Energy systems.

PHYSIOLOGICAL PHYSIOLOGICAL REQUIREMENTS OF REQUIREMENTS OF PHYSICAL ACTIVITYPHYSICAL ACTIVITY

FoodsFoods

Fuel andFuel and

Energy SystemsEnergy Systems

Where does this energy come from?

A Roger Federer serve takes 1-2 seconds A Roger Federer serve takes 1-2 seconds to perform. It’s fast & explosive. He to perform. It’s fast & explosive. He might do this hundreds of time over a might do this hundreds of time over a game. Plus he has to run fwd, bkwd and game. Plus he has to run fwd, bkwd and sideways for 1-2 hours. His Muscles sideways for 1-2 hours. His Muscles requires ENERGY to do this. requires ENERGY to do this.

Food Fuels our BodyFood Fuels our Body

1. CARBOHYDRATES 1. CARBOHYDRATES (Glycogen)(Glycogen)

2. PROTEIN2. PROTEIN

3. FATS3. FATS

CARBOHYDRATESCARBOHYDRATES

CerealsCereals

BreadsBreads

PastasPastas

RiceRice

SugarSugar

Carbohydrates are stored as Glycogen in Muscle & LiverCarbohydrates are stored as Glycogen in Muscle & Liver

CHO is the body’s preferred fuel during Exercise CHO is the body’s preferred fuel during Exercise – breaks down easily, uses little oxygen– breaks down easily, uses little oxygen

Fruit/Veges

PROTEINPROTEINRed MeatRed Meat

EggsEggs

Dairy Dairy productsproducts

FishFish

PoultryPoultry

Protein is stored as MUSCLE and AMINO ACIDS around the body.Protein is stored as MUSCLE and AMINO ACIDS around the body.

GRAINSGRAINS

5-10% contribution to endurance events: 5-10% contribution to endurance events: Mainly used for growth/repairMainly used for growth/repair

FATSFATS

ButterButter

MargarineMargarineOilsOils

CheeseCheeseNutsNuts

Food that we ingest is stored and burnt to fuel Food that we ingest is stored and burnt to fuel our musclesour muscles

This food must be converted This food must be converted into a chemical compound into a chemical compound called called ATPATP

WithoutWithout ATP -ATP - Muscles Muscles cannot contractcannot contract

A.T.P.

Adenosine triphosphate. This is energy for muscle

contraction. Energy for movement of muscle

fibres is stored in the muscle as a molecule of ATP.Adenosine P P P

Adenosine triphosphate

To use the stored ATP

To release the energy, ATP is broken down into ADP + Pi (Adenosine diphosphate + Phosphate molecule)

The energy released allows for a muscle contraction.

Adenosine P P + Pi

Energy

Resynthesis of ATP

There is only enough stored ATP for about 1-2 contractions, so….we must resynthesise ADP back into ATP.

Fuel and energy for this comes from CHO, Fats, Proteins and Creatine phosphate.

These fuel sources resynthesise the free Phosphate molecule (Pi) back to the ADP to reform ATP.

Adenosine P P Pi

Adenosine P P + Pi

CHO, Fats, Proteins, CP

Resynthesises the ADP back to ATP

ATP is used in all 3 energy systems.

The type of energy system used and the interplay

between them depends on the frequency, duration,

intensity of the activity and fitness levels of the individual.

The 3 energy systems

The ATP – PC system Alactacid system Creatine phosphate system Phosphagen system.

The Lactic Acid Systems Anaerobic glycolysis system Lactacid system

Aerobic System Aerobic Glycolysis

For activity lasting:For activity lasting: 0-10 SEC0-10 SEC ATP-PC ATP-PC SYSTEMSYSTEM

10-30/40 SEC10-30/40 SEC

Anaerobic Anaerobic Glycolytic Glycolytic SYSTEMSYSTEM

2MINS +2MINS +

AEROBIC AEROBIC SYSTEMSYSTEM

High Energy Phosphate System

ATP –PC system cont..

ATP breaks down to ADP + Pi to release energy.

The ADP + Pi must be reformed to ATP for continued muscle function.

PC provides the energy for the free Pi to be re-attached to the ADP molecule to form ATP.

ATP –PC system cont..

PC stored in the muscles breaks down anaerobically (without O2) to form Phosphate and Creatine. This releases energy for the resynthesis of ATP.

It takes 2 PC molecules to resynthesise 1 ATP molecule (one PC = 0.7 ATP).

NOTE: The resynthesis of PC (Phosphate + Creatine = PC) occurs in the recovery phase.

