1. Carbohydrate Ingestion
1.1 Role of Carbohydrates
- Primary fuel source for moderate to high-intensity exercise.
- Stored as glycogen in muscles and liver.
- Glycemic Index (GI): A ranking of carbohydrates based on their immediate effect on blood glucose levels.
- High GI foods: Rapidly digested and absorbed, causing a quick rise in blood glucose. (e.g., white bread, sports drinks)
- Low GI foods: Slowly digested and absorbed, providing a sustained release of glucose. (e.g., whole grains, legumes)
1.2 Carbohydrate Loading
- A strategy to maximize glycogen stores before endurance events lasting longer than 90 minutes.
- Involves:
- Depletion Phase (optional): A few days of reduced carbohydrate intake combined with intense exercise to deplete glycogen stores.
- Loading Phase: 3-4 days of high carbohydrate intake (8-12g/kg of body weight per day) combined with tapering (reduced training volume).
- Benefits:
- Increased glycogen stores, delaying fatigue.
- Improved endurance performance.
- Considerations:
- May cause weight gain due to water retention (glycogen binds with water).
- Not necessary for all athletes (e.g., sprinters).
- Should be accompanied by tapering to maximize glycogen storage.
1.3 Carbohydrate Intake During Exercise
- Consuming carbohydrates during prolonged exercise helps maintain blood glucose levels and spares muscle glycogen.
- Recommended intake: 30-60g of carbohydrates per hour for endurance events.
- Sources: Sports drinks, gels, and easily digestible foods.
1.4 Carbohydrate Intake Post-Exercise
- Replenishing glycogen stores is crucial for recovery.
- Consume carbohydrates within 30-60 minutes post-exercise (the “glycogen window”) for optimal glycogen synthesis.
- Recommended intake: 1-1.2g of carbohydrates per kg of body weight per hour for the first 4 hours.
- High GI foods are preferred for rapid glycogen replenishment.
KEY TAKEAWAY: Carbohydrates are vital for energy production, and strategic carbohydrate intake before, during, and after exercise can significantly enhance performance and recovery.
2. Protein Intake
2.1 Role of Protein
- Essential for muscle repair and growth.
- Contributes to energy production during prolonged endurance exercise (to a lesser extent than carbohydrates and fats).
- Important for satiety (feeling full).
2.2 Protein Intake for Athletes
- Athletes require more protein than sedentary individuals.
- Recommended intake: 1.2-1.7g of protein per kg of body weight per day, depending on the intensity and duration of training.
- Endurance athletes may need slightly less protein than strength athletes.
2.3 Protein Intake Post-Exercise
- Consuming protein after exercise helps stimulate muscle protein synthesis (muscle repair and growth).
- Recommended intake: 20-25g of high-quality protein within 1-2 hours post-exercise.
- Combining protein with carbohydrates post-exercise can further enhance glycogen replenishment and muscle recovery.
2.4 Sources of Protein
- Animal sources: Meat, poultry, fish, eggs, dairy products.
- Plant sources: Legumes, nuts, seeds, tofu, tempeh.
- Whey protein: A fast-digesting protein supplement often used post-exercise.
EXAM TIP: Be prepared to discuss the specific protein needs of different types of athletes (e.g., endurance vs. strength).
3. Hydration
3.1 Role of Water
- Essential for numerous bodily functions, including:
- Regulating body temperature.
- Transporting nutrients and oxygen to cells.
- Removing waste products.
- Lubricating joints.
- Dehydration can significantly impair performance, leading to:
- Decreased blood volume.
- Increased heart rate.
- Reduced sweat rate.
- Impaired cognitive function.
- Increased risk of heatstroke.
3.3 Hydration Strategies
- Pre-exercise:
- Consume 500-600ml of water or sports drink 2-3 hours before exercise.
- Consume 200-300ml of water or sports drink 10-15 minutes before exercise.
- During exercise:
- Drink regularly to replace fluid lost through sweat.
- Aim to drink 150-300ml every 15-20 minutes, depending on sweat rate and environmental conditions.
- Sports drinks can provide electrolytes and carbohydrates for prolonged exercise.
- Post-exercise:
- Rehydrate to replace fluid losses.
- Consume 1.5L of fluid for every 1kg of body weight lost during exercise.
- Electrolyte-rich drinks can help restore electrolyte balance.
3.4 Types of Fluids
- Water: Suitable for short-duration, low-intensity exercise.
- Sports drinks: Contain electrolytes (sodium, potassium) and carbohydrates, beneficial for prolonged, high-intensity exercise.
- Electrolyte tablets/powders: Can be added to water to replenish electrolytes.
3.5 Monitoring Hydration Status
- Thirst: Not a reliable indicator of hydration status.
- Urine color: Light yellow indicates adequate hydration; dark yellow indicates dehydration.
- Body weight: Weigh yourself before and after exercise to estimate fluid loss.
COMMON MISTAKE: Relying solely on thirst to guide hydration. Athletes should proactively drink fluids before, during, and after exercise.
4. Nutritional Strategies Summary Table
| Strategy |
Timing |
Purpose |
Examples |
| Carb Loading |
3-4 days before endurance events |
Maximize glycogen stores, delay fatigue |
Pasta, rice, bread, potatoes |
| Carb Intake (During) |
During prolonged exercise (>90 mins) |
Maintain blood glucose levels, spare muscle glycogen |
Sports drinks, gels, bananas |
| Carb Intake (Post) |
Within 30-60 mins post-exercise |
Replenish glycogen stores, promote recovery |
Sports drinks, fruit, sandwiches |
| Protein Intake (Post) |
Within 1-2 hours post-exercise |
Stimulate muscle protein synthesis, repair muscle damage |
Whey protein shake, chicken breast, Greek yogurt |
| Hydration (Pre) |
2-3 hours & 10-15 mins before exercise |
Ensure adequate hydration before exercise |
Water, sports drink |
| Hydration (During) |
Every 15-20 mins during exercise |
Replace fluid lost through sweat, maintain hydration |
Water, sports drink |
| Hydration (Post) |
Immediately after exercise |
Rehydrate, replace fluid and electrolyte losses |
Water, sports drink, electrolyte-rich drinks |
STUDY HINT: Create flashcards with the different nutritional and hydration strategies on one side and their timing, purpose, and examples on the other.
5. Factors Affecting Nutritional and Hydration Needs
- Exercise intensity and duration: Higher intensity and longer duration require more carbohydrates and fluids.
- Environmental conditions: Hot and humid conditions increase sweat rate and fluid loss.
- Individual sweat rate: Athletes sweat at different rates, affecting their fluid replacement needs.
- Body size: Larger individuals require more carbohydrates, protein, and fluids.
- Training status: Trained athletes may have different nutritional needs than untrained individuals.
APPLICATION: Consider how a marathon runner’s nutritional and hydration needs differ from a weightlifter’s.
- While not directly part of the key knowledge, it’s important to differentiate between nutritional strategies and ergogenic aids.
- Ergogenic aids are substances or practices that enhance athletic performance.
- Some nutritional strategies can be considered ergogenic aids (e.g., carbohydrate loading, creatine supplementation).
- However, not all ergogenic aids are nutritional (e.g., caffeine, blood doping). Important to be aware of WADA regulations.
VCAA FOCUS: VCAA often presents scenarios where students must apply their knowledge of nutritional and hydration strategies to optimize performance or recovery for a specific athlete or activity.
