Sam Long, aka the Big Unit, surprised many with an impressive sixth-place finish in his Kona debut. And after speaking with coach Parker Spencer, who came on board as a metabolic testing consultant just two months before the race, it’s clear that Spencer believes Long has what it takes to make the podium next year – and even contend for the win.

Here, we’ll explore where that belief comes from, along with the role metabolic testing (or physiological profiling) has played in helping Long optimize his engine and get the most out of his performances on triathlon’s biggest stages.

First, the Swim

Given we’re discussing Spencer’s belief that Long has what it takes to podium – or even win – in Kona, let’s address what some critics might call the elephant in the room: Long’s swim.

While Long didn’t make the large front pack in Kona this year, which even names like Kristian Blummenfelt and Patrick Lange unexpectedly made, Spencer believes that winning (or podiuming) in Kona is perhaps less dependent on the swim than some might think.

Recent Ironman World Championships have featured what feels like endless talk of “WhatsApp groups,” with athletes like Jamie Riddle, Marten Van Riel, and others working together to establish a gap and distance themselves from big names. But Spencer highlighted the risks of this strategy and why the importance of making the front swim pack may have become somewhat overhyped in recent years, for lack of a better word.

As he explained, over the full Ironman distance, and especially in the brutally challenging conditions of Kona, success still largely comes down to managing effort and energy expenditure efficiently throughout the day. Despite advances in fueling, it’s still, in many ways, a metabolically constrained event. And athletes who push too hard too soon (perhaps in an effort to make that front pack, or to break away altogether) may be expending more energy than makes sense in the early stages of a seven-to-eight-hour race.

(Of course, every athlete has their own tactics, and Lange credited making the front swim pack as integral to his 2024 victory. But as Spencer observed regarding this year’s Kona, “Most of those guys that came out of the water on the front weren’t even relevant halfway through the bike.”)

Looking at Long’s performance specifically, he exited the water in 54:47, roughly four to six minutes behind the five men who finished ahead of him, whose swim times ranged from 48:25 to 50:10. And while Spencer would still like to see what improvements they can find in the water, he believes even 90 seconds to two minutes could make a meaningful difference.

As he clarified, “We haven’t even worked on Sam’s swim yet, he only brought me in for the bike and run ahead of Kona. I work with short-course guys all the time on their swim and absolutely believe we can find something there. But I also believe what we need to find is less than many people think.”

On the Bike, More Power Also Isn’t the (Only) Answer

It’s part of the answer, and it certainly helps…but there’s a way to go about it that’s much more strategic than simply chasing watts.

And this is where metabolic testing, along with the broader analysis of performance data – including post-race power files – becomes particularly useful. It’s also where Spencer fits in.

“Beyond the numbers, I feel the missing piece, and the reason I did my PhD, is knowing how to take these numbers and actually use them to help someone have a performance like Sam just had,” Spencer said.

He proceeded to highlight a few interesting things: “When I tested Sam initially, I was like, everyone looks at you as a cyclist, but you’re a better runner than you are a cyclist. Also, we had to consider the way Sam was riding his bike. Because he was playing ‘catch up’ in a sense, he was surging past people fast enough to break their souls,” he said with a laugh.

Fast enough to break their souls. That certainly sums up how it feels to watch Long on the race course (or from the comfort of our living rooms on the big screen), zooming past contenders like they’re standing still. And the natural reaction is to admire (and fear!) it.

Yet Spencer highlighted the metabolic cost of those surges and noted that Long was intentionally more restrained in Kona, allowing the passing to come to him, in a sense. In fact, the majority of his overtaking occurred in the final 30 miles of the ride.

Beyond tactics and more efficient riding, Spencer also used the COSMED K5 metabolic analyzer, blood lactate testing, and INSCYD metabolic profiling software to build a detailed profile that allowed them to identify and prioritize training changes to fine-tune Long’s engine ahead of Kona.

“It wasn’t a lot of time,” Spencer said. “And what really surprised me is how much change we were able to make in a short amount of time. And massive kudos to Sam because he went all in on the approach, and it’s very different than anything he had done before.”

“For someone before the biggest race in the world, to trust a coach they’ve never worked with before, and take the advice that I gave him, and actually apply it and go all in on it…I’m glad sitting here [post-race] that I can take a deep breath and say ‘it worked.’”

