Energy Systemsfor Exercise

The human body is made to move in many ways:

• Quick and powerful• Graceful & coordinated• Sustained for many hours

And is dependent upon the capacity to produce energy

Bioenergetics • or the study of energy flow through living

systems

• No matter what sport you play, your body needs energy for top performance. Energy is supplied to your muscles from the food you eat.

• Your body breaks the food down into usable blocks of energy called Adenosine Triphosphate (ATP). ATP is the immediate source of energy for muscle contraction.

• Your body makes ATP available for muscle contraction through three main energy systems that are located within the muscle fibres. The energy system used depends on the intensity and duration of the activity.

We have a great amount of diversity

• Quick movements-lasts a few seconds• Reduced speed-lasts for several minutes• Reduced intensity(50%)-lasts for several hours

The body uses different energy systems for each activity

Cells in the body need energy to function

FOOD=ENERGY (E)

Nutrients that give us energy:

CarbohydratesFatsProteins

GlucoseFatty acidsAmino AcidsDigestio

n

Absorbed into the blood & transported to cells

(muscle, liver & nerve)

They are used to produce ATP or stored

Glucose

The glucose is then used in 3 different ways…

Here some of the glucose is stored as glycogen and used to maintain blood sugar levels.

Glucose is stored here as glycogen and is used when the body is working harder.

Glucose diffuses easily into the cells and is used to meet their energy demands.

Skeletal Muscle

LiverBody Cells

Cells don’t get Energy directly from food, it must be broken down into:

ATP-Adensosine TRIphosphate

ATP = a form of energy one can immediately use, it is needed for cells to function & muscles

to contract

• However the body only has enough ATP for 1 explosive act

• After this there is no ATP left.• Muscle Contraction cannot take place.• Therefore physical activity can no longer

continue.

ATP is stored in small amounts, therefore the rest is stored as:

• Glucose = Glycogen (muscle & liver)

• Fatty Acids = Body fat

• Amino Acids = Growth, repair or excreted as waste

D. Matthews and E. Fox, in their revolutionary book, "The Physiological Basis of Physical Education and Athletics", divided the running requirements of various sports into the following "energy pathways": ATP-CP and LA, LA-02, and 02.

ATP - Adenosine Triphosphate: a complex chemical compound formed with the energy released from food and stored in all cells, particularly muscles. Only from the energy released by the breakdown of this compound can the cells perform work. The breakdown of ATP produces energy and ADP.

CP - Creatine Phosphate: a chemical compound stored in muscle, which when broken down aids in the manufacture of ATP. The combination of ADP and CP produces ATP.

3. LA - Lactic acid: a fatiguing metabolite of the lactic acid system resulting from the incomplete breakdown of glucose. However Noakes in South Africa has discovered that although excessive lactate production is part of the extreme fatigue process, it is the protons produced at the same time that restrict further performance

4. O2 means aerobic running in which ATP is manufactured from food mainly sugar and fat. This system produces ATP copiously and is the prime energy source during endurance activities

The 4 Systems1. ATP-PCr System

• The ATP-PCr (Adenosine Triphosphate Phospho-Creatine) system is predominant in maximal or super-maximal activities lasting up to 20 seconds. As the duration of activity increases the ATP-PCr system provides a smaller portion of total energy.

• The ATP-PCr system is utilized during the transition from rest to exercise, and also during the transition from one exercise intensity to a higher intensity. A period of 30 seconds to 3 minutes is needed to replenish the energy in this system, however, during aerobic exercise ATP-PCr reserves can be restored.

2. Anaerobic Glycolysis• As the ATP-PCr system begins to fade after around ten seconds, a process known as

Anaerobic Glycolysis begins to occur. Anaerobic Glycolysis is the primary energy source in activities lasting between 20 seconds and two minutes.

• Anaerobic Glycolysis continues to supply energy during exercise lasting up to ten minutes. This system breaks down muscle and liver glycogen stores without the use of oxygen. The byproduct of this system is lactic acid.

• After about five minutes of exercise, Aerobic Glycolysis is the dominant energy system. Aerobic Glycolysis produces energy by breaking down muscle and liver glycogen stores with oxygen present. Because oxygen is present when this system is in use, there is no build up of lactic acid. This system does not produce energy as fast as the ATP-PCr system or

• Anaerobic Glycolysis thus the intensity of exercise cannot be as high. This system has the capacity to produce energy for an hour or more.

So...• There are two types of anaerobic energy systems, the ATP-CP energy

system, which uses creatine phosphate as the main energy source, and the lactic acid (or anaerobic glycolysis) system that uses glucose (or glycogen) in the absence of oxygen.

