Ely, M. R., Martin, D. E., Cheuvront, S. N., & Montain, S. J. (2008). Effect of heat stress on marathon pacing is dependent on runner ability. ACSM 55th Annual Meeting Indianapolis, Presentation Number, 1932.

This study determined how heat stress influenced the pacing of runners of differing abilities throughout a marathon. Race results were obtained from three Japanese Women’s championship marathons that included 5-km splits, finishing time, and corresponding weather conditions. A total of 62 race years’ outcomes were analyzed using the race winner and 25th, 50th and 100th place finishers.

The difference between the first (0-5-km) and last (35-40-km) 5-km split times (the pace differential) for the 100th place finishers was the same in cool (5-10°C) as temperate (15.1-21°C) conditions. The pace differential for the 50th place finishers tended to increase with heat stress but was not significantly different. In contrast, heat stress resulted in a slowing of pace for the 25th place finishers and race winners.

Implication. Heat stress had a greater negative effect on the ability of faster runners (winner, 25th place) to maintain race pace while having no significant effect on slower runners (50th, 100th place).

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