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1. ; Energy balance, fluid balance, fuelling cycle: Pre-exercise, during
exercise and during recovery;
Sports Nutrition

2. Energy Intake and Exercise
• Energy needs
• Fuel for training
• Maintain healthy weight
• Support growth (if adolescent)
• May require frequent meals and snacks

3. Carbohydrates are essential for fueling exercise, with muscle and liver glycogen stores playing a
crucial role in endurance and performance. High glycogen levels enable optimal training intensity,
while low levels lead to early fatigue and reduced performance. Research confirms that a high-
carbohydrate diet significantly increases glycogen stores, enhancing endurance.
A key study by Bergstrom et al. (1967) found that athletes on a high-carbohydrate diet stored twice
as much glycogen as those on a moderate-carb diet and seven times more than those on a low-carb
diet. When tested for endurance, high-carb athletes cycled for 170 minutes at 75% of VO2max,
compared to 115 minutes for the moderate-carb group and only 60 minutes for the low-carb group.
Sports nutritionists and exercise physiologists recommend a diet high in carbohydrates and low in fat
for athletes, as it enhances endurance and improves performance in activities lasting longer than an
hour. Since glycogen stores are limited, depletion can lead to fatigue and reduced performance.
Maintaining high pre-exercise glycogen stores is essential for improving endurance, delaying
exhaustion, and sustaining higher training intensity (Coyle, 1988; Costill & Hargreaves, 1992).
Previously, a diet with 60–70% of energy from carbohydrates was recommended (Williams &
Devlin, 1992). However, this method does not account for individual energy needs. For athletes
consuming 4000–5000 calories daily, 60% carbohydrate intake may exceed glycogen storage
capacity, while for those consuming 2000 calories daily, it may not be sufficient to maintain
glycogen stores (Coyle, 1995).

4. Energy Balance
1. Energy Balance
Energy balance refers to the relationship between energy intake (calories consumed through food and
drinks) and energy expenditure (calories burned through metabolism and physical activity). Maintaining a
proper energy balance is crucial for athletic performance, recovery, and overall health.
Components of Energy Balance
1.Energy Intake
1. Comes from carbohydrates, proteins, fats, and alcohol.
2. Measured in kilocalories (kcal) or joules (J).
2.Energy Expenditure
1. Basal Metabolic Rate (BMR): The energy required for essential bodily functions at rest (e.g.,
breathing, circulation).
2. Thermic Effect of Food (TEF): Energy used for digestion, absorption, and metabolism of nutrients.
3. Physical Activity Energy Expenditure (PAEE): Energy burned through exercise and daily activities.
Types of Energy Balance
•Positive Energy Balance: Energy intake > energy expenditure → leads to weight gain (beneficial for muscle
building but harmful if excessive).
•Negative Energy Balance: Energy intake < energy expenditure → leads to weight loss (can reduce muscle
mass and performance if prolonged).
•Neutral Energy Balance: Energy intake = energy expenditure → maintains body weight and supports
steady performance.

5. Fluid Balance
Fluid balance is the regulation of water intake and loss to maintain hydration, electrolyte balance,
and optimal physiological function.
Importance of Fluid Balance
•Regulates body temperature through sweating.
•Transports nutrients and oxygen to muscles.
•Removes metabolic waste from the body.
•Prevents dehydration and associated performance decline.
Factors Affecting Fluid Loss
•Exercise intensity and duration: More intense/longer workouts cause more sweating.
•Environmental conditions: Hot and humid weather increases fluid loss.
•Individual sweat rate: Some people sweat more than others.
Hydration Guidelines
•Pre-exercise: 400–600 mL of water 2 hours before activity.
•During exercise: 150–250 mL every 15–20 minutes.
•Post-exercise: 1.5 times the fluid lost (measured via body weight difference before and after
exercise).

