1. Exercise Science Section 5: Energy Systems and Muscle Fiber Types
An Introduction to Health and Physical Education
Ted Temertzoglou Paul Challen
ISBN

2. The Three Energy Nutrients
Carbohydrates
Proteins
Fats
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3. The Role of Carbohydrates
Carbohydrates are the most abundant organic substances in nature, and they are essential for human and animal life.
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4. Adenosine Triphosphate (ATP)
Made in the mitochondrion
Resynthesized in two ways
Aerobically
Anaerobically
ATP ADP + P + ENERGY

5. Two Energy Systems Anaerobic System Without the use of oxygen (O2)
None of its metabolic activity will involve O2
Utilizes chemicals and enzymes; occurs in the muscle fibre
Short-lived
Aerobic System
In the presence of oxygen (O2)
All of its metabolic activity will involve O2
Occurs in the mitochondria
Leads to the complete breakdown of glucose

6. Three Metabolic Pathways
ATP-PC System (anaerobic alactic)
Glycolysis
(anaerobic lactic)
Cellular respiration
(aerobic)

7. ATP-PC System ATP-PC System (anaerobic alactic)
First of two anaerobic energy pathways
Relies on the action of stored ATP and phosphocreatine
Yields enough ATP for 10–5 seconds of energy
Provides highest rate of ATP synthesis
No by-product
PC + ADP ATP + CREATINE

8. Glycolysis Glycolysis (anaerobic lactic)
Second anaerobic energy pathway
Provides additional 1–3 minutes in high-level performance
Involves 11 separate biochemical reactions
Uses glucose and glycogen to make ATP
Yields twice as much ATP
By product is lactic acid (LA)
C6H12O6 + 2ADP = 2Pi C3H6O3 + 2ATP + 2H2O (Glucose) (Lactate)

9. The Aerobic System Aerobic system (cellular respiration)
Third energy system
Glycolysis
Krebs cycle
Electron transport chain
Uses glucose, glycogen, fats, and protein to make ATP
Lasts 120 seconds and beyond
C6H12O6 + 6O2 + 36ADP + 36Pi CO2 + 36ATP + 6H2O

10. Energy Pathways

11. Energy Sources for Different Sports

12. Lactic Acid

13. Energy from Fats and Protein
Aerobic system (cellular respiration)
Third energy system
Glycolysis
Krebs cycle
Electron transport chain
Uses glucose, glycogen, fats, and protein to make ATP
Lasts 120 seconds and beyond
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14. Slow-Twitch and Fast-Twitch Muscles
Slow-twitch muscle fibres:
Most active during: long-distance running, swimming, and cycling
Red or dark in colour
Generate and relax tension slowly; able to maintain a lower level of tension for long durations
Low levels of myosin ATPase and glycolytic enzymes
High levels of oxidative enzymes
Fast-twitch muscle fibres:
Ideal for: short sprints, powerlifting, and explosive jumping
Pale in colour
Ability to tense and relax quickly; generate large amounts of tension with low endurance levels
High levels of myosin ATPase and glycolytic enzymes

15. Approximate Distribution of Muscle Fibre Types for Different Sports

16. Three Fibre Types Type I or Slow-Oxidative (SO) Generate energy slowly
Fatigue-resistant
Depend on aerobic processes
Type IIA or Fast-Oxidative Glycolytic (FOG)
Intermediate-type muscle fibres
Allow for high-speed energy release
Allow for glycolytic capacity
Type IIB of Fast-Glycolytic (FG)
Store glycogen and high levels of enzymes
Allow for quick contraction without the need for oxygen

17. Characteristics of Different Muscle Fibre Types