Optimising health & performance for high altitude
What is altitude sickness?
We all know that the air becomes ‘thinner’ at high altitude, i.e. there’s less oxygen. So this inevitably means that it gets harder for us to draw in enough oxygen to keep our muscles and organs functioning optimally.
Altitude can start to become an issue for most people at around 2500-3000 metres above sea level (m.a.s.l.).
The important thing to note is that we are all different, with a different genetic make-up, so at 3000 metres, one person might be feeling absolutely fine and be bouncing up the mountain, while another may start to struggle. Unless we have access to some very complicated and expensive genetic testing, and have altitude-simulated tests performed, there’s just no way of knowing this up front.
For 10-30% of people, altitudes between 2500-3000m start to cause issues such as headaches, appetite loss and nausea1.
The more serious concerns of pulmonary edema (abnormal build up of fluid in air sacs of lungs) can occur above 3000m and brain edema (abnormal fluid retention in the brain causing swelling) can occur above 4000m.1
Physiological adaption to high altitude
It’s very clever. Even at 1000m.a.s.l, our bodies start to adapt to the lower oxygen levels. We start to breath more frequently to try and bring more oxygen in. The clever bit is that our bodies start to produce more haemoglobin (which carries oxygen in the blood), which means a greater oxygen carrying capacity to compensate for low oxygen in the air.
At what stage we start to produce more red blood cells, is again different for each individual. This may start to occur at an altitude as low as 2500-3000m2. It therefore makes sense to ensure the body has the ‘raw materials’ essential for the formation of red blood cells.
And then after that, it’s pretty much out of our control, since our genetic make-up and levels of hormones (which trigger the production of new blood cells) are also key factors at play.
An interesting side point, is that not only do we produce more red blood cells, but we also bind oxygen molecules less tightly to these red blood cells at high altitude, making it easier for the oxygen to be delivered to where it needs to be – it’s a way of conserving energy.
The problem with increased red blood cells, however, is that the blood begins to get ‘thicker’, which means that it can become harder for the heart to pump blood around the body to deliver oxygen to our organs and muscles.
To compensate for reduced oxygen in the air, our bodies try to:
- conserve oxygen
- inhale more oxygen
How we can help ourselves to perform better at altitude
We’ve touched on a couple of points already; we need sufficient levels of the ‘raw materials’ to produce higher levels of red blood cells. We also need to work hard at making sure our circulation is spot on, so we can cope better with ‘thicker’ blood.
And we need to be aware of the signs and symptoms of altitude sickness so we can recognise these quickly in ourselves and others (listed below).
One symptom is loss of appetite and if this happens and food intake is lowered, then you could be running out of energy very quickly and spoiling a long planned, expensive trip – not cool.
Alcohol does not count as an energy producing substance. It might give you a temporary ‘energy fix’ but then it’ll deplete your energy. Just when you want your body to conserve energy for important things like lung, heart, brain and muscle function, you don’t want to be using energy for liver metabolism of alcohol!
During your trip you need to be on a high carbohydrate diet. High carbs use less oxygen to produce glucose (energy). If you’re low in carbs, you’ll start to break down protein for energy instead, which is very costly to your oxygen supply. Same goes for high fat foods – uses relatively higher amounts of oxygen. Same for alcohol.
Another consequence of high altitude is that you may experience increased urination, therefore dehydration is a risk. It is recommended that your water intake is multiplied by about 3, and we need to factor in the level of exercise we’ll be doing. So you’ll need to be drinking between 7-9 litres a day.
7 things you can start to do right now to optimise your health and reduce the severity of altitude sickness
1/ Iron get your levels checked and if low, correct it. Our Nutritional Therapists usually recommend the best iron supplement for our clients once we have a copy of your blood results. Time is of the essence, so at about 8 weeks to go, get to it! Especially if you are female or a vegetarian/vegan. If you are both, speak to a Nutritional Therapist as soon as possible. Ideally you’d need to start working on this now rather than after you have blood test results. For others, whilst waiting for blood results, make sure you are eating iron rich foods – animal and plant based.
