Hydration, Timing, and Supplements
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).
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?
1-2 mL/kg body weight
5-7 mL/kg body weight
10-15 mL/kg body weight
20-25 mL/kg body weight
Post-exercise rehydration guidelines recommend replacing what percentage of body weight lost during exercise?
100%
125%
150%
200%
What is the recommended daily maintenance dose of creatine monohydrate for athletes?
0.5-1 g/day
3-5 g/day
10-15 g/day
20-25 g/day
Which of the following supplements has strong evidence for improving high-intensity exercise capacity lasting 1-10 minutes?
BCAAs
Glutamine
Beta-alanine
Tribulus
Sections you finish are checked off in the contents.