Fueling the athlete’s body: Experts in the field of nutrition give advice on navigating exercise and nourishment at high elevations

Perched thousands of feet above the town of Breckenridge on Peak 10, Christopher Fisher found himself debilitated after pushing his body for 15 hours without thinking much about nutrition. 

As he was navigating the rocky spines of the Mosquito and Tenmile mountain ranges in pursuit of the fastest known time for the route, his legs felt like jelly and his mind became clouded. 

“With pushing so hard and not eating enough, my stomach just shut off, and I was nauseous for about the next 15 hours,” Fisher said while talking about his efforts to summit 34 peaks in 24 hours. “I was not able to put any food into my body, and I was throwing up anything I was trying to put in.”

Despite his experience with high-elevation environments, the sponsored endurance athlete said this moment was a wake-up call. 

“I did not have my nutrition dialed at that point,” Fisher said. “Even with prior events and activities, I did not know what I was doing at that time.”

Fisher is a master when it comes to scrambling up mountain peaks, but he was lacking knowledge when it came to the science of properly fueling his body while pushing its limits.

With a majority of Summit County sitting at an elevation above 9,000 feet, High Country recreation brings unique challenges. Professional athletes and Summit’s weekend warriors alike must think carefully about staying adequately fueled if they want to avoid the common high-elevation bonk associated with the Rocky Mountains.

Athletes have to understand what high elevations do to the body and find ways to nourish it before, during and after their long adventures — whether they are skiing slopes, hiking up peaks, rafting whitewater or biking beautiful mountain roads. 

Combating the effects of high elevation

As endurance mountain bike racer Lasse Konecny rotates his pedals thousands of times while training on the trails of his Breckenridge backyard, you’ll find him regularly addressing the effects that come with living at 9,600-plus feet. 

“Every 15 to 20 minutes is kind of my golden rule to take something in, whether it be a gel or drink mix,” Konecny said about his routine to take in the fluids and carbohydrate-heavy supplements he needs to remain fueled during his high-endurance pursuits. 

Nutrition experts who study the effects of elevation say metabolism, stress hormone levels, respiration rate and heart rate all increase at higher elevations, so they often advise athletes to take these things into consideration while exercising. 

One reaction to high elevations that is widely recognized by sports physiologists and dietitians is the way they affect the body at a metabolic level. 

“We do see an increase in overall energy expenditure throughout the day,” said Kylee Van Horn, a registered dietitian nutritionist who is based in Carbondale. “Metabolism does typically increase, and there tends to be a little bit more muscle protein breakdown, too ,at altitude.”

Steamboat Springs registered dietitian nutritionist Kirsten Summers said the main reason for an uptick in metabolism is due to the lack of oxygen, which makes the body work harder to support essential functions.

“Because there is less access to oxygen, your body sort of goes into more of a sympathetic nervous system load; your heart may be pumping a little harder, trying to carry the blood faster to get more oxygen to your muscles to fuel your activity,” Summers explained. “That can cause this uptick in your metabolism.” 

Jessica LaRoche is a sports nutritionist who works with top-level U.S. Ski and Snowboard athletes. She backed the statements made by Van Horn and Summers, but she noted that most of these studies are conducted at elevations above 16,000 feet. 

Despite Colorado’s lower elevation, LaRoche says it is safe to assume that athletes need to consume at least an extra 200 to 300 calories a day to cover the body’s increased needs. The extra calories can come in many forms depending on the type of exercise the person is pursuing. 

The thinner air also causes increased respiration, Summers said. As the body is trying to bring more oxygen to fatigued muscles, fluid evaporates as people exhale, so an increase in fluids is needed to stay well-hydrated. Dehydration is a main factor in altitude sickness, which has debilitating effects. 

Van Horn says ingesting enough electrolytes, like sodium and potassium, is key to exercising at higher elevations. She suggests recreationists set alarms to remind them to get enough fluids and electrolytes.

Another micronutrient that is often overlooked is iron, LaRoche said. 

It is essential in making hemoglobin — a protein in red blood cells that carries oxygen throughout the body. When people are at higher elevations, red blood cell production is increased in order to bring more oxygen to the body, so LaRoche says getting enough iron is key to performing at your best while in the mountains. 

“Iron status is No. 1,” LaRoche said. “(The Olympic committee) went as far as saying that if you don’t have good iron status before the (high elevation) camp that it is not even worth going — that they are not just going to get enough benefit from the camp if they do not have adequate iron parameters.”

Without moderate levels of hemoglobin in the body, the body can fall into an anemic state, which will cause an individual to feel tired, weak and short of breath.

But she cautioned that iron supplementation should always be done under the supervision of a doctor. 

“I think you have to have blood tests regularly,” LaRoche said. “I would never have someone supplement without having regular blood testing, whether it be every year or every two years.”

For those who don’t need help from supplementation, Summers recommends eating foods that are high in iron in moderation. Some good foods include red meat, poultry, seafood, whole grains, nuts, seeds, legumes and leafy greens.

High-elevation environments have also shown to play a role at a hormonal level with an increase in oxidative stress.

“(If) there is increased oxidative stress, different hormones are released, and it is just more stressful on the body to be at altitude,” LaRoche said. 

LaRoche has specifically seen studies that show that cortisol is elevated while exercising and living at high elevations. An increase in cortisol — often called the stress hormone — can cause recovery to be slowed down and may lead to increased high blood pressure because of the release of glucose into the bloodstream.

