If you're about to head off on a trek at high altitude and it's your first one, then you're probably feeling a bit concerned about this. Perhaps you've heard horror stories about other people suffering from altitude sickness or you've seen movies like "Everest". Altitude definitely needs to be taken seriously, but there are a few simple things you can do to minimise the impact and to get prepared.
What's the problem with high altitude?
Most of us simply aren't designed or conditioned to live up high in the mountains. As the air gets thinner, the body's ability to absorb oxygen from the lungs decreases and the tissues have a harder and harder time getting the oxygen needed for metabolism. This can lead to a state of hypoxia which simply means reduced oxygen.
The body does try to acclimatise to these changes to improve oxygen uptake. One way it does this is to increase its breathing rate. The kidneys also send more water to the bladder as urine to rid the body of more fluid - this helps to make the blood thicker and this can continue for several weeks. Eventually the body produces a greater number of red blood cells to help increase its oxygen carrying capacity - but it takes time.
Around 50% of sea-level residents who travel to moderate altitudes (2,400 to 4,250 metres) experience some degree of Acute Mountain Sickness (AMS). This is a collection of symptoms that can resemble the flu or a hangover such as a headache, insomnia, shortness of breath, nausea and weakness. AMS normally settles within a day or so of the initial ascent. In cases, where the symptoms progress the best treatment is to descend 600 to 900 metres.
If left unchecked, AMS can progress to more serious consequences and these include High-Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE). In HAPE, body fluids leak into the lungs and interfere with respiration. Symptoms include a hacking cough and increased rates of breathing and pulse. If this is allowed to advance then bubbling noises will become evident during breathing. The key way to treat HAPE is descent and a descent of 900 metres will resolve most cases. In HACE, vessels in the brain may respond to the stress of high altitude by leaking, causing the brain to swell. Early symptoms included reduced coordination, headache and loss of energy. Nausea and vomiting may also be present. HACE can strike at altitudes as low as 3000 metres and descent is critical to survival.
How do we prepare for high altitude?
Some trekkers recommend using medication such as Diamox to prepare for altitude, however, these can lead to unpleasant side-effects and allergic reactions. More recent studies show Ibuprofen to be an effective alternative that has less side-effects. Personally, however, I stay clear of medications (saving them for emergencies only) and recommend the following:
- The absolute best way to prepare for high altitude is to plan your trek appropriately so that it has a gradual ascent that allows your body time to acclimatise. A general guideline for ascent is to limit increases in sleeping elevation to 300 metres per day, above 3,000 metres and, two or three times a week, allow an additional night at the same elevation as the night before. You can climb more than 300 metres in a day, as long as you come back down and sleep at a lower altitude. When you are trekking, take it easy and don't overexert yourself.
- Stay properly hydrated. Acclimatisation is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated. The best indication of proper hydration is clear urine.
- Avoid tobacco, alcohol and other depressant drugs. These decrease the respiratory drive during sleep resulting in a worsening of symptoms.
- Ensure that you are in good health so that your body can acclimatise efficiently. Research indicates that antioxidants (naturally occurring plant nutrients such as Vitamin C and Vitamin E) can be effective in preventing AMS. It is recommended that you obtain these antioxidants through eating a nutritious whole food diet. You may also want to consider adding in a product called Juice Plus+. This is something that I've personally taken every day since 2004. It's a whole-food supplement made from 17 different, highly-nutritious fruits and vegetables and the benefits have been showcased by over 20 research studies at leading hospitals and universities around the world (including the University of Sydney). Even Bear Grylls recommends it! You can find out more about Juice Plus+ (including the research) here.
- Train properly before your trip - increasing your body's ability to tolerate sustained hard work will improve your muscles ability to use oxygen and this will really help reduce the impact of altitude. The best way to increase your body's ability to tolerate sustained hard work is through interval training. I explain how to use interval training in this short video.
- The final method of preparing for altitude before your trip is to use an altitude chamber for several weeks before your trip. This can however be expensive and personally I'd rather spend an extra day or two acclimatising on a mountain than exercising inside in a gym!
I trust you find these tips useful and remember that there's no substitute for proper acclimatisation. So plan your trip wisely, following the recommended acclimatisation guidelines, and listen to your body. If you begin to show symptoms of moderate altitude sickness, don't go higher until symptoms decrease. If symptoms increase, go down!