WHAT DO WE NEED TO BE ABLE TO MOVE?CHAPTER 3

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LEARNING GOALS SUCCESS CRITERIA

• To be able to explain the characteristics of

aerobic and anaerobic pathways and their

contribution to movement and dominant fibre

type associated with each pathway

• I can identify and explain the dominant energy

pathway utilised in a variety of aerobic or

anaerobic activities

• I can collect, analyse and report on data related to

responses to exercise and anaerobic and aerobic

pathways

MOVEMENT REQUIRES ENERGY!

Nutrients in food are converted into the body’s energy currency which is called ATP. This allows a muscle to

contract.

The energy released from the breakdown of foods cannot be transferred directly to our cells, so it has to be

stored.

ATP can only be stored in limited amounts, whether you’re a couch potato or an Olympic athlete.

MUSCULAR WORK

How we move determines our energy requirements and associated processes:

ENERGY DEMAND

Two factors determine the energy (ATP) demand of an event:

Exercise intensity – determines rate of ATP resynthesis needed

Exercise duration – determines yield of ATP resynthesis needed

Energy Systems

WHAT? 1

WHY? 2

HOW? 3

WHEN? 4

WHAT?

Energy systems break the bonds of different body fuels via a series of complex reactions to extract chemical

energy. This energy is used to resynthesise ATP for muscle contraction.

A car engine uses one type of fuel (petrol), skeletal muscle has the advantage of obtaining energy from breaking

down as many as four different fuel sources:

Creatine Phosphate (CP) or Phosphocreatine (PC)

Carbohydrates (CHO)

Lipid (fat)

Protein

These are mainly found in our diets and are stored in our bodies including our muscles, liver, adipose tissue and

blood.

WHAT?

The energy systems work together to meet the ATP requirements.

We have three energy systems or pathways that work together to supply the body with ATP, our universal energy

currency.

Anaerobic or “O2 independent”

ATP-PC system

Anaerobic glycolysis system

Aerobic or “O2 dependant”

Aerobic system

ATP-PC SYSTEM (F1 POWER)

This system provides the fastest rate of ATP resynthesis as it

uses the fuel creatine phosphate (CP) or phosphocreatine

(PC) already stored in the muscle.

This system has the fastest rate of ATP resynthesis, therefore is

used as the predominant energy system by athletes competing in

short duration, high-intensity ‘power’ events.

This is the most powerful system, but has a limited capacity to

generate ATP as it fatigues rapidly.

This can only be used as the predominant energy system for up

to 6 – 10 seconds. The first 2 – 3 seconds of maximal effort work

will rely on the breakdown of existing ATP stores in the muscle.

You may also hear this system being referred to as the alactacid

system or the phosphagen system.

ANAEROBIC GLYCOLYSIS SYSTEM (V8 SUPERCAR)

This system involves more complex chemical reactions that breakdown the fuel known as muscle

glycogen to release energy via the process of anaerobic glycolysis. This results in the formation of the by-

product lactic acid.

This system can resynthesise ATP at a fast rate allowing for the continuation of high-intensity effort. This system is

normally used in activities that last between 10 and 75 seconds.

Anaerobic glycolysis literally means ‘the breakdown of sugar independent of oxygen’.

ATP is resynthesised from the breakdown of carbohydrates mainly in the form of muscle glycogen (some can come

from blood glucose)

As oxygen is not present, glycogen is not completely broken down and pyruvic acid is formed which then ferments to

produce lactate.

AEROBIC SYSTEM (SMARTCAR)

This system is the most complex and involves the greatest number of chemical reactions. It has three

distinct stages and is able to use either carbohydrate (CHO) or lipids (fat) fuels stored inside and

outside of the working muscles. The by-products formed as a result of using this system include CO2,

H2O and heat.

The three stages are known as:

1. Glycolysis

2. Kreb’s Cycle

3. Electron Transport System (ETS)

This system has a considerably slower rate of ATP resynthesis due to a reduction in intensity, but has an unlimited

capacity for resynthesis and is therefore the predominant energy system used at rest and during events lasting

over 75 seconds.

Energy Systems

WHAT? 1

WHY? 2

HOW? 3

WHEN? 4

WHY?

We require ATP for muscle contraction and movement everyday. ATP is the body’s universal energy currency

used by all systems: cardiac, respiratory, muscular.

Actual ATP store (70kg)

50gRequired ATP for 1 day

190kg

Energy Systems

WHAT? 1

WHY? 2

HOW? 3

WHEN? 4

HOW?

Energy systems resynthesise ATP using energy released from fuels stored in the body.

