Post-Mortem: 198cm (6'6") runner aiming for Sub-3. My Berlin Marathon disaster (Heat + 120g carbs/hr) and what I'm changing.

Hi everyone,

I’m currently deep in base building for a Sub-3 attempt this summer, trying to redeem myself after a pretty humbling experience at the Berlin Marathon this year.

I wanted to share my breakdown of what went wrong, specifically regarding fueling vs. cooling, in case other taller/heavier runners are struggling with the same thing.

The Context

• Goal: Sub-3
• Height: 198cm (6'6")
• Conditions: Berlin was sunny and warm with very little shade.

The Mistake (Aggressive Fueling) I went into the race with a "more is better" mindset for carbs. I had trained my gut to handle ~120g of carbs per hour. In training (which was mostly cooler mornings), this worked great. I felt invincible.

The Reality Check On race day, the sun was brutal. Being 6'6", I have a massive surface area to cool. Around the 30km mark, I hit a wall—but not a "low sugar" wall. It was a total system shutdown. My gut stopped emptying, I felt nauseous, and my core temp skyrocketed.

My Theory: Digestion requires blood flow. Cooling requires blood flow (to the skin). Running Sub-3 pace requires blood flow. I was asking my body to do too much. Because of my height/heat disadvantage, my body prioritized cooling over digestion, and that 120g/hr of sugar just sat in my stomach like a brick until I overheated.

What I’m Changing for the Next Block

1. Respecting the Heat: I’m learning that my carb ceiling is lower when the temperature is higher. I likely need to drop to 80-90g/hr if it's sunny, just to spare blood flow.
2. Daily Nutrition > Race Day Nutrition: I used to just "eat healthy" and guess. Now, I’m treating my daily nutrition as seriously as my running. I actually stopped using generic tracking apps (which kept telling me I was overeating on long run days) and started looking for tools specifically designed for endurance athletes to track "high flux" days properly. Getting my daily recovery dialed in has made a bigger difference than any gel strategy.

Question for the sub: For the bigger runners here (185cm+), do you have a specific "heat adjustment" protocol? Do you intentionally throttle your pace or your fuel first when the sun comes out?