Marathon performance and pacing in the Doha 2019 Women’s IAAF World Championships: extreme heat, suboptimal pacing, and high failure rates

Harry Beal, Jo Corbett, Danielle Davis, Martin J. Barwood

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Abstract

Purpose: The Doha 2019 women’s World Championship marathon took place in extreme hot (32 °C), humid conditions (74% relative humidity) culminating in unprecedented (41%) failure rates. We explored whether extreme heat or suboptimal pacing was responsible for diminished performance against a temperate “control” (London 2017: 19 °C, 59% relative humidity) and whether physical characteristics (eg, body surface area, estimated maximal oxygen uptake, habitual heat exposure) explained performance.
 
Method: Five-kilometer-pace (km·h−1) data underwent repeated-measures analyses of hot (Doha, n = 40) versus temperate pacing and performance (London, n = 78) within and between marathon pacing (finisher quartiles normalized against personal best; n = 10 per group) and within hot marathon finishers versus nonfinishers (up to 10 km; normalized data). Possible predictors (multiple regression) of hot marathon pacing were explored. Tests to .05 alpha level, partial eta squared (η2p) indicates effect size. 

Results: Mean (SD) of Doha (14.82 [0.96] km·h−1) pace was slower (London: 15.74 [0.96] km·h−1; P = .00; η2p=.500). In hot conditions, athletes finishing in positions 1 to 10 (group 1) started more conservatively (93.7% [2.1%] of personal best) than slower runners (groups 3 and 4; 96.6% [2.8%] of personal best; P < .05, η2p=.303). Groups were not different at 15 km and then slowed immediately (groups 3 and 4) or after 20 km (group 2). Finishers and nonfinishers adopted similar pace up to 10 km (P > .05, η2p = .003). World ranking predicted (P = .00; r2 = .248) average pace in Doha. 

Conclusion: Extreme hot conditions reduced performance. Top 10 athletes adopted a conservative initial pace, whereas lower-placing athletes adopted a faster, aggressive start. Pacing alone does not explain high failure rates in nonfinishers. Athletes competing in the heat should initially pace conservatively to optimize performance.
Original languageEnglish
Number of pages7
JournalInternational Journal of Sports Physiology and Performance
Early online date17 May 2022
DOIs
Publication statusEarly online - 17 May 2022

Keywords

  • marathon running
  • pacing strategies
  • IAAF world championship
  • temperature change

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