Exercise physiology Flashcards
1
Q
What are the three energy sources for physical activity
A
Carbohydrates
Proteins
Fats
2
Q
What is the chemical compound stored in the muscle fibre
A
ATP
3
Q
What does ATP stand for
A
Adenosine triphosphate
4
Q
What is ATP
A
A chemical compound responsible for producing energy for movement
5
Q
How does ATP produce energy
A
1 of 3 phosphate bonds breaks and energy is released
6
Q
What is food digested into
A
Fats, proteins and carbohydrates
7
Q
What must happen when the ATP produce runs out
A
Resynthesis so that energy can be provided for longer periods of time
Only a very small amount of ATP is stored within the muscles, so ATP must continually be rebuilt/resynthesised so that energy can be provided for longer periods of time
8
Q
How can ATP be rebuilt
A
- from the breakdown of phosphate creatine or
- breakdown of macronutrients (carbohydrates, proteins and fats)
9
Q
Resynthesis
A
Energy from the breakdown of phosphate creatine or the stored forms of carbs, fats and protein are used to re-join ADP and inorganic phosphate (Pi) to resynthesis ATP
10
Q
Food fuels
A
Carbohydrates
Fats
Protein
11
Q
Chemical fuels
A
- ATP,
- phosphate creatine (PC),
- glycogen and glucose,
-free fatty acids & triglycerides, - amino acids
12
Q
Carbohydrates
A
- broken down into glucose for blood transportation
- stored as glycogen in the muscle and liver
- Carbohydrates (sugar and starches, in foods such as fruit, cereal, bread, pasta and vegetables) are the body’s preferred source of fuel, particularly during exercise
13
Q
GI
A
Glycemic index
14
Q
What is the Glycemic index (GI)
A
- a ranking of carbohydrates based on their immediate effect on blood glucose (blood sugars)
- measured on a scale of 1-100
15
Q
High GI foods
A
- break down quickly during digestion- therefore have immediate effect on increasing blood sugar levels
- Best consumed during and immediately after the event
16
Q
High GI. During exercise
A
- rapid absorption and release of energy into blood stream provides opportunity to top up glycogen stores, helping the delay of depletion of glycogen stores
17
Q
High GI. immediately after exercise (within 30 minutes)
A
- immediately after exercise muscles are most responsive to topping up fuel supplies, therefore high GI foods need to be consumed within 30 minutes of the activity finishing
18
Q
Low GI foods
A
- Break down slowly during digestion resulting in a slow release of glucose into the blood stream
- best consumed as part of the pre-event meal and after the event to replenish supplies
19
Q
Low GI. Pre-event meal (1-4 hours prior)
A
- slower release of glucose into bloodstream helps keep blood glucose levels topped up prior to race
20
Q
Low GI. after exercise (1-24 hours post exercise)
A
- assist with repletion of muscle and liver glycogen stores up the 24 hour post exercise
21
Q
Carbohydrate loading
A
- nutritional intervention aimed at delaying the depletion of glycogen stores
- occurs when the athlete increases the amount of carbohydrates consumed prior to competition with the aim being to store extra glucose in the liver and muscles
22
Q
2 main methods to load
A
-1 day method
-3 day method
23
Q
1 day method
A
- consume approximately 8-10g/kg body weight of carbohydrates the day before competition (approx 700g stored in muscle and liver)
This is equivalent to eating almost 3 loaves of bread in 1 day- you may need to use supplements - tapering or reducing training load is required to spare muscle glycogen stores
24
Q
3 day method
A
- consume approximately 7-8g/kg body weight of carbohydrates for 3 days leading up to the competition (approx. 700g stored in muscle and liver)
- players can still exercise, however there is significant tapering occurring leading up to competition so as to not deplete glycogen stores
(3 day method is not suitable for sports which require athletes to perform every week -a 3 day taper leading to a match on Saturday would require a taper starting on Wednesday which is not ideal)
25
Advantages of carbohydrates/carb loading
- Carb loading avoids the depletion of glycogen stores by increasing muscle and liver glycogen levels
- By sparing glycogen, it allows aerobic athletes to maintain a higher intensity for a longer period of time
26
Disadvantages of carbohydrates/ carb loading
Binding of water to carbohydrate molecules increases water absorption, causing an increase in weight
*during exercise, CHO stores become depleted, causing an increase in the use of fats for energy
Fats have a higher oxygen cost than CHO, therefore the body must reduce exercise intensity
27
Glycogen sparing
- glycogen sparing of the ability of an athlete to spare glycogen supplies by using an alternative fuel source during physical activity