2/ B vitamins I recommend we all start taking a B vitamin Complex daily, from about 8 weeks out, until you return. Several of the B vitamins are essential for blood formation and for energy metabolism.
3/ Gingko Biloba may (in some people) help prevent mild symptoms of altitude sickness. Gingko works by thinning the blood and thereby helps to increase circulation. Because it is a blood thinner, if you are on any blood thinning medications then you need to speak to your GP first. Gingko should be started a week before you reach altitude, and for the duration of your time there.
4/ An antioxidant complex is a good idea. At altitude we produce more free-radicals and one theory is that this negatively impacts on the blood-brain barrier3, which could play a role in acute altitude sickness symptoms.
5/ EPA & DHA – these are the 2 key components of fish oil, so if you’re not a vegetarian/vegan then make sure you’re eating 3 portions of oily fish per week. EPA & DHA are also found in smaller quantities in flax seeds / linseeds. Otherwise think about supplementing with a high quality fish oil such as Eskimo 3.
6/ Clean up your diet. It’s time to get serious. Things that you should start paying attention to are your alcohol intake, refined sugar, caffeine and foods that you find hard to digest.
You should be drinking at least 2 litres of filtered water a day. Increase your nutrient content, so lots of vegetables and fruit. Balance your blood sugar levels – if you are having a dip in energy mid afternoon, you’re either not eating as regularly as you should be, or you are lacking in protein. As a rough estimate, you should be having 1 to 1.8 grams of protein per kg of body weight. Do not have a meal or snack without a good quality protein source in there. All of this will help you to clean up your liver so you’re working as efficiently as possible at altitude.
7/ Get fit & stay fit. As highlighted above, circulation is a key factor in helping to get that ‘thicker’ more oxygenated blood to our muscles and brain, so cardio workouts will be good – both endurance and high intensity interval training.
Train hard but get as much recovery, relaxation and rest in as you can over the 8 weeks before your trip! Rest those muscles after workouts and support your adrenal glands.
Signs & Symptoms of Altitude Sickness4
If you have altitude sickness in its mildest form (AMS), you may:
- have a headache
- feel tired
- feel sick or vomit
- lose your appetite
- feel dizzy
- have difficulty sleeping
Symptoms of AMS usually start to ease within about two days as your body acclimatises to the high altitude, particularly if you don’t ascend any further. If your symptoms get worse, the best thing you can do is descend as quickly as possible.
If you ascend to an area of high altitude too quickly and don’t allow your body time to acclimatise, you may develop a serious form of altitude sickness such as HAPE or HACE. These symptoms are rare.
HAPE occurs when fluid builds up in your lungs. Symptoms usually develop between two and four days after a rapid ascent over 2,500m. You may:
- have a dry cough
- feel breathless at rest
- have a fever
- feel confused
- have pink or bloody spit
- have a bluish tinge to your skin, lips and nails (cyanosis)
If you have severe symptoms of HAPE, you may gasp for breath and make gurgling sounds when you breathe.
HAPE can occur by itself or in conjunction with HACE. HACE occurs when excessive fluid collects in your brain, causing it to swell. Fewer than two percent of people with altitude sickness develop HACE and it rarely occurs below 4,000m. If you have HACE you may:
- have a severe headache
- feel very confused
- lose co-ordination
- have blurred or double vision
- notice changes in your behaviour – for example, you may feel irritable or be unhelpful
- lose consciousness
- fall into a coma (this is rare)
The symptoms of HACE may progress rapidly from mild to life-threatening within a few hours. If you have these symptoms, you should descend to a lower altitude as soon as possible and seek urgent medical advice.
You may develop other symptoms at high altitude. For example, your face, arms or legs may swell up (peripheral oedema). This usually lasts a few days and then disappears. At altitudes of 5,000m and over, tiny blood blisters can form at the back of your eye (retinal haemorrhages), but you may not notice any symptoms and they only occasionally interfere with your vision.
To your lean, healthy, optimised future,
4. Bupa (2011) Altitude Sickness. Available at: http://www.bupa.co.uk/individuals/health-information/directory/a/altitude-sickness#textBlock199126 (Accessed: 14 Sep 11).