Carbohydrate Intake of 100 vs. 60 g·h⁻¹ During Prolonged Cycling Improves Durability Without Altering Muscle Glycogen Utilization in Male Endurance Athletes
Study Details
This randomised crossover study examined whether 60 vs 100 g/h carbohydrate influenced durability, substrate oxidation and muscle glycogen use during prolonged cycling in 15 trained male cyclists and triathletes 🔍
Participants completed 4 h of intermittent cycling at ~60% of their fresh 15-min time-trial power, including high-intensity intervals 🚴
Carbohydrate was provided as a 1:0.8 glucose-to-fructose mix at either 60 or 100 g/h 🥤
Key Findings
📉 Performance declined after 4 h in both conditions, but the reduction was significantly smaller with 100 g/h
⚡ 15-min TT mean power fell by ~6.4% with 100 g/h versus ~9.3% with 60 g/h
📈 Accordingly, late-exercise mean power was ~9 W higher with 100 g/h
🧬 Interestingly, muscle glycogen utilisation was virtually identical between conditions
↔️ Post-exercise muscle glycogen availability was also similar: 192 vs 209 mmol/kg dry weight
🔥 Whole-body carbohydrate oxidation was better maintained with 100 g/h, falling from 2.6 → 2.3 g/min, versus 2.6 → 1.9 g/min with 60 g/h
🩸 Blood glucose remained stable in both conditions, suggesting the performance difference was not explained by greater preservation of circulating glucose
💡 This means the durability benefit from higher carbohydrate intake did not appear to come from sparing muscle glycogen
⚠️ The study included only trained men, so findings should not automatically be generalised to female athletes or all endurance populations
Conclusion
For long endurance events, increasing carbohydrate intake from 60 to 100 g/h may help preserve late-race power and durability even when muscle glycogen utilisation is unchanged, supporting higher intakes when athletes can tolerate and practically execute them ✅
Reference
https://pubmed.ncbi.nlm.nih.gov/42841583/
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