Key Takeaways
- Pre-exercise hydration: 5-7 mL/kg body weight 4 hours before; an additional 3-5 mL/kg if urine is dark 2 hours before.
- During exercise: 0.4-0.8 L/hour; add sodium (300-600 mg/L) for exercise >1 hour or heavy sweating.
- Post-exercise: Replace 150% of body weight lost (1.5 L per kg lost) over 2-4 hours with sodium-containing fluids.
- Pre-workout nutrition: 1-4 g/kg carbs 3-4 hours before; post-workout: 1.0-1.2 g/kg carbs plus 20-40g protein within 2 hours.
- Evidence-based supplements include creatine (3-5g/day), caffeine (3-6 mg/kg), beta-alanine (3.2-6.4g/day), and sodium bicarbonate (0.3 g/kg).
Hydration, Timing, and Supplements
Quick Answer: Hydrate with 5-7 mL/kg 4 hours pre-exercise, 0.4-0.8 L/hour during, and replace 150% of weight lost post-exercise. Legal evidence-based supplements include creatine (3-5g/day), caffeine (3-6 mg/kg), beta-alanine (3.2-6.4g/day), and sodium bicarbonate (0.3 g/kg).
Hydration Guidelines
Maintaining proper hydration is critical for performance and safety. Even mild dehydration (2% body weight loss) impairs performance.
Pre-Exercise Hydration
| Timing | Recommendation | Purpose |
|---|---|---|
| 4 hours before | 5-7 mL/kg body weight | Achieve euhydration |
| 2 hours before | 3-5 mL/kg (if urine is dark) | Fine-tune hydration status |
Example for 70 kg athlete:
- 4 hours before: 350-490 mL (12-17 oz)
- 2 hours before: 210-350 mL if needed (7-12 oz)
Hydration Status Indicators
| Indicator | Well Hydrated | Dehydrated |
|---|---|---|
| Urine color | Pale yellow | Dark yellow/amber |
| Urine frequency | Regular | Infrequent |
| Body weight | Stable | Decreased |
| Thirst | Minimal | Strong |
During Exercise Hydration
| Condition | Fluid Intake | Sodium Needs |
|---|---|---|
| Exercise <1 hour | 0.4-0.8 L/hour | Usually not needed |
| Exercise >1 hour | 0.4-0.8 L/hour | 300-600 mg/L (sports drink) |
| Heavy sweating | Individualize based on sweat rate | 300-600 mg/L |
| Hot environment | Higher end of range | Essential |
Key Point: Don't overdrink! Hyponatremia (low blood sodium from excessive water intake) is dangerous. Match fluid intake to sweat losses.
Calculating Sweat Rate
Sweat Rate = (Pre-exercise weight - Post-exercise weight + Fluid consumed) / Exercise duration
Post-Exercise Rehydration
| Recommendation | Amount | Timing |
|---|---|---|
| Total fluid replacement | 150% of weight lost | Over 2-4 hours |
| Sodium inclusion | Include sodium-containing foods/fluids | Essential for retention |
Example: If an athlete loses 1 kg during exercise, they should consume 1.5 L of fluid over 2-4 hours post-exercise.
Exercise Nutrition Timing
Pre-Exercise Nutrition
| Timing | Carbohydrate | Protein | Fat | Fiber |
|---|---|---|---|---|
| 3-4 hours before | 1-4 g/kg | 20-30g | Moderate | Moderate |
| 1-2 hours before | 1 g/kg | 10-20g | Low | Low |
| <1 hour before | 0.5 g/kg (liquid) | Optional | Avoid | Avoid |
Key Point: Reduce fat and fiber closer to exercise to prevent GI distress.
