Energy Systems The ability to move, work or play sports is dependant on supplying sufficient energy at the required rate for the duration of the activity.

Energy Systems

The ability to move, work or play sports is dependant on supplying sufficient energy at the required rate for the duration of the activity.

All energy in the human body comes from the breakdown of complex nutrients like carbohydrates, fats and proteins.

Biologic Energy CycleBiologic Energy CycleEnergy can neither be created or Energy can neither be created or

destroyed but merely transformed.destroyed but merely transformed.

PlantsPlants

Carbohydrates Carbohydrates ProteinsProteins

Chemical EnergyChemical Energy

Sun = Solar Sun = Solar Energy.Energy.

AnimalsAnimals

Carbohydrates Carbohydrates Proteins Proteins

FatsFats

Chemical / Mechanical EnergyChemical / Mechanical Energy HumansHumans

Carbohydrates, Proteins, Fats, Carbohydrates, Proteins, Fats, ATP – PC.ATP – PC.

Chemical / Mechanical EnergyChemical / Mechanical Energy

Bioenergetic Conversion

• The breakdown of macronutrients for energy to carry out physical activity.

Carbohydrates Fats Proteins

4.1 cal/gram 9.3 cal/gram 4.3 cal/gram

Glycogen Triglycerides Amino Acids

Glycolisis Lipolysis

Glucose Fatty acids Not stored; excreted through urine

• Carbohydrates are the most abundant substances in nature – they come to us from foods that originate from plants (fruits and vegetables) and grain based products (such as bread and pasta).

• Glycogen = Storage form of glucose within skeletal muscle and the liver.

• Metabolism = the rate at which fats, proteins and carbs are created and used by the body for energy.

Review?Review?

The end result of nutrient breakdown is the production of various amounts of adenosine triphosphate (ATP). •ATP is the immediate energy source for muscular contraction.

•An ATP molecule consists of an adenosine molecule bonded to three phosphate groups.

Adenosine Triphospate (ATP)•ATP molecules are supplied by chemical reactions that take place in the mitochondria found in muscle cells.

AdenosineAdenosine PP PPPP

Adenosine Triphosphate Adenosine Triphosphate (ATP)(ATP)

To release the energy, a phosphate molecule breaks away from the phosphate group through hydrolysis to form adenosine diphosphate (ADP)

Breaking ATP into ADP releases energy and allowscross bridge formation to occur between the myosinand actin filaments inside the muscle.

AdenosineAdenosine AdenosineAdenosinePP PP PP HydrolysisHydrolysis PP PP PP

HEATHEAT

ENERGYENERGY

ATP is a renewable resource that can be regenerated by the recombination of ADP with a free phosphate. The following reaction describes the regeneration process.

++ + +

• To accomplish this synthesis, energy must be available;• Energy is supplied through the breakdown of complex food molecules, such as fats and carbohydrates.

AdenosineAdenosine AdenosineAdenosinePP PP PP PP PP PPENERGYENERGY

Summary of the Systems• Energy for muscular activity depends on a

supply of ATP that can be broken down into ADP and phosphate

• All of the body’s biochemical processes and the three energy systems require ATP

• Trained individuals are able to use ATP and remove lactic acid more efficiently than untrained individuals

• Endurance training can significantly improve the aerobic system

Two Energy Systems

1. Aerobic– An energy system which is used in

prolonged continuous activity in the presence of oxygen and does not produce lactic acid.

2. Anaerobic– Energy systems that do not rely on the

immediate use of oxygen. There are two types of anaerobic energy systems.

3 Metabolic PathwaysAnaerobic Alactic (ATP-CP) or (ATP-PC)• A short term energy of both fast and slow

twitch muscle fibres that does not require oxygen and does not produce lactic acid.

Anaerobic Lactic (glycolysis)• A fast twitch muscle energy system which

does not require the immediate use of oxygen but does produce lactic acid.

Aerobic (cellular respiration)• A slow twitch muscle energy system which

is used in prolonged continuous activity in the presence of oxygen and does not produce lactic acid.

