Marathon performance slows progressively as WBGT rises from 5 to 25 °C
Top men were 1.7% off the course record in the 5–10 °C band and 4.5% off at 20–25 °C — and slower runners lose more
Key Findings
Top men were slower than the course record by 1.7 ± 1.5%, 2.5 ± 2.1%, 3.3 ± 2.0% and 4.5 ± 2.3% in WBGT bands of 5.1–10, 10.1–15, 15.1–20 and 20.1–25 °C.
Performance slowed progressively as WBGT rose from 5 to 25 °C, and the slowing was larger for slower populations of runners.
Practical Application
The coolest band was the fastest. For a recreational marathoner the warm-day penalty is larger than for the elite: adjust the target pace by the forecast, more so the slower the runner.
Dress and pace for the heat the body will produce — see SYNTH-79.
Limitations
WBGT, not air temperature; nothing below 5 °C; the differences for top women were not significant. Abstract only was read.