| name | race-nutrition |
| description | Evidence-based nutrition and hydration protocols for trail/ultra races. Covers gut training, race-day fueling strategies, carbohydrate periodization, hydration/sodium protocols, and recovery nutrition. |
Race Nutrition
When to use this skill
Use this skill when the request involves:
- Planning race-day fueling strategies (carbohydrate intake, hydration, sodium)
- Gut training protocols in preparation for races
- Pre-race carbohydrate loading strategies
- Post-race recovery nutrition
- Troubleshooting GI issues during training or racing
- Determining optimal CHO/fluid/sodium intake rates
Core principles: "Fuel for the work required"
Evidence-based approach: Based on recent ultra-endurance nutrition research (Gateway Innovation 2025, Journal of Sports Medicine 2013, ACSM/IOC position stands)
Key concept: Trainable gut capacity
- Athletes can LEARN to absorb higher carbohydrate loads
- Progressive gut training over 4-6 weeks increases CHO tolerance
- SGLT1 (sodium-glucose transporter) capacity increases with training
Gut Training Protocols (4-6 weeks pre-race)
Progressive CHO tolerance building
Purpose: Train the gut to absorb race-day CHO targets without GI distress
Protocol:
Week 1 (long run): 20 g/h CHO
Week 2 (long run): 30 g/h CHO
Week 3 (long run): 40 g/h CHO
Week 4 (long run): 50 g/h CHO (or race target)
Week 5: Race-level testing (simulate race fueling)
Week 6 (taper): Light testing only
Implementation details:
- Test on long runs (2+ hours minimum)
- Use actual race products (gels, drink mix, real food)
- Start CHO intake within first 15-20 minutes of run
- Take CHO every 15-20 minutes (don't wait until "feeling hungry")
Monitoring:
- GI comfort scale: 0 (no issues) to 10 (severe nausea/cramping/bloating)
- Target: maintain GI comfort ≤3/10 throughout run
- If GI issues >5/10: reduce CHO next session, troubleshoot products
Red flags:
- Persistent nausea/vomiting during training fueling
- Severe bloating that doesn't improve with practice
- Diarrhea during or immediately after fueling sessions
→ If 2+ red flags: consult sports dietitian, consider alternative CHO sources (liquid vs gel vs real food)
Source: Journal of Sports Medicine (2013), Gateway Innovation (2025)
Race-Day Fueling Strategies
Carbohydrate intake targets
Duration-based recommendations:
< 6 hours (50-80 km ultras):
- Target: 40-50 g/h CHO
- Rationale: Sufficient for glycogen maintenance, lower GI risk
> 6 hours (80+ km, 24h+ events):
- Target: 50-60 g/h CHO (recreational)
- Target: 60-90 g/h CHO (elite or highly trained)
- Rationale: Higher oxidation rates, need multiple CHO sources
Practical delivery:
- Every 20 minutes: 10-15g CHO (1 gel, or 150-200ml sports drink 6-8%, or 1 date/fig)
- OR hourly package: ~50g CHO (1.5 gels + electrolyte drink, or 500ml sports drink 9-10% + 1 banana slice)
Example for 50K, 70kg athlete, 6-7h race:
- Pre-race (3h before): 1.5g/kg = 105g (porridge + honey + banana)
- During: 45g/h × 6.5h = ~300g total
- Option 1: 2 gels/h (40g) + sports drink
- Option 2: 1 gel/h + real food (banana, dates) + drink
- Option 3: Only liquid nutrition (sports drink 8-10%)
Multiple carbohydrate sources:
- For >60g/h: use glucose + fructose combination (2:1 ratio ideal)
- Single CHO source (glucose only): saturates at ~60g/h
- Multiple transporters (glucose + fructose): can absorb 90g/h