Achieved by 4 different methods
28
Glycogen sparing 4 methods
Training effect
Caffeine consumption
Pre-event meal
During the event meal
29
Training effect glycogen sparing
Through an aerobic training programme, athletes are better able to break down fats for a given intensity, sparing glycogen for later in the event
30
Caffeine consumption glycogen sparing
By consuming caffeine before the event, it better enables the athletes to break down fats at the start of the event, sparing glycogen for later in the event
31
Pre-event meal glycogen sparing
By consuming a low GI meal 1-4 hours prior to the event, it increases blood glucose levels allowing for the sparing of glycogen for later in the event
32
During the event meal glycogen sparing
By consuming high GI foods during the event, it allows blood glucose levels to be constantly topped up, sparing the use of glycogen as a fuel source
33
Fats
- Fats (In butter, margarine, cheese, oil, nuts and fatty meats) are broken down into either fatty acids (FFA), which are found in adipose tissue and the blood, or triglycerides which are stored in the muscle
- They are the body’s main source of fuel at rear and during prolonged submaximal exercise
34
Protein
— Protein (found in meat, fish, poultry, legumes, eggs and grains) makes a negligible contribution to energy production during exercise (5-10% in ultra endurance events)
—an essential nutrient in the diet; is needed to:
- build convective tissue and muscle cells
- act as enzymes which stored up chemical reactions
— stored in the muscles and around the body
—Used mainly for growth and repair (only used as a fuel in extreme circumstances)
35
What are proteins, fats and carbohydrates used to form
A chemical compound
Known as ATP
Where the breaking of phosphate bonds gives energy to make muscles work
36
What is happening when the body is performing physical work
Converting chemical energy (ATP) produced by chemical reactions into mechanical energy (muscular contraction)
37
Energy systems
Anaerobic
- ATP-CP system
- anaerobic glycolysis
Aerobic
- aerobic system
38
Anaerobic
Without oxygen
39
Aerobic
With oxygen
40
Rate of ATP production
How quickly ATP is resynthesised
41
Yield
How much ATP is resynthesised
42
ATP-CP energy system
- an immediate energy system that does not require oxygen
Fuel- used a combination of stored ATP and the stored creatine phosphate
Intensity- maximum efforts >95% max HR
Duration- short duration (fuel depleted after 10 seconds)
Rate of resynthesis- very fast
Yield- low
43
Alternate names of ATP-CP
Phosphocreatine system (PC)
Creatine phosphate system (CP)
Phosphagen system
Anaerobic alactic system
44
Anaerobic glycolysis
Relies on the breakdown of glycogen, in the absence of oxygen, to produce energy
Fuel- carbohydrate
Intensity- 80-95% max HR
Duration- will take over as predominant system when ATP-CP system fatigues (PC stored depleted at around 5-10 seconds). Predominant 10-60 second events. Peak power is usually reached between 5-15 seconds
Rate of resynthesis- fast
Yield- low-medium 2 ATP
45
Anaerobic glycolysis used for
Used for sustained sprint or muscular endurance activities usually lasting between 45-60 seconds
- 400m sprint
- 200m swim
- repeated high intensity efforts during a continuous game
Provides ATP for longer during submaximal activities (when PC is depleted) and thus provides a ‘stop gap’ until enough oxygen is transported to working muscles for the aerobic system to become the major contributor
46
Glycolysis
• Takes place in the cytoplasm, where the enzymes required are present
• Does not require energy as a larger molecule is being broken down (catabolism)
• ‘Lysis’ means to destroy so the term glycolysis is to destroy or break down glucose
• As it involves a number of complex reactions, it’s not as quick of the marks as the ATP-CP system, but produced twice as much ATP
• Because oxygen is not present, the glycogen is not totally broken down and a by product called lactic acid ( lactate + hydrogen ions) is formed
47
Lactic acid
• Use of the anaerobic glycolysis system results in the production of lactic acid
• What happens when we accumulate lactic acid?
• Lactate purely serves as an indicator that the body is no longer working aerobically. It also represents the accumulation of hydrogen ions
• Although 80% of lactate diffuses from the muscles and is transported back to the liver for conversion to glucose or glycogen some hydrogen ions accumulate in muscle tissue
• An increase in lactate levels means pH levels are dropping (a pH level of 7 indicates neutral – less than 7 means your muscles are becoming acidic!) which decreases the activity of enzymes which break down glycogen.
