I hit the pool for my first swim workout upon arriving in Cuenca, Ecuador. At 8,200 ft. I felt like I was swimming through molasses, breathing through a straw, and was a bit dizzy exiting the water. I was experiencing first hand the effects of acute altitude illness, sometimes referred to as mal de montaña.
Traveling or living in moderate altitude (3,000 to 8,000 ft.), high altitude (8,000 to 12,000 ft.), or extreme altitude (12,000 ft. or above) can cause an array of altitude-induced symptoms including: shortness of breath, fatigue, dizziness or light-headedness, frequent urination or diarrhea, lack of appetite, lower blood sugar, and cold hands and feet.
It can also induce more severe conditions such as acute mountain sickness (AMS), high altitude cerebral edema (HACE), or high altitude pulmonary edema (HAPE).
What happens when you go up?
As you ascend to moderate or high elevations the pressure in the surrounding air decreases. Therefore, at 8,200 ft. the pressure in the air is approximately 75% of that at sea level. The decreased pressure exerted on the heart and lungs can significantly affect heart/lung function resulting in shortness of breath, fatigue, and many related symptoms.
General exertion, whether from daily activities or a scheduled bout of vigorous exercise, will require greater effort until acclimatization (training your body to use less oxygen) occurs. Acclimatization usually takes two to three weeks at a moderate altitude and longer at higher altitudes. Only 1-3% of people living in moderate to higher elevations are unable to acclimatize.
Specific and noticeable changes at high altitude
Initial responses as you gain elevation may include the following:
- Elevated resting and exercise heart rates and ventilation rate
Your resting heart rate and ventilation rate can be 10% higher and your maximum heart rate can be 10% lower during the first weeks in altitude.
Along with a decrease in blood volume your stroke volume, cardiac output, and MaxVO2 all function less optimally.
You are not going to tolerate much physical activity or high-intensity exercise starting out! Start activity with short, easy bouts. Your body will gradually adjust to performing with less oxygen.
- Fatigue
Changes in your hemoglobin mass and your hematocrit, in addition to iron uptake (which can increase almost 100% in the first few days at altitude), create feelings of lethargy and fatigue. Normal iron stores during this time are not sufficient to meet the demand for hemoglobin synthesis.
A multiple vitamin, as well as iron supplementation, is recommended (200-300 mg/day beginning two to three weeks prior to heading to the mountains and continuing for two to three weeks upon arriving).
- Slower recovery
Increased fatigue, accompanied by lactic acid accumulation, requires longer and more frequent rest intervals when performing daily physical tasks and between exercise bouts. Rest periods should be extended 15-30% at altitude for adequate recovery. Oh yes, more daily naps!
- Dehydration
Increased urination and sometimes diarrhea can be common in the first weeks at altitude and lead to dehydration. Eliminating fluids results in decreased plasma volume, sometimes as much as 25% in the first 8-10 days. Drink lots of fluids and keep the diuretics (caffeine) to a minimum. Salt will help to retain fluids. So bring on the beer (or coconut water) and salted plantain chips!
- Glucose management
Altitude can alter glucose regulation. Cold temperatures and altitude can complicate an accurate reading of glucose monitoring equipment and storage of insulin. However, some people with diabetes may find their blood sugar control is more manageable at altitude.
Additionally, there are several risk factors that may predispose you to altitude illness or difficulty acclimating. These include:
- Preexisting heart disease
- Preexisting pulmonary hypertension or COPD
- Preexisting high blood pressure
- Preexisting kidney disease
- A family member who has experienced altitude illness
- Obesity
- A family history of gout or preexisting gout
- Smoking
- Heavy alcohol consumption
If you are thinking of relocating to a higher elevation (especially from sea level) it would be wise to visit the location and see how you physiologically respond before making a final decision. The good news is that most individuals will acclimate to living and exercising at altitude. You can also talk to expats who are living in moderate to high altitude cities on the TCI website to exchange ideas on how they acclimated or what elevations might be best for you.
I personally know the pool workouts are going to get easier the longer I am swimming at 8200 ft. And when I return to a lower elevation I’ll feel like a dolphin slicing through the water!
Do you love to exercise? Have high-altitude tips you’d like to share with the rest of us?
by: Gwen Hyatt
