Sports Nutrition and Exercise Performance

Energy Requirements for Athletes

Activity Level	Energy Needs	Example
Sedentary (≤ 30 min/day)	1.2-1.4 × BMR	Office worker
Moderate (30-60 min/day)	1.6-1.8 × BMR	Recreational athlete
High (60-90 min/day)	1.8-2.2 × BMR	Competitive athlete
Extreme (≥ 3-6 hours/day)	2.2-3.0 × BMR	Endurance athlete

Macronutrient Guidelines for Athletes

Carbohydrates

Activity	Recommendation	Examples
General daily intake	5-12 g/kg/day	All athletes
Moderate exercise (1 hr/day)	5-7 g/kg/day	60-70 kg athlete: 300-490 g/day
Endurance (1-3 hr/day)	7-10 g/kg/day	Marathon, cycling
Extreme (≥ 3 hr/day)	10-12 g/kg/day	Ultramarathon, Tour de France
Pre-exercise (1-4 hr before)	1-4 g/kg	Small meal/snack
During exercise (> 1 hr)	30-60 g/hour	Sports drink, gel, banana
Post-exercise recovery	1-1.5 g/kg within 30 min	Refuel glycogen stores

Protein

Goal	Recommendation	Timing
General daily intake	1.2-2.0 g/kg/day	Spread across 3-6 meals
Strength/power athletes	1.6-2.2 g/kg/day	0.3-0.5 g/kg every 3-4 hours
Endurance athletes	1.2-1.8 g/kg/day	Post-exercise for repair
Weight-restricted (lean mass maintenance)	1.8-2.7 g/kg/day	Higher during calorie deficit
Maximum useful amount per meal	0.4-0.55 g/kg (20-40 g per meal)	Beyond this → oxidation

Fat

Goal	Recommendation	Notes
General daily intake	20-35% of total calories	≥ 15% (hormone function)
Essential fatty acids	2-3 g/day omega-3 (EPA + DHA)	Anti-inflammatory
Pre-exercise	Low fat (slow digestion)	2-4 hours before
Endurance adaptation	Moderate fat (60-70% VO₂max)	Fat adaptation protocols

Hydration for Athletes

Phase	Recommendation	Fluid Type
Before exercise (4 hr)	5-10 mL/kg body weight	Water or sports drink
Before exercise (2 hr)	Additional 3-5 mL/kg if no urine output	Water
During exercise	0.4-1.0 L/hour (individualized)	Water + electrolytes (for > 1 hr)
After exercise	1.25-1.5 L per kg lost	Sports drink, water with electrolytes
Daily baseline	35-45 mL/kg	Water

Electrolyte Requirements During Exercise

Electrolyte	Sweat Loss Range	Replacement Strategy
Sodium	460-1,840 mg/L	Sports drinks (300-700 mg/L Na⁺), salt tablets
Potassium	120-300 mg/L	Sports drinks, bananas, coconut water
Magnesium	15-60 mg/L	Nuts, seeds, leafy greens
Calcium	20-100 mg/L	Dairy, fortified sports drinks

Dehydration Effects on Performance

Fluid Loss (% body weight)	Effect
1%	Thirst, impaired thermoregulation
2%	↓ Endurance performance, ↑ perceived exertion
3%	↓ Strength, ↓ power, ↓ cognitive function
4%	↓ Muscle endurance (20-30% reduction), heat cramps
5%	Heat exhaustion, significantly impaired performance
≥ 6%	Heat stroke risk, medical emergency

Nutrient Timing

Pre-Exercise (1-4 Hours Before)

Time Before	Meal Size	Examples
3-4 hours	Large (3-4 g/kg CHO)	Pasta with lean meat, rice bowl
2-3 hours	Medium (2-3 g/kg CHO)	Peanut butter sandwich, oatmeal
1-2 hours	Small (1-2 g/kg CHO)	Banana, granola bar
< 1 hour	Liquid/snack (0.5-1 g/kg CHO)	Sports drink, gel

During Exercise

Duration	Carbohydrate	Protein	Hydration
< 45 min	Not needed	Not needed	Water
45-75 min	Small amount (mouth rinse)	Not needed	Water or sports drink
1-2.5 hours	30-60 g/hour	Not needed	Sports drink (6-8% CHO)
> 2.5 hours	60-90 g/hour (glucose + fructose)	0.15-0.25 g/kg/hour	Sports drink + electrolytes
Ultra-endurance (> 5 hr)	90-120 g/hour (multiple transportable CHO)	0.25 g/kg/hour	Complete nutrition

Post-Exercise Recovery

Timing	Carbohydrate	Protein	Rationale
0-30 min (“anabolic window”)	1.0-1.5 g/kg	0.3-0.5 g/kg (20-40 g)	↑ Glycogen synthase, ↑ MPS
30 min - 2 hours	Balanced meal	Same	Continued recovery
2-4 hours	Regular meals	Spread across meals	Maintain positive protein balance

Ergogenic Aids and Supplements

Supplement	Evidence Level	Effective Dose	Recommendation
Caffeine	Strong	3-6 mg/kg 60 min before	Endurance, power, cognitive
Creatine monohydrate	Strong	5 g/day (loading: 20 g/day × 5-7 days)	Strength, power, lean mass
Beta-alanine	Strong	3.2-6.4 g/day (2-4 weeks loading)	High-intensity performance (1-4 min)
Sodium bicarbonate	Moderate	0.3 g/kg 60-90 min before	Buffering (400-1000 m events)
Beetroot juice (nitrate)	Moderate	500 mL (6-8 mmol nitrate) 2-3 hours before	Endurance, ↓ O₂ cost
BCAAs	Weak	Minimally effective	Adequate protein intake sufficient
Beta-hydroxy-beta-methylbutyrate (HMB)	Limited	3 g/day	Muscle preservation (detraining)

Body Composition for Athletic Performance

Sport	Typical Body Fat % (Male)	Typical Body Fat % (Female)
Endurance running	6-12%	14-22%
Cycling	8-15%	15-23%
Swimming	8-14%	16-24%
Sprint/power	8-14%	16-24%
Team sports (soccer, basketball)	8-15%	16-24%
Strength/powerlifting	10-18%	18-26%
Bodybuilding (competition)	3-6%	10-15%

Special Considerations

Scenario	Recommendation
Training at altitude	↑ Iron status, ↑ hydration, ↑ antioxidants
Training in heat	↑ Sodium/fluid, acclimatize 7-14 days
Weight class sports	Gradual weight loss (0.5-1%/week), avoid dehydration for weigh-in
Female athlete triad	Low energy availability + menstrual dysfunction + low BMD: treat with ↑ energy intake
Travel across time zones	Gradually adjust meal timing, maintain hydration, consider melatonin
Overtraining syndrome	Rest, ↑ energy intake, ↑ sleep, ↓ training volume