• Contracting muscles don’t like acid, so when pH levels drop, they stop working as a feedback mechanism to prevent injury. As a result, the Anaerobic glycolysis pathway is compromised and exercise intensity must be reduced
48
Aerobic
Fuel- carbohydrate, proteins and fats ( depending on intensity and duration)
Intensity- during rest and at sub maximal intensities < 80% HR max
Duration- gradual increase in contribution as oxygen becomes available. Predominant energy system after 30-60 seconds (depending on intensity)
Rate of resynthesis- slow
Yield- very high (36-38 ATP)
49
Reasons why the aerobic system takes a while to get going
- lungs work harder to bring in more oxygen
- Heart pumps harder to transport oxygen rich blood to the muscles
-Arteries expands to increase blood flow
50
Once oxygen becomes available to the muscle cell a different chemical reactions known as
Aerobic glycolysis takes place
51
Which system has the greatest capacity to produce ATP but is the slowest to do so
(High yield but low rate)
Aerobic system
52
When is the aerobic system activated
It is activated at the start of intense exercise and contributes significant amounts of ATP during high intensity activities lasting 1-2 minutes and continues to be the major contributor as the anaerobic glycolysis system decreases its contribution
53
Fuel sources during aerobic system
Carbohydrates for the first 90 minutes then fats til 4 hours
Carbs are the preferred energy source during high intensity exercise as fats can produce more ATP than carbs but require more oxygen to produce an equivalent amount of ATP
54
Lactic acid when using aerobic
When using the aerobic system predominantly, any accumulated lactic acid has the opportunity to be oxidised (removed) is converted back into glycogen to be used again as an energy source
- called gluconeogenisis and involves using non carbohydrate sources (such as lactate) to create glucose/glycogen in the liver
This can only occur when there is sufficient oxygen to do so
55
Macronutrients
Carbohydrates
Proteins
Fats
56
Pyruvate can be shuttled off into one of two pathways depending on
Whether there is sufficient oxygen
57
What happens if the cell has adequate oxygen for aerobic metabolism
Then pyruvate (formed from glucose) is converted to Acetyl CoA and enters the citric acid cycle
58
Aerobic system by products
Carbon dioxide
Water (sweat)
Heat
59
Aerobic lipolysis (lipids=fats)
- fats can produce more ATP than carbs
They require more oxygen
Increased oxygen cost from carbs to fats as main fuel source
Less oxygen becomes available to working muscles
60
Athletes slow down when fats are used
Fatiguing/limiting factors
- Fuel depletion- using fats when glycogen is depleted leads to fatigue as fats take longer to break down and require more oxygen than carbs, which means less oxygen is available for muscles
61
Type of recovery
Active recovery. Eg. Salts walking/jogging included in cool down processes or on a rest day
62
Heat (elevated body temperature)
As core temperature increases sweat rates increases and blood is redistributed to the skins surface
Less blood, oxygen and fuels for working muscles, so aerobic exercise may become increasingly anaerobic
HR and cardiac output also increases to continue supplying oxygen to working muscles
63
Energy system interplay
- Interplay of the three energy energy systems in relation to the intensity, duration and type of activity
- The fuel source used for ATP production is based on the duration and intensity of exercise
- most sports and activities there is interplay between energy systems
- all energy systems contribute but there is a predominant system depending on the requirements of the specific activity/effort
64
Energy system interplay at rest
At rest, the energy required for resynthesis of ATP is almost completely derived from the aerobic system
- fats are responsible for contributing about 2/3 of energy required
- CHO are responsible for contributing about 1/3 of the energy required
65
Energy system interplay during exercise
-at the commencement of exercise, all 3 energy systems start contributing to the production of ATP at the same time
- in the early stages of physical activity (0-5 seconds), the ATP-PC system makes the most significant contribution as it is able to produce ATP at the fastest rate, however runs out shortly after
- where this system begins to deplete (at about the 5-6 second mark) the anaerobic glycolysis system begins to take over as the dominant provider of ATP. This system is also about to produce ATP quickly, however produces fatiguing by-products. It remains the dominant provider until about the30 second mark
- from 30 seconds onwards the aerobic system started to produce ATP at a rate which meets the bodies demand for ATP and therefore becomes the dominant provider of ATP
- the aerobic system remains the dominant provider for the remainder of the event unless exercise intensity increases, at which point the anaerobic glycolysis system increases in its contribution to the production of ATP
66
Energy system interplay during exercise to exhaustion
ATP-PC
ATP-PC system
• Main source of energy in first 10 seconds
• Peaks in output at approx 5 seconds
• Fatigue quickly due to depletion ATP/PC
67
Energy system interplay during exercise to exhaustion
Anaerobic glycolysis system
Anaerobic glycolysis system
• Main source of energy from 10 - 30 seconds
• Peaks in output at approx 20 seconds
• Fatigues due to build up of lactic acid
• Provides energy for up to 2 minutes
68
Energy system interplay during exercise to exhaustion
Aerobic system
Aerobic system
• Main source of energy from 30 seconds (point when oxygen supply has increased sufficiently to contribute ATP)
• Unlimited capacity to work unless insufficient fuel supply (food)
69
Steady state exercise
• Oxygen consumption rises sharply during first minutes of exercise.
