Organisers said start times for athletics, rhythmic gymnastics and the marathon swimming events had been slightly adapted in consultation with relevant stakeholders, including the Olympic Broadcasting Service.

The marathon swimming events had initially been scheduled to begin at 7am local time at the Odaiba Marine Park.

Tokyo 2020 say the events will now begin at 6.30am, with the expectation they will conclude by 9.10am.

The decision to alter the start time was discussed with the International Olympic Committee and the International Swimming Federation.

The move was considered as part of heat countermeasures for the Games.

The women's 10 kilometre marathon swim event is scheduled for August 4 next year, with the men's following a day later.

Prior to the coronavirus pandemic, the Tokyo heat was a headline topic for organisers in the build-up to the Olympics and Paralympics which have now been postponed to next year. 

A heatwave hit Japan in 2019 during the same period the Olympics were due to have been held this year, resulting in a number of deaths.

Start times in long distance track and field races, equestrian, rugby sevens, triathlon and mountain biking were revised to help combat the heat fears.

The Olympic marathon and race walks were also moved to Sapporo, more than 800 kilometres to the north of Tokyo.

Tokyo 2020 said the other amendments to the competition schedules are for operational reasons and have been agreed with the respective international federations.

The start time of athletics competitions on August 7 has been amended to 7pm.

The end time of the rhythmic gymnastics individual all-around final on the same day has been altered to 6pm, while the group all-around final on August 8 should conclude at 12.55pm local time.

Tokyo 2020 also said it had amended sessions for the men's compound and women’s recurve archery ranking rounds at the Paralympic Games on August 27.