The period of time your body takes to adapt to thinner air and the lack of oxygen at altitude. It can take a body 1-3 days to acclimate.

This is the elevation above sea level.

Altitude Training:
The theory that exposure to high altitude could improve an athlete’s capacity to exercise.

Bag a peak:
slang v. Making it to the summit of a mountain.

slang v. Cycling’s term for hitting the wall or otherwise expiring during a ride. Same as boink.

slang v. To fall and crash violently from a great height. To fail utterly.

Extreme Altitude*:
Above 18,000 feet (above 5,500 meters).
* As defined by the International Society for Mountain Medicine.

High Altitude*:
5,000-11,500 feet (1,500-3,500 meters).

A serious condition caused by a severe lack of sufficient oxygen.

The field, bunch or pack that is the large main group in a road bicycle race.

Respiratory Rate:
The number of breaths you take in a minute.  A normal respiratory rate would be 10-14 breaths per minute.

At high altitude, your body needs to breathe harder in order to take in more oxygen and your respiratory rate increases.

Three-hour tour:
slang v. When something takes much, much longer than you thought it would. A reference to Gilligans Island.

Very High Altitude*:
11,500-18,000 feet (3,500-5,500 meters).