6. Pre-Exercise Nutrition:
 Impact on Performance: What, when, and how much you eat before exercise affects
your endurance, strength, and overall performance.
 Carbohydrate Intake Before Exercise: Consuming carbohydrates before exercise
increases glycogen burning but also delays fatigue and improves performance.
 Morning Workouts & Fat Loss: Exercising on an empty stomach may promote fat
burning due to low insulin and high glucagon levels, but it can also lead to early fatigue.
 Timing of Pre-Exercise Meal: The best time to eat is 2–4 hours before exercise. Studies
show that eating a high-carb, low-fat meal 3 hours before training improves endurance.
 Risk of Hypoglycemia: Delaying meals too long before exercise may result in low blood
glucose, leading to early fatigue and reduced performance.
 Recommended Carbohydrate Intake: Around 2.5 g/kg of body weight (e.g., 175g
carbs for a 70 kg person) about 3 hours before exercise boosts endurance by 9%.
 Best Pre-Exercise Foods: Low Glycemic Index (GI) foods like lentils, fresh fruits, milk,
or yogurt provide sustained energy. Combination meals with carbs, protein, and healthy
fats (e.g., cereal with milk, chicken sandwich) are also effective.
 High vs. Low GI Foods: Studies suggest that low GI meals before exercise improve
endurance compared to high GI foods like glucose drinks or baked potatoes.

7. Nutrition During Exercise:
 Water for Short Workouts (< 1 Hour): If exercising for less than an hour, water is
sufficient as long as muscle glycogen levels are high from prior carbohydrate intake.
 Carbohydrate for Longer Workouts (> 60 Minutes): If exercising for more than an
hour at moderate to high intensity (>70% VO max), consuming carbohydrates during the
₂
session helps delay fatigue and maintain performance.
 Muscle Glycogen Depletion:
o During the first hour, muscle glycogen is the primary energy source.
o After an hour, glycogen levels drop, and muscles rely more on blood glucose.
o After 2–3 hours, blood glucose and fat become the main energy sources.
o Eventually, blood glucose decreases, leading to fatigue, light-headedness, and
reduced exercise intensity ("hitting the wall").
 Carbohydrate Intake Recommendation: 30–60 g of carbohydrate per hour is ideal
during prolonged exercise.
 Timing of Carbohydrate Intake: Start consuming carbohydrates within the first 30
minutes of exercise, as it takes at least 30 minutes for absorption.
 Food & Drink Choices:
o High or Moderate Glycemic Index (GI) foods are best for quick energy.
o Liquid vs. Solid Carbohydrates: Both are effective, but sports drinks are more
convenient as they provide both fuel and hydration.
If consuming solid carbohydrates, drink water alongside them to aid digestion

8.  Homemade Sports Drinks: You don’t need commercial sports drinks—homemade versions
using fruit juice, sugar, squash, and water are effective alternatives.
 Solid vs. Liquid Carbohydrates:
 Solid carbohydrate options: Energy bars, sports gels, ripe bananas, raisins, and fruit bars.
 Always drink water alongside solid carbohydrates for proper digestion.
 Hydration: Aim to consume at least 1 liter of fluid per hour during prolonged exercise.
 Protein + Carbohydrate Intake:
 Studies suggest that consuming a carbohydrate-protein drink during exercise improves
endurance more than carbohydrates alone.
It may also reduce muscle breakdown and enhance recovery post-exercise
Nutrition During Exercise conti..

