Energy Metabolism During Exercise Flashcards
Characteristics of type 1 fibers
Slow oxidative
Prefer TAG as energy
Slow contraction
Characteristics of type 2A fibers
Fast oxidative
Intermediate fibers
High glycogen content
Fast contraction
Characteristics of type 2x fibers
Very fast contraction
High glycogen content
White fibers
3 energy sources during exercise
- ATP-CP system
- Lactic acid system
- Aerobic system
•Lactic acid system is for
(anaerobic glycolysis)
Aerobic system is for
(aerobic glycolysis, TCA cycle, oxidation of fatty acids)
At rest or during normal daily activities: What percentage of macronutrients are being used?
–FAT provides 80-90%
–Carbs provide 5-18%
–Protein provides 2-5%
When do amino acids become an important source of energy?
Very long durations of physical activity
At 2-30% VO2 max:
plasma fatty acids and muscle TAG are the main sources of energy
•Up until 50% VO2 max:
fatty acids are the preferred substrate (also muscle glycogen)
At 65% VO2 max (moderate intensity):
–Fat oxidation increases (probably due to muscle TAG)
–Plasma fatty acids and muscle TAG contribute equally to energy expenditure
At 60-75%:
–Fatty acid oxidation cannot keep up
–50% of energy derived from carbohydrate oxidation
At intensities between 65-85% VO2 max:
–Rate of lipolysis in adipose is high but fewer fatty acids are released into plasma
–May be because of insufficient blood flow and albumin delivery of FA
–FA are thought to become trapped in adipose tissue at higher intensity exercise
The higher the VO2 max the more
Glycogen is used for energy
Carb loading is only beneficial to what type of athletes
Long distance runners
