GLOSSARY

Altitude and hypoxia refers to the fall in the partial pressure of oxygen in the air with increasing altitude and its consequences (hypoxia, or tissue oxygen deficiency) for performance and health.

Altitude Classification

• Low: below 1,500 metres; negligible effect.
• Moderate: 1,500–2,500 metres; reduced VO₂max; the common range for altitude training.
• High: 2,500–3,500 metres; risk of acute mountain sickness.
• Very high and extreme: above 3,500 and 5,500 metres.

Immediate Responses

• Increased ventilation (the hypoxic ventilatory response) and respiratory alkalosis.
• Higher heart rate and cardiac output at submaximal intensity.
• Reduced VO₂max: about 7–8 percent per 1,000 metres above about 1,000–1,500 metres.

Adaptations (Days to Weeks)

• Increased EPO and haemoglobin mass.
• Reduced plasma volume in the first days.
• Increased 2,3-BPG and muscle adaptations.

Altitude Illnesses

• Acute mountain sickness (AMS): headache, nausea, fatigue, insomnia, 6–12 hours after ascent.
• High-altitude cerebral oedema (HACE) and high-altitude pulmonary oedema (HAPE): life-threatening; the main treatment is immediate descent.
• Prevention: gradual ascent (above 3,000 metres, no more than 300–500 metres increase in sleeping altitude per day) and, if needed, acetazolamide.

Relevance to Sport

• Live high, train low (LHTL): living at about 2,000–2,500 metres for at least 12–16 hours a day for 3–4 weeks while doing intense training at low altitude improves performance by about 1–2 percent in some athletes, with highly variable individual responses.
• Competing at altitude: arrive 2–3 weeks early to acclimatise, or arrive at the last moment (24 hours before) before AMS symptoms appear.
• Practical example: at the 1968 Mexico City Olympics (2,240 metres), sprint and jump records improved (because of thinner air and less resistance), but endurance results were slower.