A teenager died from multiple organ failure three days after he succumbed to heatstroke during rugby league training in Perth, an inquest has heard.

Torran Jake Thomas, who was 190cm tall at age 15, had been pushing himself hard on the first day back at training with the West Coast Pirates following the Christmas break on 5 January 2015.

Temperatures peaked at 44.4C but training went ahead about 5.30pm when it had eased to 34.3C, the Western Australian coroners court heard on Monday.

A message went out on Facebook earlier in the day, advising players to drink plenty of water before training.

Edward Easter, who was then an NRL game development officer but stopped being a sports trainer after Torran’s death, arrived early to check conditions and ensure all that was needed was there, including water and ice.

He went through the NRL heat guidelines checklist, which assesses 10 factors, and came up with a score of 57.

Training or play can go ahead for scores of between 56 and 65 but extra precautions are recommended including fans in the change rooms and extra drink breaks.

He also started off the session with a longer than usual talk to the teenagers to give more time for conditions to cool.

Easter said Torran was pushing himself hard and performing well at first. But he began to struggle, slowed in pace, stopped completely and sat down.

He was out of breath but could communicate, saying he was exhausted, and was encouraged to keep going.

“I just assumed he was conceding to the fatigue and tried to get him to push through,” coach Luke Daniel Young said.

Easter said he also thought Torran was just tired at that point. But he began to mumble, then closed his eyes and stopped talking.

His breathing and pulse rates, which had settled, came back up again, alarming Easter.

“I hadn’t seen that before,” Easter said. “It didn’t really make sense … I was a bit surprised by the way it went. I thought it was fatigue-related, not heat-related.”

The men, who had put Torran in the recovery position and tried to cool him with ice, then called an ambulance.

“I acknowledge it was hot ... but I don’t believe it was the hottest day,” Young said. “It just didn’t strike me as an extremely hot day, given Perth summer.”