8.1 Energy Systems: 2

Question 1

How does the energy transfer during short duration/high intensity exercise work?

Answer 1

• During short duration/high intensity exercise, energy has to be produced rapidly
• Aerobic system is too complicated to produce energy rapidly so body needs to rely on anaerboic respiration- using ATP-PC system & anaerobic glycotic system - however these systems cannot produce energy for long periods of time
• ATP-PC system can only produce energy for high intensity activities lasting up to 10 secs- anaerboci glycolytic system can last for longer (up to 3 min) but depends what intensity performer is working at

Question 2

What is lactate accumulation?

Answer 2

• Using anaerobic glycolytic system produces by-product, lactic acid as a result of glycolysis
• The higher the intensity of excercise the more lactic acid produced
• Lactic acid quickly breaks down releasing hydrogen ions
• As lactate accumulates in muscles, more hydrogen ions are present & it is actually the prescence of hydrogen ions that increases acidity
• This slows down enzyme activity which affects breakdown of glycogen causing muscle fatigue
• The lactate produced in the muscles diffuses into the blood & blod lactate can be measured

Question 3

What is the lactate threshold?

Answer 3

• The point during exercise at which lactic acid quickly accumulates in the blood

Question 4

What is OBLA?

Answer 4

Onset Blood Lactate Accumulation
- The point when lactate levels go above 4 millimoles per litre

Question 5

How does the lactate threshold & OBLA work?

Answer 5

• As exercise intensity increases, body moves from working aerobically to anaerobically
• This crossing of the aerobic/anaerobic threshold is also known as lactate threshold- point which lactic acid rapidly accumulates in the blood
• We are constantly producing small amounts of lactate due to red blood cell activity when working at low intensity but the levels are low & body deals w these effectively
• However as intensity of exercise increases & the body is unable to produce enough oxygen to break down lactate, the levels of lactate build up/accumulate & this is know as OBLA
• OBLA & Lactate threshold are different ways of measuring the same thing
• At rest approx 1-2 millimoles per litre of lactate can be found in the blood
• During exercise levels of lactate will rise dramatically & as it starts to accumulate OBLA ocurs
• Measuring OBLA gives indication of endurance capacity - some individuals can work at higher intensity levels than others- before OBLA & can delay when threshold occurs

Question 6

How is lactate threshold expressed?

Answer 6

• Lactate threshold is express as a percentage of VO2 Max

Question 7

What is the relationship between levels of fitness and lactate threshold?

Answer 7

• As fitness increases the lactate threshold becomes delayed
• Average performers may have a lactate threshold that is 50-60% of their VO2 Max
• Whereas elite performers may have a lactate threshold that is 70/80 or even 90% of their VO2 max
• Training has a limited effect on VO2 max because VO2 max is largely genetically determined

Question 8

When we exercise what level is our lactate threshold?

Answer 8

• When we exercise we tend to work at or just below our lactate threshold
• At a level where fatigue (caused by lactate) is not going to cause our performance to deteriorate
• The fitter we are the higher our lactate threshold as a percentage of our VO2 max & hence the harder we can work.

Question 9

What factors affect the rate of lactate accumulation?

Answer 9

• Exercise intensity
• Muscle fibre type
• Rate of blood lactate removal
• The respiratory exchange ratio
• Fitness of the performer

Question 10

How does exercise intensity affect the rate of lactate accumulation?

Answer 10

• Higher the exercise intensity- greater demand for energy (ATP) & faster OBLA occurs
• Fast twitch fibres are used for high intensity exercise & can only maintain their workload with use of glycogen as a fuel
• When glycogen is broken down in the abscence of oxygen into pyruvic acid, lactic acid is formed

Question 11

How do muscles fibres affect the rate of lactate accumualtion?

Answer 11

• Slow twitch fibres produces less lactate than fast twitch fibres
• When slow twitch fibres use glycogen as a fuel, due to the prescence of oxygen, the glycogen can be broken down much more effectively & w little lactate production

Question 12

How does the rate of blood lactate removal affect the rate of lactate accumulation?

