Marathon running in the mountains: what altitude does to a time
Races above two thousand metres draw growing fields. Runners should expect to be slower, and here is roughly how much.
Sea-level personal bests do not travel uphill. Thinner air means less oxygen per breath, and endurance performance falls measurably from around 1,500 metres. (World Athletics)
The rule of thumb used by coaches is a few per cent slower per thousand metres of elevation, more for the unacclimatised.
Acclimatisation and health
Arriving two to three weeks early helps; arriving two days early is the worst of both worlds. Medical guidance also warns runners with blood pressure conditions to check with a doctor before racing high. (Various)
References
Various. “Hypertension in low- and middle-income countries.” BMJ, 2023, www.bmj.com. Accessed 1 Apr. 2025.
“World Rankings.” World Athletics, 2025, worldathletics.org/world-rankings. Accessed 1 Apr. 2025.
Cite this story
Dispatch Report (2025) ‘Marathon running in the mountains: what altitude does to a time’, 1 April. Available at: https://thedispatchreport.com/article/marathon-running-in-the-mountains-what-altitude-does-to-a-time (Accessed: 5 October 2026).
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