• This consumption begins to plateau between 3-4 mins and will remain stable for the duration of exercise.
• This means there is a balance between energy required by working muscles and ATP produced by the aerobic pathway.
• This is referred to a steady state ‘exercise’.
70
Oxygen deficit
• When exercise commences, O₂ consumption does not reach “steady state” plateau immediately.
• Oxygen deficit is the state in which there is a discrepancy (shortfall) between oxygen supply and demand and the oxygen required to meet the energy requirements of the activity.
• Energy used during O₂ deficit period is supplied through Anaerobic pathways
• Endurance-trained athletes reach steady state more rapidly, with smaller oxygen deficit.
• The oxygen deficit occurs because the respiratory and circulatory systems take some time to adjust to the new oxygen demand and, consequently, the amount supplied lags behind the amount needed
71
The bodies systems will adjustments to increase oxygen supply
This includes
• increased respiratory frequency
• increased tidal volume
• increased heart rate
• increased stroke volume
72
EPOC stand for
Excess post exercise oxygen consumption
73
EPOC
Is the amount of oxygen consumed during the recovery period(after the end of activity). It is an increased rate of oxygen consumption above that required during rest
• Oxygen can be viewed as the ‘currency’ the body uses in order to ‘purchase’ (resynthesise) ATP. In other words, oxygen must be used in order for ATP to be produced.
• After the cessation of exercise, oxygen uptake or consumption does not immediately return to resting levels, despite the fact that the demand for ATP resynthesis decreases dramatically. Rather, oxygen consumption remains temporarily elevated. This elevated oxygen consumption, which exceeds that normally experienced at rest, is referred to as excess post-exercise oxygen consumption (EPOC).
74
Purpose of EPOC
• replenish ATP-CP stores
• remove lactic acid
• Replacing depleted oxygen stores in body
• Supply oxygen to heart and respiratory muscles-still active
• Supply oxygen to body tissues to be used-because of increased body temperature resulting from exercise.
75
VO2 max
An athletes aerobic capacity
76
Energy from the breakdown of phosphate creatine or the stored forms of CHO, fats and protein are used to
Rejoin ADP and inorganic phosphate to resynthesis ATP
77
Cross over concept
(CHO and fats)
• The ‘crossover concept’ is a theoretical model that explains the balance of CHO and Fat usage during sustained exercise.
• The crossover point is the intensity at which energy from CHO predominates over energy from fats, with further increases in intensity resulting in greater CHO use and decreased fat oxidation.
• Low to moderate exercise intensity – trained individuals will delay the switch to CHO as they are better able to utilise fats as a fuel source, resulting in glycogen sparing.
78
Hitting the wall
• The fuel source used for ATP production is based on the duration and intensity of exercise:
1. Low intensity / rest – stored fats are the main fuel source
2. As intensity of exercise increase, the contribution of muscle glycogen increases to meet the more immediate demands for fuel.
3. There is enough glycogen stored in muscles to fuel up to 60 minutes depending on intensity (and also training and CHO loading). Athletes “hit the wall” when muscle glycogen runs out.
4. When muscle glycogen stores run out, the stored liver glycogen becomes the primary fuel source allowing exercise to continue but performance starts to diminish.
5. Depletion of liver glycogen affects the brain – decision making ability affected
6. Fats now become the primary fuel source and intensity of exercise is reduced as fats require more complex chemical reactions and greater amounts of oxygen
7. Depletion of fats results in protein being used as a fuel source
This is only likely to occur in ultra endurance events
79
Rebound hypoglycaemia
- Athletes must be careful they don't consume high GI foods 30 – 120min prior to event as it may cause REBOUND HYPOGLYCAEMIA
- Immediately after eating CHO, there is a rise in blood sugar levels resulting in the hormone insulin being released into the blood and lowering blood sugar levels.