ATP-PC ATP-PC SYSTEMSYSTEM

Uses stores of CP (Creatine Phosphate) to REMAKE ATP

Only have 10 Only have 10 seconds of CP seconds of CP in musclesin muscles

CP instantly CP instantly available, but available, but runs out runs out quicklyquickly

Used for high Used for high intensity intensity Jumps, Throws, Jumps, Throws, SprintsSprints

If activity lasts longer than 10 sec, ATP must be If activity lasts longer than 10 sec, ATP must be REMADE by some other means…..REMADE by some other means…..

Training the High Energy Phosphate System

a) Interval training:

- 20% increase in CP (creatine phosphate) stores- no change in ATP stores- increase in ATPase function (ATP -> ADP+P)- increase in CPK (creatine phosphokinase)

function (CPK breaks down CP molecule and allows ATP resynthesis)

b) Sprint training:

- increase in CP stores up to 40%- 100% increase in resting ATP stores

Summary

Each ATP molecule is made up of an adenosine part and three phosphate groups. When 1 mole (1) of ATP is broken down, 7 to 12 Kcal (2) of energy is released.

Besides ATP, there is still another high-energy compound called phosphocreatine (PC) inside the human muscle cells. When PC is broken down, energy is released for the resynthesis of ATP.

Summary Cont…

However, the total amount of PC stored in the human body is also extremely limited. There are altogether 450 to 510 mM PC, or 4.5 to 5.1 Kcal of energy in the human body. The energy released from the breaking down of ATP is also required to resynthesize PC. Nevertheless, this process will be carried out when the human body is in the recovery stage.

The complete ATP-PC system can only supply 5.7 to 6.9 Kcal of energy, which can maintain about 10 seconds of maximal efforts.

Summary cont…

The importance of the ATP-PC system is that it is the instant

energy source in the human body.

The ATP-PC system does not require oxygen in the muscles for proper functioning. Besides, the required fuels (ATP and PC) have already been stored in the muscle cells

The chemical reactions involved when PC is broken down are fewer than the other two energy systems.

The ATP-PC system is particularly important for high-intensity and high- speed activities that need to be completed in a few seconds (e.g., starting, jumping, throwing, and weight lifting).

Anaerobic Glycolytic Anaerobic Glycolytic SYSTEMSYSTEM

Body uses stored fuel of GLYCOGEN to REMAKE ATP

Downside – by-product called Lactate. Hydrogen Ions also released which inhibit muscle contraction

Need Oxygen to Need Oxygen to do this properlydo this properly

Happens because of lack Happens because of lack of enough Oxygen to of enough Oxygen to break down Glycogenbreak down Glycogen

400m run, 800m at high intensity400m run, 800m at high intensity

About 2-3 About 2-3 hours of hours of glycogen glycogen stored in stored in body.body.

The Anaerobic Glycolytic

System

Glycolysis A biochemical process that releases energy in the

form of ATP from glycogen and glucose anaerobic process (in the absence of oxygen) The products of glycolysis (per molecule of

glycogen):

- 2 molecules of ATP

- 2 molecules of pyruvic acid The by-product of glycolysis (per molecule of

glycogen):

- 2 molecules of lactic acid

The highly complex metabolic pathways of

glycolysis

)

Anaerobic Threshold The exercise intensity at which lactic acid begins to

accumulate within the blood The point during exercise where the person begins to

feel discomfort and burning sensations in their muscles Lactic acid is used to store pyruvate and hydrogen ions

until they can be processed by the aerobic system

The Anaerobic Glycolytic System cont. Starts when:

the reserves of high energy phosphate compounds fall to a low level

the rate of glycolysis is high and there is a buildup of pyruvic acid

Substrates for the anaerobic energy system

The primary source of substrates is carbohydrate

Carbohydrates: primary dietary

source of glucose primary energy

fuels for brain, muscles, heart, liver

Glucose stored in blood

Glycogen stored in muscle or liver

Complex Carbohydrates

Digestive system

Glycogen

Gluconeogenesis

Circulation of glucose around body

GlucoseBlood Stream

Carbohydrate breakdown and storage

Effect of Training on the Anaerobic Glycolytic System

Rate of lactate accumulation is increased in the trained individual

This rate can be decreased by:

a) reducing the rate of lactate production - increase in the effectiveness of the aerobic oxidative system

b) increasing the rate of lactate elimination - increased rate of lactic acid diffusion from active muscles

- increased muscle blood flow - increased ability to metabolize lactate in the heart, liver and in

non- working muscle

AEROBIC SYSTEMAEROBIC SYSTEMUsed in Used in longer, sub-longer, sub-max max activities. activities. Long run, Long run, swim, cycle.swim, cycle.

