
Fiona Moriarty
IRONMAN 70.3® Campeche
Fiona's headline numbers
Fiona's strategy
Fueling
T - 1-4hrs: Ate a carb rich meal (Low in fat & fibre)
T - 15mins: Took in a final dose of carb
"I had a big dip in energy around mile 8 on the run once I ran out of liquid in my flasks. I couldn’t turn over any faster, but I felt it was definitely due to the heat."
With the race starting later into the afternoon, Fiona had to adjust her race day fuel schedule to include an additional (but smaller) serving of her typical breakfast. As a Celiac athlete, Fiona has an extra finicky gut, and she’s struggled with sickness and nausea during races, especially when temperatures creep up. Using both PF 30 Gels and a bottle of Carb Only Drink Mix on the bike provided two separate sources of fuel, and enabled her to hit ~88g/h. Since her carb intake dropped to ~68g/h on the run, and she noticed a dip in energy, it might be beneficial to add an additional PF 30 Gel to carry her through to the end and finish strong.
Hydration
Taking on board an appropriate amount of fluid and sodium is essential to maintaining blood volume and supporting the cardiovascular effort needed to perform on race day.
Whilst the absolute amount of sodium and fluid consumed per hour is important, it’s critical to consider these in relation to each other. This is known as 'relative sodium concentration' and it’s expressed in milligrams per litre (mg/L). How much sodium you’re taking in per litre of fluid is more important than the absolute amount taken in per hour.
Fiona1146mg/L
Fiona has been Sweat Tested to dial in her hydration plan
Sweat sodium concentration (mg/L) is largely genetically determined and remains relatively stable. Knowing how salty your sweat is enables you to replace a good proportion of your sweat losses, which can range from 200-2,000mg/L.
Given Fiona's losses are High (1,146mg/L), nailing her hydration strategy becomes especially crucial when it's hot and/or humid.
Learn moreT - 60mins: Drank ~500ml of strong electrolyte drink
"My strategy on the bike worked like a dream, and I felt great heading out onto the run!"
The race conditions were far higher than ideal, reaching a whopping 45℃ (~114℉). This necessitated a high fluid and electrolyte intake to account for Fiona’s increased sweat losses. To reduce the stress on her gut, she decoupled her hydration and fuel by using PH 1000 and PH 1500 tablets in most of her fluid on the bike. This way, she could stay hydrated from water and electrolytes without overloading her stomach with carbs every time she consumed fluid. On the run, she supplemented her Soft Flask of PH 1500 with cups of water and ice from the aid stations in an attempt to stay cool in the blazing heat. Although she didn’t experience any cramping in this race, it would be worth carrying some Electrolyte Capsules to more closely match her losses for a full-distance race, when she’d be more likely to accumulate race-impacting levels of dehydration.
Caffeine
Beyond the Three Levers of Performance (carb, sodium and fluid), caffeine is one of only a few substances that is proven to improve performance for most endurance athletes as it can help stave off mental and physical fatigue.
Consuming caffeine in the hours before the start may have increased perceived energy levels
Though caffeine is a commonly used ergogenic aid in sports nutrition, it’s not suitable for everyone. Fiona knows that she doesn’t usually feel great with caffeine, and especially considering her tricky gut, she opts to stay away from it for races. This goes to show that each athlete should figure out if caffeine is helpful for *their* strategy before adding it in.
How Fiona hit her numbers
Here's everything that Fiona ate and drank on the day...
Final thoughts
“It was insanely hot out there which felt like an effort limiter. But this race was a HUGE step forward for me. No gut issues, no urging to go to the bathroom… What a miracle!”

“After a difficult experience at the IRONMAN® World Champs in Kona at the end of 2023, Fiona consulted with the PF&H Sport Science team to work on a race nutrition plan that would work for her. This meant training her gut, learning her sweat sodium losses, and having a hydration strategy that’s not completely tied to her carb intake. It was a massive win to have her not only crack the top five, but report 9 (out of 10) GI comfort levels!”
Fiona's full stats
Data Confidence
We rate each of our case studies from 1-5 based on the level of accuracy, and our confidence in the data.
There is an adequate level of accuracy in the data collected and the numbers reported. The athlete manages to recall what they ate and drank including most specifics (brands flavours quantities plausible estimations of volumes). However there are estimations made within the data which affect the overall confidence level in the data reported.