Energy systemsLearning outcomes: All are able to demonstrate understanding of the energy sources required for ATP resynthesisAll are able to describe the Lactic Acid energy systemMost are able to explain the use of PCr in ATP resynthesisMost are able to apply their understanding of thelactic acid system to sporting examples.Some can analyse the lactic acid and determine advantages and disadvantages

Starter activityResearch has been conducted into “activity cycles” of

intermittent sports such as soccer, hockey and rugby, which are reliant

onefficient energy systems.

a) Identify the principal energy source for each of thefollowing activity cycles in these types of physicalactivities:(i) walking;(ii) sprinting;(iii) jogging. (3 marks)

b) What are the disadvantages of using fat as an energy source during exercise? (2 marks)

Answera) i)Walking – free fatty acid /triglycerides/fats;ii) Sprinting-muscle glycogen/ATP/carbohydrates/PC;ii) Jogging-mixture of fatty acids and muscle

glycogen/fats/carbohydrates 3 marks

b) 1 Less efficient energy yield per unit of oxygen;2 Cannot be used anaerobically for sprint type

activities/ can only be used aerobically;3 Requires the presence of carbohydrates to be used;4 Slow to produce energy/ insoluble in blood. 2 marks

Homework List ten different activities where a performer might benefit from

taking a creatine supplement. Give reasons in support of your answer

Research and make notes on the factors that affect the rate of lactate accumulation:

Muscle fibre type Exercise intensity Rate of blood lactate removal Training Respiratory exchange ratio

OBLA can be expressed as a percentage of VO2 max. What do you understand by this term and how is it different in trained and untrained performers. What factors affect VO2 max?

Energy systemsThe conversion of these fuels into energy

which can then be used to resynthesise ATP occurs through one of 3 energy systems:

1-The ATP-PC System2- The Lactic Acid System3- The Aerobic system

The Energy Systems

Immediate:Immediate:ATP-PCrATP-PCr

Short-term:Short-term:Lactic acid Lactic acid (glycolysis)(glycolysis)

Long-term: Long-term: AerobicAerobic

Energy Systems: What we need to knowThe type of reaction (eg. Aerobic or anaerobic)The chemical or food used (eg. Glycogen)The specific site of the reactionThe energy yield (eg. 2ATP from lactic acid

system)Specific stages within a systemThe by-products produced (eg. Lactic acid)The enzyme controlling the reaction.When each system is predominantly used during

exercise

ATP –PC SystemATP-PC system is the first of the anaerobic

systems.Energy is released rapidly so used for high

intensity maximum work There is a limited store of phosphocreatine in

the muscles and can only last for 3 - 10 seconds

100m sprint, performing a vault, smash in tennis, slam dunk

ATP-PC SystemPhosphocreatine (PCr) stored in the sarcoplasm

of the muscles

The following reaction takes place (facilitated by the enzyme creatine kinase)

PCr ------------ Pi + Creatine + EnergyThis energy is used to recycle ATPEnergy + ADP + Pi = ATPThese two reactions together are called a coupled

reaction

Only 1 molecule of ATP can be resythesised by 1 molecule of PC

ActivityCritically analyse the ATP – PC system.What are the strengths and weaknesses of

this system to an athlete.

ATP-PC SystemAdvantages DisadvantagesATP resynthesis is very

rapidPCr stores recover very

quickly (2-3 mins)Anaerobic processNo fatiguing by-productsCan use creatine

supplementation

Limited store of PCr in muscle cell, sufficient for 10 secs

Fatigue occurs when PCr levels fall and can not sustain ATP resynthesis

Resynthesis of PCr needs sufficient oxygen

Only 1 molecule of ATP can be resythesised by 1 molecule of PC

Quick recap Site of reaction –Fuel used –Active enzyme –Molecules of ATP

produced -

ATP SPLITTINGmuscle cellATPATPase

ATP-PC SYSTEMmuscle cellPhosphocreatineCreatine kinase1 molecule

100m sprint- ATP split to drive away from blocksPCr supplies energy for rest of race

ATP-PC SystemTip: Rebuilding or re-synthesising ATP from ADP + P is an endothermic reaction (energy is required)

ActivityUsing the pictures demonstrate your understanding

of the Lactic Acid system (Anaerobic glycolysis).One person in your group will move to another

group to share your understanding and gain further knowledge.

