PHYS-14 · Principle
How much slower will I be at 2000 m?
Noticeably in anything aerobic. Thinner air lowers VO2max, more the higher you go and often more in the highly trained; two weeks there may win back about half. Pace by effort, not sea-level power.
How the body works, agreed across the reviews below; a study entry shows what one experiment measured.
Practical Application
How much slower will I be at 2000 m? Noticeably in anything aerobic. Thinner air lowers VO2max, more the higher you go and often more in the highly trained; two weeks there may win back about half. Pace by effort, not sea-level power.
What it means for training: at altitude set targets by effort and heart rate, not sea-level power, and take camp dose, iron and timing from SYNTH-06; sprints and short power suffer little (Fulco 1998).
Mechanism
Lower inspired oxygen pressure lowers alveolar and arterial oxygen and with them delivery to muscle and brain (Ulrich 2017). On arrival ventilation and heart rate rise with little fall in stroke volume, and plasma volume falls over 24-48 h; higher up, maximal heart rate and peak cardiac output fall (Bärtsch & Saltin 2008).
Over weeks red-cell production raises haemoglobin mass and restores arterial oxygen content, yet peak VO2 after 4 or more weeks is essentially that of acute exposure (Bärtsch & Saltin 2008); at 2340 m, 8 elite cyclists' VO2max fell 12.8% on day 1, then rose 3.2% by day 7 and 4.8% more by day 14 (Schuler et al. 2007); submaximal performance improves without a rise in VO2max (Fulco 1998).
Elite athletes who desaturate at sea level, 40-50% of them, lose more on short exposure (Powers 1993); at a simulated 3000 m the fall grew with sea-level VO2max in 12 athletes (REF-708, B); haemoglobin mass rose more with oral iron (REF-969, B, observational). Camp gains may also come from ventilation, buffering and economy (REF-209).
Common misreading
"Altitude camp, new blood, faster race"; "my power is down at altitude, so I am losing fitness".