Macronutrient Timing Flashcards
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Read the first 7 Macronutrient Timing flashcards as text
Which branched-chain amino acid acts as the primary leucine-sensing trigger for mTORC1 activation and subsequent muscle protein synthesis?
Answer: Leucine
Leucine is the key anabolic trigger that activates the mTORC1 signaling pathway, making it the most critical BCAA for initiating muscle protein synthesis.
A cyclist completing a 3-hour race consumes carbohydrate only in the final 30 minutes. What is the primary consequence of this poorly timed intake?
Answer: Suboptimal glycogen sparing in the first two hours
Without early carbohydrate supplementation, muscle glycogen is depleted faster in the first two hours, impairing performance well before the late intake can counteract it.
In the context of pre-exercise nutrition, why is a low-glycemic index meal preferred 3–4 hours before competition compared to a high-GI meal?
Answer: It sustains blood glucose and avoids pre-exercise hyperinsulinemia
A low-GI pre-exercise meal maintains steady blood glucose without an insulin spike that could suppress fat mobilization and cause rebound hypoglycemia at exercise onset.
Which protein source has the highest leucine content per 100g of protein, making it particularly effective for post-exercise MPS?
Answer: Whey protein
Whey protein contains approximately 10–11% leucine by amino acid content, the highest of commonly used protein supplements, supporting rapid and robust MPS activation.
Carbohydrate ingestion immediately post-resistance training primarily benefits which physiological process?
Answer: Blunting cortisol and replenishing muscle glycogen
Post-resistance exercise carbohydrates blunt cortisol-induced catabolism and replenish muscle glycogen, supporting recovery even though glycogen use during resistance training is modest.
An athlete undergoing two-a-day training sessions should prioritize carbohydrate intake within what timeframe after the first session to maximize glycogen resynthesis before the second session?
Answer: Within 15 minutes
Glycogen synthase activity is highest in the first 15–30 minutes post-exercise; consuming carbohydrates immediately (within 15–30 minutes) maximizes resynthesis rates when recovery windows are short.
Which condition most significantly impairs the anabolic response to post-exercise protein intake in an endurance athlete?
Answer: Training in a carbohydrate-depleted state without subsequent carb intake
Severe glycogen depletion without carbohydrate recovery diverts amino acids toward gluconeogenesis rather than MPS, blunting the anabolic response to protein.