Fuelling New Heights

Fuelling New Heights

Evan Lynch ·

Altitude training is a tool used the world over by athletes aiming to squeeze the physiological adaptations in order to derive better sports performances. There are a variety of ways that athletes or fitness enthusiasts alike can try to gain these benefits, these include using altitude training masks (train high method), sleeping in an altitude tent overnight (sleep high, train low) or most popular, head off to somewhere a few thousand feet up to train away for a few weeks, the sleep & train high approach. Due to the changes that happen in your body with altitude responses, as a result of adaptations to lower oxygen levels, there are a number of things that need to be accounted for from a nutritional point of view.

What will you learn?

  • How altitude training affects your body & what exactly changes
  • The nutritional changes that need to be made during altitude training
  • Typical models of altitude training

What part of the puzzle is this?

Knowing that your nutrition requirements change quite significantly and that your environment can result in major changes in your nutritional requirements is pretty important. The same is true with hot climates, knowing that whilst you can approach your nutrition the same on any given day, it doesn’t mean you should, this article shows you how you yourself or those you coach would optimise their results from a nutritional point of view. 


Before we dive into the nutritional aspects of altitude training, let’s look first at what exactly happens (and why) in your body in response to altitude training, and how it is typically structured into training programs. Fun fact about altitude training, the Mexico City Olympics in the 1960s was the major catalyst that drove the evolution of altitude training, as it is over 2000m altitude, forcing many athletes to acclimatise and be prepared. Typical altitude training models require an athlete to spend between 2-6 weeks at altitude camps at elevations of between 1600-2400m being the most popular, with some camps being situated at approx. 3000m or above, this is considered to be very high, and in all likelihood would render any form of aerobic exercise impractical, at least until an athlete is well acclimatised, which can take between 10-14 days depending on elevation, but the process begins to occur within minutes. Undertaking two to three stints of altitude training of 4-6 weeks during a training year is more beneficial than one major stint, with your key race occurring within 2 weeks of finishing an altitude block.

As elevation rises, there are changes in the composition of the air, we all know that the higher up we go, the less oxygen there is in the air, but there is also a drop in the relative humidity in the air & a decrease in barometric. This causes a condition known as hypobaric hypoxia, resulting in a chronic reduction of arterial oxygen partial pressure, causes haematological adaptations mainly based around erythropoietic responses causing increases in haemoglobin (your oxygen-carrying molecule), more myoglobin is also created (tissue version of haemoglobin) and you get alterations in capillary density and ventilation capacity to help bring what little oxygen that is available to all parts of your body. The sharp increase in erythropoiesis can increase the requirements for specific nutrients.

Given the drop in humidity at increasing altitudes, there is a sharper increase in the difference in water concentration and that of the air, or in other words, there is an increase in the relative humidity of the body surface in comparison to the air, leading to a sharper evaporation gradient, resulting in higher fluid losses. Hydration is a key factor in managing performance at altitude.


The first port of call is to make sure that any given athlete is doing everything they should be doing regardless of altitude levels, conceptualise it like this, focus on sea level nutrition before we change for altitude capacities, as there are relatively small evidence bases of athletes at moderate altitudes of 1600-2400m, so do what we know we need to do first & foremost. This includes making sure you hit your protein regularly, you have healthy patterns, you get your 6-8 portions of fruit and veg a day (athletes need more fruit & veg as they require more antioxidants) and make sure that there is an overall balance present – this is outside the scope of the article, but there’s no point in nailing your hydration at altitude if you don’t fuel properly for training, it’s like putting fresh alloys on a car with no engine.

Iron is a major requirement and something to pay attention to when going altitude training, due to the major ramp-up of red blood cell production, with some research showing a 10% haemoglobin and red cell mass over an altitude stint. This is one of the rare occasions where an iron supplement is probably a good idea. A pre-altitude blood test is a good idea and a discussion with your GP or sports physician would be warranted, as always with iron supplements, it has been seen that supplementing with 100-200mg of elemental iron per day prior to and during altitude training, this can result in more favourable adaptations. Single doses are preferable to multi-day doses pre-bed would be a good idea.

There are no clear-cut guidelines for energy intake that differentiates altitude training from sea-level training, as the body of evidence isn’t big enough to provide concrete guidelines. However, what can and should be done is ensuring that you are consuming enough to fuel your training, and possibly a little extra, as weight loss is not recommended at altitude, given that low energy availability can impair erythropoietic responses. Ensuring there are adequate carbs in the diet (5g/kg per day and an extra 1.5g/kg/hr exercise) and that your pre-workout nutrition is managed would be a great start, as would ensuring that there are no large gaps between eating occasions. Low energy availability can occur during periods of the day and can be similarly thought of as muscle nitrogen balance, which can peak and trough during the day depending on eating patterns!

Hydration is of the utmost importance due to the aforementioned reasons, getting a minimum of 35ml/kg per day as a background requirement would be desirable and doing a sweat test in location to assess fluid losses per hour can help tailor fluid intake during sessions (60mins easy, weigh before & after, no fluid ingested between weigh-ins or bathroom breaks), losses of up to 600ml per hour can be replaced during training, with the residual to be multiplied by 1.5 and replaced within 2-3hrs post-training. Keeping to isotonic drinks would be best, as higher fluid losses with only water replacement will result in potentially severe electrolyte dilutions (not a good or desirable thing). Close monitoring of hydration would be a good thing to look at, practically speaking ensuring you have mostly clear urine and that you are doing your best in training with fluids and with pre-empting thirst. In the absence of a dedicated sports scientist or crew, this is the best way to manage.

Increased oxidative stress at altitude is commonly seen,  it is suggested to get antioxidant-rich foods (not supplements) to keep you healthy at altitude, without interfering with your adaptive responses. For you, this might mean eating varied colours of fruit & veg, getting in some dark chocolate and even a glass of red wine – aim to consume the rainbow, as many colours as possible, particularly those darker, richer ones.

These make up the bulk of the guidelines that you would want to look at for an altitude stint. Enjoy the views and make sure to tick these boxes!

Happy training,


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