Answer 12

• If rate of lactate removal is equivalent to rate of lactate production then the concentration of blood lactate remains constant
• If lactate production increases, then lactate will start to accumulate in the blood until OBLA is reached

Question 13

How does the respiratory exchange ratio affect the rate of lactate accumulation?

Answer 13

• It is the ration of carbon dioxide produced compared to oxygen consumed
• When glycogen is the preferred fuel, this ratio has a value close to 1:0 & there is a greater chance of the accumulation of lactate.

Question 14

How does the fitness of the performer affect the rate of lactate accumulation?

Answer 14

• A person who trains regularly will be in a better position to delay OBLA as adaptions occur to trained muscles.
• Increased numbers of mitochondria & myoglobin together w an increase in capillary denisty, improve the capacity for aerobic respiration & therefore avoid the use of the anaerobic glycolytic system

Question 15

How does buffering work in lactate-producing capacity & sprint/power performance?

Answer 15

• Elite athletes & power athletes will have a much better anaerobic endurance than non-elite sprinters
• This is because their body has adapted to cope w higher levels of lactate
• Through buffering they will be able to increase rate of lactate removal & consequently have lower lactate levels.
• Athlete will be able to work at higher intensities for longer before fatigue sets in
• As well as being able to tolerate higher levels of lactate, the trained status of their working muscles will lead to adaptive responses
• There will be greater number & size of mitochondria & the associated oxidative enzymes, increase capillary density & more myoglobin

Question 16

What factors are there that affect VO2 max & aerobic power?

Answer 16

• VO2 max is the max volume of oxygen that can be taken up & used by the body per minuet
• An individuals VO2 max will determine endurance performance in sport
• Elite athletes have more oxygen going to the muscles & can utilise this oxygen to provide energy to enable a high rate of exercise
• One of reasons why this is possible is that their bodies have adapted as a result of this training to take up & use more oxygen

Question 17

What measurements of energy expenditure are there?

Answer 17

• Indirect calorimetry
• Lactate sampling
• VO2 max test
• Respiratory exchange ratio

Question 18

What does an indirect calorimetry do?

Answer 18

• A technique that provides an accurate estimate of energy expenditure
• It is a technique that provides an accurate estimate of energy expenditure through gas exchange
• It measures how much carbon dioxide is produced & how much oxygen is consumed at both rest & during aerobic exercise
• Calculating the gas volumes also enables us to find out the main substrate being used

Question 19

What is lactate sampling?

Answer 19

• Involves taking a tiny blood sample & a handheld device analyses the blood & indicates how much lactate is present
• This is an accurate & objective measure of the level of lactate in the blood
• Can also be used as a means of measuring exercise intensity
• The higher the exercise intensity at which the lactate threshold occurs the fitter the athlete is considered to be
• It will allow performer to select relevant training zones whether they are expressed in terms of heart rate (BPM) or power (WATTS)

Question 20

What tests are used to study the VO2 max test?

Answer 20

• Bleep (multistage fitness test)
• Harvard step test
• Cooper’s 12 minuet run
  Tests using this method involve increasing intensities on a treadmill, cycle ergometer or rowing machine
  The volume & concentration of oxygen in the expired air is then measured & compared w the percentage of oxygen that is in the atmospheric air to see how much O2 has been used during the task

Question 21

What is the respiratory exchange ratio?

Answer 21

• The ratio of carbon dioxide produced compared to oxygen consumed
• Used as a measure of exercise intensity
• Provides info about fuel usage during exercise
• Energy sources such as carbohydrates, fat & protein can all be oxidised to produce energy
• For a certain volume of oxygen, the energy released will depend upon the energy source

Question 22

What is the formula used to calculate the respiratory exchange ratio?

Answer 22

• RER= Carbon dioxide expired per minute (VCO2)/ Oxygen consumed per minute

Question 23

What do the different RER values mean?