9. Post-Exercise Recovery:
Factors Affecting Refueling Time:
1. Glycogen Depletion – The more glycogen used during exercise, the longer replenishment takes.
2. Muscle Damage – Eccentric exercises (e.g., heavy lifting, plyometrics, intense running) delay glycogen
storage.
3. Carbohydrate Intake – Higher carbohydrate consumption speeds up glycogen replenishment.
4. Training Experience & Fitness Level – Well-trained individuals may recover faster due to adaptation.
Glycogen Replenishment Timeline:
 Minimum: 20 hours (Coyle, 1991).
 Prolonged/Exhaustive Exercise (e.g., marathon): Up to 7 days.
 Muscle Damage from Eccentric Workouts: Full replenishment may take 7–10 days.
Impact of Workout Type:
 High-intensity aerobic or explosive activities (e.g., sprinting, jumping, weightlifting) deplete glycogen
faster.
 Longer duration workouts require more recovery time.
Role of Carbohydrate Intake:
 Low-carb diets (250–350g/day) result in incomplete glycogen replenishment over multiple training days
(Costill et al., 1971).
 High-carb diets (550–600g/day) allow full glycogen recovery and better performance in subsequent
workouts.

10. Sports Drinks & Hydration
 Ideal sports drink composition:
o 40-80g CHO per liter.
o 400-1200 mg sodium per liter.
o Moderate hypotonic to isotonic osmolality.
 Hydration Guidelines:
o Monitor sweat loss by checking body weight pre- and post-exercise.
o Drink fluids regularly, but consuming more than 2L/hour may cause
gastrointestinal discomfort.
o Taste & palatability are crucial for promoting fluid intake.

11. Fluid Balance Restoration
1. The rate of fluid balance recovery depends on:
o Quantity of fluid consumed.
o Composition of the fluid, especially CHO-sodium content.
2. Hydration Considerations
o Low sodium beverages (e.g., plain water, fruit juices) retain only 50% of consumed fluid.
o CHO-electrolyte solutions (40-80 g CHO and 600-1200 mg sodium per liter) improve fluid retention to 70-80%.
o Post-exercise fluid intake should be 150-200% of water lost through sweat.
Practical Considerations
3. Appetite is often suppressed post-exercise; hence, beverages with high GI CHO sources (6 g/100 ml) should be available.
4. Easily digestible CHO-rich solid foods (e.g., ripe bananas, rice cakes) can be consumed.
5. To ensure adequate glycogen replenishment:
o 10 g CHO/kg body weight from moderate to high GI foods should be consumed within 24 hours.
o Low-fat foods help in maintaining proper CHO intake.
6. Pre-sleep CHO intake should provide sufficient CHO (e.g., 250 g for a 10-hour fasting period).

12. Essentials of Drinking During Sports
Timing of Fluid Intake
To maintain optimal sports performance, it is essential to prevent dehydration caused by:
1. Large sweat losses.
2. Carbohydrate depletion due to the breakdown of stored carbohydrates for energy.
Dehydration can be prevented by ingesting fluids in amounts that approximate the weight lost during
exercise. Carbohydrate depletion can be delayed by consuming carbohydrate sources that provide
energy to muscles, reducing the need to break down local carbohydrate stores. This combination
delays fatigue and improves performance.
Athletes should drink carbohydrate-containing fluids in situations where sweat loss or carbohydrate
breakdown is significant and performance-limiting. This is typically required in:
 High-intensity exercise lasting more than 45 minutes.
 Events where carbohydrate stores alone may not sustain performance.
 Endurance sports lasting longer than 90 minutes, where glycogen depletion becomes a concern.

13. What is the Optimal Composition of a Sports Drink?
A good sports drink should efficiently supply fluid and carbohydrates to the body, ensuring:
 Rapid gastric emptying from the stomach.
 Efficient absorption in the gut.
Key Factors Influencing Sports Drink Composition
1. Carbohydrate/Energy Content: Drinks should contain 40-80 g of carbohydrates per liter.
2. Mineral Content & Sodium Addition: Adding 600-1200 mg of sodium improves fluid retention and
rehydration.
3. Osmolarity: The concentration of dissolved particles affects absorption rates.
o Isotonic: Matches body fluid osmolarity (~300 mosmol/kg).
o Hypotonic: Lower osmolarity, absorbed faster.
o Hypertonic: Higher osmolarity, delays fluid absorption and may cause gastrointestinal issues.

