Comprehensive Fuelling and Gut Training Protocol for Ultramarathons

This fully detailed protocol integrates strategies for carbohydrate (CHO), protein, fat, hydration, fatigue management, muscle damage mitigation, and microbiome support. It aims to prepare athletes for the extreme demands of endurance and ultra-endurance events, emphasising durability and fatigue resistance at every phase.

Phase 1: Baseline Assessment and Initial Adaptation (2-4 Weeks)

Phase 1: Baseline Assessment and Initial Adaptation (2-4 Weeks)

Objective:

  • Establish individual baselines for hydration, fuelling, GI health, and performance metrics.

  • Introduce low-level gut training and education on the physiological principles of endurance nutrition.

Why This Phase Matters

Durability, or the ability to maintain performance under fatigue, starts with a solid understanding of your unique physiology. Early assessments ensure your fuelling, hydration, and gut strategies are tailored to meet your needs. Initial adaptation to low-level CHO intake prepares the gut for progressive increases while minimizing GI distress.

  1. Fuelling and Fatigue:

    • Your muscles rely on glycogen for sustained energy. Without sufficient CHO intake, glycogen depletion accelerates fatigue, impairing performance.

    • This phase introduces CHO fuelling at low doses to acclimate the gut for future demands.

  2. Hydration and Energy:

    • Dehydration contributes to cardiovascular strain and reduced energy efficiency. Understanding your sweat rate ensures that hydration strategies align with training demands.

  3. Protein and Fat:

    • Baseline protein and fat intake support recovery and long-term endurance adaptations.

Key Actions

  1. Baseline Testing:

    • GSRS Questionnaire: Assess baseline GI health (e.g., symptoms like bloating, diarrhoea, reflux).

    • Sweat Rate Test: Conduct a 60-90 minute moderate-intensity session:

      • Weigh pre- and post-session.

      • Record fluid intake to calculate sweat rate and determine fluid replacement needs using the precision fuel and hydration spreadsheet.

    • Food Diary: Track macronutrient intake, meal timing, and typical pre-training meals.

  2. Gut Training:

    • Introduce small CHO doses (30-40 g/h) during 1-2 hour sessions to familiarize the gut with energy intake during exercise.

  3. Protein and Fat:

    • Maintain balanced daily intake:

      • Protein: 1.6-2.0 g/kg/day distributed across meals to support muscle repair.

      • Fat: ~25-30% of total calories to support long-term endurance and recovery.

  4. Microbiome Support:

    • Include prebiotic-rich foods (e.g., oats, bananas) and fermented foods (e.g., kefir, yogurt) in your daily diet to promote gut diversity.

  5. Gut-Brain Axis:

    • Begin daily vagus nerve stimulation exercises:

      • Deep breathing (5 seconds inhale, 5 seconds exhale for 10 minutes).

      • Humming or gargling post-meals to improve gut motility.

Educational Guidance for Athletes

  • Durability Starts Here: This phase prepares your body and gut for higher fuelling demands while addressing hydration needs and identifying potential GI risks.

  • Fuel for Recovery: Protein and fat intake support repair and endurance adaptations, forming the backbone of your nutrition strategy.

Example Sessions

  1. Low-Intensity CHO Trial:

    • Purpose: Test tolerance to small CHO loads.

    • Session: 60-minute zone 2 run consuming 30 g CHO from a drink. Evaluate GI symptoms using GSRS.

  2. Sweat Rate Test:

    • Purpose: Identify hydration needs.

    • Session: 90-minute bike ride with pre- and post-weight measurements and 500 mL/hour fluid intake. Calculate sweat rate for personalized hydration planning.

Phase 2: Building Tolerance (CHO and Fluids) (3-6 Weeks)

Objective:

  • Gradually increase CHO intake to ~60 g/h and fluid consumption to match sweat rate.

  • Introduce strategies to train the gut for higher fuelling demands and simulate race-specific conditions.

Why This Phase Matters

Building CHO tolerance and fluid intake capacity prepares you for the metabolic demands of ultra-endurance racing. Simultaneously, this phase introduces techniques to enhance fat oxidation during lower-intensity sessions, ensuring energy availability as glycogen depletes late in a race.

