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Co-ingesting whey protein with dual-source carbohydrate enhances amino acid availability without compromising
Sophie C Hannon1, James McStravick1, Libby Henthorn1
1Institute of Sport, Department of Sports & Exercise Science, Manchester Metropolitan University, Manchester, UK.
The Journal of Physiology
|July 9, 2025
Summary
Co-ingesting whey protein with a maltodextrin and fructose blend enhances amino acid availability without hindering liver glycogen resynthesis post-exercise. This dual-source carbohydrate strategy supports muscle remodelling and rapid glycogen replenishment for endurance athletes.
Area of Science:
- Exercise Physiology
- Nutritional Biochemistry
- Sports Science
Background:
- Endurance athletes often combine carbohydrates and protein post-exercise to optimize recovery.
- Understanding the impact of different carbohydrate sources and protein co-ingestion on glycogen resynthesis is crucial for performance.
- Whey protein is a common supplement for muscle repair and recovery.
Purpose of the Study:
- To investigate the effects of ingesting maltodextrin and/or fructose, with or without whey protein, on post-exercise liver and muscle glycogen resynthesis.
- To compare the efficacy of different carbohydrate formulations (maltodextrin, fructose, maltodextrin+fructose blend) combined with whey protein on recovery markers.
- To assess hormonal responses (insulin, glucagon) and substrate availability during recovery.
Main Methods:
- Ten well-trained male cyclists completed glycogen-depleting exercise.
- Participants ingested 60 g/h carbohydrate from maltodextrin (MAL), fructose (FRU), a 1:1 maltodextrin+fructose blend (MF), or MF plus 30 g whey protein (PRO) over 5 hours.
- Liver and muscle glycogen concentrations were measured using 13C magnetic resonance spectroscopy and imaging.
Main Results:
- Liver glycogen concentrations were significantly higher after 5 hours with FRU, MF, and PRO compared to MAL.
- Muscle glycogen concentrations did not differ significantly between any of the trials.
- Protein co-ingestion (PRO) resulted in elevated serum insulin and plasma glucagon compared to FRU and MF.
Conclusions:
- Co-ingesting whey protein with a 1:1 maltodextrin and fructose blend does not impair post-exercise liver glycogen resynthesis.
- This strategy enhances amino acid availability, providing substrates for muscle remodelling alongside effective glycogen replenishment.
- Dual-source carbohydrate (maltodextrin+fructose) with whey protein is a practical approach for athletes seeking to optimize recovery.
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