The aim of this study was to investigate the impact of heat acclimatization on athletic performance during the 7-day Marathon des Sables (MdS) which takes place in the Sahara Desert.


Anonymous data for nationality and average running speed (km/h) of all runners who ran the MdS during the period 2000–2015 were collected from the official website of the race and other related websites. Average maximum temperature for each runner’s country during the month preceding the MdS was collected from www.weatherbase.com. Athletes were divided into two Torigin groups as follows: 25 to 15°C (i.e., cold countries) and 15 to 35°C (i.e., warm countries).


Overall, 12467 (10828 men; 1639 women) athletes from 78 countries (37 cold; 41 warm) participated in the MdS during the 16-year study period. The ambient temperature of these countries one month prior to the MdS ranged from 24.2 to 34.4°C. Athletes’ average running speed during the MdS ranged from 2.9 to 13.4 km/h. Moreover, athletes who originated from warm countries ran the MdS 10.7% faster compared to athletes from cold countries.


The natural heat acclimatization achieved by living in warmer countries seems to provide an advantage during the MdS.