize the affects of the altitude on any ascent. In our party, all but one of us have lived at an altitude over 7,000′ for at least one year. Most of us have lived over 9,000′ for several years. But this was the first hut trip over 10,000′ for three of us, one of whom flew in two days before from sea level.

Fortunately, no one in the group experienced any severe symptoms of acute mountain illness, and I credit that to our meticulous supervision of each person’s blood oxygen saturation as well as our slow ascent. The first night we were at the hut, the lowest oxygen saturation we saw was 85%, but most were between 85 and 90%, which, at over 11,000′ is not surprising. If some slow, deep breaths hadn’t brought oxygen levels up, I would have been more concerned.

Hitting kickers behind Section House.

As seems to be tradition on our expeditions, we arrived well after dark. But these days, sunset is at 4:30 pm. Luckily, the weather was calm, and the trail is quite obvious. Our biggest concern after dark was the tremendous drop in temperature. With no cloud cover and a recent cold front, it was well below freezing, and the only thing that kept us from freezing was the constant movement, which kept us progressing forward.

Ken’s Hut, next to Section House.

By the time we had all made it to the hut and built up a fire warm enough to kick our boots off, our socks were steaming in spite of how cold our extremities were. It took well into the night to heat up the hut, and we all spent the first night sleeping around the wood stove. Yes, it took seven hours for the last of us to make it to the front door of Section House, but the spring trip to the Benedict Huts outside of Aspen was still loads more difficult — and we didn’t even pull any sleds! The next day was windless, sunny, clear, and warmer outside than it was inside, which allowed us to get back out on our skis and snowboards to enjoy the backcountry without weight on our backs.

robert-ebert-santos

Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not developing applications and graphics, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.

Effects of High Altitude on Appetite and Weight Loss

It’s no secret that people living in high elevation areas such as Summit County seem to be healthier than the general population. But aside from the active lifestyles of many people who choose to live in the mountains, could there be other effects from living at high altitude that result in healthier outcomes?

Several studies have been conducted to examine the association between living at high altitude and weight loss. The overall findings suggest simply ascending to a higher altitude generally results in a reduction of weight. Whether this is due to relative low pressure hypoxia or increased physical activity is another question examined by researchers. Overall, a higher energy expenditure and decreased appetite have both been seen in those living at higher altitudes. One study found that those living below 500 m elevation on average had a 4.6 times higher risk of obesity compared to those living above 3000 m while controlling for differences in exercise, diet, and lifestyle.

Leptin is a hormone produced by the body that results in suppression of hunger. When our bodies secrete more leptin our hunger decreases. Multiple studies have shown that when people not acclimated to altitude are brought to higher elevation, leptin increases and appetite decreases. One such study took ten obese males to altitude and allowed them to eat as much as they would like and also did not allow them to exercise more than their regular amount during the study. After one week the study found the males consumed on average 730 calories less than what they usually ate at lower altitude. This resulted in a 3 pound weight loss over one week, and on average, they kept two pounds off after returning to their base altitude a month after the one week study was completed.

Leptin levels were increased for a time after returning to lower elevation and appetite remained lower than their baseline.

A follow-up study looked to determine exactly what factor of altitude causes this increase in leptin and used a hypobaric chamber to simulate a hypoxic environment similar to Mt. Everest. Subjects in this experiment lived in low oxygen conditions for 40 days and had an average of 16.7 pounds of weight loss and consumed 1,347 fewer calories. This study helped to suggest hypoxia as the driving factor for increases in leptin at altitude, and also showed an increased effect with the higher elevations.

Another possible factor leading to higher rates of weight loss at altitude could be linked to an increase in basal metabolic rate. Basal metabolic rate, or BMR, is the amount of energy or calories humans burn each day without accounting for exercise or general physical activity. In the same study that measured appetite and leptin levels in obese men brought to altitude for one week, BMR was also measured. These measurements showed an increased BMR at the end of one week at altitude and a return to baseline BMR two weeks after returning to lower altitude. This means that people tend to burn more calories just by being at a higher altitude, even without increasing exercise. This increased burning of calories paired with decreased appetite are likely the main driving forces between the weight loss seen in those newly introduced to altitude and lower weights and BMI’s seen in those that have lived at altitude for a long time.

With these findings of weight loss and overall decreased appetite when coming to altitude, it is important for visitors from low altitudes to be aware of these changes and plan appropriately. First of all, in order to avoid unintended weight loss, those new to the mountains should be aware of just how much they are eating. Apps such as MyFitnessPal are great for tracking your calories and can even factor in exercise such as hiking and skiing that may be causing you to burn extra calories. Based on your BMR and exercise, you can see just how many calories you should be eating to maintain your current weight. It is also essential to be aware of the kinds of food you are eating. In the studies showing decreased appetite, it was also shown that study subjects had a decreased likelihood of choosing carbs in their diet. Carbohydrates are an excellent source of energy and should be a main staple of the diet for anyone coming to altitude, especially if they plan to partake in any of the great outdoor activities places like Summit County have to offer. Good examples of healthy carbs include fruits, vegetables, nuts, and whole grains like quinoa, oats, and brown rice.