Anaerobic Alactic - ATP-CP SystemAn immediate - high energy phosphate system

Involves high power output activities that require an immediate high rate of energy production for a short period of time.

Involves activities such as weight lifting, high jump, long jump, shot put, discus 50 metre sprint, 25 metre swim.

Adenosine PP P

HEATHEAT

ENERGYENERGY

As muscle contraction begins, the body’s metabolism may not be

able to supply ATP to the contracting muscle cells as rapidly asrequired…The body must then make use of creatine phosphate.Creatine phosphate serves as a quick available energy reservefor muscles as it is broken down into creatine and phosphate.

+

The free phosphate ions bonds with ADP to produce ATP andleave behind creatine.The new ATP molecule is stored as potential Energy.

ATPATP ENERGYENERGY

Adenosine P P PCP CPCP CPCP CPCP CPCP CPCP CP

CreatineCreatine

Anaerobic Alactic Characteristics

• Only a small amount of ATP and CP is stored in muscle fibres;

• Uses very large amounts of energy in a short period of time;

• The rate of recovery is relatively rapid. After a brief rest, the system is recharged and ready for the next sprint;

• Oxygen is not required;• Lactic acid is not produced;• The system can only provide energy for muscles for the first 10-15 seconds of high intense activity;

• Uses both fast and slow twitch muscles;• Work output is relatively high (high intensity)

If an athlete must continue vigorous work a second energy system uses a complex biochemical process which breaks down carbohydrates to release energy.

CarbsCarbs

Glucose/glycogenGlucose/glycogenENERGYENERGY

Lactic Lactic AcidAcid

ADP + P ATPADP + P ATP

Anaerobic Lactic - GlycolysisAnaerobic Lactic - Glycolysis

2ADP 2ATP

Glucose GLYCOLYSIS 2 Pyruvate 2 LACTATE

Energy is produced with a buildup of lactic acidEnergy is produced with a buildup of lactic acid

Anaerobic Glycolysis

The Effects of Lactic Acid

During intense exercise, lactic acid builds up in the blood faster than it can be removed.• As lactic acid builds up an athlete will reach their anaerobic threshold (AT).

– This is the point where a person begins to feel discomfort and a burning sensation in their muscles (there is some debate as to whether lactic acid directly causes it).

– the muscle loses it ability to contract resulting in muscle fatigue.

• As work increases, the body reaches the:Anaerobic Threshold (AT)

• At this point the anaerobic system can no longer keep pace with the increasing requirements of the muscles.

LowSlow twitch fibres dominate

Exercise Intensity

ModerateFast-twitch type A fibres are

recruited

The anaerobic thresholdis the highest intensity ofworkload at which lactateclearance still keeps pacewith lactate production.

Once this level is reachedthe intensity level mustdecrease to reduce theamount of lactic acid buildup

HighFast-twitch Type B fibres

dominate

The Effects of Lactic Acid• Lactic acid causes pH changes in the muscle

fibres and they can no longer respond to stimulation.

• Lactic acid interferes with cross- bridge bonding by limiting the strength of the fibre contraction.

• A high production of lactic acid ultimately limits continued performance in intense activities

• When lactic acid accumulates, extreme fatigue sets in and oxygen debt develops.Oxygen debt is the reason you must breathe

rapidly and deeply for a few minutes after strenuous exercise.

The Effects of Lactic AcidThe Effects of Lactic Acid

Oxygen Debt• Oxygen debt refers to post exercise oxygen

consumption where the body needs to pay back its debt incurred after the exercise is over

• You will notice that even after you are done racing you will continue to breath hard.

• At this point your body is still trying to repay the oxygen debt that was created when you were working hard.

• After you stop anaerobic exercise, your body needs extra oxygen to burn up the excess lactic acid and return your energy reserves to normal.

• Lactic acid cannot be removed until extra oxygen is supplied to convert it to harmless, re-usable products.