• Events or activity that last up to about thirty seconds rely primarily on the former, phosphagen, system. Beyond this time aerobic and anaerobic glycolysis begin to predominate.

• Anaerobic glycolysis uses glucose inefficiently, and produces by-products such as lactic acid that are thought to be detrimental to muscle function; this limits activity based predominantly on anaerobic glycolysis to about 2 minutes.

Lactate threshold (LIP or Lactate Inflection Point)

• The lactate threshold (LT) is the exercise intensity at which lactic acid starts to accumulate in the blood stream. This happens when it is produced faster than it can be removed (metabolized). This point is sometimes referred to as the anaerobic threshold (AT), or the onset of blood lactate accumulation (OBLA).

• When exercising below the LT intensity any lactate produced by the muscles is removed by the body without it building up. The lactate threshold is a useful measure for deciding exercise intensity for training and racing in endurance sports (e.g. long distance running, cycling, rowing, swimming, motocross, and cross country skiing), and can be increased greatly with training.

3. Oxidative Phosphorylation

• Oxidative Phosphorylation provides the body with energy during exercise of long duration and moderate to low intensity. This system breaks down the bodies fat stores to supply energy to working muscles.

• As the intensity of exercise decreases, the body relies more on this energy system. This energy system can supply virtually unlimited supplies of energy. Endurance sports such as cross-country running, swimming, soccer and lacrosse all rely heavily on this system.

• However, speed and power can often be the determining factor in winning and losing. Therefore careful attention must be paid to developing both energy systems to achieve top performance.

• As the graph on the next slide shows, all three energy systems are active at any given time, but depending on the intensity and duration of the activity, different systems will be primarily stressed. High intensity, short duration activities stress the ATP-PCr system.

• As the intensity slightly decreases and the time increases Glycolysis kicks in. Then as the intensity is further reduced and the time increased, the Aerobic System is primarily used.

ATP-CP Energy SystemATP is stored in the muscle & liver for “Quick Energy”

• Nerve impulses trigger breakdown of ATP into ADP• ADP = Adenosine Diphosphate & 1 Phosphate• The splitting of the Phosphate bond = Energy for work

Ex. Muscle Contraction, Moving hand from a hot stove, Jumping & Throwing

The ATP Molecule

Adenosine

Adenosine

Energy

a. Adenosine Triphosphate (ATP)

b. The breakdown of ATP:

PP

P

PP P

ATP = ADP + energy for biological work + P

(ADP = Adenosine Diphosphate)

Energy for cellular function

For contractions to continue… ATP must be REBUILT

This comes from the splitting of CP (Creatine Phosphate a Hi energy source, automatic)

When ATP is used – it is rebuilt – as long as there is CP

Energy released from CP breaking down, resynthesizes the ADP & P

REMEMBER – only small amounts of ATP are stored = only 2-3 sec. of Energy

ATP-CP = 8-10 sec. of Energy

The usefulness isn’t the AMOUNT of Energy but the QUICK & POWERFUL movements

For longer periods of work = The Aerobic & Anaerobic Energy System must be utilized

The Immediate Resynthesis of ATP by CP

CreatineP

Creatine P

Energy

High energy bond

a. Creatine Phosphate (CP)

b. CP = Creatine + energy for resynthesis of ATP + P

Adenosine PP

P

c. ADP + energy from CP + P = ATP (reversal of ATP = ADP + P + energy for work)

Anaerobic Energy System• Without oxygen = Activities

that require a large burst of energy over a short period of time

• Anaerobic Glycolysis = Production of ATP from Carbohydrates without oxygen

(breakdown of glucose)

Since glycogen is stored in the muscle & liver, it is available quickly

This system provides ATP when ATP-CP runs out

Again, ATP-CP lasts for a few seconds, the Anaerobic Energy System allows for 2-3 minutes of work

1. The process to produce ATP is not as fast as ATP-CP, which makes muscle contraction slower

2. When oxygen is not present the end product of glycolisis is lactic acid, which causes the muscles to fatigue

3. Anaerobic Glycolisis is less efficient in producing ATP than Aerobic Glycolisis, BUT is needed for a large burst of energy lasting a few minutes

Oxygen Deficit = The body can not supply enough O2 to the muscles that the muscles demand

•When the muscle does not get enough oxygen, exhaustion is reached causing immediate and involuntary reduction in intensity

Oxygen Debt = “pays back” the deficit

recovery time

Aerobic Energy System• With Oxygen = Using large muscle groups continuously over a

period of time

• Aerobic Glycolisis & Fatty Acid Oxidation = The production of ATP from Carbohydrates & Fat

1. O2 enters the system, stopping the breakdown of glycogen to lactic acid

2. With oxygen, glycogen breaks down into: ATP + CO2 + H20

3. These byproducts are easier to get rid of

CO2 is expelled by the lungs

H20 is used in the muscle

4. Anaerobic Energy System = Carbohydrates are the only fuel source

5. With prolonged exercise, Carbohydrates are the first fuel choice, as exercise continues, FAT becomes predominant

6. Protein is not a main fuel source except in an emergency

•Each system plays an important role in energy production

•This gives us a variety of movements

•The systems interact to supply Energy for the activity

Examples

Anaerobic Anaerobic 2 Aerobic

Facts about Aerobic Respiration

How Aerobic Respiration Happens…

Glucose and oxygen are carried by the haemoglobin in the red blood cells.

