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Published on: May 16, 2021
Carbohydrate does not augment exercise-induced protein accretion versus protein alone.
Aaron W Staples1, Nicholas A Burd, Daniel W D West
1Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.
Consuming carbohydrates with protein does not enhance muscle protein synthesis or reduce muscle protein breakdown more than protein alone. This finding applies both at rest and after resistance exercise, suggesting no additive benefits from carbohydrate coingestion.
Area of Science:
- Exercise Physiology
- Nutritional Biochemistry
- Muscle Metabolism
Background:
- Muscle protein synthesis (MPS) and muscle protein breakdown (MPB) are key determinants of muscle mass.
- Coingestion of carbohydrates (CHO) with protein is often recommended post-exercise, but its additive effects on muscle protein kinetics are debated.
Purpose of the Study:
- To investigate if coingesting carbohydrates with protein augments MPS and inhibits MPB at rest and after resistance exercise.
- To determine the role of insulin in mediating the effects of CHO and protein on muscle protein metabolism.
Main Methods:
- Nine healthy men underwent unilateral knee extension resistance exercise.
- Muscle biopsies and stable isotope tracers were used to quantify MPS and MPB.
- Participants consumed either whey protein (PRO) or whey protein plus maltodextrin (PRO+CARB) post-exercise.
Main Results:
- Exercise increased both MPS and MPB, but no significant differences were observed between PRO and PRO+CARB conditions.
- Insulin and glucose responses were significantly higher with PRO+CARB compared to PRO.
- While Akt phosphorylation increased with PRO+CARB, it did not lead to greater MPS or reduced MPB compared to PRO alone.
Conclusions:
- Coingestion of carbohydrates with a maximally effective dose of protein does not further stimulate MPS or inhibit MPB.
- Insulin elevation from carbohydrate coingestion does not appear to be additive or synergistic to the effects of protein on muscle protein kinetics.
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