We’re yet to see a single sub 2:30 marathon in a men’s full-distance race – but one of the sport’s leading coaches believes it will soon become commonplace.

Reigning IRONMAN World Champion Patrick Lange has gone closer than anyone – he clocked 2:30:27 at Challenge Roth in 2023.

And even though Magnus Ditlev has smashed the overall full-distance record at the same race in each of the last two years, his marathon times were 2:37 and 2:34.

But Olav Aleksander Bu, the coach behind Kristian Blummenfelt’s remarkable best-ever 7:21 overall time at Cozumel, thinks we’re about to see some huge gains over 26.2 miles at the end of full-distance triathlons.

Swim and bike are complex

We caught up with him ahead of the 2025 full-distance season to see where he thinks the biggest progression will come.

He says it’s hard to justify making the swim the primary focus given that it’s less than an hour out of the full time.

The bike dynamics afterwards are complex but he does think those times will continue to come down. They’ve been the biggest change in the last few seasons for the men, albeit Kona last year saw plenty potentially waste too much energy on two wheels.

Bu told us: “The bike is going to get faster, but not because people start to put out more power. It will come simply through improved aerodynamics and a little bit from technology.

“But you can’t over-pace yourself on the bike – I think people got a good example of that last year. However, triathletes don’t have the same limitations as you do in the UCI so one of the places where I think you will see improvement in IRONMAN racing moving forward is that you will see more, let’s say, a more extreme position, though from a comfort point of view it’s actually not extreme.

“But today people bike almost equally fast as the uber bikers, but they run much faster. And that’s where times will really come down.”

‘A ridiculous gap’

Carbon shoes over the last few years have obviously made a difference but as Bu readily admits there still remains a huge gap between the best marathon runners and the best triathlon marathon runners.

He says: “It’s a ridiculous gap. We’re getting closer – Kristian was 2:32 in Frankfurt last year – but there’s still a 30-minute gap between the best marathon runner and the triathletes.

“You can ask why and there are some obvious reasons [including the fact they’ve done a long swim and bike] but I think it will stabilise for the top men probably somewhere around 2:25 to 2:30 in let’s say five or so years time.”

And he thinks the fundamental reason for the gap comes down to training.

“Look at the top marathon runners,” says Bu. “During a training week they basically encompass what they do in a race multiple times.

“Massive distances. So when you then come to race day you know you’re just doing maybe as little as 10% of what you actually put down in one week of training.

“That’s very different to the swimming and cycling parts for triathletes where they are probably doing race distances in just one session, let alone a week.

“So for the run there are natural limitations simply because you’re not able to put in the volume that is needed to really bridge it all the way down to their efficiency.”

Yee an incredible case study

One man who could provide a fascinating case study in the next few months is Alex Yee.

The Olympic champion is taking a gap spell out of triathlon to focus on the London Marathon, a long-held ambition.

His 10K times would give him a realistic chance of his target marathon time of 2:07-2:10 so it will be fascinating to see how he goes.

And as a final word, Bu says things are very much moving in the right direction ahead of his two big athletes – Blummenfelt and Gustav Iden – returning to the long-distance fray.

He added: “You saw with the overall Kona times – 16 men under eight hours – that people are doing things which were unheard of not long ago.

“So the cool thing is that we are getting closer to peak human performance in Ironman.”