1.1.c – Energy for exercise

Learning objectves

To describe how ATP is released and regenerated.

To explain the ATP-PC and glycoltc systems.

To understand the 3 stages of the aerobic energy system

To understand the energy contnuum and examples of sports placed on it.

To describe the factors that efect intermitent exercise and the interplay of energy systems.

Energy for exercise

How does the body contnually provide energy for exercise?

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We need a constant supply of energy so that we can perform everyday tasks. The more exercise we do the more energy is required.

Energy for exercise

The intensity and duraton of an actvity play an important role in the way in which energy is provided.

ATP is the usable form of energy in the body.

The energy from foods that we eat, such as carbohydrates, has to be converted into ATP before the potental energy in them can be used.

Adenosine

P P P

An ATP molecule consists of

adenosine and 3 Phosphates

ATP – (Adenosine Triphosphate)

ATP breakdownEnergy is released from ATP by breaking down the bonds that hold this compound together.

Adenosine

P P P

ENERGY

Enzymes are used to break down ATP.

ATP-ase is the enzyme used to break down ATP into ADP (adenosine diphosphate) and a single phosphate.

This type of reacton is an exothermic reacton.

Think. Pair. Share – What is meant by an exothermic reacton?

ATP resynthesisATP within muscle fbres are used up very quickly (2-3 seconds) and therefore needs to be replenished immediately.

ADP

P P P

For ATP to be rebuilt an endothermic reacton has to occur. This is a chemical reacton which absorbs energy.

Resynthesis of ATP is done through the joining of ADP and a single phosphate. This energy regeneraton is only possible through one of three energy systems.

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ATP STORE

ATPATP can provide several powerful contractons lastng only 2-3 seconds. This can be shown on a graph similar to the one below.

There are three energy systems that regenerate ATP: • ATP-PC system • Glycolytc system • Aerobic system

Each energy system is suited to a partcular

type of exercise depending on the

intensity and duraton and whether oxygen

is present.

Energy systems

Depleted ATP stores trigger the release of creatne kinase which causes phosphocreatne (PC) to be broken down anaerobically.

ATP-PC system

Phosphocreatne is an energy-rich chemical produced naturally by the body. This compound found in the sarcoplasm of the muscles.

This rapid availability of PC is important for providing contractons of high power, such as in the 100 m or in a short burst of intense actvity during a longer game i.e. a fast break in basketball.

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ATP-PC SYSTEM

ATP-PC systemHowever, there is only enough PC to last for up to 10 seconds and it can only be replenished when the intensity of the actvity is sub-maximal.

Advantages of ATP-PC System

Disadvantages of ATP-PC System

ATP can be regenerated rapidly. Limited supply of PC in the body.

PC stores are replenished within 3 minutes.

1 ATP molecule regenerated for 1 molecule of PC.

No fatguing by-products. Regeneraton can only take place in the presence of oxygen.

The ATP-PC system can be extended through the use of a creatne supplement.

ATP-PC systemThink. Pair. Share – Discuss and write down all the advantages and disadvantages of the ATP-PC System.

This breaking down of PC to release

energy is a coupled reacton.

For every one molecule of PC broken down there is enough energy released to create one molecule of ATP.

This is not very efcient system but it does have the advantage of not producing by-products and its use is important in delaying the onset of the lactc anaerobic system.

ATP-PC system

Once PC is depleted (at around 10 seconds) the glycoltc system takes over and regenerates ATP from the breakdown of glucose.

The breakdown of glucose is only possible in the presence of an enzyme Phosphofructokinase (PFK)

Glycogen

Enzyme: Phosphofructokinase

Glucose

Glycolysis

2 ATP

ENERGY

Glycoltc system

The process of glucose breakdown in the absence of oxygen is called anaerobic glycolysis and causes the producton of pyruvic acid.

The longer exercise contnues the higher the rise in lactc acid and pH levels. The slowly inhibits enzyme actvity causing fatgue and eventually OBLA.

Glycogen

Enzyme: Phosphofructokinase (PFK)

Glucose

Glycolysis

Pyruvic Acid

2 ATP

Lactic Acid

ENERGY

Glycoltc system

Enzyme: Lactate dehydrogenase (LDH)

Glycoltc systemGlycoltc ATP resynthesis will contnue for up to 3 minutes but peaks at 1 minute. This is partcularly useful for cycling sprint events or a counter atack in football.

Think. Pair. Share – What other events will predominantly use this system?

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GLYCOLTIC SYSTEM

Glycoltc systemThe graph below shows the glycoltc system ATP concentraton over tme.

