Macronutrients

Macronutrients

1. Carbohydrate

   • Fuel sources
     • Blood glucose
       • From liver glycogen
       • Increased usage with intensity
     • Muscle glycogen
       • GREATLY increased usage with intensity
   • Rely more on CHO during high-intensity exercise
     • Rate of energy transfer 2x fat/protein
   • Storage
     • 500 g (2000 kcal)
     • Plasma glucose
       • 4 g (16 kcal)
     • Liver glycogen
       • 100 g (400 kcal)
     • Muscle glycogen
       • 400 g (1600 kcal)
   • Glycogen
     • Importance of glycogen
     • Muscle glycogen depletion during exercise
     • Key to endurance performance
       • Carb depleted
         • Can't maintain workload
         • Lower plasma glucose
         • Lower plasma lactate
         • Higher FA oxidation
   • Glucose
     • Falls after 1 hour endurance exercise
     • Production by liver
       • Glycogenolysis
         • Major backup source for blood glucose
           • Increases with exercise time
           • Increases with intensity
         • Uses metabolic byproducts
       • Gluconeogenesis
       • Increases with intensity
     • Glucose uptake increases with intensity

2. Fat

   • Fuel sources
     • Plasma fatty acid
       • From adipose tissue
       • Decreased usage with intensity
     • IMTG
       • Increases, then decreases with intensity
   • Rely more on stored fat during low-intensity exercise

3. Protein