At long last, the 2025 IAU 50k World Championships will take place — in March of 2026.
Originally scheduled for December 7, 2025, but postponed due to air quality concerns, the event is hosted in New Delhi, India, on Saturday, March 14, 2026. The International Association of Ultrarunners (IAU) announced the postponement of the original event just two weeks before it was set to run after the Air Quality Index (AQI) in the Indian capital city, with a population of 30 million people, reached 370 parts per million (ppm), a value that sits in the severe range. The postponement followed an announcement by the Indian Supreme Court, supported by the Commission for Air Quality Management in the area, requesting that all schools cancel outdoor activities for the next couple of months.
The women’s podium from the 2023 IAU 50k World Championships held in Hyderabad, India (left to right): 3. Sarah Webster, 1. Carla Molinaro, 2. Andrea Pomaranski. Photo courtesy of the International Association of Ultrarunners.
Now, just over three months later, sporting events in the area appear to be resuming, as evidenced by the recent New Delhi Marathon on February 21, when 30,000 runners took to the streets of the city in marathon, half-marathon, 10-kilometer, and 5k races, and the International Cricket Council T20 Cricket World Cup taking place from late February through to early March.
Conditions on the day could play a big part in the race outcome, with air quality, temperature, and humidity potentially influencing overall times. The 4 a.m. start time is more than 2.5 hours before sunrise and will avoid the daytime high temperatures, which average 30 degrees Celsius (86 degrees Fahrenheit) during this time of year.
As of this writing, the current daily AQI is hovering between 150 and 200 ppm, which falls within the unhealthy range. The AQI is based on measurements of ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. The current measurements are significantly lower than in December, when AQIs of over 300 ppm were a daily occurrence, but are still considered poor air quality for sports competitions. New Delhi’s air quality is a longstanding issue, and the IAU’s decision to hold events in this location has sparked concern and debate in the ultra community about federations’ and governing bodies’ care for runner health and safety.
The 2023 IAU 50k World Championships men’s podium (l-to-r): 3. Jesus Angel Olmos, 1. Chakib Lachgar, and 2. Alejandro Jimenez. Photo courtesy of the International Association of Ultrarunners.
With the return of the IAU 50k World Championships, athletes are again vying for both individual and team titles for the first time since 2023. The 50k event is held every other year, alternating years with the IAU 100k World Championships. After the postponement announcement, national teams had the option of changing their rosters if needed, and the new entry list includes runners from 17 nations competing for both individual and team medals. There are a total of 86 athletes — 49 men and 37 women — on the start lists. The original December start lists featured 98 entries, 50 men and 48 women, and the majority of the original entrants are still entered. The decrease in numbers can be partially attributed to a few runners’ continued concerns about the AQI, and some athletes already having commitments to spring races prior to the rescheduling.
In the team competition, the times of a country’s top three finishers are added, and the aggregate time determines the team rankings. In the last edition, Spain led India and Great Britain in the men’s team competition, and Great Britain won the women’s team competition ahead of the U.S. and Croatia.
After a long wait from 2023, and a further three-month delay from December 2025, the event is a welcome return for the 50k global championships.
Find the full entrants’ lists on the IAU website.
IAU 50k World Championships History
The first IAU 50k World Championships were held in 2015. Prior to that, the IAU 50k World Trophy event was considered the world championships of the distance. The world trophy events were held from 2005 to 2014, with a few cancellations. These were races in which runners who’d earned a spot through qualification races competed alongside those selected by federations.
The top-three women at the 2019 IAU 50k World Championships (from left to right): 2. Helen Davies, 1. Alyson Dixon, and 3. Alicia Perez. Photo: International Association of Ultrarunners
In 2015, the IAU staged the first official IAU 50k World Championships in Doha, Qatar, with backing from World Athletics. This was the first time the world championships event was restricted solely to athletes selected by national federations. In 2016, the event returned to Qatar, and was subsequently canceled in 2017 and 2018 before taking place in 2019 in Brașov, Romania. After the following edition was canceled due to the COVID-19 pandemic, the event was held again in 2023 in Hyderabad, India.
As with all events backed by the national federations, there are varied levels of support and participation from around the world. Although some countries appear not to prioritize 50k as much as other world championships, those that do draw not just on experienced ultrarunners but also on competent marathon runners making the short step up in distance. This yields an interesting mix of runners.
2025 IAU 50k World Championships Men to Watch
Spain, which swept the men’s podium in 2023 and won the team event, is not sending a team this year. While the field is smaller than anticipated and lacks Chakib Lachgar (Spain), the defending champ, several strong teams have entered from countries that have historically placed well in the 50k competition, including the U.S., Great Britain, Poland, and Japan. CJ Albertson of the U.S., who is not racing, holds the current men’s 50k world record of 2:38:43, set in 2022.
Japan
Team Japan is led by the 2023 IAU 100k world champion, Jumpei Yamaguchi. The 29-year-old has a 50k personal best (PB) of 2:51 from 2022, and a marathon PB of 2:16. He is backed up by Haruki Okayama, also with a 50k PB of 2:51 from 2022, and Toru Somiya with a 50k PB of 2:58. Okayama won the 2022 IAU 100k World Championships. Hiroki Kai, who is known more as a trail runner than a 50k specialist, is also racing and has great leg speed. In addition to results such as second place at the 2025 Tarawera 100k and fourth place at the 2025 Sonoma Fall Classic 50 Mile, he holds a strong 50k PB of 2:53 from 2022.