Advantages of glycoltc system

Disadvantages of glycoltc system

ATP can be regenerated quickly due to few chemical reacton being needed.

Lactc acid is a by-product of this system.

With oxygen present, lactc acid is converted back to in glycogen.

Only a small amount of energy is released from glycogen while under anaerobic conditons.

This energy system is useful for producing an extra burst of energy.

Glycoltc systemThink. Pair. Share – Discuss and write down all the advantages and disadvantages of the glycoltc system.

Aerobic system of energy producton needs oxygen to functon. The complete oxidaton of glucose can produce up to 38 molecules of ATP and has 3 distnct stages.

Aerobic system

1st Stage – Aerobic glycolysis: This process is the same as anaerobic glycolysis but occurs in the presence of oxygen. Lactc acid is not produced and the pyruvic acid is converted into a compound called acetyl-coenzyme-A (acetyl CoA).

Glycogen

Pyruvic Acid

ENERGYGlycolysis

Aerobic system

2 ATP

Acetyl Co-A moves to the mitochondria within the muscle cell where the remaining stages are actvated.

Aerobic system

2nd Stage – Kreb’s cycle:Once the pyruvic acid difuses into the matrix of the mitochondria a complex cycle of reactons occurs in a process known as the Krebs cycle.

Acetyl-CoA

Citric Acid

2 ATP yielded

The reactons produces two molecules of ATP, as well as carbon dioxide.

Hydrogen is taken to the electron transport chain.

Hydrogen

Carbon Dioxide

Aerobic system

3rd Stage - Electron transport chain:Hydrogen is carried to the electron transport chain by hydrogen carriers. This occurs in the cristae of the mitochondria. The hydrogen splits into hydrogen ions and electrons and these are charged with potental energy.

The hydrogen ions are oxidised to form

water, while providing energy to resynthesise ATP. Throughout this process, 34 ATP molecules are

formed.

Hydrogen

34 ATP yielded

H-

H-

H+

H+

Water

Aerobic system

Total energy yield from the aerobic system is....

38 molecules of ATP

Aerobic system

Fats can also be used as an energy source in the aerobic system. The Krebs cycle and the electron transport chain can metabolise fat as well as carbohydrate to produce ATP.

Triglycerides (stored fat in muscle)

Glycerol and Free Faty Acids

Enzyme: Lipase

Kreb’s Cycle

Acetyl Coenzyme A

Aerobic system and Free Faty Acids

Metabolised aerobically

Beta Oxidaton

More ATP can be made from one molecule of faty acids than from one molecule of glycogen but the intensity must be low.

This is why in long duraton exercise, faty acids will be the predominant energy source.

Aerobic system and Free Faty Acids

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AEROBIC SYSTEM

Aerobic systemThe graph below shows the aerobic system ATP concentraton over tme.

Advantages of Aerobic System Disadvantages of Aerobic System

More ATP produced than anaerobic systems

It can take oxygen a while to become available.

No fatguing by-products (CO2 and Water which are exhaled).

Faty acid transportaton to muscle sites are slow.

Plenty of glycogen and triglyceride stores.

Aerobic systemThink. Pair. Share – Discuss and write down all the advantages and disadvantages of the aerobic system.

All the energy systems contribute during all types of actvity but one of them will be the predominant energy provider.

The intensity and duraton of the actvity are the factors that

decide which will be the main energy system in

use.

Energy Contnuum

Think. Pair. Share – What energy system would an 800m runner utlise during their race?

800m race:•ATP-PC System – Start of race.

•Aerobic System – Majority of race.

•Glycoltc System – Sprint fnish.

Energy Contnuum

Energy Contnuum

Think. Pair. Share – How many other sports can you place on the energy contnuum?

This is where the exercise intensity changes frequently. i.e. a basketball player is required to walk, run, sprint and jump at various points in the game.

Intermitent exercise

The point at which an athlete moves from one energy system to another is known as a threshold. This depends on the exercise intensity and fuel available.

Glycoltic

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Intermitent exercise

The ATP-PC/glycoltc threshold is the point at which the ATP-PC energy system is exhausted and the glycoltc system takes over.

Intermitent exercise

As a midfelder, performers would need to make short 3 second sprints to get free or beyond a defender (ATP-PC) but will also need the glycoltc system to make recovery runs back to help defend.

The glycoltc/aerobic threshold – this would occur when the ball is in phases of play away from the player. A performer will stll track and scan players movement but at a lower intensity.

