Sports

Role of Carbohydrates

Primary fuel for contracting skeletal muscle, especially at higher intensities.

Muscle Glycogen

Stored as muscle glycogen (~300–400 g) and liver glycogen (~80–110 g).

Glycogen Depletion

A major cause of fatigue in endurance exercise.

High Intensity Exercise

Muscle depends heavily on carbohydrates, glycogen use increases.

Hypoglycemia

Blood glucose level <3 mmol/L causing dizziness, poor motor skills, and decreased concentration.

Glycogen Loading

A strategy to maximize glycogen stores before endurance events.

Classical Carbohydrate Loading Model

3–4 days of low CHO + hard training followed by 3–4 days of high CHO.

Modified Carbohydrate Loading Model

3 days of high CHO (8–12 g/kg BM/d) + tapering exercise, more practical.

Carbohydrates & Fatigue

Carbohydrate loading boosts glycogen, delays fatigue, and improves performance.

Fat Role in Exercise

Fat serves as a major energy reserve and provides sustained energy at low–moderate intensities.

Fat Oxidation at Low Intensity

Mostly plasma FFA oxidation.

Moderate Intensity Exercise

Fat oxidation peaks with a mix of plasma FFA and IMTG.

High Intensity Exercise

CHO dominates due to faster ATP needs and inhibited fat metabolism.

Endurance Training Adaptations

Increase mitochondrial density, IMTG storage, and capacity to mobilize & oxidize fat.

Nutritional Ergogenic Aids

Substances like caffeine and creatine that enhance performance.

Caffeine Benefits

Increases endurance, alertness, and reduces perceived exertion.

Creatine

Increases phosphocreatine stores and supports high-intensity short-duration exercise.

Vitamin D Role

Regulates calcium, bone health, muscle function, and immunity.

Vitamin D Deficiency

Can lead to increased risk of stress fractures and impaired muscle recovery.

Recommended Daily Protein for Athletes

Endurance: 1.2–1.6 g/kg/d; Strength/power: 1.6–2.2 g/kg/d.

Protein Timing

Consume protein within 0-2 hours post-exercise to enhance recovery.

Whey Protein

Fast-digesting and high in leucine, potent for muscle protein synthesis.

High-Fat Diet Performance Effects

May increase fat oxidation but impair high-intensity performance.

Hydration before Exercise

5–7 mL/kg BW approximately 4 hours prior to exercise.

Electrolytes Importance

Sodium replacement is crucial for events lasting >2 hours.

2% Dehydration Effects

Can impair performance, cognition, and thermoregulation.

Exercise and T2D

Regular physical activity reduces the risk of Type 2 Diabetes by ~30-40%.