Answer 23

• RER value close to 1=performer using carbohydrates
• RER value of approx 0.7= performer using fats
• RER value greater than 1=anaerobic respiration so more CO2 being produced than O2 consumed

Measuring respiratory exchange ratio requires an athlete to be attached to a gase analyser while on a treadmill or cycle ergometer so that accurate readings can be taken on amount of co2 produced compared to oxygen consumed

Question 24

What is the altitude training & the impact on the energy systems

Answer 24

• Usually done at 2500 m above sea level where the partial pressure of oxygen is lower
• Partial pressure of O2 drops as altitude increases, usually by up to 50% at an altitude of 5000m
• There is a reduction in the diffusion gradient of oxygen between the air & the lungs & between the alevoli & the blood
• This means not as much oxygen diffuses into the blood so haemoglobin is not as fully saturated w oxygen, which results in the lower O2 carrying capacity of the blood
• As less O2 is therefore delivered to the working muscles, there is a reduction in aerobic performance & VO2 max & a quicker onset of anaerobic respiration

Question 25

What are the benefits to performers carrying out altitude training?

Answer 25

• An increase in the number of red blood cells & concentration of haemoglobin
• An increase in capillarisation & EPO resulting in enhanced oxygen transport
• Altitude training can also lead to an increase in lacrate tolerance
• Altitude training is done to acclimatise players to the lower level of oxygen avaliable in the atmosphere

Question 26

What are the disadvantages of altitude training?

Answer 26

• When athlete first experiences altitude, it is very difficult to train at the same intensity due to the reduction of partial pressure of oxygen so there can be a loss of fitness or detraining
• Altitude sickness is a possibility-which can have a detrimental effect on a training programme
• The benefits gained from altitude training can be lost v quickly on return to sea level & body can only produce a limitef amount of EPO
• Living away from home can also result in psychological problems such as homesickness

Question 27

What is high intensity interval training (HIIT)?

Answer 27

• A form of training in which periods of work are interspersed with recovery periods
• Used for both aerobic & anaerobic training
• 4 main variables are used to ensure the training is specific

Question 28

What are the 4 mian variables used for HIIT training?

Answer 28

• Duration of the work interval
• Intensity or speed of work interval
• Duration of recovery interval
• Number of work intervals & recovery intervals

Question 29

How is HIIT training carried out?

Answer 29

• Involves short intervals of maximum intesity exercsie followed by a recovery interval of low to moderate intensity exercise
• The work interval is anaerobic & the recovery aerobic
• HIIT improves fat burn potential as harder u work more calories u burn
• There are many variations of HIIT that involve: Different numbers of high intensity work intervals & low intensity recovery intervals, different lengths of time for the work & recovery intervals, different exercise intensity for the recovery interval (low or medium intensity)

Question 30

What is plyometric training?

Answer 30

• Involves repeated rapid stretching & contracting of muscles to increase muscle power
• Training involves high intensity explosive activities such as hopping, bounding, depth jumping & medicine ball work &uses fast twitch fibres
• It works on the concept that muscles can generate more force if they have previously been stretched
• So if an eccentric contraction occurs first (which stretches the muscle) followed by a concentric contraction, the force generated can be increased dramatically
• This is called the stretch shortening cycle

Question 31

What is the stretch shortening cycle?

(Remember PAM)

Answer 31

Consists of 3 phases:
- Eccentric phase or pre loading/pre streching phase- On landing the muscle performs an eccentric contraction where it lengthens under the tension
- Amortisation phase- The time between the eccentric & concentric muscle contractions- this time needs to be as short as possible so the energy stored from the eccentric contraction is not lost- when an eccentric contraction occurs, a lot of the energy required to stretch or lengthen the muscle is lost as heat but some of the energy can be stored & is then avaliable for the subsequent concentric contraction
- Muscle contraction phase: Uses the stored energy to increase the force of the contraction

Question 32

What is speed, agility & quickness (SAQ)?

Answer 32

• Speed refers to how fast a person can move over a specified distance or how quickly a body part can be put into motion
• Good agility requires a combination of spped, co-ordination, balance & flexability

Question 33

What is SAQ training?

Answer 33

• A type of training that aims to improve multi-directional movment through developing the neuromuscular system
• Drills inclue zig,zag runs & foot ladders
• As SAQ training uses activities performed w maximum force at high speed, energy is provided anaerobically