LaRoche says the best way to combat the effects of increased cortisol and other hormones such as adrenaline and noradrenaline is by getting in foods that are rich in natural antioxidants.

“Most of the research finds more of a benefit in eating an antioxidant-rich diet instead of taking supplements, — lots of fruit and veggies, whole grains in order to combat that increased stress,” LaRoche said.

These foods may also help the body to repair any muscle soreness athletes may feel after a turn-heavy ski day or quad-crushing trail run.

Finding the right fuel

After his failed speed attempt to traverse the Mosquito and Tenmile ranges, Fisher said he recognized that something was not quite right nutritionwise.

“A big part of it was not fueling properly before and during the early part of the effort,” Fisher said. 

Fisher was spot on with his assessment, according to nutrition experts. Not only is fuel needed during long forms of exercise, but Summers also recommends that individuals get in a full-sized meal two to three hours prior to heading out the door. 

“A meal that has got complex carbohydrates, protein and fat in it,” Summers clarified. “About 30 minutes before the workout, you want something with simple carbohydrates, something that your body can absorb pretty quickly — like a banana or something like half a bagel with some jelly.”

While out exercising, it is also important to fuel based on the form of exercise and the duration. In the case of someone like Fisher — who is engaging in a longer aerobic-based exercise — Van Horn recommends supplementing with simple carbohydrates and sugars periodically if you are exercising for over an hour. 

Fisher has found that he specifically enjoys Honey Stinger gels, sour candy, salty snacks and other quick-hitting nutrition supplements, which often have carbohydrates and amino acids, to help his glycogen and blood sugar levels reach an adequate level in order to keep pushing forward. 

The same is true for weekend warriors going for a jog around Summit County’s recreation path or a hard ride up Boreas Pass Road in Breckenridge.

Van Horn says that for anaerobic activities like sprinting, weight lifting, high-intensity interval training or hard, quick-hit bike sessions, carbohydrates are almost exclusively used for fuel. Since most workouts are rather short but intense, Van Horn recommends getting in carbohydrates beforehand and then refueling after.

For activities like skiing or snowboarding that do not really fall under anaerobic or aerobic exercise umbrellas, LaRoche recommends a complex meal beforehand and then a snack or meal with liquids during the day in order to keep energy levels at a high enough state to finish out strong. 

After exercise, Van Horn and Summers both recommend that an individual tries to fuel with a fast, small snack within 30 minutes of a session. The 30-minute window is often referred to as an individual’s optimal recovery window and is important as the quick fuel helps begin the process of recovery.

“When you are out and you are exercising, you are using up your glycogen stores in your muscles, and right when you are done your muscles are ready to refill that,” Summers said. 

Some foods that Summers recommends for refueling after exercise are chocolate milk, a sports drink with carbohydrates, a banana or a bagel.

Within an hour or two of finishing a workout at a high elevation, a balanced and complex meal needs to be consumed. Summers and Van Horn recommend whole grains, vegetables, legumes or beans with some protein as well.

“You want that combination of the carbohydrate and the protein within a couple hours afterwards,” Summers said.

The only problem that people may encounter when trying to implement this fueling strategy, however, is that appetites are often diminished when at higher elevations and are even further diminished after exercise. 

“You might not be motivated to eat, so go in with a plan and have a strategy,” LaRoche said. “Hunger is not the best gauge when you are at altitude because you are not going to feel as hungry.”

Fisher experienced this problem while trying to traverse the Mosquito and Tenmile mountain ranges. Fisher’s mind did not feel like it needed or wanted to eat, but his body desperately needed calories if he wanted to continue to stay alert and mobile enough on the series of treacherous peaks. 

With a better understanding of altitude and appetite, Fisher was able to successfully traverse the Mosquito and Tenmile mountain ranges in September of last year — in large part because of a firm fueling strategy. 

“(I made) sure I was eating a certain amount of calories every hour on the hour,” Fisher said of his fueling strategy. “Two-hundred to 350 calories an hour for the first part of the effort really set me up for success for the rest of (the traverse).”

Despite having a plan, Fisher says he did eventually reach a point where his body could not handle solid food anymore because of the altitude and the exercise. For those like Fisher who have trouble eating because of a lack of appetite or intense exercise, Van Horn recommends trying to find fueling options that are easier to stomach. 

“This is something I even work with people not at altitude,” Van Horn said. “Trying to figure out maybe liquid options like smoothies that might be easier to get calories in — or things that sound good to you versus maybe the health of something.”

Fisher specifically combats his episodes of decreased appetite by getting in easy calories through a can of Coca-Cola soda in order to realign his stomach.

“That’s the main reason I carried the Coke because I knew (the lack of appetite) would happen eventually,” Fisher said. “When I get to the point of being nauseous and bonking, having something acidic to realign my stomach so I can put down calories is huge. It has played a huge part in every one of my endurance endeavors since then. You have to keep eating for sure and you have to have something to realign your stomach.”

Ultimately, Van Horn, Summers, LaRoche, Konecny and Fisher all agree that fueling is highly personal and it takes time to nail down a specific fueling strategy. 

“Definitely trial and error,” Konecny said of finding a fueling strategy that works for him. “Growing up in the sport of cycling — especially at high altitude — I never really found the importance of fueling and staying hydrated. It has been a learning process going into the elites (mountain biking division).”

However, with patience, a fueling method can be found that prevents individuals from the dreaded mid-exercise bonk and adequately fuels them through their next Summit County adventure.