Ultimately, ascent to higher altitudes has been shown to cause a decrease in appetite, increase in basal metabolic rate, and an overall decrease in body weight. Some of these factors return to closer to baseline after acclimatization, but this can take weeks to months depending on the person. Anyone who is traveling to higher altitudes or who has recently moved to a higher altitude should take good notice of their general nutrition and calorie intake to make sure they are giving their body the fuel it needs to succeed in these unique conditions.

Mitch Tiedke is a physician assistant student at the Red Rocks PA Program in Arvada, Colorado. He grew up in Oak Grove, Minnesota and achieved his undergraduate degree in Genetics, Cell Biology, and Development, with a minor in Public Health from the University of Minnesota-Twin Cities. He has previously worked as a personal care assistant for developmentally delayed adults and as a nursing assistant on a pediatric oncology, GI, and med/surg inpatient unit. In his free time he enjoys hiking, snowboarding, biking, and movies.

References

Buchzik, B. (2014). Hypobaric hypoxia causes body weight reduction in obese males, double-blinded, placebo-controlled study. European Respiratory Journal, 44(58). Retrieved from https://erj.ersjournals.com/content/44/Suppl_58/P3650.short

Lippl, F. J., Neubauer, S., Schipfer, S., Lichter, N., Tufman, A., Otto, B., & Fischer, R. (2010). Hypobaric Hypoxia Causes Body Weight Reduction in Obese Subjects. Obesity, 18(4), 675–681. doi: 10.1038/oby.2009.509

Palmer, B. F., & Clegg, D. J. (2013). Ascent to altitude as a weight loss method: The good and bad of hypoxia inducible factor activation. Obesity, 22(2), 311–317. doi: 10.1002/oby.20499

Rose, M. S., Houston, C. S., Fulco, C. S., Coates, G., Sutton, J. R., & Cymerman, A. (1988). Operation Everest. II: Nutrition and body composition. Journal of Applied Physiology, 65(6), 2545–2551. doi: 10.1152/jappl.1988.65.6.2545

Voss, J. D., Masuoka, P., Webber, B. J., Scher, A. I., & Atkinson, R. L. (2013). Association of elevation, urbanization and ambient temperature with obesity prevalence in the United States. International Journal of Obesity, 37(10), 1407–1412. doi: 10.1038/ijo.2013.5

Increased Risks of Orthopedic Surgery at Altitude

With orthopedic surgeries becoming more common at higher altitudes, it is important that we understand the increased risks of surgery at higher elevations. Patients locally (Eagle, Summit, Pitkin, Grand, Lake and other high-altitude counties in Colorado) and those that travel from all over the world to undergo surgery by our orthopedic surgeons are at an increased risk for complications post-surgery. Patients that have surgery at a lower altitude and return to higher elevations post-surgery are also at higher risk for post-operative complications. These risks are higher for everyone having surgery at altitude regardless if you live at higher elevations or are from sea level.

High altitude is defined as 8-12,000 feet. However, increased surgical risks are seen starting at 4000 feet. There are no differences for increased risk if you are acclimated to the altitude (live here) or are visiting. The increased risk of surgery at high altitude is the same for all.

High altitude increases the coagulation state of blood (clotting ability) and hyperventilation (breathe out more than you breathe in), and oxygen saturation of blood and tissues is 10% lower at high altitude compared to low altitudes, leading to a hypoxic state. The hyperventilation state promotes the hypercoagulable state which causes the immune system to respond with a pro-inflammatory state. Acclimation does occur, we adapt, are able to breathe easier and function normally as our bodies make more red blood cells to compensate for the lower available oxygen in the air. However, the hypercoagulability of blood remains, because the hyperventilation state is sustained at high elevations (even if you live here). At high elevations there are physiological differences in pulmonary circulation (blood through the lungs), heart function, and fluid imbalances which induce dehydration that accompanies blood changes contributing to the increased risk of surgery at high elevations.

Risk factors for blood clots from orthopedic surgery for the general population include: decreased mobility or sitting around more, length of surgery (greater than 4 hours increases blood clot risk), joint replacements, smoking, diabetes, and other illnesses.

