Tibet is a mysterious and sacred place, a holy land longed for by cyclists. It boasts incredible natural wonders, sacred religious culture, unique ethnic customs, an average altitude above 4,000 meters, and one of the purest natural climates... For their dreams, cyclists brave long and arduous journeys, even risking their lives to ride to this sacred land to witness what is called the closest place to heaven.
Of course, many cyclists know that Tibet’s high-altitude regions are not places you can just visit casually. The main reason is its plateau mountain climate, which is harder to adapt to compared to other countries’ high-altitude areas. The air is thin, the air pressure is low, oxygen levels are scarce, solar radiation is strong, daylight hours are long, temperatures are relatively low, daily temperature variations are large, the year is clearly divided into distinct dry and rainy seasons, and the climate is complex with significant vertical variations. Therefore, anyone traveling to Tibet’s highlands usually needs to acclimate to the local climate first—even cyclists in very good physical condition may experience altitude sickness. So before planning to go to Tibet, cyclists should first thoroughly understand the discomfort the region’s climate may cause to the human body.
Generally speaking, during the first two days at high altitudes in Tibet, or upon reaching elevations of 4,800 meters, almost everyone will experience more or less headaches, chest tightness, tinnitus, etc. It is advised not to engage in strenuous exercise during this time, and you may adapt within one or two days. However, for those in poor physical condition or visiting the Tibetan plateau for the first time—especially without prior experience—the likelihood of experiencing altitude sickness is high, and symptoms may be severe.
What Is Altitude Sickness?
Altitude sickness is divided into two types: acute altitude sickness (hypoxia type) and chronic altitude sickness (physiological dysfunction type). Most cyclists entering Tibet primarily experience acute altitude sickness.
1. Acute Altitude Sickness: When transitioning from a plain to a plateau or from a plateau to a higher altitude area, the body undergoes a series of hypoxic symptoms in a short period, known as acute altitude sickness. This mainly occurs in first-time visitors to Tibet, individuals with weaker constitutions, or those with heart disease, cardiovascular issues, or respiratory conditions—even native high-altitude residents may experience acute altitude sickness.
The low-oxygen environment of high altitudes causes hypoxia in the body, which is the primary cause of acute altitude sickness. Scientific research has found that changes in atmospheric pressure at high altitudes are also a significant contributing factor. Hypoxia and the sudden changes in atmospheric pressure affect the nervous system, respiratory system, cardiovascular system, digestive system, and others, leading to a range of corresponding clinical symptoms. Additionally, increased oxygen consumption by the body—due to factors such as mental stress, excessive fatigue, or upper respiratory infections—can further worsen the imbalance between oxygen supply and demand, triggering or worsening acute altitude sickness.
Acute altitude sickness is also a stress response of the body to the high-altitude environment. It represents the clinical symptoms that appear as various bodily functions adjust through neurohumoral regulation to reach a new balance. These symptoms often subside on their own after some time.
2. Chronic Altitude Sickness: From a scientific perspective, this mainly refers to cases where, despite prolonged and continuous adjustment, the body fails to achieve balance on the new basis, resulting in a state of plateau physiological dysfunction that manifests as a series of clinical symptoms—this is known as chronic altitude sickness. It is also referred to as “physiological dysfunction.”
The characteristics of chronic altitude sickness include: diverse clinical manifestations, with symptoms primarily from one system but possibly involving multiple systems simultaneously; symptoms that come and go, but generally disappear upon returning to lower altitudes; and most patients can maintain normal work and life at high altitudes.
Since the clinical symptoms of chronic and acute altitude sickness are quite similar, to distinguish between them, any symptoms persisting in whole or part three months after entering the plateau may be considered chronic altitude sickness. (Chronic altitude sickness is generally not dangerous, with no obvious positive signs in medical examinations. Some patients may have numerous symptoms but none are specific. Therefore, when diagnosing chronic altitude sickness, it is essential to rule out the possibility of other diseases before confirming the diagnosis.)