13.6% of racers are between the ages of 50 and 59.20.1% of racers are between the ages of 40 and 49.23.3% of racers are between the ages of 30 and 39.17.8% of racers are between the ages of 18 and 29.Only about 16.9% of endurance racers were under the age of 18 in 2018, according to Run Signup.For 50K (31-mile) ultramarathon races, peak performance for women happens around 40, whereas, for men, peak ultramarathon time is mostly seen at the age of 39, according to a March 2018 Open Access Journal of Sports Medicine study.Peak marathon performance among women occurs at the age of 32, whereas for men, peak marathon performance occurs at the age of 34, according to a June 2019 International Journal of Environmental Research and Public Health study.Generally, women achieved their best half-marathon performance at an earlier age than men.
France and the Czech Republic have the highest proportions of half-marathon runners in the world, compared to other distances, according to the IIRM.Norway and Denmark have the biggest proportions of 10K runners in the world, compared to other distances, according to the IIRM.The U.S., the Philippines and South Africa have the highest proportions of 5K runners, compared to other distances, according to the IIRM.About 0.2% of the United Kingdom's population (about 133,300 people) races.About 0.2% of the Netherlands's population (about 34,600 people) races.About 0.5% of Ireland's population (about 24,500 people) runs races, which is the highest proportion of race runners in the world, according to the IIRM.