Millet is, appropriately, very academic in his description of altitude training and its benefits. In layman’s terms, we’re talking about training at 7,000 to 8,000 feet above sea level, ...

you can probably return to that altitude without problems as long as you are properly acclimatized. The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg.

If you look on any topographical map, you’ll notice that elevations are reported in height above (or occasionally, below) sea level. Pilots often report altitudes in AMSL, or Above Mean Sea Level.

All of these changes, we can plot them and if we look exponentially, we see catastrophic effects in the next few years, ...