  1. CHO Intake Progression:

    • Increasing CHO intake from 30 g/h to ~60 g/h supports moderate-intensity sessions while improving GI resilience. We recommend PFH products, eg. 2 gels per hr to start with.

  2. Hydration and Electrolytes:

    • Increasing fluid intake (~750 mL/hour) mimics real-world conditions, especially in heat or altitude. Testing sodium levels ensures proper electrolyte replacement to reduce cramping and maintain energy metabolism.

  3. Protein During Training:

    • Introducing ~5 g/hour of protein during longer sessions supports muscle preservation and recovery. Eg. add a SuperNaturalFuel pouch into the mix.

  4. Fat Adaptation:

    • Under guidance, consider "Train low" sessions—where CHO intake is restricted to improve mitochondrial efficiency and fat oxidation, critical for endurance performance. However, immediate refuelling afterwards is essential. Only do these sessions under guidance and support from your coach and nutritionist. Far greater gains are made by improving overall nutrition and fuelling.

Key Actions

  1. CHO Training:

    • Gradually increase CHO intake by 10-15 g/h weekly, experimenting with dual-source CHO products (e.g., glucose 2:1).

  1. Fatigue Management:

    • Conduct low-intensity, fasted sessions (e.g., 2-hour runs) to improve fat metabolism while hydrating adequately.

  2. Protein and Recovery:

    • Include small protein doses during exercise and prioritize post-session meals combining CHO and protein (4:1 ratio).

  3. Microbiome Support:

    • Rotate fibre sources and include antioxidant-rich foods (e.g., berries, spinach) to support gut health and recovery.

Educational Guidance for Athletes

  • Why Fat Matters: During longer events, as glycogen stores decline, your body increasingly relies on fat for energy. Training your body to efficiently use fat delays fatigue.

  • CHO Tolerance is Key: Increasing your CHO intake progressively reduces the risk of GI distress while ensuring energy availability for high-intensity segments.

Example Sessions

  1. Dual-Source CHO Trial:

    • Purpose: Test higher CHO loads.

    • Session: 2-hour zone 2 run with 60 g/h CHO from gels and isotonic drinks.

  2. Train Low Session (if supported by nutritionist / coach):

    • Purpose: Improve fat oxidation.

    • Session: 2-hour fasted ride, hydrating only (500-750 mL/hour).

  3. Hydration and Electrolytes:

    • Purpose: Increase fluid intake to match sweat rate.

    • Session: 2-hour bike ride in warm conditions, drinking 750 mL/hour with 1,000 mg sodium/L.

Phase 3: Progressive Overload and Long Session Simulations (3-6 Weeks)

Objective:

  • Achieve race-day CHO targets (~90-120 g/h) and hydration (~750-1,000 mL/hour).

  • Build durability by simulating late-stage fatigue and addressing muscle damage through tailored nutrition strategies.

Why This Phase Matters

This phase focuses on training the body to sustain energy demands during prolonged efforts while resisting fatigue and muscle damage. By mimicking race-day conditions, athletes developthe ability to maintain CHO oxidation, hydration, and gut function under stress. Incorporating protein supports muscle preservation, while targeted fat utilization ensures energy availability in the later stages of ultra-endurance events.

  1. Carbohydrate for Durability:

    • Late-stage fatigue often coincides with reduced CHO oxidation. By training at full CHO loads (90-120 g/h), you prepare your gut to sustain high-intensity efforts during long races.

  2. Protein and Fat for Long-Duration Performance:

    • Including protein (~5-10 g/hour) during long runs minimizes muscle damage from repetitive impact (e.g., downhill running). Small amounts of fat (~5 g/hour) provide an additional, slow-burning energy source for ultra-endurance. Products such as the SuperNaturalFuel pouches are a good way of achieving this as part of your overall fuel mix.

  3. Hydration and Fatigue:

    • Fatigue can impair fluid absorption. Practicing hydration (~750-1,000 mL/hour) in conditions that simulate race environments ensures you’re prepared for heat, altitude, or other challenges.

  4. Muscle Damage Mitigation:

    • Eccentric loading (e.g., downhill running) causes exercise-induced muscle damage (EIMD). Fuels rich in antioxidants (e.g., tart cherry juice) and proper protein/CHO intake reduce recovery time and enhance durability.

