TOKYO • The running segment in the 2020 Olympics women's triathlon qualifying event yesterday was cut from 10km to 5km because of heat concerns, the latest test event to be beset by extreme temperatures.

The International Triathlon Union made the decision based on concerns that, with temperatures around 32 deg C, conditions at the end of the swim-bike-run race would fall within "extreme levels".

Soaring temperatures have killed at least 57 people across Japan since late July, highlighting the possible health threat to athletes and spectators at next year's July 24 to Aug 9 Games.

Tokyo 2020 spokesman Masa Takaya said lessons will be learnt.

"The ITU informed Tokyo 2020 that a comprehensive review is necessary soon after the competitions this week," Takaya said in a statement to Reuters.

"Tokyo 2020's collaboration with the ITU led to the implementation of measures to combat summer heat, including change of races' start time, revised heat stress protocols, specially trained personnel and extra water stations on the course."

The 1.5km swimming and 40km cycling legs were unaffected after the ITU deemed the water quality and temperature in the Odaiba Marine Park course to be within regulation. Athletes had complained about a bad smell during the swimming marathon test event at the venue last weekend.

Kyodo News reported last weekend that several athletes were treated for heatstroke at the World Rowing Junior Championships, another test event, at the Sea Forest Waterway course in Tokyo Bay between two reclaimed islands.

There were also complaints from spectators at the lack of protection from the sun because the venue's roof covered only about half of the 2,000 seats.

REUTERS, ASSOCIATED PRESS