Cori Cyle• the process by which lactic acid is converted

to pyruvate for future conversion to glucose and glycogen

• lactate is transported by the blood to liver where most of it is converted back to glucose, from which glycogen is formed in a process of gluconeogenesis

• about one-sixth of the lactate is oxidized to carbon dioxide

Raising Your Anaerobic Threshold

Since it is not possible to convert fast twitch fibres to slow twitch fibres, raising your anaerobic threshold depends on improving the condition of the fast twitch muscle fibres. This occurs when effort intensifies.

How do you know if your workouts are pushing your Anaerobic Threshold?

• Pay attention to how your running feels.

• After several workouts, you'll notice the feeling when you are in the anaerobic zone.

• Elite athletes use the Conconi test which requires a hand-held device that directly measures blood lactate concentration. The corresponding heart rate at the AT gives you a convenient way of monitoring your workouts.

The Effect of Training on the Lactic Acid System

At any level of work, the rate of lactic acid build-up is decreased through training.– The anaerobic threshold rises.– The individual can work out at a higher rate of

activity before lactic acid build-up begins.– The individual is able to “handle” a higher level

of lactic acid.– Trained individuals are able to remove lactic

acid faster from exercising muscles.– Improvements in the cardiovascular system

deliver an increased blood flow to the working muscle

Characteristics of the Lactic Acid System

• The energy source is entirely carbohydrate;• Oxygen is not required• Energy is provided for 15 seconds to 120

seconds (3 min.) depending on conditioning• Uses predominately fast twitch muscle fibres• Work output is moderate• Used in sports such as football, basketball

and hockey.

The Aerobic System: Long-Term Energy

• Exercise performed at a lower intensity level relies almost exclusively on the aerobic system for energy production and requires the athlete to use oxygen as its source of energy.o Most daily activities use energy provided by the

aerobic energy systemo The oxygen energy system is the most important

energy system in the body.

• While this pathway cannot generate the speed of the anaerobic, it does provide a great deal more efficiency and endurance.

The Aerobic System (Cellular Respiration)

• The aerobic system energy requires the metabolism of

Glucose(Glycogen)

FatsProteins

Oxygen

Combine to produce

ADP + P ATPADP + P ATP

Using energy produces

ENERGYENERGY

CO2 Water

Sub-Pathways – Cellular Respiration

Aerobic Glycolysis • first stage • in the presence of oxygen, pyruvic acid is

converted to acetyl-CoA (co-enzyme) (rather than lactic acid)

• acetyl CoA then enters a more complicated pathway known as the KREB’S CYCLE

Kreb’s Cycle• Central pathway for the metabolism

of fats and proteins • series of 8 reactions, two ATP

molecules are produced at this stage, along with new compounds

• capable of storing “high energy” electrons

• high energy electrons are sent to a process within the mitochondria, known as, the electron transport chain

Electron Transport Chain• During the final stage of aerobic

respiration, large amounts of ATP are produced, with carbon dioxide and water as the only by-products

• Electrons pass down the chain, highly reactive molecules (known as free radicals) are by-products and these molecules may be a contributor to long-term muscle fatigue

Aerobic PowerOxygen uptake• The power of the aerobic system is

generally evaluated by measuring the maximum volume of oxygen that can be consumed in a given amount of time. – This can be measured by determining the

amount of oxygen exhaled as compared to the amount inhaled.

• As the intensity of work increases the capacity of aerobic system reaches a maximum.

• The greatest rate at which oxygen (volume) can be taken in and used during exercise is referred to maximal oxygen consumption or (VO2max)

Aerobic Power –VO2Max

Each person has his or her own maximal rate of oxygen consumption (VO2 max).

• The maximal rate at which oxygen can be used is genetically determined.

• A normal VO2 max for most high school athletes would fall somewhere between 45 and 60 range.

• The VO2 max values of trained athletes will reach 80-90 for males and 75-85 for females

The more active we are the higher the VO2 max will be in that

range.