Key Actions

  1. Gut Training:

    • Progressively increase CHO intake to race-day targets (~90-120 g/h). Test various formats (e.g., gels, chews, liquids) to ensure tolerability.

    • Emphasize liquid CHO in the final hour of long runs to simulate late-race fuelling.

  2. Protein and Fat During Exercise:

    • Add ~5-10 g protein/hour using recovery-focused drinks or energy bars during long runs.

    • Test tolerance for ~5 g/hour of fat from real-food options (e.g., peanut butter, trail mix) for ultra-long sessions.

  3. Hydration and Electrolytes:

    • Train to consume ~1,000 mL/hour in hot or humid conditions. Incorporate sodium based on your sweat rate (e.g., 500-1,000 mg/L).

  4. Fatigue Management:

    • Introduce caffeine (~30-60 mg) in the final hour of long sessions to boost late-stage CHO oxidation and alertness. eg. use the Caffeine PFH gel

    • Include progressive intensity segments in long runs to simulate race surges and train the gut under higher effort levels.

  5. Muscle Recovery:

    • Incorporate antioxidant-rich foods and drinks (e.g., beet juice, tart cherries) into post-run recovery.

    • Use protein (0.3 g/kg) and CHO (1.2 g/kg) within 30 minutes post-session to repair muscle damage and replenish glycogen.

  • Why Late-Stage CHO Matters: As fatigue sets in, maintaining CHO availability becomes critical for high-intensity efforts. Training your gut to process 90-120 g/h ensures you can sustain power output.

  • The Role of Protein and Fat: Protein protects your muscles during long sessions, while small amounts of fat provide steady energy for ultra-endurance events.

  • Hydration Under Fatigue: Fatigue can impair fluid absorption, so consistent hydration strategies must be tested under similar race conditions.

Example Sessions

  1. Progressive CHO Simulation:

    • Purpose: Train the gut for increasing CHO loads under fatigue.

    • Session:

      • 3-hour run with 60 g/h CHO in the first 90 minutes and 90 g/h in the final 90 minutes.

      • Use a mix of gels, drinks, and chews. Test late-stage liquid fuelling.

  2. Downhill Simulation:

    • Purpose: Mimic race-day downhill sections and test protein integration.

    • Session:

      • 2-hour run on hilly terrain with 10-15 minutes of downhill running every 30 minutes.

      • Consume 90 g/h CHO + 5 g protein/hour using energy bars or protein-enhanced drinks.

  3. Heat and Hydration Trial:

    • Purpose: Train hydration and sodium strategies under warm conditions.

    • Session:

      • 3-hour bike ride or run in heat, consuming 1,000 mL/hour fluid with ~1,000 mg sodium/L.

      • Evaluate fluid tolerance and late-stage energy levels.

  4. Race Simulation with Fat Inclusion:

    • Purpose: Test small fat intakes for ultra-endurance sessions.

    • Session:

      • 4-hour run on mixed terrain. Fuel with 90 g/h CHO + 5 g/hour fat (e.g., peanut butter packets or trail mix).

Phase 4: Race-Specific Gut Training (2-4 Weeks)

Objective:

  • Finalize race-day fuelling, hydration, and fatigue management strategies.

  • Prepare the gut to handle the physiological stress and substrate demands of race-day intensity and duration.

  • Train to sustain energy and hydration under the extreme fatigue and mechanical stress encountered in late-race conditions.

Why This Phase Matters

Fatigue in ultra-endurance events is multifactorial, resulting from glycogen depletion, dehydration, muscle damage, and reduced CHO oxidation efficiency. This phase aims to simulate race-specific fatigue scenarios while refining nutritional strategies. Practicing late-stage fuelling and hydration builds the durability needed to maintain performance through the finish line.

  1. Durability and CHO Oxidation:

    • Under fatigue, the body’s ability to oxidize CHO decreases, leading to a shift toward less efficient fat metabolism. Consistent high-CHO fuelling (~90-120 g/h) late in long sessions ensures that glycogen stores are preserved and high-intensity efforts are sustained.