Summarise your understanding of the Lactic Acid system.

Extension - analyse the system and determine its advantages and disadvantages

Lactic Acid SystemMost activities last for longer than 10 secs.

Once phosphocreatine is depleted the lactic acid system (anaerobic glycolysis) takes over and re synthesises ATP from the breakdown of glucose.

Glucose is stored in the muscles and liver as glycogen.

In order to provide energy to make ATP glycogen has to be converted to glucose. This process is called glycolysis. (Sarcoplasm)

Lactic Acid System Glucose is broken down into 6 phosphates (2 ATP) and pyruvic acid.

The main enzyme responsible for the break down of glucose is phosphofructokinase (PFK) activated by low levels of phosphocreatine

Pyruvic acid is converted into lactic acid in the absence of oxygen.

Lactic Acid systemOverall summary:

C6H12O6 (glucose) 2(C3H6O3) (pyruvic acid) + ENERGY ENERGY 2ADP + 2Pi 2ATP

The energy released from the breakdown of each molecule of glucose is used to make two molecules of ATP

The lactic acid system actually provides sufficient energy to re-synthesise three molecules of ATP but the process of glycolysis itself requires energy (one molecule)

The lactic acid system provides energy for high-intensity activities lasting up to 3 minutes but peaking at 1 minute, for example the 400m

Lactic Acid SystemAdvantages DisadvantagesFew chemical reactions so

ATP can be resynthesises quickly

Anaerobic so do not need to wait for the 3 minutes or for sufficient oxygen

Lactic acid can be converted back into liver glycogen

can be called upon to produce an extra burst of energy (10,000m)

If lactic acid accumulates in the muscle, the pH of the body is lowered and this has an effect on enzyme action. PFK, the controlling enzyme, is then inhibited and the ability to re-generate ATP is reduced. This affects performance, for example ‘burning out’ at the end of a race

Only a small amount of energy (5%) locked inside a glycogen molecule can be released in absence of oxygen.

Quick recapSite of reaction –

Fuel used –Active enzyme –

Molecules of ATP produced -

Sacroplasm of muscle cell

Glycogen (stored CHO)

Phosphofructokinase2 molecules

400m raceFirst 10 secs ATP-PCLactic Acid will provide for the rest

Exam QuestionWhat are the main energy sources used by an

athlete during a 400M sprint? Explain the predominant energy system used during this time.

(7 Marks)

Make notes on your own to answer this question.

Share with the person beside you.Share with the whole class.

Candidate AThe main energy sources used by a 400m

runner are carbohydrate and phosphocreatine. The ATP/PC system is used for the first part of the race and is a simple system to use. It uses phosphocreatine as the fuel and there are no fatiguing by products. The energy yeild is ATP. After 10 seconds the lactic acid system is used.

Candidate BThe energy sources used by the sprinter are

phosphocreatine and glucose. The main energy system is the lactic acid system. This is anaerobic and glucose is broken down into pyruvic acid. Two molecules of ATP are formed and lactic acid is the by product. This system takes place in the sarcoplasm.

Energy systemsLearning outcomes: All are able to demonstrate understanding of the energy sources required for ATP resynthesisAll are able to describe the Lactic Acid energy systemMost are able to explain the use of PCr in ATP resynthesisMost are able to apply their understanding of thelactic acid system to sporting examples.Some can analyse the lactic acid and determine advantages and disadvantages

Plenary ActivityAll write down one question and answer that

would demonstrate the progress you have made in this lesson.