- When an athlete consumes HIGH GI foods just prior to physical activity, we see a rapid rise in blood sugar levels causing an overshoot in insulin release.
- This significantly reduces blood sugar levels which impairs CNS functioning during exercise causing a negative effect on performance!
80
Immediate response to physical activity
- heart rate (HR)
- stroke volume
- blood pressure (BP)
- cardiac output
- tidal volume
- respiratory rate
- gas exchange
- arteriovenous oxygen difference
- blood redistribution
81
Cardiovascular
- cardiac output
- Heart rate
- stroke volume
- Blood pressure
- Redistribution of blood flow
- a-vO difference
- Venous return
82
Respiratory
- respiratory rate
- Tidal volume
- Ventilation
- Diffusion
- Oxygen uptake
83
Short term effects of physical activity (immediate)
Cardiovascular
1. Increased cardiac output (HR x SV)
2. Increased heart rate (HR)
3. Increased stroke volume (SV)
4. Increased venous return
5. Increased blood pressure
6. Blood redistribution
7. Increased arteriovenous oxygen difference
84
Increased cardiac output (HR x SV)
- Total amount of blood the heart pumps every minute
- Calculated by Heart Rate * Stroke Volume
- Fit male at rest – approx. 5L/min. During exercise can reach over 30L/min
- Fit female at rest – approx. 4L/min. During exercise can reach over 20L/min
85
Increased Heart Rate (HR)
- Number of times heart beats per min
- To provide more rapid supply of fuel and energy to the muscles, heart rate increases during exercise
- This increase is directly proportional to the workload
- At rest, fit individual 50-60bpm. During exercise max HR = 220-age
86
Increased stroke volume SV
- The amount of blood that is ejected from the left ventricle with each beat of the heart
- At rest, fit male approx. 80ml/beat. During exercise can reach over 150ml/beat
- At rest, fit female approx. 60ml/beat. During exercise can reach over 110ml/beat
During exercise, the body's demand for oxygen increases and as a result, Cardiac Output, Heart Rate and Stroke Volume all increase proportionally to cater for this.
87
Increased blood pressure
- Arterioles supplying working muscles vasodilate, so more blood is forced from arterioles into the capillaries surrounding the muscle
- Systolic BP sees a significant increase (compared to Diastolic BP), particularly in exercises which use large muscle groups such as running, cycling or swimming
- Strengthening activities cause greater increases in both Systolic and Diastolic BP
88
Blood redistribution
- During exercise, arteries open up and contract to allow more or less blood to reach certain areas of the body.
- Arteries taking blood to working muscles open up (vasodilate) to allow more blood flow to the muscle whilst arteries taking blood to non active areas of the body contract (vasoconstrict) to reduce blood flow. This increases the amount of blood available to the working muscles.
- To avoid overheating, the blood acts as a temperature regulator, taking heat from within the body to the skin surface, where evaporation of sweat assists in cooling the body.
89
Increased arteriovenous oxygen difference
a-vO2 diff = A comparison of the oxygen in the arteries compared with the veins provides a measurement of muscle oxygen use.
- As more oxygen is extracted by the muscles during exercise, the avO2 difference increases – more oxygen is in the arterioles delivering the blood than is present in venules taking the blood away from the muscle.
- Increased cardiac output to the muscle and extraction of oxygen = greater oxygen availability at the muscle to be used during exercise.
90
Immediate respiratory responses to physical activity
1. Increased respiratory rate
2. Increased tidal volume
3. Increased ventilation
4. Increased gas exchange/pulmonary diffusion
5. Increased oxygen uptake
91
Increased respiratory rate
- The increased need for oxygen and the removal of carbon dioxide during exercise results in an increased respiratory rate.
- At rest approximately 15 breaths per minute
- During exercise up to 40-50 breaths per minute
- During exercise respiratory rate increases to meet the body’s demands to supply oxygen to the working muscles
92
Increased tidal volume
- Tidal volume refers to the amount of air inhaled and exhaled during normal respiration
-The increased need for O2 and the removal of CO2 during exercise results in an increased tidal volume.
