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Energy for Muscular Activity

Chapter 5

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Learning Objectives:

To develop an awareness of the basic chemical processes the body uses to produce energy in the muscles

To develop an understanding of the body’s three main energy systems

To introduce the effect of training and exercise on the energy systems

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The Chemistry of Energy Production Energy in the human body is derived from the breakdown of

complex nutrients like carbohydrates, fats, and proteins

The end result of this breakdown is production of the adenosine triphosphate (ATP) molecule

ATP provides energy necessary for body functions

Carbohydrates

Fats

Proteins

ATP Muscular Work

Digesting Food

Thermoregulation

Breakdown of Energy currency Biochemical processes

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ATP Cycle Overview

a) ATP breakdown

b) Phosphorylation

c) ATP resynthesis

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1. Hydrolysis of the unstable phosphate groups of

ATP molecule by H2O

3. Energy is released (38 to 42 kJ, or 9 to 10 kcal/mol ATP)

ATP H2O++ Energy++ Pi++

2. Phosphate molecule (Pi) is released from ATP (ATP ADP)

ADP

a) ATP breakdown (ATP turnover)

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1. Energy released by ATP turnover can be used by body when a free Pi group is transferred to another molecule (phosphorylation)

Energy for muscle contractionMolecule Pi++

b) Phosphorylation

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1. Initial stores of ATP in the muscles are used up very quickly and ATP must be regenerated

2. ATP is formed by recombination of ADP and Pi

ATPADP Energy++ Pi++

3. Regeneration of ATP requires energy (from breakdown of food molecules)

c) ATP resynthesis

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The Energy Systems

a) High energy phosphate system

b) Anaerobic glycolytic system

c) Aerobic oxidative system

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The Roles of the Three Energy The Roles of the Three Energy Systems in Competitive Systems in Competitive

SportSport

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High Energy Phosphate System Overview

Primary energy source:

Duration of activity:

Sporting events:

Advantages:

Limiting factors:

Stored ATP, CP

7 to 12 s

Weightlifting, high jump, long jump, 100 m run, 25 m swim

Produces very large amount of energy in a short amount of time

Initial concentration of high energy phosphates (ATP, PC)

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High Energy Phosphate System

CreatineCreatinePP ENERGYENERGY

ADP + Pi ATPADP + Pi ATP