Fueling for Strength Training vs. Endurance
Nutrition isn’t one-size-fits-all — especially when it comes to performance. The energy systems and recovery needs for a powerlifter and a marathoner are fundamentally different. To train smarter (and recover faster), it helps to understand what’s happening under the hood.
Energy Systems: Where Your Power Comes From
The three energy systems our bodies use are:
⚡️ 1. ATP–PC System (Phosphagen System)
Duration: 0–10 seconds
Fuel Source: Stored ATP and phosphocreatine (PC) in muscles
Used for: Short, explosive bursts of power (e.g., sprinting, jumping, heavy lifting)
Oxygen required: ❌ No (anaerobic)
Example: 100-meter sprint or a one-rep max lift
How it works:
Your body breaks down stored phosphocreatine to quickly regenerate ATP. This system provides immediate energy but depletes fast.
🔥 2. Glycolytic System (Anaerobic Glycolysis)
Duration: ~10 seconds to 2 minutes
Fuel Source: Carbohydrates (glucose or glycogen)
Used for: Moderate to high-intensity efforts (e.g., 400m run, HIIT workout)
Oxygen required: ❌ No (anaerobic)
Byproduct: Lactic acid, which can cause muscle “burning” sensation
How it works:
Carbs are broken down without oxygen to make ATP. It’s faster than using oxygen but less efficient and produces fatigue more quickly.
🫁 3. Oxidative System (Aerobic System)
Duration: 2 minutes and beyond
Fuel Source: Carbohydrates, fats, and (sometimes) protein
Used for: Long-duration, lower-intensity activities (e.g., jogging, cycling, walking)
Oxygen required: ✅ Yes (aerobic)
Example: Marathon running, endurance training
How it works:
Your body uses oxygen to break down carbs and fats for ATP. It’s slower but produces a large amount of energy and can last for hours.
Implication:
Strength athletes need enough immediate energy (carbohydrates) and amino acids to rebuild muscle tissue afterward.
Endurance athletes need consistent glycogen stores and electrolyte balance to maintain long-term energy and prevent fatigue.
Pre-Workout Fueling: Match the System
Before training, you’re essentially priming the energy system you’ll rely on most.
For strength sessions: A moderate-carb, high-protein meal works best. The carbs provide quick ATP resynthesis, while amino acids (especially leucine) support muscle protein synthesis after lifting.
Example: Chicken and rice, Greek yogurt with oats, or eggs and toast.
For endurance workouts: Your glycogen stores are the main determinant of performance. Aim for 3–5g of carbohydrate per kilogram of body weight in the 24 hours before long sessions.
Example: Oatmeal, pasta, potatoes, or rice-based meals — plus fluids and electrolytes.
Why it matters:
Glycogen depletion leads to early fatigue (“hitting the wall”), while low protein intake post-strength training reduces muscle protein synthesis by up to 50%.
Recovery: The Repair and Refill Phase
Recovery nutrition serves two roles:
Refill glycogen (energy storage)
Repair muscle tissue (protein synthesis)
After strength training: Aim for ~20–40 g of high-quality protein (whey or lean animal proteins) plus 0.5–1 g/kg of carbs to replenish energy. The amino acid leucine triggers the mTOR pathway, which drives muscle growth and repair.
After endurance training: Prioritize carbohydrates (1–1.2 g/kg/hour for the first few hours) to rapidly restore glycogen, and add ~15–25 g of protein to reduce muscle breakdown.
Timing counts:
The “anabolic window” may be longer than once thought (up to 2 hours post-workout), but immediate fueling still optimizes recovery and reduces soreness.
Final Thought:
Think of strength and endurance fueling like two different engines.
Strength runs on power and repair — fueled by protein and quick carbs.
Endurance runs on steady oxidation — fueled by glycogen and hydration.
Once you align your nutrition with your energy system, performance, recovery, and long-term progress all move in sync.
-Coach Austyn