Teenage Broncos recruit Payne Haas is considered one of the hottest prospects in rugby league.

Haas turns heads at Broncos training

His pure size brought him to the attention of NRL and NFL scouts but it was 16-year-old Payne Haas's aerobic capabilities that impressed coaching staff and seasoned rep stars in his first outing with the Broncos senior squad on Tuesday.

Considered the hottest young forward prospect under the age of 18, the Australian Schoolboys representative had his pick of NRL clubs and the Keebra Park High School product chose Wayne Bennett's Broncos.

Standing at 196 centimetres and weighing 116 kilograms, the only thing to distinguish the youngster physically from members of Brisbane's first grade squad was the yellow T-shirt he was wearing, impressing members of the coaching staff with his ability to keep pace with veteran NRL players.

He pushed Josh McGuire in the gruelling conditioning session and the Test and Origin representative was impressed by what he saw.

"I was very surprised with his aerobic (capacity)," McGuire said.

"Obviously it's his first session so the adrenaline was there and he was excited but he's got a great opportunity to play 20s this year and it will be good for him to play against kids a bit bigger.

"Obviously he's been a big kid his whole life so it will be good for him to come up against other big kids and see where he's at."

The third-eldest of 10 children in the Haas household and previously contracted to the Titans, Payne has used his considerable size to dominate the junior grades but there have been plenty of big teens who have failed to make the transition into the senior levels of rugby league.

"Payne Haas is a kid of the future obviously and he's getting his opportunity to train one day a week which is good," said McGuire.

"He's a big human being. He's only young, he's a baby still but all the foundations are there for a good football player.

"He's got to make sure that he trains and eats well and definitely comes in and stays on the right track and trains hard.

"There are some real athletes there but it takes a long time to learn the trade, especially in the middle. Hopefully these kids can all come through and take my spot someday."