For the fast runners :
Same as what Holly Archer found out recently.
Based on recent research involving elite trail runners, fueling with
120g/hr of carbohydrates (CHO) is considered superior to 60g/hr for a high-intensity, sub-3:15 marathon because it drastically reduces neuromuscular fatigue, improves running economy, and accelerates recovery, provided the gut is properly trained.
PubMed Central (PMC) (.gov) +2
While 60g/hr was the traditional recommendation, 120g/hr (using specific glucose-fructose blends) increases carbohydrate oxidation rates (the amount of fuel actually used by muscles) and lowers metabolic strain.
Science In Sport +1
Here is why 120g/hr is better for high-performance marathon running:
1. Reduced Muscle Damage and Fatigue (Lower TRIMP)
Studies comparing 60g/hr, 90g/hr, and 120g/hr during mountain marathons (approx. 4h–4h45m) found that those consuming 120g/hr had significantly lower markers of Exercise-Induced Muscle Damage (EIMD).
National Institutes of Health (.gov) +1
- Lower Markers: Reduced creatine kinase (CK), lactate dehydrogenase (LDH), and glutamic oxaloacetic transaminase (GOT) 24 hours post-race.
- Lower Internal Load: 120g/hr significantly lowers the internal training impulse (TRIMP)—the perceived effort and physiological stress on the body—compared to 60g/hr.
Freetrail +3
2. Improved Running Economy and Metabolic Efficiency
- Better Efficiency: A 120g/hr intake improves running economy by up to 3% compared to 60g/hr, meaning the body requires less oxygen to maintain the same pace.
- Higher Oxidation Rate: As intake increases to 120g/hr, the body burns more ingested carbohydrates (up to 1.68 g/min) and relies less on fat oxidation, which is less efficient for maintaining high speeds near lactate threshold.
- Sustained Energy: 120g/hr maintains blood glucose levels more effectively and spares muscle glycogen, preventing the severe "bonking" or "hitting the wall" often seen in the last 10km of a sub-3:15 attempt.
PubMed Central (PMC) (.gov) +3
Over three separate 2-hour treadmill runs, we tested: • 60g carbohydrates per hour • 90g carbohydrates per hour • 120g carbohydrates per hour
During each trial we measured: • Heart rate • Blood lactate • Oxygen consumption • Exogenous carbohydrate oxidation (how much of the carbs I consumed I was actually burning)
The results were fascinating. At 120g per hour, I experienced:
✔ Lower perceived effort (RPE)
✔ Better perceived energy levels
✔ Improved fluid retention
✔ Less body mass loss
✔ A delayed shift toward fat oxidation
This matters because carbohydrate produces more energy per litre of oxygen than fat, making it the more efficient fuel at marathon pace.