During Exercise Nutrition
| Duration | Carbohydrate Needs | Source |
|---|---|---|
| <45 minutes | Not needed | Water only |
| 45-75 minutes | Small amounts or mouth rinse | Sports drink |
| 1-2.5 hours | 30-60 g/hour | Sports drinks, gels |
| >2.5 hours | Up to 90 g/hour | Multiple carb sources (glucose + fructose) |
Post-Exercise Nutrition
| Nutrient | Amount | Timing | Purpose |
|---|---|---|---|
| Carbohydrate | 1.0-1.2 g/kg | Within 30-60 min, continue for 4-6 hours | Glycogen resynthesis |
| Protein | 20-40g (0.3 g/kg) | Within 2 hours | Muscle protein synthesis |
| Fluid | 150% of weight lost | Over 2-4 hours | Rehydration |
Glycogen Resynthesis: Rate is highest immediately post-exercise. Consuming carbs within 30-60 minutes takes advantage of this "glycogen window."
Evidence-Based Supplements
Only a small number of supplements have strong evidence supporting their ergogenic effects. Always verify supplements are third-party tested for banned substances.
Tier 1: Strong Evidence
| Supplement | Dose | Loading | Benefit | Best For |
|---|---|---|---|---|
| Creatine Monohydrate | 3-5 g/day | Optional: 20g/day for 5-7 days | Increased strength, power, muscle mass | Strength/power sports |
| Caffeine | 3-6 mg/kg | 30-60 min before exercise | Increased endurance, reduced perceived exertion | All sports |
| Beta-Alanine | 3.2-6.4 g/day | Divide into 0.8-1.6g doses | Increased high-intensity capacity | 1-10 minute efforts |
| Sodium Bicarbonate | 0.3 g/kg | 60-90 min before exercise | Buffer lactic acid | 1-7 minute high-intensity |
Creatine Details
| Aspect | Information |
|---|---|
| Mechanism | Increases phosphocreatine stores for ATP regeneration |
| Loading protocol | 20g/day (4 x 5g) for 5-7 days, then 3-5g/day |
| No-loading protocol | 3-5g/day (takes 3-4 weeks to saturate) |
| Best form | Creatine monohydrate (most studied, effective) |
| Side effects | Initial weight gain (water retention), generally safe |
Caffeine Details
| Aspect | Information |
|---|---|
| Mechanism | Adenosine receptor antagonist; reduces perceived exertion |
| Dose | 3-6 mg/kg (low doses still effective) |
| Timing | 30-60 minutes pre-exercise |
| Forms | Coffee, pills, gum, energy drinks |
| Considerations | Tolerance develops; may disrupt sleep |
Beta-Alanine Details
| Aspect | Information |
|---|---|
| Mechanism | Increases muscle carnosine, buffers H+ ions |
| Loading | Takes 2-4 weeks of daily use to saturate |
| Side effect | Paresthesia (tingling)—harmless, reduce dose if bothersome |
| Best for | Repeated high-intensity efforts lasting 1-10 minutes |
Sodium Bicarbonate Details
| Aspect | Information |
|---|---|
| Mechanism | Extracellular buffer, delays fatigue from acidosis |
| Protocol | 0.3 g/kg, 60-90 minutes before exercise |
| Side effects | GI distress common—practice in training |
| Alternative | Sodium citrate (fewer GI issues) |
Third-Party Testing
Athletes should only use supplements verified by third-party testing programs:
| Program | Description |
|---|---|
| NSF Certified for Sport | Tests for banned substances and label accuracy |
| Informed Sport | Banned substance testing program |
| BSCG (Banned Substances Control Group) | Independent testing for banned substances |
Warning: Many supplements are contaminated with banned substances or don't contain what the label claims. ALWAYS use third-party tested products.
Supplements with Limited or No Evidence
| Supplement | Status |
|---|---|
| BCAAs | Limited evidence; adequate protein intake sufficient |
| Glutamine | No ergogenic benefit for healthy athletes |
| HMB | May help untrained individuals; limited benefit for trained |
| Tribulus | No evidence for testosterone or performance enhancement |
| Most "testosterone boosters" | No evidence; may contain banned substances |
How much fluid should an athlete consume 4 hours before exercise to achieve proper hydration?
Post-exercise rehydration guidelines recommend replacing what percentage of body weight lost during exercise?
What is the recommended daily maintenance dose of creatine monohydrate for athletes?
Which of the following supplements has strong evidence for improving high-intensity exercise capacity lasting 1-10 minutes?