Source: Gateway Innovation (2025), ACSM position stand
Hydration protocols
Fluid intake:
- Target: 450-750 ml/h
- OR: 150-250 ml every 20 minutes
- Adjust for:
- Heat/humidity: ↑ toward 750 ml/h
- Cold/altitude: ↓ toward 450 ml/h
- Sweat rate (individual): use sweat test data if available
Practical strategies:
- Use handheld bottle, vest with soft flasks, or hydration pack
- Pre-mark bottles with time intervals (e.g., "drink by mile 5")
- Aid station strategy: drink 200-250ml at each station (if spaced ~30-45 min apart)
Monitoring hydration status:
- Urine color: pale yellow = adequate, dark amber = dehydrated
- Body weight change: aim for <2-3% loss during race
- Thirst: drink to thirst, but don't wait until "very thirsty"
Warning: Hyponatremia risk
- Overhydration + insufficient sodium = dangerous
- Symptoms: nausea, headache, confusion, swelling (hands/feet)
- Prevention: adequate sodium intake (see below)
Sodium (electrolyte) protocols
Sodium targets:
- Standard: 300-600 mg/h
- OR: 500-700 mg/L fluid
- Heat/high sweat rate: ↑ toward 600-700 mg/h
Practical delivery:
- Electrolyte tablets/capsules (e.g., SaltStick: 215mg Na per cap)
- Sports drink with electrolytes (check label for Na content)
- Real food (pretzels, salted nuts, broth at aid stations)
Example for 70kg runner, 6h race, moderate heat:
- Fluid: 600 ml/h × 6h = 3,600 ml
- Sodium: 500 mg/h × 6h = 3,000 mg
- Delivery: 600ml sports drink (500mg Na/L) + 1 electrolyte cap/h
Individual variation:
- "Salty sweaters" (white residue on clothes/skin): ↑ toward 700 mg/h
- Low sweat rate, cool conditions: can use 300-400 mg/h
Source: ACSM/IOC consensus, Gateway Innovation (2025)
Pre-Race Carbohydrate Loading
Evidence-based protocol (NOT the old "week-long" method)
Timeline: 36-48 hours before race
Carbohydrate target:
- 8-12 g/kg/day × 2 days
- Example for 70kg athlete: 560-840g/day
Practical implementation:
- Day -2: Normal breakfast, then ↑ CHO at lunch/dinner/snacks
- Day -1: High-CHO all meals (pasta, rice, bread, fruit, juice)
- Focus on familiar foods (avoid GI experimentation)
What this looks like (example for 70kg, target 600g/day):
- Breakfast: oatmeal (60g CHO) + banana (30g) + honey (20g) = 110g
- Snack: juice (40g) + energy bar (30g) = 70g
- Lunch: pasta (80g CHO) + bread (30g) + fruit (20g) = 130g
- Snack: smoothie (50g CHO) + dried fruit (30g) = 80g
- Dinner: rice (100g CHO) + potatoes (40g) + dessert (30g) = 170g
- Evening snack: cereal (30g) + juice (20g) = 50g
- Total: 610g CHO
Fiber management:
- Reduce fiber 24-36h before race (avoid whole grains, raw vegetables)
- Rationale: prevent GI issues during race
Pre-race meal (1-4h before start)
Carbohydrate target:
- 1-4 g/kg depending on timing and tolerance
- Closer to race: lower amount, more easily digestible
- Further from race: can be larger
Examples:
- 3-4h before: 3-4 g/kg (e.g., 210-280g for 70kg) — full meal (pasta, rice, oatmeal)
- 2-3h before: 2-3 g/kg (140-210g) — moderate meal (oatmeal + banana + honey)
- 1-2h before: 1-2 g/kg (70-140g) — light meal (toast + jam, energy bar + banana)
Avoid:
- High fat (slows digestion)
- High fiber (GI risk)
- New/untested foods
- Large protein portions (not needed pre-race)
Caffeine (optional):
- 3-6 mg/kg body weight 30-60min before start
- Example: 70kg athlete = 210-420mg (2-4 espressos or 1-2 caffeine gels)
- Benefits: ↑ alertness, ↓ perceived exertion, ↑ fat oxidation
- Test in training first!
