Nutrition & Exercise Physiology

Nutrition Basics

Nutrition provides the substrate for every physiological process that supports physical activity. Macronutrientscarbohydrates, proteins, and fatsare the primary energy sources, while micronutrients (vitamins and minerals) play essential roles in metabolic pathways, immune function, and tissue repair.

Carbohydrates

Carbohydrates are the bodys preferred fuel for highintensity exercise. Glycogen stored in muscles and the liver can sustain activity for 6090 minutes before depletion. Choosing complex carbs (whole grains, legumes, fruits) ensures a steady release of glucose and preserves glycogen stores.

Proteins

Protein supplies amino acids necessary for muscle protein synthesis (MPS) and recovery. Current research recommends 1.22.0gkgday for active individuals, with higher intakes (up to 2.2gkg) for strengthfocused training.

Fats

Fats become the dominant fuel during prolonged, lowtomoderate intensity work. Emphasize unsaturated fatty acids (olive oil, nuts, fatty fish) to support hormone production and reduce inflammation.

Micronutrients

• Iron: Essential for oxygen transport; deficiency impairs endurance.
• Calcium & Vitamin D: Critical for bone health and muscle contraction.
• Antioxidants (vitamins C & E, selenium): Help mitigate oxidative stress from intense training.

Exercise Physiology Fundamentals

Exercise physiology examines how the body responds and adapts to physical stress. Central concepts include energy systems, muscle fiber types, and cardiovascular adaptations.

Energy Systems

• Phosphagen (ATPCP) System: Supplies immediate energy for the first 10 seconds of maximal effort (e.g., sprint, heavy lift).
• Glycolytic System: Breaks down glucose without oxygen, supporting efforts lasting 30 seconds to 2 minutes (e.g., 400m run).
• Oxidative System: Relies on aerobic metabolism, providing sustained energy for activities longer than 2 minutes.

Muscle Fiber Types

TypeI fibers are slowtwitch, fatigueresistant, and optimized for aerobic work. TypeIIa fibers are fasttwitch but retain some oxidative capacity. TypeIIx (or IIb) fibers are purely glycolytic, generating rapid, powerful contractions but tiring quickly.

Cardiovascular Adaptations

Regular aerobic training enlarges stroke volume, lowers resting heart rate, and improves capillary density. Resistance training increases arterial pressure during lifts but can also enhance endothelial function over time.

Integrating Nutrition with Exercise

The greatest performance gains arise when nutrition is timed to complement training demands.

PreExercise Nutrition

Consume a carbohydraterich meal 23hours before training (14gkg). Include a moderate amount of protein (0.2gkg) to prime MPS. Keep fat and fiber low to avoid gastrointestinal distress.

During Exercise

For sessions longer than 60minutes, ingest 3060g of carbohydrate per hour (e.g., sports drinks, gels). In ultraendurance events, adding 510gprotein/h can aid muscle preservation.

PostExercise Recovery

The anabolic window extends up to 2hours after exercise. Aim for a 3:1 or 4:1 carbohydratetoprotein ratio (0.50.7gproteinkg and 11.2gcarbohydratekg). This mixture maximizes glycogen resynthesis and MPS.

Hydration

Maintain fluid balance by drinking 510mLkg of water 2hours preactivity, then 150250mL every 1520minutes during exercise. Replace electrolytes (sodium, potassium) especially in hot environments.

Practical Tips for Everyday Life

• Plan meals around training. Use a weekly calendar to align highcarb days with intense sessions.
• Prioritize whole foods. Whole grains, lean meats, legumes, fruits, and vegetables supply nutrients more efficiently than processed alternatives.
• Snack smart. Pair a piece of fruit with Greek yogurt or a handful of nuts for balanced pre or postworkout snacks.
• Monitor iron status. Women and endurance athletes should check ferritin levels annually.
• Adjust for goals. Endurance athletes may need 610gcarbkgday, while strength athletes often thrive on 35gcarbkgday with higher protein.
• Sleep and stress. Recovery is as much about rest as nutrition; aim for 79hours of sleep and incorporate relaxation techniques.

Sample Day for a Recreational Runner (70kg)

1. 07:00 Breakfast: Oatmeal (80g) with banana, whey protein (20g), and a drizzle of honey. (~70g carbs, 25g protein)
2. 10:00 Snack: Apple + 15g almonds.
3. 12:30 Lunch: Grilled chicken breast, quinoa (100g cooked), mixed vegetables, olive oil dressing.
4. 15:30 Prerun snack: 30g rice cakes with almond butter.
5. 16:00 Run (60min, moderate): Water + 500mL sports drink.
6. 17:30 Recovery shake: 250mL lowfat milk + 1 scoop whey (30g carbs, 25g protein).
7. 19:00 Dinner: Baked salmon, sweet potato (150g), steamed broccoli, side salad.
8. 21:00 Light snack: Cottage cheese (150g) with berries.

This plan supplies ~260g carbohydrate (3.7gkg), 130g protein (1.9gkg), and ample micronutrients for recovery and performance.