CSSD Macronutrient Timing 2 — Questions and Answers
Question 1: During a 90-minute endurance run, at approximately what point does exogenous carbohydrate intake become necessary to maintain performance?
- After 30 minutes
- After 45 minutes
- After 60 minutes (Correct answer)
- After 75 minutes
Correct 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.
Question 2: Which carbohydrate source has the fastest gastric emptying rate during exercise and is therefore preferred for rapid energy delivery?
- Fructose alone
- Glucose alone
- Glucose-fructose blend (2:1 ratio) (Correct answer)
- Maltodextrin alone
Correct 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.
Question 3: A strength athlete consumes 40g of protein post-workout. How does this compare to the evidence-based recommendation for maximizing muscle protein synthesis?
- Too low; at least 60g is needed
- At the upper range; 20–40g is optimal for most athletes (Correct answer)
- Excessive; more than 30g is not utilized
- Insufficient; 50g is the minimum effective dose
Correct 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.
Question 4: Which scenario best illustrates the concept of 'second meal effect' in carbohydrate timing?
- Eating a large lunch improves dinner digestion
- A low-GI breakfast improves glycemic response to a subsequent meal (Correct answer)
- Protein at dinner enhances carbohydrate absorption the next morning
- Post-workout carbs prime glycogen for the next day's training
Correct 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.
Question 5: For an athlete training twice per day, what is the minimum recommended protein intake per meal to stimulate muscle protein synthesis at each session?
- 10 g
- 20 g (Correct answer)
- 30 g
- 40 g
Correct answer: 20 g
Approximately 20g of high-quality protein is the minimal dose shown to maximally stimulate muscle protein synthesis in young adult athletes.
Question 6: An ultra-endurance athlete completing a 5-hour event should target what carbohydrate intake rate per hour to maximize oxidation without gastrointestinal distress?
- 30–45 g/hr
- 60–90 g/hr (Correct answer)
- 100–120 g/hr
- 120–150 g/hr
Correct 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.
Question 7: Which meal composition strategy best supports liver glycogen resynthesis overnight for a morning training session?
- High-protein, low-carb evening meal
- Casein protein shake only before bed
- Moderate-to-high carbohydrate evening meal with adequate protein (Correct answer)
- Fat-dominant meal to spare glycogen
Correct 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.
CSSD Macronutrient Timing 2
During a 90-minute endurance run, at approximately what point does exogenous carbohydrate intake become necessary to maintain performance?