- At rest, tidal volume is approx. 500-600ml
- During exercise, it increases up to 3-4L/min
93
Increased ventilation
- Amount of air inspired/expired in a minute (L/min)
- Ventilation increase prior to the beginning of exercise and continues to rise to meet the oxygen demands of the exercise
- Increases in ventilation are a result of an increase in TV, RR or both
- At submaximal exercise intensities:
- Ventilation will increase linearly with oxygen consumption (VO2) until a steady state is reached
- At maximal intensities:
- Ventilation increases until the exercise is stopped
94
Increased gas exchange/pulmonary diffusion
- Diffusion – movement of a gas from high concentration to low concentration
- The air we breath in is high in O2 content and low in CO2
- The air we breath out is low in O2 content and high in CO2
- As a result O2 diffuses from the alveoli into the surrounding capillaries whilst CO2 diffuses from the surrounding capillaries into the alveoli
- During exercise, ↑ need for oxygen and removal of CO2 see’s ↑ diffusion takes place. An athlete uses more of the available oxygen when at work compared to at rest.
- When working, the athlete uses more of the available O2 in the air breathed in than when at rest.
95
Increased oxygen uptake
- Oxygen uptake increases dramatically during first few minutes of exercise (oxygen deficit) as the anaerobic energy system is the dominant energy provider
- Once steady state is reached oxygen demand is met by oxygen supply
- At this point an increase in exercise intensity is met by an increase in oxygen consumption
- When an increase in exercise intensity no longer leads to an increase in oxygen consumption, the athlete has reached a point known as there VO2 MAX
- As a result, athletes are forced to rely on their anaerobic (without O2) energy system to supply energy to the working muscles
- At the completion of exercise, oxygen consumption remains high (oxygen deficit) to assist with the recovery process
- NOTE: VO2 max refers to the maximum capacity of an individual's body to transport and utilize oxygen during exercise, reflecting the aerobic capacity of the individual and is measured in L/min.
96
Aerobic training
Cardiovascular
Respiratory
Muscular
97
Anaerobic training
Muscular
98
Long term adaptations to training
- cardiac output
- heart rate (HR)
- blood pressure (BP)
- blood volume/haemoglobin
- stroke volume
- maximum oxygen uptake (VO2 max)
- Capillarisation
- Ventilation
- oxygen exchange
- muscle hypertrophy
- increased flexibility
- increased aerobic and anaerobic capacity
99
Aerobic training cardiovascular adaptations
- Increased Myocardial contractility
- Increased Size of left ventricle
- Increased SV
- Decreased HR during submaximal exercise & rest
- Increased Cardiac output (Q) during maximal exercise
- Increased Blood volume ( plasma volume & RBC count)
- Decrease Blood pressure
- Increase Volume of haemoglobin
- Increased Capillarisation around heart & skeletal muscle
— Cardiovascular adaptations are those which occur to the structure & function of the heart, blood vessels (arteries, veins & capillaries) & the blood.
100
The heart
Increased myocardial contractility
- The heart is a muscle (myocardium) & responds to training by getting bigger & stronger
- The increase in size of the heart enables the left ventricle to stretch more & thus fill with more blood
○ This increases the contractility, resulting in increased SV & increased blood supply to the body
101
The heart
Increased size of left ventricle
- Aerobic training results in hypertrophy of the heart muscle, characterised by:
—Increase in the size of the left ventricular cavity
—Thickening of the ventricle walls
102
The heart
Increased stroke volume (SV)
- SV increases (at rest & during sub-maximal exercise) due to:
1. Increase contractility of the myocardium – your heart can beat harder and can therefore eject more blood with each beat
2. An increased cavity size of left ventricle allows more filling of blood and therefore a greater volume to be ejected
3. Reduced heart rate allows longer rest period between beats and more opportunity for blood to enter left ventricle
103
The heart
Decreased heart rate (HR) during submaximal exercise and rest
- The heart doesn’t have to work as hard to provide the required O2 & nutrients to the muscles
- Decrease steady state heart rate
- Increase efficiency of the cardiovascular system means that at submaximal intensities, trained athletes will reach a steady state at a lower HR
At sub maximal exercise, Cardiac Output will remain unchanged, however, HR & SV will change following an aerobic training program
104
The heart
Increased cardiac output (Q) during maximal exercise
- Increase in maximum cardiac output due to increase in SV
- Cardiac Output increases at maximal workloads, which increases the delivery of oxygen & the removal of by-products & allows greater aerobic glycolysis to occur
- See the following examples:
—Rest:
Untrained: 5000ml = 70 bpm x 71 ml
Trained: 5000ml = 50 bpm x 100 ml
—Maximal Exercise:
Untrained: 20,000 ml = 200 bpm x 100ml
Trained: 30,000ml = 200 bpm x 150ml
An increased maximum cardiac output benefits the athlete as there is an increased ability to carry O2 to the working muscles which increases the capacity to work.
