For the British triathletes Jessica Learmonth and Georgia Taylor-Brown it should have been a moment of pure triumph. Throughout a key Olympic Games test event in Tokyo they had matched each other stroke for stroke, pedal for pedal and stride for stride - and so moments before the finish line they decided to spontaneously join hands to celebrate beating the rest of the world’s top athletes.

Unbeknown to them, however, they had fallen foul of the International Triathlon Union’s competition rule 2:11f, which states that triathletes must not “finish in a contrived tie situation where no effort to separate the finish times has been made”. So, while Learmonth was initially given the victory after a photo finish, she and Taylor-Brown were quickly disqualified.

Ashes fun, Community Shield antics and skateboarding tweens | Classic YouTube Read more

An appeal was rejected, which meant that another British athlete, Vicky Holland, moved up from fifth to third behind the new winner, Flora Duffy of Bermuda.

Ironically the rules relating to tied races were changed after Britain’s Olympic gold medallist Alistair Brownlee famously dragged his brother Johnny, who was suffering from heatstroke, across the line in a race in Mexico in 2016.

Playing the good samaritan has also been banned by the ITU, with its rules now stating that “an athlete cannot physically assist the forward progress of another athlete on any part of the course. This will result in both athletes being disqualified.”

What had made the performances of Learmonth, 31, and Taylor-Brown, 25, so impressive was they had to battle through extreme heat in Japan’s capital, with temperatures rising well above 30C and the humidity pushing above 80% despite a 7.30am start.

The conditions were so severe that organisers had earlier halved the distance of the running section to five kilometres. Even with those precautions the French athlete, Cassandre Beaugrand, had to be taken to hospital with suspected heatstroke.

Both Learmonth, who is a European, Commonwealth and World Triathlon Series medal winner, and Taylor-Brown, who won a maiden World Triathlon Series race earlier this year, were too upset to speak afterwards. However, British triathlon’s national performance director, Mike Cavendish, praised their performances.

“It’s obviously disappointing to have Jess and Georgia disqualified but it’s a testament to the depth of our female squad that we still have another athlete on the podium,” he added.

Holland, who won an Olympic bronze at the Rio Olympics in 2016, echoed Cavendish’s comments. “I really feel for Jess and Georgia because they raced exceptionally well and I feel like they absolutely smashed it and deserved the first and second finish,” she said. “I don’t know how British Triathlon will choose things now. I wouldn’t want to be a selector.”

A British Triathlon spokesperson confirmed that all three British athletes are likely to have to wait until next May to find out whether they have been chosen for the Olympics, although an initial selection meeting will be held in October. Three men and three women will be picked for the team.

Despite the widespread sympathy for the British triathletes on social media, one leading law expert told the Guardian that the ITU had no option but to disqualify them.

Peter Charlish, a principal lecturer in law at Sheffield Hallam University, said: “The decision is clearly right by the letter of the law, even though it is debatable as to whether this should be regarded as a contrived finish. Of course it is horribly harsh for the British athletes. But if the ITU didn’t apply its own rules, others would have surely challenged them.”

Meanwhile, with less than a year to go until the start of the Olympics, how competitors and spectators will cope with the extreme heat which has killed at least 57 people across Japan during the past fortnight is an increasingly pressing concern. Earlier this week several athletes were also treated for heatstroke at the world rowing junior championships in Tokyo.

• This article was amended on 12 October 2019. In an earlier version the International Triathlon Union was incorrectly abbreviated to ITF, rather than ITU.