  2. Fatigue-Resistant Hydration:

  1. Dehydration impairs energy production and cognitive function, compoundingg fatigue. Practicing hydration strategies under simulated race conditions ensures your ability to manage fluid balance even when absorption is compromised by fatigue.

  2. Late-Stage Gut Resilience:

    • Mechanical stress (e.g., downhill running) and reduced gut motility under fatigue can increase the risk of GI distress. Testing liquid-based fueling and lower-residue foods during high-fatigue states helps prevent late-race GI symptoms.

  3. Muscle Damage Management:

    • Eccentric muscle contractions (e.g., downhill running) exacerbate fatigue. Including protein during long sessions helps minimize muscle breakdown, while antioxidants reduce inflammation and support recovery.

      Key Actions

    • Gut Training for Late-Stage Fatigue:

      • Practice full race-day CHO loads (~90-120 g/h), focusing on maintaining intake during the final third of long sessions.

      • Use liquid-based CHO in the last hour to improve digestion and absorption under fatigue.

    • Hydration and Sodium Refinement:

      • Train fluid intake to match sweat rate (~750-1,000 mL/hour).

      • Adjust sodium intake (~500-1,000 mg/L) based on environmental conditions (e.g., heat, altitude).

    • Protein and Fat Integration:

      • Include ~5-10 g protein/hour to minimize muscle breakdown, particularly in sessions with significant downhill segments.

      • Test ~5 g/hour fat intake (e.g., nut butter, avocado) for ultra-distance runs exceeding 4 hours.

    • Fatigue Management Strategies:

      • Introduce caffeine (~30-60 mg) in the final hour of long runs to support late-stage CHO oxidation and reduce perception of fatigue.

      • Incorporate progressive intensity surges (e.g., tempo bursts) in the last hour to simulate race surges and train the gut under stress.

    • GI Risk Mitigation:

      • Test emergency options (e.g., cola, salted crackers) to handle unexpected GI symptoms or bonking late in the race.

      • Use low-FODMAP, low-fibre pre-run meals to minimize GI distress during long sessions.

    • Why Fatigue Training is Key: Fatigue reduces your body’s ability to metabolize CHO and absorb fluids. Simulating late-race conditions trains your gut to maintain energy delivery when it matters most.

    • The Role of Protein: Protein during training protects muscles, minimizing soreness and damage from long sessions. This ensures faster recovery and better late-race durability.

    • Hydration Focus: Proper hydration sustains energy and mental clarity during prolonged efforts, preventing dehydration from compounding fatigue.

      Example Sessions

    • Full Race Simulation:

      • Purpose: Refine race-day fuelling and hydration under fatigue.

      • Session:

        • 4-hour run on race-like terrain, using complete fuelling strategy: ~90-120 g/h CHO, ~750-1,000 mL/hour fluid, ~1,000 mg sodium/L.

        • Incorporate 1-2 downhill sections (~10 minutes each).

        • Add caffeine (~30 mg) in the final hour.

    • Fatigue-Resistant Hydration:

      • Purpose: Train late-stage hydration under fatigue.

      • Session:

        • 3-hour run in heat or high humidity, consuming 1,000 mL/hour fluid with ~1,000 mg sodium/L.

        • Use liquid CHO (~90 g/h) in the final hour.

    • Late-Stage Tempo Simulation:

      • Purpose: Simulate race surges during fatigue.

      • Session:

        • 3-hour run with progressive tempo bursts in the final hour:

          • 5 x 5 minutes at zone 3, 5 minutes easy between bursts.

        • Fuel with 90 g/h CHO, transitioning to liquid CHO in the last 30 minutes.

    • Downhill Muscle Damage Simulation:

      • Purpose: Test gut resilience and muscle damage strategies.

      • Session:

        • 2-hour hilly run with downhill running (~10-15 minutes every 30 minutes).

        • Consume 90 g/h CHO + 5 g protein/hour using protein-enhanced sports drinks or bars.

    • Emergency Fuel Test:

      • Purpose: Prepare for unexpected fuelling needs.

      • Session:

        • 2-hour run with planned bonking simulation (intentional depletion in the final 30 minutes).

        • Practice using cola or simple CHO sources to recover energy quickly.