Plenty of Oxygen available to remake ATP . So no LA or H+ is accumulated

Oxygen supply Oxygen supply meets demandmeets demand

Will keep suppling ATP Will keep suppling ATP for as long as Fitness for as long as Fitness levels allowlevels allow

We use this We use this system at REST system at REST (Now!) – except we (Now!) – except we burn…burn…

FAT!!!!FAT!!!!

Like the LA Like the LA system, the system, the Aerobic uses Aerobic uses Glycogen to Glycogen to remake ATP.remake ATP.

Aerobic Oxidative System

The Aerobic Oxidative System

The most important energy system in the human body Blood lactate levels remain relatively low (3-6mmol/L bl) Primary source of energy (70-95%) for exercise lasting

longer than 10 minutes provided that: a) working muscles have sufficient mitochondria to meet

energy requirements b) sufficient oxygen is supplied to the mitochondria c) enzymes or intermediate products do not limit the Kreb’s

cycle Primary source of energy for the exercise that is

performed at an intensity lower than that of the anaerobic oxidative system

The Oxidative Phosphorylation System Two Pathways: Krebs Cycle & Electron Transport Chain Biochemical process used to resynthesize ATP by combining ADP

and P in the presence of oxygen Takes place in mitochondrion (contains enzymes, co-enzymes) Energy yield from 1 molecule of glucose is 36 ATP molecules Energy yield from 1 molecule of fat up to 169 ATP molecules By-products of this reaction: carbon dioxide, water

Cori Cycle Lactic acid is taken to the liver to be

metabolized back into pyruvic acid and then glucose

The Power Of The Aerobic System Evaluated by measuring the maximal volume of oxygen

that can be consumed per kilogram of mass in a given amount of time

This measure is called aerobic power or VO2 max (ml/min/kg)

Factors that contribute to a high aerobic power:

a) arterial oxygen content (CaO2)- depends on adequate ventilation and the O2-carrying capacity of

bloodb) cardiac output (Q = HR x stroke volume)- increased by elevation of the work of heart and increased

peripheral blood flow

c) tissue oxygen extraction (a-vO2 diff)- depends upon the rate of O2 diffusion from capillaries and the

rate of O2 utilization

The Substrates for the Aerobic System

Carbohydrates ( glycogen and glucose) and fats (triglycerides and fatty acids)

Fats: found in dairy products, meats, table fats, nuts, and

some vegetables body’s largest store of energy, cushion the vital organs,

protect the body from cold, and serve to transport vitamins

each gram of fat contains 9 calories of energy

Effect of Training on Aerobic Systems

Endurance training is the most effective method (long duration several times per week):

- increases vascularization within muscles

- increases number and size of mitochondria within the muscle fibres

- increases the activity of enzymes (Krebs cycle) - preferential use of fats over glycogen during exercise

Endurance training increases the max aerobic power of a sedentary individual by 15-25% regardless of age

An older individual adapts more slowly

During RESTDuring REST

Any rest, short Any rest, short OR Long, CP is OR Long, CP is being being replenished, replenished, so we can so we can ‘sprint’ again.‘sprint’ again.

BUT, need 3 BUT, need 3 minutes rest minutes rest to get all CP to get all CP back! back!

Any Lactate and Hydrogen Ions are Any Lactate and Hydrogen Ions are removed from muscles & blood stream removed from muscles & blood stream too.too.

Things to remember:Things to remember:

The 3 Energy The 3 Energy Systems are not like Systems are not like TRAFFIC LIGHTS. TRAFFIC LIGHTS. One does not switch One does not switch off and another goes off and another goes on.on.

All 3 turn on at All 3 turn on at once no matter once no matter what the what the activity. activity.

However, depending on intensity and duration of the activity, ONE system will contribute more than the other TWO.

The Role of Three Energy Systems During an All-out Exercise Activity of Different Duration

Discussion Questions:

1. What are the differences between the 3 energy systems?2. List one advantage and one disadvantage of each of the 3

energy systems.3. Give an example of three activities or sports that use each of

(a) the high energy phosphate system, (b) the anaerobic glycolytic system, and (c) the aerobic oxidative system as their primary source of energy (one sport for each energy system).

4. What is the most important source of fuel in the body for all types of energy production - a substance also known as the energy currency of the body?

5. Define ATP turnover and ATP resynthesis.6. Describe how each of the three energy systems could be

trained most efficiently.