Japan’s Haruki Okayama (left), on his way to winning the 2022 IAU 100k World Championships, alongside teammate Nao Kazami, who finished sixth.
U.S.
Team USA has a five-man team lining up for the event. Ryan Root, Jeff Seelaus, and Adam Vadeboncoeur all have 50k best times of 2:53. They will be backed up by Steve Mance and Nolan McKenna, with 50k PBs of 2:56 and 2:58, respectively.
Great Britain
The British men’s team is made up of a mix of solid ultrarunners and experienced marathon runners, led by Alex Milne, who boasts a 50k PB of 2:51, and who lowered his marathon PB to 2:11:44 in February 2026. In 2025, he also placed inside the top 10 at the Comrades Marathon for the second year in a row. He will be backed up by current British 100k national champion, Henry Hart, who has a 50k PB of 2:50. The four other British runners — Kevin Campbell, Charlie Davis, Sean Hogan, and Logan Smith — all have marathon bests in the 2:14 to 2:19 range.
Great Britain’s Alex Milne placed seventh at the 2024 IAU 100k World Championships. Photo: André Mingneau
Poland
The Polish team has a solid trio of men: Patryk Pawłowski, Mateusz Baran, and Damian Rudnik. All three men have marathon bests in the 2:19 to 2:22 range.
India
The host nation will field a strong men’s team that will certainly be used to local conditions. The team features competent marathon runners and is led by Srinu Bugatha, who has a marathon PB of 2:14. With three other runners — Kulbir Singh, Mohit Rathore, and Pralhad Dhanavat — with known marathon PBs of 2:17 to 2:18, their homefield advantage could make them team contenders.
Others
There are several individual athletes from countries not sending multiple runners to the championships. Norway’s Abdulaziz Ebrahim, who was fourth at the 2023 50k World Championships with 2:52, has a PB at the distance of 2:48. His experience of having raced the 2023 event, which was also held in India, could prove useful.
Lithuania’s Remigijus Kančys, with a 50k PB of 2:49 and a marathon PB of 2:12, could also be a contender.
2025 IAU 50k World Championships Women to Watch
As with the men, Great Britain, Japan, Poland, and the U.S. are all sending strong teams. Defending champion Carla Molinaro of Great Britain is not returning this year. The current women’s world record is held by Des Linden of the U.S. The two-time Olympic marathoner ran 2:59:54 in 2021.
Japan
The Japanese team is led by Mai Fujisawa and Haruna Takano, who are both experienced with longer distances. They have marathon PBs of 2:35 and 2:38, respectively. Fujisawa was third at the 2018 IAU 100k World Championships and placed ninth at the 2023 50k World Championships. Hina Shiozaki is the team’s third member with a marathon PB of 2:43.
Mai Fujisawa (Japan) finished third at the 2018 IAU 100k World Championships. Photo: iRunFar/Bryon Powell
Great Britain
The British team returns as the defending champions. While they lack the top three women from the 2023 team, they will be led by Becky Briggs and Naomi Robinson. The pair have marathon PBs of 2:29 and 2:30, respectively, from 2022. They are backed up by the experienced 100k runner Melissah Gibson, who was fifth at the 2024 IAU 100k World Championships and is a Comrades Marathon top-10 finisher. In February 2026, she set a marathon PB of 2:36. They are joined by Katrina Buchanan with a 2:35 marathon PB, and Heather Townsend with a 2:37 marathon PB.
Melissah Gibson (Great Britain) at the finish of the 2024 IAU 100k World Championships. Photo: Adrian Stott
U.S.
The Team USA women are led by Courtney Olsen. She had stellar form in 2025, starting with a 50k PB of 3:16 while winning the USATF 50k Road National Championships in April. She then finished ninth at the Comrades Marathon before becoming just the second woman ever to break seven hours for the 100k distance in a licensed race with her 6:59 at the Tunnel Hill 50 Mile in the autumn. The time set a new women’s American record.
Joining her is Sophie Seward, who ran 3:17 at the 2025 USATF 50k Road National Championships behind Olsen, and has a marathon PB of 2:33. Also on the six-woman team are Melissa Tanner and Lindsay Kostelnick, both with 50k PBs of 3:21. Tanner placed 11th at the 2023 IAU 50k World Championships, and Kostelnick is a trail runner with results including a sixth place at the 2024 JFK 50 Mile on her resume. Alexandra Niles, who ran a 3:25 50k PB in 2022 and raced at the 2023 IAU 50k World Championships, and Christine Guerrero, with a 3:29 PB for the 50k, round out the team.
Courtney Olsen (U.S.) crossing the line to set a new women’s 50-mile world record at the 2024 Tunnel Hill 50 Mile. Photo: Micki Colson, Colson Photography
Poland
Team Poland will be led by Dominika Stelmach, who was third at the 2022 IAU 50k European Championships and fourth a year later at the 2023 IAU 50k World Championships. Along with Olsen, she is probably the most experienced ultrarunner in the field, with five Comrades Marathon top-10 finishes and a 50k PB of 3:10:27. She also has a 100k PB of 7:04.
Dominika Stelmach on her way to setting a women’s 12-hour world record in 2023. Photo: Tomer Feder/Sport Photography
Others
Petra Pastorová of Czechia, with a 50k PB of 3:20 and a marathon PB of 2:36, could also be one to watch. She was seventh at the 2023 IAU 50k World Championships.
Call for Comments
- Who else is racing at the 2025 IAU 50k World Championships that we should have an eye on?
