1. Energy Systems Flashcards
What is energy?
The ability to do work (joules)
How many energy systems are there?
3 - 2 anaerobic, 1 aerobic
What is ATP?
adenosine triphosphate - a molecule that stores and supplies energy
What is chemical energy?
energy from food
What is kinetic energy?
movement energy (skeletal muscle contraction)
What is potential energy?
stored energy
What is work?
force x distance (joules)
What is power?
work performed over a unit of time (watts)
What are the 4 substrates / food fuels?
PCr, glucose, lipids, amino acids
What are the 2 anaerobic energy systems called?
ATP-PCr system, anaerobic glycolysis/lactic acid system
What is the aerobic energy system called?
Aerobic glycolysis
What source of energy is immediately available?
adenosine triphosphate (ATP)
What does the breakdown of ATP result in?
energy for movement
How long does ATP last for before needing to be resynthesised?
2-4 seconds
What type of exercise is the ATP-PCr system used for?
very high intensity, 90-100% maximum heart rate
What is the energy yield for the ATP-PCr system?
1mol ATP per 1 mol PCr
What is PCr?
Phosphocreatine - compound stored in sarcoplasm in muscle
What is creatine kinase?
An enzyme that detects high levels of ADP
What is ADP?
adenosine diphosphate
PCr breakdown equation
PCr > P + Cr + energy > ADP + Pi + energy > ATP
How long does the ATP-PCr system last?
8-12 seconds
How long does it take for PCr stores to be replenished?
3 mins for approx. 98% stores
Advantages of ATP-PCr system:
-immediately available energy
-doesn’t produce lactic acid
-no waste products
-doesn’t require oxygen
-replenishes ATP quickly
Disadvantages of ATP-PCr system:
-only a short store of energy
-long recovery time
-low ATP yield per PCr
ATP-PCr system example sporting activities
-heavy weightlifting
-100m sprint
What occurs in the anaerobic glycolysis system?
breaks down glucose and glycogen to form ATP
How is glucose stored in the body?
as glycogen in liver and muscle cells
Anaerobic glycolysis equation
glycogen > glucose > (energy) > pyruvic acid > lactic acid > lactate/hydrogen ions
Anaerobic glycolysis energy yield
2 mol ATP per 1 mol glycogen
How do hydrogen ions affect exercise?
They cause fatigue by increasing the blood acidity causing enzymes to denature so their ability to catalyse reactions is slowed
What type of exercise is the anaerobic glycolysis system used for?
High intensity, 2-3mins but peaks at 1 min
Anaerobic glycolysis example sporting activities:
-netball
-football
-400m-800m race
Advantages of anaerobic glycolysis system:
-higher energy yield - 2 ATP per 1 glycogen
-oxygen not needed
-lasts 3mins
-rely on food to replace glucose
-sustain high intensity activity for longer
Disadvantages of anaerobic glycolysis system:
-peaks at 1min so inconsistent
-produces lactic acid (H+ ions)
-produces fatiguing by-product
-takes longer to replenish ATP
What 3 ways does the aerobic glycolysis system produce ATP?
-krebs cycle
-electron transport chain
-beta oxidation
Aerobic glycolysis equation
glycogen > glucose > (energy - 2 ATP) > pyruvic acid > (O2) > acetyl coenzyme A > krebs cycle > (CO2, H- electrons) (2 ATP) > electron transport chain > (CO2, H2O) (34 ATP)
aerobic glycolysis energy yield
38 ATP
aerobic glycolysis example sporting activities
-marathon
-long distance cycle
What type of exercise is the aerobic glycolysis system used for?
low intensity, 5+mins
advantages of aerobic glycolysis system:
-greater energy yield - 38 ATP
-no fatiguing by-products
-utilises 3 energy substrates/food fuels
disadvantages of aerobic glycolysis system:
-generates ATP slowest
-needs sufficient amount of oxygen
aerobic lipolysis equation:
fats > glycerol + free fatty acids > acetyl coenzyme A > krebs cycle > electron transport chain (147 ATP)
Energy continuum principle
Energy systems don’t switch from one system to another
There is a more predominant energy system however all are active but interchanging
Factors influencing energy system used
-Intensity
-Duration
- fitness level
Exercise intensity - influence on energy system
- the more intense the exercise, the more amount of PC and muscle glycogen (anaerobic stores) will be used
- lower to medium intensity will predominantly use the aerobic system
Exercise duration - influence on energy system
-If exercise is a longer duration it is more likely to use the aerobic system
- shorter duration & higher intensity will use the anaerobic system
Fitness level - influence on energy system
- Higher level of aerobic system will take longer to reach anaerobic threshold
- when performing anaerobically there is limited energy available
-If exercise continues performer will run out of anaerobic stores so return to aerobic & intensity will drop - greater anaerobic fitness means performer can work anaerobically for longer producing more powerful movements
Food fuels / energy substrates
- PCr → 90 - 100% max HR (ATP-PC), 8 - 12 secs
- Glucose (carbohydrates) → 80 - 90% (anaerobic glycolysis) 3 mins, 60 - 80% (aerobic glycolysis) 5+ mins
- Lipids (fats) → 40 - 60%, when glucose depleted
- Amino acids (proteins), when glucose/lipids depleted