Food Fuels Chemical fuels (substrates) Energy system

Lipids

(Fat)

Free Fatty Acids – FFA (blood)

Triglycerides (adipose tissue, muscle)

Aerobic

Carbohydrate

(CHO)

Glucose (blood)

Glycogen (muscle, liver)

Aerobic

Anaerobic Glycolysis

Creatine

(Cr)

Phosphocreatine – PC or CP (muscle) ATP-PC

Protein

(AA)

Amino acids – AA (blood, muscle) Aerobic

Substrate: is a fuel stored in the body in a chemical form that is broken to release energy for ATP.

Energy Systems

WHAT? 1

WHY? 2

HOW? 3

WHEN? 4

WHEN?

Energy

System

Predominant

fuel(s)

Predominant Power

(rate)

Capacity

(yield)

By-products Fatigue

mechanism

Event

ATP-PC Phosphocreatine

(PC)

6 – 10 sec Fastest Smallest None Fuel depletion (PC) 100m sprint, field

events,

weightlifting

Anaerobic

Glycolysis

Muscle glycogen

Glucose

30 to 60 sec Fast Small H+, lactate Accumulation of

by-products (H+)

400m sprint, 100m

freestyle

Aerobic Muscle

glycogen/glucose

Muscle triglyceride

Free Fatty Acids

1-2 mins to 3

hours

4 hours +

Medium

Slow

Large

Largest

CO2, H2O,

heat

Accumulation of

by-products (H+)

Fuel depletion

(MG)

Thermoregulation

1500m freestyle,

800m run

Ironman

(triathalon)

Aerobic glycolysis

Aerobic lipolysis

ENERGY SYSTEM INTERPLAY

The energy systems do not work in isolation. The way they work together is referred to as interplay.

The energy system said to be contributing the most to ATP resynthesis is referred to as the predominant energy

system.

Energy systems are not switched on or off, but instead increase and decrease their contributions.

At the start of any event, all 3 systems will contribute with ATP.

RELATIVE CONTRIBUTIONS TO MEET THE REQUIREMENTS OF HIGH-

INTENSITY EFFORTS.

Match the bars in

the graph with the

following events.

a) 400-metre sprint

b) 200-metre run

c) 3-kilometre run

d) 100-metre sprint

Refer to the graph.

a) Identify which graph best represents a 3-

kilometre run. Justify your answer.

b) Identify the times at which the anaerobic

systems would have been predominant.

c) Explain the contribution of the anaerobic

energy systems in the activity.

EXAM QUESTIONS

Question 1

Christine Ohuruogu ran a time of 49.62 seconds to win the gold medal in the 400-metre event at the 2008 Beijing Olympics. Identify the predominant fuel her body used for this event.

1 mark

Question 2

Identify the three by-products of the aerobic energy system.

1 mark

Question 3

Carbohydrates, fats and proteins are the three main food groups. Identify the chemicals that these three food groups are stored as in the muscles.

1 mark

Sport or event A B C D E F G H I

Percentage anaerobic energy contribution 10 20 30 40 50 60 70 80 90

Percentage aerobic energy contribution 90 80 70 60 50 40 30 20 10

Question 4

The table below shows the percentage of energy contribution for various activities

a) Which of the following would best match the letters A, E and H from the table in relation to the percentage

contribution of anaerobic and aerobic energy systems for that particular sport or event?

• Steve Hooker's pole vault world record attempt

• John Van Wisse's winning 48-kilometre swim around New York's Manhattan Island

• An AFL centre player's first quarter of football

• An Australian soccer striker attempting a shot on goal

• Olympic standard shot-put event

• Elite male 400-metre running event

• School cross-country run

• Secondary school swimming team 50-metre freestyle swimming race

3 marks

For each of the events selected, justify your choice.

3 marks

ENERGY SYSTEMS AND MUSCLE FIBRE TYPE

Muscle Fibre Characteristics Fuel Source used ATP

generation

Event type

Slow Twitch High resistance to fatigue

Large capacity to resynthesise

ATP

Red

Muscle glycogen

Blood glucose

FFA

Triglycerides

Aerobic Endurance

Fast Twitch (IIa) Resynthesise ATP at a fast rate

Fast oxidative fibres

Red

(Mixture of both) Aerobic

Anaerobic

Many team sports e.g.

hockey, netball

Fast Twitch (IIb) Contract rapidly

Large force

White

Phosphocreatine

Muscle glycogen

Anaerobic Short

Explosive

Powerful

KEY TERMS

ATP

Energy systems

Interplay

Resynthesis

ADP

Pi

High-energy phosphate

Phosphocreatine (PC)

Carbohydrate (CHO)

Lipid (Fat)

Protein

Adipose Tissue

Anaerobic

Aerobic

Predominant

Glycogen

Triglycerides

Amino Acids

Power

Capacity

Glycolysis

Oxygen-independent

Aerobic glycolysis

Aerobic lipolysis

Free Fatty Acids (FFA)