14. Best Practices for Hydration
 Endurance events: Ingest drinks with 40-80 g carbohydrates per liter to sustain
energy levels.
 Cool conditions: If dehydration is not a major concern, consume more
concentrated carbohydrate drinks (130-150 g/L) to optimize energy intake.
 Temperature preferences: Athletes should experiment in training to determine
their ideal drink temperature. Cool drinks (~5-10°C) may be preferable in hot
conditions, while warm drinks can be beneficial in cold climates.
Do Women Need More Fluid Than Men?
 No, women generally lose less sweat due to more efficient sweating mechanisms.
 Women should still monitor fluid loss and rehydrate accordingly, ensuring weight
loss does not exceed 1 kg after exercise.

15. Protein and Exercise
• Protein recommendations
• Adults: 0.8 grams per kg body weight
• Endurance athletes: 1.2–1.4 g/kg
• Resistance-trained athletes: 1.6–1.7 g/kg
• Protein sources
• Foods: lean meats, fish, low-fat dairy, and egg whites
• Protein intake after exercise
• Helps replenish glycogen
• Dangers of high-protein intake

16. Fluid Needs During Exercise
• Exercise and fluid
loss
• Increased losses
from sweat
• Increased with
heat, humidity
• Risk for
dehydration
© PhotoDisc

17. Fluid Needs During Exercise
• Hydration
• Adequate fluids before,
during, after exercise
• Water vs. sports drinks
• Duration
• Intensity
• Environmental factors

18. Nutrition Needs of Youth in Sports
• Priority on growth and development
• Meals/snacks both before
and after exercise
• Caution: High tolerance
for exercise in heat
© Glen Jones/ShutterStock, Inc.

19. Daily Caloric Intake
• Every male athlete should ingest at least 23 calories per pound every
day, and every female athlete needs at least 20 calories per pound.
• So, a 200 lb male needs at least 4,600 calories/day, and a 120 lb
female needs at least 2,400 calories/day.
• Now, the trick is to learn how to spread those calories out during the
day

20.  Between events?
• <1 hour: drink at least 8 ounces of
fluid and have high carbohydrate snack .
Examples: water, sports drink, bagels,
graham crackers, fig bars, saltines, grapes,
berries, apple slices, bananas, fruit juice
• >1 hour: drink at least 12 ounces of
fluid and have carbohydrate/protein
snack. Examples: ½ peanut butter & jelly
sandwich, bagel with cheese, pb &
crackers, trail mix, yogurt with cereal, or
sports bar
Several competitions or races in one day

21. Eating for recovery
• Restore fluid & electrolytes (sodium & potassium) lost in sweat
• Replace energy in the muscle, by consuming carbohydrates within 30
minutes of exercise
• Provide protein to aid in repair of damaged muscle tissue and to
stimulate new tissues.
• Eat within 15-60 minutes post workout
• Consume a full meal within 2 hours post exercise
• If you do not have an appetite following performance, chose liquid
foods (smoothies, milk, sports beverages)

22. Protein
• Provides essential amino acids (building blocks) to your body’s cells
• Aids in the development of new tissues for growth and repair
• Helps make important enzymes, hormones and antibodies
• Keeps your body’s cells in fluid balance
• Transports important substances in the blood
• Provides small amounts of energy during exercise

23. • More is not always better!
Many athletes consume too
much protein. Excess protein
can lead to dehydration and
weaken your bones. It may
also cause kidney and liver
damage.
• Protein contributes to less
than 10% of the fuel used
during exercise, unless your
exercise is longer than 2-3
hours or your carbohydrate
stores are inadequate.
Estimated Protein Needs
Maintain
Muscle Mass
Gain Muscle
Mass
Moderate
Workouts
Intense
Workouts
Weight Low end (.5
grams/per
pound)
High end (1.0
grams/per
pound)
120 pounds 60 grams 120 grams
240 pounds 120 grams 240 grams
Protein