In general, there is a 40-60% chance of a blood clot following knee or hip replacement surgery. At altitude that risk doubles. There is a 3.8 times greater risk of thromboembolism (blood clots) for knee surgeries at high elevations. Total shoulder replacement surgery also demonstrates a 2-times greater risk of pulmonary embolism at altitude or 39.5%, compared to a 15% chance at sea-level. For rotator cuff repair of the shoulder, there is also an increased risk for blood clots. There is a 1.4-times greater risk for pulmonary embolism (blood clot in the lungs) for lumbar fusions at high altitude. Higher elevation is an independent risk factor for blood clots which lasts up to 90 days post orthopedic surgery.

Anesthesia at high altitude has its own risk. The sustained hyperventilation state at high altitude also leaves the patient more vulnerable to hypoxia and pulmonary edema with anesthesia. These risks can be minimized, however remain elevated for surgeries requiring general anesthesia above 4000 feet.

For patients returning to high altitude following surgery at lower elevations, there exists multiple risks due to hypercoagulable state, increased inflammatory response, and hyperventilation that higher elevations induce. Acclimatization to high altitude is lost within 2 days of being at a lower elevation and can take 3-4 months to achieve again. In as little as 2 hours after arriving at high altitude, the body initiates the above changes and this puts the post-operative patient returning to altitude at risk for a multitude of complications: dehydration, thromboembolisms, hypoxia, atelectasis, and pulmonary edema.

I recently spoke with a patient that grew up in Leadville (10,151 feet) and lives in Summit County (average of 7947 feet). She underwent hip surgery (twice) in Denver. Upon returning to Summit County, she developed high altitude pulmonary edema (HAPE) both times. When she underwent an ankle surgery in Edwards, the surgeon prophylactically treated her for high altitude sickness given her previous history. She did not develop HAPE, but was hypoxic and required oxygen therapy following surgery for a few days. She is a prime example that even those living their entire lives at altitude are susceptible to these increased risks from surgery.

These risks can be minimized by drinking plenty of fluids, using compression socks (TED hose) or sequential compression devices (SCDs), blood thinners (aspirin, Eliquis, or the like), doing ankle pumps and glute squeezes, and getting up and walking around every 1.5-2 hours for 10-15 minutes, all of which help decrease the likelihood that patients will experience blood clots following orthopedic surgeries.

To reduce respiratory or lung related complications it is important to do deep breathing exercises or incorporate the use of an inspirometer post-surgery, use supplemental oxygen if necessary, as well as continue to do these exercises after returning from a lower elevation for at least 2-3 weeks.

High altitude is an independent risk factor for orthopedic surgery complications. However, these increased risks have been seen in trauma patients and other surgical patients as well. The hyperventilation state, hypercoagulability, and elevated inflammatory response are not isolated to orthopedic patients, but exists in everyone living at and visiting higher elevations.

— Jessica Guthrie, BSN, RN

References

Cancienne, J., Diduch, D., & Werner, B. (2017). High altitude is an independent risk factor for postoperative symptomatic venous thromboembolism after knee arthroscopy: A matched case-control study of Medicare patients. Arthroscopy: The Journal of Arthroscopic and Related Surgery 33(2). https://dx.doi.org/10.1016/j.artho.2016.07.031

Damodar, D., Donnally, C., Sheu, J., Law, T., Roche, M., & Hernandez, V. (2018). High altitude an independent risk factor for venous thromboembolisms after total hip arthroplasty. Journal of Arthroplasty 33(8), 2627-2630. https://doi.org/10.1016/j.arth.2018.03.045

Damodar, D., Vakharia, R., Vakharia, A., Sheu, J., Donnally, C., Levy, J., Kaplan, L., & Munoz, J. (2018). A Higher altitude is an independent risk factor for venous thromboembolisms following total shoulder arthroplasty. Journal of Orthopedics 15(4). https://doi.org/10.1016/j.jor.2018.09.003

Donnally, C., Vakharia, A., Sheu, J., Vakharia, R., Damodar, D., Shenoy, K., & Gjolaj, J. (2019). High altitude is an independent risk factor for developing pulmonary embolism, but not a deep vein thrombosis following a 1 to 2 level lumbar fusion. Global Spine Journal 9(7) 729-734. https://doi.org/10.1177/2192568219828349

Tyson, J., Bjerke, B., Genuario, J., & Noonan, T. (2016). Thromboembolic events after arthroscopic knee surgery: Increased risk at high elevation. Arthroscopy: The Journal of Arthroscopic and Related Surgery 32(11), 2350-2354. https://dx.doi.org/10.1016/j.arthro.2016.04.008

Wani, Z. & Sharma, M. (2017). High altitude and anesthesia. Journal of Cardiac Critical Care 1(1), 30-33. https://doi.org/10.1055;s-0037-1604203