(For reference, Long continued to write his own training plan, incorporating the advice emerging from Spencer’s consultations.)

“One of the most meaningful changes we achieved was reducing Sam’s VLamax,” Spencer continued. “This also highlights the difference in demands between 70.3 and full Ironman racing, and why it’s so challenging to do well at both.” (Notably, Long skipped the Ironman 70.3 World Championships in Nice to go all-in on Kona.)

“We also looked at his FatMax and carb combustion rate,” Spencer shared, noting that they were able to run the math on Long’s carbohydrate intake and reverse-engineer how fast he could sustainably ride without compromising what he still needed to accomplish over the final 42.2 kilometres.

Through modified training and a revised, data-informed race strategy, Long rode PR Ironman bike power (in the challenging conditions of Kona no less!), while still managing the metabolic demands of the effort well enough to deliver an incredibly impressive 2:42 marathon on debut.

2:42 on Debut

Looking back at the results sheet, Long rode within striking distance of the fastest bike split of the day (Gregory Barnaby’s 4:11:23 compared to Long’s 4:12:50), and still delivered a remarkable 2:42:57 marathon. Of the five men who finished ahead of him, only three ran faster: Luis, Iden, and Le Corre.

Another noteworthy statistic: Iden recorded the fastest combined bike-run time of the six athletes, but Long was just 1:39 behind across the two disciplines. That’s pretty compelling when considering Spencer’s belief that Long has what it takes to contend.

(Those “strongest legs in triathlon” are shining through! Although perhaps Iden has something to say about that now?!)

Again, the strategy on the run was very much about sticking to Long’s plan, informed by his physiological assessments, and trusting it rather than getting caught up in what was happening ahead of or behind him. And as others faltered, including Magnus Ditlev and Blummenfelt, Long kept going, running his way into sixth place. The emotion was evident as he celebrated crossing the finish line!

The Best of Sam Long Is Yet to Come

While it’s worth celebrating what Long has already achieved, his Kona debut naturally raises the question: how much more potential is there to unlock?

A longer-term partnership between Spencer and Long appears to be in the works, with opportunities to further optimize the bike and run, and potentially address the swim as well. And given what they accomplished in just six weeks, it’s intriguing to consider what might be possible with more time.

Of course, the rest of the field won’t be standing still either. But given how many had ruled Long out ahead of Kona, only for him to finish sixth on debut, perhaps there’s good reason to reconsider what he’s capable of.

And perhaps the world hasn’t yet seen the best of Sam Long.

Footnotes: Sam Long’s Numbers and What the Terminology Means

VO₂max: The maximum amount of oxygen an athlete can use during intense exercise. Think of it as the size of the aerobic engine.

VLamax: An estimate of the maximum rate of glycolytic energy production. A higher VLamax can benefit explosive efforts but may also increase carbohydrate demands at sustained intensities.

FatMax: The exercise intensity at which the body burns fat at its highest rate. Power at FatMax helps indicate how much work an athlete can produce while relying heavily on fat for fuel.

Maximum Fat Oxidation: The highest estimated rate at which the body can burn fat for energy.

MLSS (Maximal Lactate Steady State): The highest exercise intensity at which blood lactate can remain relatively stable over time. It’s an important indicator of sustainable performance.

Running Economy: How much oxygen an athlete uses to maintain a given running speed. The less oxygen required at the same pace, the better the running economy. Spencer tested three ASICS shoe models to assess which offered Long the greatest physiological efficiency.

The Tools: Parker Spencer used a COSMED K5 metabolic analyzer, blood lactate testing, and INSCYD software to assess Long’s physiological profile. Repeat testing allowed them to track progress and assess whether the training adjustments were producing the desired adaptations.

The Outcomes: Comparing Long’s initial metabolic assessment with his final pre-Kona profile revealed some remarkable changes. And perhaps the most interesting finding? His measured absolute aerobic capacity (VO₂max) didn’t meaningfully increase. In other words, Long didn’t necessarily develop a bigger engine – as Spencer shared, six weeks was too little time for that. Instead, he improved how effectively he could use the one he already had.

Physiological measure	Change
Estimated VLamax	43% lower
Power at FatMax	16% higher
Estimated maximum fat-oxidation capacity	30% higher
Estimated MLSS power	Nearly 10% higher