Energy Systems Study Notes

Energy Systems Overview

  • Metabolism: All chemical processes for life's maintenance.

    • Anabolism: Constructive phase (e.g., glucose → glycogen).

    • Catabolism: Destructive phase (e.g., triglycerides → glycerol + fatty acids).

    • Aerobic: Requires oxygen. Anaerobic: Independent of oxygen.

Mitochondria's Role

  • Essential for energy provision in all cells (excludes red blood cells).

  • Site of aerobic metabolism (Krebs cycle, electron transport chain).

Energy Currency: ATP

  • ATP: Energy from organic molecules; releases energy when phosphate bonds break.

  • Connects anabolic and catabolic reactions; facilitates energy transfer.

Muscle Contraction Energy

  • Requires significant ATP; initial 2 seconds from stored ATP.

  • Longer activities depend on ATP from carbohydrates and fats.

Carbohydrate Metabolism

  • Digestion converts carbohydrates to monosaccharides (e.g., glucose).

  • Glycolysis: Breakdown of glucose to pyruvate (anaerobic process).

  • Under aerobic conditions: pyruvate → carbon dioxide + water; anaerobically → lactate.

Glycogenesis and Glycogenolysis

  • Glycogenesis: Glucose stored as glycogen (excess glucose).

  • Glycogenolysis: Breakdown of glycogen to glucose (when more glucose is needed).

Aerobic Energy Systems

  • Glucose Oxidation: Pyruvate to acetyl CoA; enters Krebs cycle.

  • Fat Oxidation: Beta-oxidation breaks down fatty acids to acetyl CoA.

Energy Systems Characteristics

  • Phosphagen system is fastest; fat oxidation is the slowest.

  • Energy system activation varies with exercise intensity.

Hormonal Regulation

  • Controlled by insulin, glucagon, epinephrine, etc.

  • Insulin: Increases glucose uptake and promotes glycogenesis.

  • Glucagon: Stimulates glycogenolysis and increases blood glucose.

VO2max and Endurance

  • VO2max: Max oxygen uptake; varies by sex and age.

  • Higher training improves VO2max due to cardiovascular adaptations.

Oxygen Deficit and Recovery

  • Initial ATP demand met by stored ATP, creatine phosphate, then anaerobic glycolysis.

  • EPOC: Oxygen consumption continues post-exercise to recover from anaerobic effects.