Marathon PB, World Champs Podium, 13 Days Apart – How Sam Macaulay Did It

Sam Macaulay is a New Zealand-born, London-based endurance runner and one of the world's most versatile long-distance athletes. 

The 2025 XTERRA Trail Run World Champion, Sam followed up with another podium finish at the 2026 edition in Gozo, Malta, becoming one of only two New Zealand athletes to podium at consecutive XTERRA Trail Run World Championships.

Sam also competes on the road, running for London Heathside AC, and arrived at the 2026 London Marathon looking to improve on his PB of 2:24:57 from Valencia.

As a researcher in ecological and biological environmental sciences at Imperial College London, Sam follows the evidence when it comes to supplements and checked out CurraNZ’s scientific credentials before embarking on a trial with his training and competition.  

Here, Sam charts his progress since trialling our award-winning fitness aid this year, as he took on the London Marathon - XTERRA World Champs double, less than two weeks apart. 

2026 – Big Targets and World Champs

Sam writes:
“After connecting with CurraNZ following my win at the Tarawera UT50 in February, I set myself a pretty formidable challenge: an eight-week build to the London Marathon, followed by the 2026 XTERRA Trail Marathon World Championships in Gozo just 13 days later.

“I'd run trail races within two weeks of each other before, but there's something about pounding the pavements for 42.2 km that can hit the legs differently. With that in mind, my plan for London was to pace the first half conservatively, build throughout the race and hopefully finish strongly enough to still run a PB.”

What He Noticed In Training

Sam initially started using 1 capsule of CurraNZ a day, but played around with dosing and found better effects with 2 capsules.

“During my eight-week build trialling CurraNZ, I noticed improved muscle recovery, particularly after harder sessions. My muscles seemed to feel less fatigued and ready to go again for another session a few days later. I also felt like I had better endurance towards the end of longer, harder sessions, with less muscular fatigue late in the effort.”

London Marathon: A PB and 11^th Fastest Negative Split In The Field

Incredibly, that training quality translated to race day, where after a pre-race four-capsule dose of CurraNZ, Sam recorded a new PB. Not only that, he scorched to a 2+ minute negative split of 1:11:16 for the second half against a first half of 1:13:24, in a race of tens of thousands of runners, on one of the most competitive marathon days in history.

The 2026 London Marathon was the race where Sabastian Sawe of Kenya became the first person in history to run a sub-two-hour marathon in official race conditions, winning in 1:59:30 – shattering the world record.

Sam reflects, “All that good training translated into race day where I was able to run the 11th fastest 35-40 km 5k split of the mass field, including the elites – and finished with a new PB of 2:24:40.

“It was the best I have ever felt in the second half of a marathon, including others where I have previously run a negative split.

“This fits with some proposed mechanisms behind CurraNZ, including enhanced fat oxidation and reduced carbohydrate use during exercise, which may have helped preserve carbohydrate stores for longer during the marathon (Cook et al. 2017; Fortis et al. 2022). Recent trials have also shown CurraNZ can increase muscle glycogen storage capacity by 39% (Jones et al, 2026) which could be another contributor to improved endurance.”

One Week Later: Back in the Hills

Most athletes would be in recovery mode after a sub-2:25 marathon effort, but Sam was back on the trails within days, and continuing to dose on CurraNZ every day to support his recovery.

“Just a week after the marathon, I was able to get back into the hills for a final 20 km hilly run with a few hundred metres of vert to give the legs some final hill efforts before the XTERRA World Champs six days later. I’ve never felt so quickly recovered after a road marathon (at PB effort) before.”

XTERRA World Champs: Third place and a Course Record Smashed

The XTERRA World Champs in Malta was a different challenge: a technical 50 km trail race around the perimeter of Gozo. Racing on Marathon-stressed legs in the Mediterranean sun, was going to be a challenge.

Sam reflects: “Midway through, I definitely felt some fatigue in my quads and hamstrings and wondered whether I had bitten off a little more than I could chew by racing again so soon after London.

“But I persevered, sticking to the fuelling and cooling plan – plus a quick head-dunk in the Mediterranean when the course came down to the sea-side! – and I was able to push through, keeping up a strong effort through the second half of the race.

“Running in for 3rd place – with a time that was 13 minutes ahead of the previous course record – was a result I was very happy with, especially so soon after London. To come away with both a marathon PB and a 50k podium finish was hugely satisfying from this block.”

What’s Next:

“I’m now looking forward to continuing with CurraNZ into the Broken Arrow Skyrace in Olympic Valley, Tahoe this month and seeing what I can do among a world-class Elite Men’s Skyrunning field.

“I’ve been genuinely impressed by how well CurraNZ has fitted into my training and recovery routine. It’s become an important part of the routine that helped me recover, train consistently and race well. I’m looking forward to continuing to use CurraNZ in training and racing across roads, trails and mountains, and sharing that journey.”

Try CurraNZ for Yourself

Sam’s block – a marathon PB, record-breaking World Champs podium, and the fastest recovery of his career, was underpinned by CurraNZ every step of the way. If you want to experience the same science-backed edge in your own training and racing, now is the time.