Effects of 10, 90, 120 and 150 G.H -1 CHO on Substrate Metabolism, Exogenous Oxidation and Exercise Capacity: Implications for CHO Personalization
Study Details
This randomised crossover study examined how 10, 90, 120 and 150 g/h carbohydrate affected substrate metabolism, exogenous carbohydrate oxidation and exercise capacity in 8 trained male cyclists 🔍
Participants cycled for 3 h, followed by an exercise-capacity test at 150% of lactate threshold 🚴
The 90, 120 and 150 g/h conditions used a 1:0.8 glucose-to-fructose ratio 🥤
Key Findings
📈 Exogenous carbohydrate oxidation increased dose-dependently, reaching 1.23, 1.48 and 1.62 g/min with 90, 120 and 150 g/h respectively
🔥 However, whole-body carbohydrate oxidation did not differ between 120 and 150 g/h
⬆️ Both 120 and 150 g/h produced greater whole-body carbohydrate oxidation than 90 and 10 g/h
🩸 Blood glucose was significantly lower with 10 g/h than with 90, 120 or 150 g/h
⏱️ Total exercise duration was significantly shorter with 10 g/h than with both 90 and 120 g/h
↔️ There were no significant performance differences between 90, 120 and 150 g/h
📊 Modelling suggested optimal exercise capacity occurred at approximately 107 g/h, with a 95% CI of 92–122 g/h
⬆️ Increasing intake from 120 → 150 g/h therefore increased exogenous carbohydrate oxidation, but did not further increase whole-body carbohydrate oxidation or exercise capacity
🧩 Importantly, individual responses varied substantially, with the authors highlighting the potential value of personalising carbohydrate intake rather than assuming more is always better
⚠️ This was a very small study involving only 8 trained men, so the exact “optimal” intake should not be treated as a universal prescription
Conclusion
For prolonged endurance exercise, carbohydrate intakes around 90–120 g/h appear to support substantially greater performance than very low intake, while pushing intake to 150 g/h may increase exogenous oxidation without providing additional performance benefit; tolerance and individual response should therefore help determine the athlete’s target ✅
Reference
https://www.ovid.com/jnls/acsm-msse/abstract/10.1249/mss.0000000000004176
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