Source: ACSM/IOC position stand
Post-Race Recovery Nutrition
Immediate recovery window (0-30 minutes)
Carbohydrate priority:
- Target: 1.0-1.2 g/kg body weight
- Example: 70kg athlete = 70-84g CHO
- Purpose: Rapid glycogen replenishment
Practical options:
- Recovery drink (e.g., chocolate milk: 500ml = 60g CHO + 16g protein)
- Gels + electrolyte drink
- Real food if tolerated (banana + bread + juice)
Protein addition (optional but beneficial):
- 15-25g protein with CHO
- Enhances muscle protein synthesis
- Ratio: 3:1 or 4:1 CHO:protein ideal
Extended recovery (2-24 hours)
Carbohydrate replenishment:
- First 4-6 hours: 1.0-1.2 g/kg every 2h (if quick recovery needed)
- OR: spread across meals at 6-10 g/kg/day total
Hydration:
- Drink 1.5L per kg body weight lost
- Example: lost 1kg during race → drink 1.5L over next 4-6h
- Include sodium to enhance fluid retention
Protein:
- 1.6-2.0 g/kg/day for muscle repair
- Distribute across 4-5 meals (20-40g per meal)
Anti-inflammatory foods (optional):
- Tart cherry juice: reduces muscle soreness
- Turmeric, ginger: natural anti-inflammatories
- Omega-3 (fish, walnuts, chia): supports recovery
Avoid:
- Alcohol (impairs recovery, dehydration)
- Excessive fat immediately post-race (slows CHO absorption)
Source: ACSM/IOC position stand
Common Mistakes & Troubleshooting
Mistake 1: Waiting until "feeling hungry" to eat
Problem: By then, glycogen depletion has already begun
Solution: Start fueling at 15-20 min, continue every 15-20 min regardless of hunger
Mistake 2: Not practicing race-day fueling
Problem: GI distress on race day
Solution: Use gut training protocol (4-6 weeks), test exact products
Mistake 3: Trying new products on race day
Problem: Unpredictable GI response
Solution: "Nothing new on race day" — only tested products
Mistake 4: Insufficient sodium intake
Problem: Hyponatremia, cramping, nausea
Solution: Target 300-600 mg/h, ↑ in heat/high sweat rate
Mistake 5: Overhydrating
Problem: Hyponatremia (dilution of blood sodium)
Solution: Drink to thirst + adequate sodium, don't exceed 750-800ml/h
Mistake 6: High-fiber pre-race meals
Problem: GI issues during race
Solution: Reduce fiber 24-36h before, focus on easily digestible CHO
Mistake 7: Relying only on aid station food
Problem: Timing gaps, unfamiliar food, insufficient CHO
Solution: Carry own nutrition, use aid stations as supplement
Individual Variation & Adaptation
Factors affecting requirements:
- Body weight: heavier athletes need more absolute CHO/fluid
- Sweat rate: measure via pre/post-run weight (1kg loss = 1L sweat)
- Heat/humidity: ↑ fluid needs, ↑ sodium needs
- Altitude: ↓ fluid needs (less sweat), ↑ CHO needs (higher metabolic rate)
- Pace/intensity: faster = higher CHO oxidation rate
Adaptation timeline:
- Gut CHO absorption: improves significantly in 4-6 weeks
- Fat oxidation capacity: develops over months (aerobic base training)
- Sweat rate adaptation: 1-2 weeks in new heat conditions
When to seek professional help:
- Persistent GI issues despite gut training
- History of hyponatremia
- Extreme sweat rates ("salty sweater")
- Pre-existing GI conditions (IBS, Crohn's, etc.)
- Weight loss >5% during races despite fueling
→ Consult sports dietitian (RD, CSSD credential)
Integration with Training Phases
Base Period: Low-intensity nutrition
- Opportunity for "train low, compete high" sessions (once/week)
- Practice fasted morning runs (Z1, <90 min) to enhance fat oxidation
- Most long runs: normal fueling to support volume
Build Period: Gut training phase
- Start 4-6 week gut training protocol
- Test all race-day products
- Practice aid station strategy (if applicable)
Specific Period: Race simulation
- Full dress rehearsal: race-day fueling on key long runs
- Test pre-race meal timing and composition
- Verify hydration strategy under race-specific conditions
Taper: Carb loading prep
- Week -2: normal nutrition
- Week -1: initiate carb loading (day -2, day -1)
- Pre-race meal: tested protocol, 1-4h before
Source: Ultrarunning Training Essentials (Koop), Gateway Innovation (2025)
Key Takeaways
- Gut is trainable: 4-6 weeks progressive CHO loading prepares GI system
- Start early, stay consistent: Begin fueling at 15-20min, continue every 15-20min
- CHO targets: 40-50g/h (<6h), 50-60g/h (>6h), 60-90g/h (elite/>24h)
- Hydration: 450-750ml/h + 300-600mg Na/h (adjust for conditions)
- Carb loading: 8-12g/kg/day × 2 days (NOT week-long)
- Recovery: 1.0-1.2g/kg CHO within 30min post-race
- Nothing new on race day: Test everything in training
Remember: Nutrition is the "4th discipline" in ultra-endurance — neglecting it undermines all your training.