Intermitent exercise

Sufcient oxygen will be available throughout to allow for ATP resynthesis.

Anaerobic sports such as rugby and basketball rely heavily on the ATP-PC system. Although the PC stores are depleted afer 8-10 seconds they also recovery quickly.

Recovery periods

This energy system is 50% recovered in just 30 seconds and fully recovered afer 3 minutes.

This makes tmeouts an essental part of a game of basketball.

Training must include the correct work to relief ratos. This will ensure sufcient oxygen supply and blood fow are able to break down the build up of lactc acid.

Recovery periods

Recovery periods also provide an opportunity to rehydrate, and replenish glucose stores in the form of glucose tablets, gels, bananas and isotonic drinks.

An athlete with a high aerobic capacity will be able to utlise a large volume of oxygen. This will increase the intensity with which they can work at before OBLA is reached and fatgue sets in.

Fitness Levels

Bufering capacity to lactc acid is also improved with higher ftness levels as is the ability to utlise FFA’Fs before glycogen stores.

There are a number of other factors that determine energy system contributon:

•Positon of players: A goalkeeper will not use the same energy systems as an outield player

•Tactcs and strategies: Man to man marking will raise the intensity and require a larger involvement of the anaerobic energy systems.

•Level of oppositon: Tougher opponents will push the demands of the game and rely on anaerobic systems for ATP resynthesis.

•Size of playing space: A larger feld (hockey feld) will slow the intensity of the game down in comparison to a smaller space (netball court) which increases the demands of the anaerobic system.

Additonal factors

Apply it! What has stuck with you?

Exam questons1. Two netballers were arguing about the positoning of netball on the energy contnuum.

Discuss the suggeston from their teacher that there are many factors to consider and that they may both be correct. [5]

Practce it!

Exam questons2. An elite marathon runner will have a very high aerobic capacity.Explain how the aerobic system provides energy during a marathon and how cardiovascular adaptatons as a result of an aerobic training programme can enhance aerobic capacity. [20]

Practce it!

Marks Scheme:

1. Five marks from: (depends on) positon on court. e.g. C will do more anaerobic work than GK.(depends on) standard of game. e.g. As standard rises, speed of game/anaerobic % increases(depends on) tactcs employed. e.g. high tempo game will result in more anaerobic work.motvaton/efort put in by player/pressure to win/importance of game. e.g. Presence of scout/selector/cup fnal will increase anaerobic %.

Practce it!

Marks Scheme:2. 1. Glycolysis - glycogen/glucose broken down to pyruvate in the sarcoplasm. Enzymes – Glycogen phosphorylase (GP) /

phosphofructokinase (PFK) - 2 ATP produced.

2. Pyruvate is converted in the link reacton - into acetyl co-enzyme A/CoA - which enters the Kreb’Fs cycle/citric acid cycle.

3. (acetyl CoA) - combines with oxaloacetc acid to form citric acid/cyclical set of reactons in (matrix of) mitochondria = 2 ATP produced - carbon dioxide released (and expired) - hydrogen produced (which enters ETC).

4. (Fats) - faty acids also used as fuel - beta-oxidaton - much larger amounts of ATP produced (dependent on type of fat).

5. (ETC) - (hydrogen enters) electron transport/transfer chain (hydrogen carried by) carrier molecules / NADs and FADs to cristae (of mitochondria) - (where H is split into) H+/protons/ions and electrons - H+ combines with oxygen to produce water - 34 ATP produced / 38 ATP in total.

6. (efect of ftness) - Aerobic capacity is very high (which means): runner is able to use more fats as fuel because he can get more oxygen to the muscles - fats need more oxygen to metabolise/break down for energy - runner can conserve stores of glycogen.

7. (adaptatons – heart) - myocardial hypertrophy, stronger contractons, increased stroke volume, increased maximal cardiac output.

8. (adaptatons – vascular) - Increased capilliarisaton at both muscles/tssues and lungs + greater surface area/greater gaseous exchange/more oxygenated blood to muscles / quicker removal of waste products/CO2. Increased bufering capacity + improved vascular shunt mechanism + increased elastcity of arterial walls.

9. (adaptatons – blood) - increased blood (plasma) volume + decreased viscosity of blood + increased haemocrit/red blood cells/haemoglobin.

10. (explanaton) - almost all of the adaptatons will increase oxygen to muscles + speed up lactate breakdown/removal + improve blood fow + (improved elastcity of arterial walls means) lower blood pressure/increased ability to cope with higher blood pressures.

Practce it!