At high altitude the air is 'thinner', containing less oxygen than at sea level. The higher we go, the thinner it gets. Climbing or skiing at high altitude places enormous demands upon the breathing muscles. In order to compensate for the thinner air, the lungs must work much harder, and exercise, which at sea level brings on nothing more than a slight increase in breathing, can push your breathing to its limits at high altitude. At 3km (3000m) the amount of oxygen in the air decreases by 30%, and at 5km its half that at sea-level. This means that at around 1km you begin to experience breathlessness during moderate exercise, and at 4km you feel breathless at rest.
At sea level, your ability to exercise is limited by the capacity of your heart to pump blood to the exercising muscles. At high altitude, you become limited by the ability to pump air in and out of the lungs.
Just to put things into perspective: whilst resting at sea level, you breathe about 12 litres of air in and out of your lungs each minute. At the summit of Mt. Everest (8848m) it requires almost maximal levels of breathing (in excess of 150 litres per minute) just to put one foot before the other. This level of breathing can be sustained for only a couple of minutes at a time.
Human beings tend to 'learn' from experience what is an appropriate level of breathing for a given exercise task. When there is a mis-match between your previous experience and your current experience (as occurs at high altitude), you get a heightened sensation of breathlessness. Also, if your respiratory muscles are working very hard, they can 'steal' blood from the legs to meet their own requirement for oxygen, thus impairing leg performance. Finally, all that respiratory work can lead to chronic fatigue of your breathing muscles, which also increases breathlessness and impairs performance.
By training with POWERbreathe prior to trekking / climbing at high altitude, or a skiing trip, you can prepare your breathing for the rigours of the increased work of breathing, minimise fatigue and breathlessness, and improve performance and enjoyment. Short of spending a few weeks doing lots of aerobic exercise at 3000m, there's not much else to rival POWERbreathe's ability to get your breathing prepared for the mountains!
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