Bioenergetics And Muscle Metabolism

chapter

Learning Objectives
• Learn how our bodies change the food we eat into ATP to provide our muscles with the energy they need to move • Examine the three metabolic systems that generate ATP

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Fuel for Exercise : Bioenergetics and Muscle Metabolism

Terminology
• Substrates
– Fuel sources from which we make energy (adenosine triphosphate [ATP]) – Carbohydrate, fat, protein

Measuring Energy Release
• Can be calculated from heat produced • 1 calorie (cal) = heat energy required to raise 1 g of water from 14.5°C to 15.5°C • 1,000 cal = 1 kcal = 1 Calorie (dietary)

• Bioenergetics
– Process of converting substrates into energy – Performed at cellular level

• Metabolism: chemical reactions in the body

Metabolism and
Oxidative System

• ATP yield: depends on substrate
– 32 to 33 ATP/1 glucose – 100+ ATP/1 FFA

• Duration: steady supply for hours • Most complex of three bioenergetic systems • Occurs in the mitochondria, not cytoplasm

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Oxidation of Carbohydrate
• Stage 1: Glycolysis • Stage 2: Krebs cycle • Stage 3: Electron transport chain

Figure
In the presence of oxygen, pyruvic acid from glycolysis is converted to acetyl coenzyme A (acetyl CoA) 2. Acetyl CoA enters the Krebs cycle and forms 2 ATP, carbon dioxide, and hydrogen 3. Hydrogen ion created during glycolysis and through the Krebs cycle combines with two coenzymes (NAD and FAD) 4. NAD and FAD carry hydrogen ions to the electron transport chain (NAD and FAD → NADH and