Altitude training: Does it work?
Does hypoxic training work? How about other advances in altitude or simulated altitude training?
Hypoxic training is a method of training that reduces the availability of oxygen to the body. Some people, including athletes, believe that it can lead to physiological changes that allow the blood to carry more oxygen thereby improving physical endurance.
One way to expose the body to less oxygen is by living or exercising at high altitudes, called altitude training (a type of hypoxic training). The idea became popular after the 1968 Olympic Games, which were held in Mexico City, elevation 7545 feet — a higher elevation than Denver, Colorado. Experts began to hypothesize about how the Olympians’ bodies were adapting to performing at such a high altitude. The current understanding of hypoxic training is that a gene known as HIF-1 (whose functions include creating oxygen-carrying red blood cells and blood vessels among others) does its job at a higher rate when the person is coping with less oxygen.
The question is: does this theory hold water? Because of the inconclusive nature of the studies done so far, the answer to that question is still up in the air. The only specific training technique that has substantial evidence to support its effects is Live High Train Low. During this training, (which typically lasts for a few weeks), athletes live at high altitudes for most of the day but train at lower altitudes for a couple hours each day where there is more oxygen available. Some athletes claim that hypoxic training has increased their athletic ability, but so far this has been difficult to verify. It’s possible that the placebo effect — getting a boost from the belief that something is helping you — may be at play.
What researchers do know is that constant exposure to low levels of oxygen can do more harm than good to the body (think altitude sickness among hikers and climbers). Over time, it can cause chronic stress, detraining, and edema (fluid buildup in the lungs and brain). In some cases, blood can thicken too much, raising the risk of death due to blood clotting. It's recommended to talk with a health care provider before starting any hypoxic training to make sure factors like blood iron levels are in the healthy range.
Heading for the hills isn't the only way to achieve the effects of hypoxic training. As you mentioned, there are now many ways to simulate high altitude training: breathing intermittently with a nitrogen mask, sleeping in a nitrogen tent, living or sleeping in a barometric chamber, and living in a nitrogen house. Nitrogen replaces a proportion of the oxygen in the air in many of these methods, leading to oxygen deprivation and therefore creating a hypoxic environment. However, all of these tools come with disadvantages and may not work for everyone, so you may want to speak with a health care provider if you are thinking of using them.
The jury is still out on how much hypoxic training actually improves athletic performance. What is much more certain is how lifestyle choices like plenty of sleep, a balanced diet, stress reduction, and strength training (among others) do improve a person’s athletic potential.