Sports Nutrition Basics: Fueling Performance and Recovery

Diet Accounts for 30–40% of Athletic Performance — Training Cannot Compensate for Poor Nutrition

A survey of elite athletes found that fewer than 20% met the carbohydrate recommendations appropriate for their training load. Glycogen depletion — not fitness — was limiting their performance. Sports nutrition is not about eating "clean" or avoiding particular foods. It is about strategic fueling: providing the right nutrients, in the right amounts, at the right times to support training, accelerate recovery, and optimize body composition. The fundamentals are simpler than supplement marketing suggests.

Macronutrient Foundations

Carbohydrates: The Primary Fuel

Carbohydrates are the dominant fuel for moderate-to-high intensity exercise. Stored as glycogen in muscles (~400g) and liver (~100g), glycogen depletion is the primary cause of performance decline in sessions lasting more than 60–90 minutes. Carbohydrate needs scale with training intensity and duration:

Light training (under 60 min/day): 3–5 g/kg body weight/day
Moderate training (1–3 hours/day): 5–7 g/kg body weight/day
High-intensity endurance (3–4 hours/day): 6–10 g/kg body weight/day
Very high volume (4+ hours/day): 8–12 g/kg body weight/day

A 75kg (165 lb) athlete training moderately needs 375–525g of carbohydrates daily — far more than general population recommendations and far more than low-carb dietary guidelines suggest.

Protein: For Muscle Repair and Synthesis

Athletes need significantly more protein than sedentary individuals. International Society of Sports Nutrition position stands recommend:

1.4–2.0 g/kg/day for endurance athletes
1.6–2.2 g/kg/day for strength and power athletes
Up to 2.4–3.1 g/kg/day during caloric restriction to preserve muscle mass

Distributing protein across 4–6 meals/day of 20–40g each maximizes the frequency of muscle protein synthesis stimulation — more effective than consuming the same total in 1–2 large meals.

Dietary Fat: Essential Functions

Fat supports hormone production (testosterone, cortisol, estrogen), fat-soluble vitamin absorption, and provides fuel for low-intensity aerobic work. Athletes should not fall below 20% of total calories from fat. Extremely low-fat diets impair hormonal function and vitamin absorption without improving performance. Sources rich in omega-3 fatty acids (fatty fish, walnuts, flaxseed) reduce exercise-induced inflammation and may support recovery.

Pre-Workout Nutrition

Timing	Recommended Intake	Purpose
3–4 hours before	Full mixed meal: carbohydrates (1–4 g/kg), moderate protein, low fat	Top off glycogen; provide sustained energy without GI distress
1–2 hours before	Lighter snack: carbohydrate-focused (1–2 g/kg), small protein	Immediate energy without digestive discomfort during exercise
Under 60 minutes before	30–60g fast-digesting carbohydrate only (if needed)	Quick energy; high protein or fat at this timing can cause GI issues

Intra-Workout Nutrition

For sessions under 60 minutes: water is sufficient. No carbohydrate intake needed for most training sessions of this length.

For sessions 60–90 minutes: 30–60g/hour of carbohydrates. Glucose-based sports drinks, gels, or easily digestible carbohydrate foods.

For sessions over 90 minutes: 60–90g/hour using multiple carbohydrate types (glucose + fructose), which use different intestinal transporters and can absorb faster than single-carbohydrate sources.

Evidence-Based Supplements

Supplement	Evidence Level	Recommended Use	Effective Dose
Creatine Monohydrate	Strong (A-grade)	Power, strength, high-intensity intervals; muscle mass during resistance training	3–5g/day; loading phase optional (20g/day for 5 days)
Caffeine	Strong (A-grade)	Endurance, strength, power; reduces perceived exertion	3–6 mg/kg body weight 45–60 min before exercise
Beta-Alanine	Moderate (B-grade)	High-intensity exercise 1–4 minutes; buffers muscle acid	3.2–6.4g/day (divided doses to reduce tingling)
Sodium Bicarbonate	Moderate	Brief maximal efforts; buffers blood pH	0.3g/kg 60–90 min before intense exercise
Protein Powder	Strong (for hitting protein targets)	Convenient protein source; not superior to whole food protein	As needed to meet daily protein targets
Vitamin D	Moderate	Deficiency impairs muscle function; supplementation helps deficient athletes	Varies by blood level; 1,000–4,000 IU/day common range

Hydration Strategies

Dehydration of 2% body mass impairs endurance performance by 4–8% and cognitive function measurably. Hydration strategy depends on sweat rate and sodium losses, which vary enormously between individuals.

Before exercise: Drink 5–7 mL/kg 2–4 hours before; an additional 3–5 mL/kg 2 hours before if not producing clear urine
During exercise: Drink to thirst for most sessions; drink on a schedule for sessions over 90 minutes in heat
Electrolytes: For sessions over 60 minutes, especially in heat, sodium replacement (300–1,000 mg/hour) prevents hyponatremia and maintains thirst drive
After exercise: Replace 125–150% of fluid lost (weigh before and after; each kilogram lost = approximately 1 liter deficit)

Energy Availability and RED-S

Relative Energy Deficiency in Sport (RED-S) occurs when energy intake is chronically insufficient relative to training demands. Originally identified as the "female athlete triad" (disordered eating, amenorrhea, low bone density), RED-S is now recognized as affecting all athlete genders. Consequences include hormonal disruption, stress fractures, immune suppression, psychological effects, and impaired performance — the opposite of the intended goal.

Disclaimer: Nutritional needs vary based on individual physiology, training type, and health status. Consult a registered dietitian with sports nutrition expertise for personalized guidance.