The Foundation: Energy Availability
Before diving into specific nutrients, we need to talk about the most fundamental concept in sports nutrition: energy availability. This is the energy left over for your body's basic functions after accounting for the energy you burn during training.
Energy Availability (EA) = [Energy Intake - Exercise Energy Expenditure] / Fat-Free Mass
🔬 What Research Shows
Studies demonstrate that chronic energy availability below 30 kcal/kg fat-free mass per day leads to:
- Impaired muscle function and training adaptation
- Hormonal disruptions (especially menstrual dysfunction in women)
- Decreased bone density and increased injury risk
- Compromised immune function
- Reduced endurance, strength, and coordination
Optimal EA: At least 45 kcal/kg fat-free mass per day supports health and performance.
Low energy availability isn't always intentional. Many endurance athletes inadvertently under-fuel due to high training volumes, poor planning, or simply not recognizing their increased energy needs. The consequences can be severe and long-lasting.
Carbohydrate: Your Primary Performance Fuel
Despite what various diet trends might claim, carbohydrate remains the most versatile and efficient fuel for high-intensity exercise. Your muscles and brain prefer it, and research consistently shows that maintaining high carbohydrate availability enhances performance.
Training Nutrition vs. Competition Nutrition
Your carbohydrate needs are not static — they should change based on your training phase and goals:
Daily Carbohydrate Targets (per kg body weight)
- Light training (low intensity/skill-based): 3-5 g/kg/day
- Moderate training (~1 hour/day): 5-7 g/kg/day
- High training (1-3 hours moderate-high intensity): 6-10 g/kg/day
- Very high training (4-5 hours/day): 8-12 g/kg/day
For a 70 kg athlete doing moderate training, that's 350-490 grams of carbohydrate per day. That's roughly 10-12 servings of rice, pasta, or bread spread throughout the day.
Competition Carbohydrate Strategy
Race-day carbohydrate intake should match the duration and intensity of your event:
- Events under 45 minutes: No carbs needed during exercise
- 45-75 minutes: Small amounts (mouth rinse or 10-20g) can enhance perception and work rate
- 1-2.5 hours: 30-60 g/hour via sports drinks, gels, or foods
- Over 2.5 hours: Up to 90 g/hour using products with multiple carb types (glucose + fructose)
💡 Key Insight: Carbohydrate isn't just fuel — it also affects your brain's perception of effort and your ability to maintain optimal pacing.
Pre-Event Carbohydrate Loading
For endurance events lasting over 90 minutes, carbohydrate loading can increase muscle glycogen stores by 50-100%. The protocol is simple: consume 10-12 g/kg body weight per day for 36-48 hours while tapering training volume.
For our 70 kg athlete, that's 700-840 grams of carbs per day — roughly 15-18 servings of carb-rich foods. This is not the time for high-fiber or high-fat meals; focus on easily digestible carbohydrate sources.
Protein: Building and Repairing Your Engine
Protein's role goes far beyond building muscle mass. It's essential for repairing tissue damage from training, supporting immune function, and optimizing training adaptations in all athletes — not just strength athletes.
🔬 Evidence-Based Protein Guidelines
- Daily intake: 1.2-2.0 g/kg body weight per day
- Post-workout: 0.25-0.3 g/kg (roughly 15-25g) within 2 hours of training
- Distribution: Consume protein every 3-5 hours throughout the day
- During energy restriction: Up to 2.0 g/kg to preserve muscle mass
Research shows that muscle protein synthesis (MPS) remains elevated for at least 24 hours after exercise, meaning your protein intake throughout the entire day matters — not just immediately post-workout.
Timing and Quality Matter
The most effective approach is consuming moderate amounts of high-quality protein regularly throughout the day. Aim for 20-40 grams per meal, with at least one serving within the first 2 hours after key training sessions.
High-quality protein sources include dairy (milk, Greek yogurt, cottage cheese), lean meats, fish, eggs, and soy products. Dairy proteins (whey and casein) are particularly effective due to their leucine content and digestion kinetics.
Hydration: The Often-Overlooked Performance Factor
Dehydration is one of the most common and preventable causes of performance decline. Even a 2% loss in body weight from fluid loss can impair cognitive function and aerobic performance, especially in the heat.
