Introduction
At high altitudes, the atmosphere contains less oxygen due to lower air pressure. The human body has to adapt to this decreased availability of oxygen, which can lead to a range of physiological responses and challenges. The higher you go, the more pronounced these effects become. Here’s a step-by-step breakdown of what happens as you ascend:
Reduced Oxygen Availability
As you climb higher, atmospheric pressure decreases, meaning each breath contains fewer oxygen molecules. For example, at 3,500 meters (around 11,500 feet), the oxygen level is about 60% of what it is at sea level.
Increased Breathing Rate (Hyperventilation)
The body’s immediate response is to breathe faster and deeper to compensate for the reduced oxygen. This increases oxygen intake but can also lower carbon dioxide levels in the blood, potentially causing dizziness, tingling, or shortness of breath.
Increased Heart Rate
The heart works harder to pump more oxygen-rich blood to the tissues. At high altitudes, it’s common to experience an elevated heart rate even while resting.
Reduced Exercise Tolerance
Physical exertion becomes more difficult as muscles receive less oxygen. Simple tasks that are easy at lower altitudes can feel much more strenuous as you climb higher.
Dehydration
Breathing faster leads to more fluid loss through respiration. High-altitude environments often have dry air, which accelerates dehydration. Inadequate fluid intake further increases the risk of altitude sickness.
Sleep Disturbances
The combination of hyperventilation and reduced oxygen can lead to periodic breathing (Cheyne-Stokes respiration) during sleep, where breathing alternates between rapid breaths and pauses. This can result in fragmented sleep and feelings of fatigue.
Altitude Sickness
If the ascent is too rapid or the body fails to acclimatize properly, altitude sickness can develop. It typically starts with Acute Mountain Sickness (AMS) and, if not managed, can progress to more severe conditions like High-Altitude Pulmonary Edema (HAPE) and High-Altitude Cerebral Edema (HACE).