The Effect of Training on the Aerobic System

A person’s ability to perform an activity is limited by their maximal rate of oxygen consumption. The most efficient method for improving the aerobic energy system is endurance training/exercise.

Long, slow distance training or exercise at the low end of your target heart rate tends to use slow twitch fibres. ST fibres are slower to fatigue and are well suited for endurance activities.

Endurance exercise consists of repeated, sustained effort of long duration several times per week.

Generally, the higher the intensity, the greater the oxygen consumption. When exercising the target heart rate (THR) should be raised to 70% of max.

The Effect of Training on the Aerobic System Con’t

Examples include: running, swimming or biking for 40 minutes or more at a heart rate of 130-140 bpm

Note: A highly trained or elite athlete should be able to sustain a heart rate of 85% of their VO2 max. This type of training does not raise your anaerobic threshold.

Endurance training has four major effects on the aerobic system:

• Improved delivery of oxygen and nutrients to the muscles• Increase the size and number of mitochondria in muscle fibres• Increased activity of enzymes involved in the aerobic pathway• Preferential use of fats over glucose during exercise which saves the muscles limited store of glycogen

Characteristics of the Aerobic System

The oxygen system is highly efficient. When oxygen is used in muscle cells:– it prevents the build-up of lactic acid– an individual can work out longer before

lactic acid build-up begins– it is able to remove lactic acid from

muscles allowing the muscle to continue to contract allowing exercise to continue

– it promotes the re-synthesis of ATP for energy when work output is low.

Characteristics of the Aerobic System con’t

As the duration of activity increases, the contribution of the aerobic system to the total energy requirement increases. Due to this, there are two limitations to the aerobic system:

• The system requires a continuous supply of oxygen and fuel sources necessary for the aerobic metabolism.

• The use of ATP must be relatively slow to allow the process to meet the energy demands

Using The Systems Together

While running at a comfortable pace you use both systems, butthe anaerobic: aerobic ratio is low enough that the lactategenerated is easily removed, and doesn't build up.

As the pace is increased, eventually a point is reached where the production of lactate, by the anaerobic system, is greater than its removal (anaerobic threshold).

Note: Depending upon the distance, and effort,the body can use different proportions ofboth of these systems. For example, the 800mrace is too long to be a sprint, but tooshort to be a distance race. Therefore, it isrun at the cross-over between the aerobicand anaerobic systems.

The best method to train all of the systems together is interval training. Interval work consists of repeating a series of short, high intensity, runs alternating with rest (recovery) periods.

Whichever method is used, the athlete must continually pushing themselves into a lactate burdened state which makes their body adapt. Regardless of the race distance you are training for, 5k or marathon, interval work will help you run faster.

Training The Systems Training The Systems TogetherTogether

Training The Systems Together

Pushing the body past the 'comfortable' speed of running increases aerobic capacity, trains the fast twitch muscles to operate at a higher /faster level and makes the athlete more tolerant of lactic acid build up.

The result of interval training is that a runner who can comfortably run at eight-minute/mile pace and runs their intervals at a seven-minute/mile pace will be able to increase their steady comfortable pace under an eight-minute/mile pace.

Summary - The Energy Systems

• Energy for muscular activity depends on a supply

of ATP that can be broken down into ADP and

phosphate

• All of the body’s biochemical processes and the

three energy systems require ATP

• Trained individuals are able to use ATP and

remove lactic acid more efficiently than

untrained individuals

• Endurance training can significantly improve the

aerobic system

A Comparison of the Three Energy Systems

Energy Energy systemsystem

Anaerobic Anaerobic AlacticAlactic

Anaerobic Anaerobic LacticLactic

AerobicAerobic

Type of ActivityType of Activity short sprints used inshort sprints used in

baseball, pole vaultbaseball, pole vault

long jump triple jumplong jump triple jump

games such as games such as football, football,

Basketball, HockeyBasketball, Hockey

long distance long distance runningrunning

cross country skiingcross country skiing

swimmingswimming

Range of Range of Maximum Work Maximum Work

TimesTimes

0 – 10 seconds0 – 10 seconds 10 to 60 or 120 seconds 10 to 60 or 120 seconds (depending on (depending on conditioning)conditioning)