Glucose and oxygen pass into all the muscle cells of the body and is used to help produce energy for muscular contractions.

Aerobic respiration produces carbon dioxide & water as waste products.

During aerobic respiration, the heart and lungs supply the muscles with plenty of oxygen.

The carbon dioxide is breathed out via the lungs, while the water is lost as sweat, urine or in the air we breathe out as water vapour.

As long as the muscles are supplied with enough oxygen, exercising aerobically can be carried out for a long period of time.

1 2 3

Aerobic Respiration – With Oxygen

1. Glucose and oxygen are transported to the working muscles bythe blood.

Aerobic respiration involves the release of energy from the slow breakdown of glucose using oxygen, inside the cells.

2. Glucose and oxygen are then used by the muscles of the body to produce energy.

3. This process creates carbon dioxide and water.4. The carbon dioxide passes back into the blood for removal.

The Process of Aerobic Respiration

Energy for Musclesto contract and

create Movement

Water

CarbonDioxide

Glucose

Oxygen

Aerobic respiration is how marathon runners produce the energy that is used in long periods of less intensive effort.

Glucose and oxygen produce…

Aerobic respiration is how marathon runners produce the energy that is used in long periods of less intensive effort.

Glucose and oxygen produce…

Some is used formuscle contractions,creating movement.

Aerobic respiration is how marathon runners produce the energy that is used in long periods of less intensive effort.

Glucose and oxygen produce…

Carbon dioxide, which is carriedaway by the blood& excreted through the lungs.

Water, which is carried away by the blood and excreted through the lungs, sweat and urine.

Some is used formuscle contractions,creating movement.

The rest is converted into heat to warmthe body.

Anaerobic respiration involves the release of a little energy, very quickly from the incomplete breakdown of glucose without using oxygen, inside the cells.

1. Glucose is made available by the breakdown of glycogen stored in the working muscles.

2. The glucose is used by the muscles of the body to produce energy, without the use of oxygen.

3. This process creates lactic acid, which passes back into the blood for removal.

Anaerobic Respiration – Without Oxygen

The Process of Anaerobic Respiration

Glucose

Energy for muscles to contractand create movement

Lactic Acid

Glucose is transported to the muscles of the body via the blood.

How Anaerobic Respiration Happens

Glucose passes into the muscles cells and is used to produce energy for muscularcontractions.

Anaerobic respirationproduces lactic acidas a waste product.

Facts about Anaerobic Respiration

During anaerobic respiration, your muscles are not supplied with enough oxygen.

The lactic acid builds up due to the shortage of oxygen. This is known as an oxygen debt, which needs to be paid back once exercising has finished.

The lactic acid build-up will soon make your muscles feel tired and painful, so exercising anaerobically can only be carried out forshort periods of time.

1 2 3

Oxygen DebtQuestion: How do sprinters pay back their oxygen debt at the end of a race?

Answer: Sprinters will continue to breathe more deeply and rapidly for a number of minutes at the end of their race. This will enable them to pay back the oxygen debt, and allow lactic acid levels to fall.

Anaerobic Respiration is how sprinters produce the energy that is used in short periods of ‘all out effort’ - high intensity.

Glucose Produces…

Oxygen cannot reach the muscles fast enough, so anaerobic respiration is used.

Anaerobic Respiration is how sprinters produce the energy that is used in short periods of ‘all out effort’ - high intensity.

Glucose produces…

Lactic acid quickly builds up & makes the

muscles feel tired & painful. ‘All out effort’

cannot last for very long!

Oxygen cannot reach the muscles fast enough, so anaerobic respirationis used.

Some is used formuscle contractions,creating movement.

Anaerobic Respiration is how sprinters produce the energy that is used in short periods of ‘all out effort’ - high intensity.

Glucose produces…

Lactic acid quickly builds up & makes the muscles feel tired & painful. ‘All out effort’ cannot last

for very long!

The rest is converted into heat to warm the

body.

Oxygen cannot reach the muscles fast enough, so anaerobic respiration is used.

Some is used formuscle contractions,creating movement.