Altitude training is classed as training at more than 2000metres/6500feet above sea level.
At sea level the oxygen (O2) in the air is about 20% and your normal oxygen levels (oxygen saturations) in your blood are about 98-100% depending on your health ( if you have any vascular or respiratory disorders this may lead to a reduction in O2 levels to as low as 85% in extreme cases).
At altitudes of 2500 metres the air is thinner and the oxygen levels are lower at around 15% and at 3000metres it's about 12%. Oxygen saturation levels above 1500 meters/5000 feet are normally about 90% and as you go higher the lower your blood saturations are. For example at about 4000 metres the oxygen consumption in your work of breathing is more than your ability to ventilate.
Your bodies systems can function normal at oxygen saturations as low as 88% and if you have end stage chronic respiratory disorders your saturation levels can be lower however they need to supplement oxygen so your body is amazing at accommodating and managing in varied environments and acclimatises well. However for training you can't function with blood oxygenation levels this low.
So, training at altitude means you work your anaerobic systems harder due to the low oxygen levels. This isn't a new idea and has been known for years however in the last 10-20 years technology has improved so there are low oxygen level training centres and you can train with a masks that limit your O2 levels so the need to travel to high altitude locations like denver in colorado, new mexico, sun city in south africa for months at a time isn't needed.
The benefits of high-altitude training in athletes is increased red blood cell count.
1. Increased Red Blood Cell (RBC) count and intern increase your haemoglobin.
2.Formation of small vessels (angiogenesis) which assist with point 5.
3. Your lungs are able to work more efficiently and perfuse higher levels of blood O2 across the alveolar-capillary membrane
4. Maximising you strength and power (studies have shown that reducing a blood flow to a muscle and exercising it over a 6 week period can improve its power better than if you don't! This surprised me as muscle needs oxygen but in relation to high altitude training it makes sense)
So when you train at high altitudes your body produces a hormone called erythromycin (EPO) which increases your ability to reproduce RBC. This in turn makes your blood thicker ( due to the increase red blood cells) and as a result can put you at risk of blood clots and increase the work of your heart. EPO is what is used in endurance athletes to give them the edge and famously the Tour de France winner Lance Armstrong used. Blood doping also gives you similar effects by taking a pint of blood out and then putting it back in to your body before you competition not as effective.
The main point with altitude training is, it can take 4 weeks to acclimatise yourself to high altitude training but the minute you come back down sea level your body will adjust very rapidly and will be back to normal levels with in 2 weeks. Based on the research and evidence training centres where you mimic training at high altitude environments wont be effective unless you live in that environment for 6-12 weeks.
You may or may not be aware but a common drug that is helpful for managing altitude sickness and low O2 saturation levels is sildenifil/Viagra. This has been shown to increase your performance by up to 45% if you are responsive to the drug, as some may have no improvement at all. Viagra is a drug that was originally designed to treat hypertension as it causes blood vessels in certains parts of your body to to relax particularly the lungs. So you can see how it can help as this would improve your cardiac output.
In conclusion, to get the benefits of altitude training you need to live in that environment for 4 weeks to accommodate and thrn a further 6 weeks minmum to train and then when you compete at sea level you need to do it with in 2-4 weeks to get the benefits. All of the evidence that I have read has left it open and known effects of training centre is kind of woolly but the theory is sound, and with all things it's very dependent on the person as some may get good effects from it and some won't.
I'm not amazing at research and I'm always learning but to give you a little tip regarding research:
- it's not all published,
-word count can limit the detail in the research,
-certain journals will accept everything and some are very specific,
-some seem to be biased towards certain companies or products although they are not suppose to be and will only report the positives,
-testing people is always a bias as there are so many variables that can affect an outcome and research costs a lot of money.
- it takes time to learn how to read literature so don't worry if it's a jumble of words but keep an open mind and read the method and the results and see if you agree, if it's written well you maybe able to form your own conclusions before reading the discussion and conclusion.
- A lot of reading research is about knowing the background so plenty of reading lol.
So be careful if you read research what it is, it's a nightmare and long winded to do the background search but worth it in the end.