Practical Hydration Strategy
Hydration Protocol
- Before exercise: 5-10 mL/kg body weight 2-4 hours before
- During exercise: 0.4-0.8 L/hour (adjust based on sweat rate and conditions)
- After exercise: 150% of fluid lost (to account for ongoing urinary losses)
- Monitor: Track morning body weight and urine color/specific gravity
⚠️ The Overhydration Risk
Drinking too much can be more dangerous than drinking too little. Hyponatremia (low blood sodium) occurs when fluid intake exceeds sweat losses, diluting blood sodium levels. This is particularly common in slower-paced endurance events lasting over 4 hours. Symptoms include bloating, nausea, confusion, and in severe cases, seizures or death.
Electrolytes and Sodium
Sodium helps retain the fluids you consume and should be included during exercise lasting over 2 hours, especially in hot conditions or if you're a "salty sweater" (visible salt residue on skin/clothing after training).
Aim for 500-700 mg sodium per liter of fluid during prolonged exercise. This can come from sports drinks, electrolyte tablets, or even salted foods.
Evidence-Based Supplements That Actually Work
Most supplements are unnecessary and don't enhance performance. However, a small number have strong scientific support for specific applications. Here are the ones worth considering:
☕ Caffeine
Effect: Reduces perception of effort and enhances endurance performance
Dose: 3-6 mg/kg body weight, 60 minutes before exercise
Caution: High doses (>9 mg/kg) can cause jitters, anxiety, and GI distress without additional benefits
💪 Creatine
Effect: Improves repeated high-intensity efforts and may enhance muscle protein synthesis
Dose: 3-5 g/day maintenance (after optional 20 g/day loading phase for 5-7 days)
Caution: Expect 0.6-1 kg weight gain from water retention
🧪 Beta-Alanine
Effect: Increases muscle carnosine, buffering acid during high-intensity exercise (60-240 seconds)
Dose: 3-6 g/day split into doses, taken for 4+ weeks
Caution: May cause harmless tingling sensation (paresthesia)
🥤 Sodium Bicarbonate
Effect: Buffers acid accumulation during high-intensity efforts lasting 60-240 seconds
Dose: 0.3 g/kg body weight, 60-90 minutes before exercise
Caution: Commonly causes GI upset; test extensively in training
🥗 Nitrate (Beetroot Juice)
Effect: Improves exercise economy and tolerance, especially in recreational athletes
Dose: ~500 mg nitrate (2-3 shots beetroot juice), 2-3 hours before exercise
Note: Benefits are less clear in elite athletes
Practical Implementation: Making Science Work for You
Understanding the science is only the first step. The real challenge is implementing these strategies in your training and competition. Here's how to do it:
Your Action Plan
- Calculate your needs: Use the formulas above based on your body weight and training load
- Plan your meals: Distribute carbs and protein evenly throughout the day
- Test everything: Never try new foods, drinks, or supplements on race day
- Monitor hydration: Track morning weight and adjust fluid intake accordingly
- Keep it simple: Complex plans fail under pressure; simple plans succeed
- Periodize nutrition: Match intake to training demands — high on hard days, moderate on easy days
- Prioritize recovery: Post-workout nutrition (carbs + protein) accelerates adaptation
The Golden Rule Remains
No matter how solid the research is, individual responses vary. What works in a lab doesn't always work for everyone. Your digestive system, metabolism, sweat rate, and preferences are unique. The only way to know what works for YOU is through systematic testing in training conditions that mimic race day.
🎯 Science provides the framework, but personal experimentation determines what actually works for your body.
The Bottom Line
Sports nutrition doesn't have to be complicated. Focus on these evidence-based fundamentals:
- Maintain adequate energy availability to support training and health
- Match carbohydrate intake to training demands (higher on hard days, lower on easy days)
- Consume protein regularly throughout the day (every 3-5 hours)
- Develop and test a hydration strategy based on your individual sweat rate
- Consider proven supplements only after nailing down your diet foundation
- Keep your competition nutrition plan simple, tested, and reliable
Remember: supplements and fancy nutrition products cannot compensate for inadequate energy intake, poor carbohydrate availability, or chronic dehydration. Master the basics first.
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