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

HomeworkResearch and make notes on the factors that

affect the rate of lactate accumulation:Muscle fibre typeExercise intensityRate of blood lactate removalTrainingRespiratory exchange ratio

Complete tasks 1.13 & 1.14OBLA 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?

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 2(C3H6O3) + 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

Onset of Blood Lactate Accumulation (OBLA)

Onset of blood lactate accumulation (OBLA) is the point at which lactate starts to accumulate in the blood.

This occurs at around 4 mmol lactate per litre of blood

Lactate is produced when hydrogen is removed from the lactic acid molecule.

We are constantly producing lactic acid even when working at a low level but we are able to deal with it. (Normal 1 to 2 mmol)

Look at diagram –Blood lactate and running speed to show Onset

of Blood Lactate Accumulation (OBLA)

OBLAOBLA is expressed

as a percentage of your VO2 max.

OBLA can be used to predict the endurance capacity of a performer; since the longer an athlete can delay the build up of blood lactate, the longer he/she can perform exercise

OBLAExercise can be sustained beyond

OBLA for approximately 1 minute, since the dramatic increase in lactic acid causes acute muscle fatigue

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.