Altitude Training – Why, When And How To Get High (Part 2)
[Article by Tait Hearps of Sweat Elite] [This is Part 2, continued from Part 1]
The answer to this question is multi-faceted, complex and highly variable between runners, but there are some physiological mechanisms that are inextricably linked to the endurance benefit that altitude training can provide.
Firstly, we must establish what qualifies as “altitude training”. It is generally accepted that between 1800m (~6,000 feet) and 3000m (~10,000 feet) is most beneficial. However, research to elucidate the optimal parameters under which altitude training impacts performance – the altitude that generates the most significant physiological changes – is still ongoing. Many professionals agree that around 8,000 ft is the ideal elevation for training, however due to the variability of how athletes react to altitude, it is difficult to conclusively determine a sweet spot.
How does training at altitude differ to training at sea level? The key difference is the air pressure. As you ascend into the sky, air pressure diminishes. This means that in a given volume of air there are fewer particles of oxygen. Each lungful that you inhale brings with it fewer and fewer particles of oxygen as you climb up the side of a mountain. People commonly believe that there is less oxygen at altitude however the air is the same mixture as at sea level – nitrogen, oxygen, carbon dioxide and other components are all present in the same proportions – only the particles are more dispersed. For example, barometric pressure decreases from 760mmHg at sea level to 604mmHg at 2000m, meaning that each litre of air has only 80% of the oxygen that a litre at sea level does. Lower pressure, less oxygen, so what?
Low pressure and less oxygen per breath means that less oxygen enters the bloodstream, which results in hypoxia (low blood oxygen concentration). This hypoxic change triggers the release of EPO from the kidneys. EPO, sound familiar? Yes, altitude training is essentially a natural form of doping. The reason EPO is used as a performance enhancer by athletes is that it signals for the bone marrow to upregulate haematopoiesis – generating more red blood cells (erythrocytes). This has huge benefits to athletic performance as it is the erythrocytes that carry oxygen on the haemoglobin they contain.
EPO peaks between 24-48 hours after arriving at altitude. Studies with elite athletes show that haemoglobin levels can increase by around one percent per week at altitude. This is an adaptation to enhance oxygen carrying capacity, compensating for the lower levels available at altitude, and translates to a benefit in aerobic performance when returning to the oxygen dense air at sea level. Evidence suggests that non-elite athletes – who have lower initial haemoglobin levels – stand to benefit from an even more potent boost than the elites.
Not only does the lower oxygen partial pressure result in hypoxia and haematopoiesis, it also can have greatly beneficial psychological effects. The shortage of oxygen entering the blood means that respiratory centres in the brain are stimulated. You’ll be panting whilst running at what would be an easy pace back at sea level. Hypoxia results in anaerobic metabolites being generated, muscles feel heavier and sessions have a higher perceived level of exertion, even when the pace is decreased. This means that you can push harder and become more accustomed to severe discomfort with less stress on joints and muscles compared to that which running faster or farther at sea level would cause.
This sounds great, right? I mean, aside from the discomfort and panting, a natural boost in performance is a pretty big drawcard. So now, how do you go about trying out altitude training for yourself?
Firstly, you need to select a high-altitude location to train. Choices are endless. Pick somewhere with good trails, some flatter terrain for specific workouts, and maybe somewhere already established as a running hub where you will be able to find people to train with.
How long should you stay for? This is a difficult question with no definitive answer. Your work or family commitments may also mean that any more than a week or two isn’t feasible. Staying for only a week will mean that most of the benefits are coming from the body’s reaction to hypoxia rather than the training you’re doing, but they are benefits nonetheless. Importantly a week away in the hills, devoting time to running and recovering, should leave you in a more relaxed headspace than when you arrived. Staying for a few weeks to months will allow more time to acclimate to the altitude and let the body adapt to the workouts.
During a short stay at altitude it will be tempting to cram in as many hard workouts as possible to reap the benefits for which you’ve travelled so far. Many athletes fall into the trap of working too hard, too soon. This can overstress the immune system, interfering with the generation of red blood cells and leaving you flat and low on energy.
For the initial days at elevation cut back on mileage and stick to easy runs, it’s important to go easy as the body is already subjected to significant stress. If flying from sea level to a significant enough elevation (generally over 2500m), altitude sickness is a real risk – and, importantly, aerobic fitness isn’t a protective factor. Watch out for developments of nausea, headache, trouble sleeping or significant shortness of breath.
To start with, focus on feeling, not pace. Pay heed to your perceived level of exertion. It may feel like you’re struggling to even handle a crawling pace, this is a normal part of the adaptation to altitude. If you finish an easy run feeling like you’ve just run a hard race you should be cutting back. Make sure to keep pace easy and only progress to faster workouts after around a week of adaptation.
It is also important to hydrate. The commonly dry environment that accompanies the high altitude can result in significant water loss through the lungs and skin. And this insensible water loss doesn’t generate as significant a thirst as does sweating. Another thing to be mindful of is iron: a key component of haemoglobin. When generating red blood cells and haemoglobin high levels of iron are required. Foods rich in iron include red meat, spinach and legumes (beans, chickpeas etc.). Some athletes will supplement with iron when traveling to altitude however we haven’t found it necessary when spending time in Kenya and Ethiopia.
A final consideration is timing the descent. Timing the return to lower altitude can be tricky and may require some experimentation. Some athletes feel no ill-effects and within days of returning, others find that they need a week or so to readjust before they feel like they are reaping the rewards of the altitude training. For a first timer, be cautious and come back a few weeks prior to a goal race.
Kipchoge and his counterparts have developed their aerobic machinery breathing in the thin mountain air of the Kenyan highlands, and although a short stint at altitude isn’t going to make up for a lifetime of living at sea level, the physiological and psychological adaptations stimulated by training at elevation are undoubtedly of value. The specific altitude and duration of stay that will optimise the return on investment is impossible to generalise and is something each individual must experiment with. So, what are you waiting for? Go get high!
