Nutrition and Performance
Domain 5: Nutrition and Performance
The exam tests fueling, hydration, body composition, and supplement risk. Questions usually ask you to match intake to training demand and to spot unsafe or unsupported practices.
Core rules
- Carbohydrate needs scale with training: roughly 3–5 g/kg/day for light activity, 5–7 for moderate, 6–10 for heavy endurance, and up to 10–12 g/kg for extreme loads.
- Before exercise, a carbohydrate meal 1–4 h out supports glycogen and blood glucose. During exercise longer than about 60–90 min, 30–60 g carbohydrate/h is common; multiple transportable carbohydrates can approach 90 g/h.
- Protein: 1.2–2.0 g/kg/day for most athletes; 20–40 g per meal with leucine supports muscle protein synthesis. Total daily intake matters more than a narrow “anabolic window.”
- Hydration: losing about 2% body mass can impair performance. Replace with fluids and sodium, especially in heat; avoid overdrinking to prevent hyponatremia.
- Supplements with reasonable evidence include caffeine (3–6 mg/kg), creatine monohydrate (3–5 g/day), beta-alanine, and dietary nitrate. Check banned-substance risk and third-party testing.
Worked example
A 70 kg cyclist faces a 3 h ride. A pre-ride meal provides 1–2 g/kg carbohydrate. During the ride, she targets 60–90 g/h from sports drink and gels, drinks to limit loss to under 2% body mass, and includes sodium. Afterward, she takes 20–40 g protein plus carbohydrate. This plan matches fuel demand; simply taking more protein would not fix glycogen depletion.
Traps
The “30-minute window” is not a hard deadline. More protein does not automatically build more muscle. A supplement labeled “natural” is not guaranteed clean. Overhydration can be dangerous. Also, body-mass loss is not a direct measure of fat loss.