8.1 Energy Systems: 2 Flashcards
1
Q
How does the energy transfer during short duration/high intensity exercise work?
A
- 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
2
Q
What is lactate accumulation?
A
- 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
3
Q
What is the lactate threshold?
A
- The point during exercise at which lactic acid quickly accumulates in the blood
4
Q
What is OBLA?
A
Onset Blood Lactate Accumulation
- The point when lactate levels go above 4 millimoles per litre
5
Q
How does the lactate threshold & OBLA work?
A
- 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
6
Q
How is lactate threshold expressed?
A
- Lactate threshold is express as a percentage of VO2 Max
7
Q
What is the relationship between levels of fitness and lactate threshold?
A
- 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
8
Q
When we exercise what level is our lactate threshold?
A
- 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.
9
Q
What factors affect the rate of lactate accumulation?
A
- Exercise intensity
- Muscle fibre type
- Rate of blood lactate removal
- The respiratory exchange ratio
- Fitness of the performer
10
Q
How does exercise intensity affect the rate of lactate accumulation?
A
- 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
11
Q
How do muscles fibres affect the rate of lactate accumualtion?
A
- 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
12
Q
How does the rate of blood lactate removal affect the rate of lactate accumulation?
A
- 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
13
Q
How does the respiratory exchange ratio affect the rate of lactate accumulation?
A
- 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.
14
Q
How does the fitness of the performer affect the rate of lactate accumulation?
A
- 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
15
Q
How does buffering work in lactate-producing capacity & sprint/power performance?
A
- 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
16
Q
What factors are there that affect VO2 max & aerobic power?
A
- 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
17
Q
What measurements of energy expenditure are there?
A
- Indirect calorimetry
- Lactate sampling
- VO2 max test
- Respiratory exchange ratio
18
Q
What does an indirect calorimetry do?
A
- 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
19
Q
What is lactate sampling?
A
- 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)
20
Q
What tests are used to study the VO2 max test?
A
- 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
21
Q
What is the respiratory exchange ratio?
A
- 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
22
Q
What is the formula used to calculate the respiratory exchange ratio?
A
- RER= Carbon dioxide expired per minute (VCO2)/ Oxygen consumed per minute
23
Q
What do the different RER values mean?
A
- 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
24
Q
What is the altitude training & the impact on the energy systems
A
- 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
25
Q
What are the benefits to performers carrying out altitude training?
A
- 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
26
Q
What are the disadvantages of altitude training?
A
- 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
27
Q
What is high intensity interval training (HIIT)?
A
- 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
28
Q
What are the 4 mian variables used for HIIT training?
A
- Duration of the work interval
- Intensity or speed of work interval
- Duration of recovery interval
- Number of work intervals & recovery intervals
29
Q
How is HIIT training carried out?
A
- 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)
30
Q
What is plyometric training?
A
- 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
31
Q
What is the stretch shortening cycle?
(Remember PAM)
A
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
32
Q
What is speed, agility & quickness (SAQ)?
A
- 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
33
Q
What is SAQ training?
A
- 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
