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Kate Southwood

Kate Southwood

Precision Fuel & Hydration IRONMAN 70.3® World Championship

8th November, 2025SpainMarbellaCompleted, F60-64

Kate's headline numbers

~50g
Carb per hour
Recommended 60g/h
~286ml
Fluid per hour
Recommended 250-750ml/h
~790mg
Sodium per litre
Recommended 800-1200mg/L
~2.9mg
Caffeine per kg
Recommended 3-6mg/kg

Kate's strategy

Fueling

Carbohydrate is the main fuel you burn when racing. Failing to fuel properly is a leading cause of underperformance in longer races.
Carb-rich meal

T - 1-4hrs: Ate a carb rich meal (Low in fat & fibre)

Pre-fueled

T - 15mins: Took in a final dose of carb

Carb per hour
Recommended 60g/h
~50g
Kate's Energy Rating9/10

"I didn’t experience any dips in energy because I paced myself well. I felt a real high from completing the bike so then I just enjoyed the run."

Our thoughts

Kate executed a textbook pre-fueling strategy, consuming a carb-rich breakfast a few hours before the start followed by a PF 30 Caffeine Gel in the final 30 minutes. This pre-race carb intake ensured she started with fully-loaded glycogen stores and elevated blood glucose to power her through the swim. A PF 30 Gel in T1 kicked off her in-race fueling which consisted of a mixture of gels, chews and real foods to avoid flavour fatigue. On the bike, this meant Kate hit the ~60g/h recommendation for an event of this intensity and duration, but her intake decreased slightly to ~47g/h on the run. She would benefit from training her gut to increase this back up to the recommendation by adding another PF 30 Gel early on in the run along with the bananas she took from aid stations.

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.

Pre-loaded electrolytes

T - 60mins: Drank ~500ml of strong electrolyte drink

Fluid per hour
Recommended 250-750ml/h
~286ml
Sodium per litre
Recommended 800-1200mg/L
~790mg
Kate's Hydration Rating9/10

"Living in Qatar, my training has predominantly been in much hotter conditions than Marbella, so I drank what I felt I needed and didn’t experience any issues. "

Our thoughts

Kate is used to exercising in the heat so the conditions in Marbella felt familiar, although she still made sure to support her thermoregulation by pouring water over herself at every aid station. Kate drank to thirst throughout the race with her bike intake sitting nicely at ~485ml/h. However, this dropped to ~108ml/h on the run, which in future races, should be increased to prevent a significant body weight change over the course of a race of this duration. The PH 1000 on course allowed Kate to maintain a relative sodium concentration close to the average sweat sodium concentration we’ve identified in our database. To further dial in her individual sweat sodium losses, Kate would benefit from having a Sweat test, especially if future races will take place in hotter conditions where she has experienced cramp in the past.

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.

Pre-caffeinated

T - 0-4hrs: Had a final hit of caffeine

Caffeine per kg
Recommended 3-6mg/kg
~2.9mg
Our thoughts

Kate consumed two PF 30 Caffeine Gels during her race, one before the swim and another in T2. While these doses will have provided her with a psychological boost and reduced her perception of fatigue, Kate could benefit from another 100mg caffeine dose during the race to place her within the 3-6mg/kg recommended range.

How Kate hit her numbers

Here's everything that Kate ate and drank on the day...

Before race (>30 mins)
Pre-race (<30 mins)
Bike
Run

Final thoughts

Kate's Satisfaction Rating10/10

I absolutely loved it! I felt such a sense of achievement to be standing on the start line surrounded by incredible athletes and to race alongside them but with no pressure on myself was wonderful. I hope I can inspire people to get involved even if they aren’t an elite athlete because it’s so much fun!

Kate

Kate nailed this race, and better yet, she had a smile on her face from start to finish! Her fuel and hydration strategy worked well for her individual needs and provided her with the energy she required to have a great time and finish strong.

PF&H

Kate's full stats

Overall
410g total carb50g per hour
2,350ml total fluid286ml per hour
1,856mg total sodium226mg per hour
790mgSodium per litre
200mg total caffeine2.9mg per kg
Bike and Run
Bike
Run

Data Confidence

We rate each of our case studies from 1-5 based on the level of accuracy, and our confidence in the data.

12345

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.

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