Macronutrient Timing Flashcards
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Read the first 7 Macronutrient Timing flashcards as text
During a 90-minute endurance run, at approximately what point does exogenous carbohydrate intake become necessary to maintain performance?
Answer: After 60 minutes
Endogenous glycogen stores typically support about 60 minutes of sustained moderate-to-high intensity exercise, after which exogenous carbohydrate intake is recommended.
Which carbohydrate source has the fastest gastric emptying rate during exercise and is therefore preferred for rapid energy delivery?
Answer: Glucose-fructose blend (2:1 ratio)
A 2:1 glucose-to-fructose blend utilizes multiple intestinal transporters (SGLT1 and GLUT5), maximizing absorption and oxidation rates compared to single-source carbohydrates.
A strength athlete consumes 40g of protein post-workout. How does this compare to the evidence-based recommendation for maximizing muscle protein synthesis?
Answer: At the upper range; 20–40g is optimal for most athletes
Research supports 20–40g of high-quality protein post-exercise to maximize muscle protein synthesis, with larger athletes potentially benefiting from the higher end.
Which scenario best illustrates the concept of 'second meal effect' in carbohydrate timing?
Answer: A low-GI breakfast improves glycemic response to a subsequent meal
The second meal effect refers to how a low-glycemic index first meal reduces the glycemic response to a subsequent meal, partly via altered gut fermentation and insulin dynamics.
For an athlete training twice per day, what is the minimum recommended protein intake per meal to stimulate muscle protein synthesis at each session?
Answer: 20 g
Approximately 20g of high-quality protein is the minimal dose shown to maximally stimulate muscle protein synthesis in young adult athletes.
An ultra-endurance athlete completing a 5-hour event should target what carbohydrate intake rate per hour to maximize oxidation without gastrointestinal distress?
Answer: 60–90 g/hr
Evidence supports 60–90g/hr using a mixed carbohydrate blend (glucose + fructose) for events exceeding 2.5 hours, balancing oxidation capacity and GI tolerance.
Which meal composition strategy best supports liver glycogen resynthesis overnight for a morning training session?
Answer: Moderate-to-high carbohydrate evening meal with adequate protein
Liver glycogen is depleted during the overnight fast, and a carbohydrate-rich evening meal helps restore hepatic stores prior to morning training.