120 seconds plus120 seconds plus

Oxygen RequiredOxygen Required NoneNone None or very littleNone or very little YesYes

Lactic Acid Lactic Acid ProducedProduced

NoneNone Yes, accumulated faster Yes, accumulated faster than it can be removedthan it can be removed

Depends on intensityDepends on intensity

Energy SourceEnergy Source Chemical energy stored Chemical energy stored in muscles, ATP and CPin muscles, ATP and CP

Entirely carbohydrateEntirely carbohydrate Mixture of fat and Mixture of fat and carbohydratecarbohydrate

End Products of End Products of Fuel BreakdownFuel Breakdown

Adenosine Diphosphate Adenosine Diphosphate Creatine Phosphate plus Creatine Phosphate plus

energyenergy

Lactic AcidLactic Acid COCO22 and H and H22OO

Muscle Fibre Muscle Fibre RecruitedRecruited

Fast and slow twitchFast and slow twitch Predominately fast Predominately fast twitchtwitch

Slow twitch and some Slow twitch and some fast twitchfast twitch

Work Output per Work Output per Unit of TimeUnit of Time

HighHigh MediumMedium LowLow

Roles of the Three EnergySystems in Competitive Sport

Anaerobic PathwaysAnaerobic Pathways Aerobic PathwaysAerobic Pathways

Primary Primary Energy Energy SourceSource

ATP produced without the presence of ATP produced without the presence of oxygenoxygen

ATP produced with the presence of ATP produced with the presence of oxygenoxygen

Energy Energy SystemSystem

Immediate Immediate AlacticAlactic

Short-term LacticShort-term Lactic Long-term OxygenLong-term Oxygen

FuelFuel ATP and CPATP and CP Glycogen + glucoseGlycogen + glucose Glycogen, glucose, fat and proteinGlycogen, glucose, fat and protein

DurationDuration 0s 10s 40s 70s 2 min 6 min 25 min 1 hr 2hr 0s 10s 40s 70s 2 min 6 min 25 min 1 hr 2hr 3hr 3hr

Sport Sport EventEvent

SprintingSprinting

100 m dash100 m dash

ThrowingThrowing

JumpingJumping

WeightliftingWeightlifting

Ski jumpingSki jumping

DivingDiving

Vaulting inVaulting in

GymasticsGymastics

TrackTrack

200-400 m,200-400 m,

500m500m

SpeedskatinSpeedskatingg

Most Most

gymnasticsgymnastics

Events,Events,

Cycling(tracCycling(track)k)

50 m swim50 m swim

100 m Swim100 m Swim

800 m track800 m track

Gymnastic Gymnastic floorfloor

exerciseexercise

Alpine skiingAlpine skiing

Cycling 1000m Cycling 1000m

pursuitpursuit

Middle Middle

distance distance track,track,

swimming, swimming,

speedskatingspeedskating

1000 m 1000 m canoecanoe

Boxing, Boxing,

WrestlingWrestling

RowingRowing

Figure Figure skatingskating

Cycling Cycling pursuitpursuit

Long Distance Long Distance

Track,swimming, Track,swimming,

canoeing,canoeing,

speedskatingspeedskating

Cycling road Cycling road racingracing

MarathonMarathon

TriathlonTriathlon

Most team Sports/Racquet SportsMost team Sports/Racquet Sports

ATP - CP System

Glycolytic System

Aerobic System

When the systems are used

Feel the burn!

Page 103 Figure Page 103 Figure 5.75.7

Picture all 3 systems

Questions:

• Describe the role of Carbohydrates, Fats and Proteins in energy production.

• Describe the characteristics of the three fibre types.

• What is the importance of Myoglobin?• What features of the Kenyan

runners/athletes allow for such results at world-class levels?

• body characteristics• muscle fibre type • social factors