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Revision Questions
1. What is the definition of energy and what are the units of measurement?
The capacity to perform work and is measured in joules or calories
2. What is a calorie?
Amount of heat energy needed to raise 1g of water through 1°C
3. What is a joule
4. What is a watt?
Equivalent to the use of one joule per second
5. What is power?
The work performed per unit of time and is measure in watts.
6. Define work
Force x distance (measured in calories or joules)
7. What is ATP and why is it so important for the release of energy in the body?
ATP is the only usable form of energy in the body. Therefore all food we eat has to
be converted into ATP, which is a high energy phosphate compound made up of
adenosine and 3 phosphate molecules.
8. What are the 3 ways in which ATP can be produced?
1. Phosphocreatine system (ATP/PCr) or alactic system
2. The lactic acid system or glycolysis
3. The aerobic system
9. Give an overview of how ATP is produced in the ATP/PCr energy system.
This system is only capable of producing energy for short duration in activities that
demand large amounts of energy.
As PC is stored in the muscle it is readily accessible as an energy source and can
produce energy very rapidly.
Phosphocreatine is a high energy phosphate which is found in the sarcoplasm of
Potential energy is stored in the bond of this compound (Phosphocreatine  P +
Creatine + Energy with use of catalyst creatine kinase).
Creatine kinase is activated when the level of ADP increases in the muscle cells. This
results from a reduction of ATP in these cells. There is enough PC stores in muscle to
sustain all out effort for about 10 seconds.
The energy has to be released from the breakdown of PC before any ATP can be
The energy released by the breakdown of PC is used to convert ADP to ATP.
No fatiguing by-products are released during this process.
10. Give an overview of how ATP is produced in the lactic acid system (glycolysis) energy
This is an anaerobic process, taking place in the sarcoplasm.
The energy comes from the food we eat – involving the partial breakdown of glucose.
The breakdown of PC does not rely on the availability of oxygen.
This process is more complex than the PCr and therefore stores more energy.
Glucose is broken down anaerobically (in the absence of oxygen).
Because there is no oxygen, lactic acid is formed.
The breakdown of the bonds in the glucose causes energy to be released.
The energy is used to synthesize ATP.
The lactic acid system (glycolysis) takes longer to produce energy than the ATP/PCr.
It supplies energy for high intensity activities for about 1 minute.
E.g. 400m sprint
11. What causes fatigue from the lactic acid (glycolysis) system?
When glycogen is broken down anaerobically, lactic acid is produced.
If lactic acid accumulates, then the pH of the body will be lowered.
The drop in pH affects the action of all the enzymes in the body, especially
It also affects lipoprotein kinase, which is the enzyme that helps to breakdown fats.
These conditions reduce the ability of enzymes to function optimally and therefore
the body’s ability to synthesize ATP is temporarily reduced which causes fatigue.
12. Give an overview of ATP production in the aerobic system, with reference to each
stage of this energy system.
This energy system requires oxygen.
At the onset of exercise, there isn’t enough oxygen to break down foods into ATP –
so the 2 anaerobic energy systems are used.
As heart rate and the rate of ventilation increases, more oxygen is taken up by the
working muscles.
Within 1 – 2 minutes, the working muscles are supplied with enough oxygen to allow
effective aerobic respiration to occur.
Stage 1: Aerobic glycolysis
Aerobic glycolysis is the same as anaerobic glycolysis.
Glucose is broken down into pyruvic acid.
As oxygen is present in the reaction, the process of aerobic glycolysis can proceed
further than anaerobic glycolysis.
Lactic acid is not produced.
2 molecules of ATP are synthesized at this stage.
Stage 2: The TCA/ Citric acid/ Kreb’s cycle
The pyruvic acid produced in the first stage diffuses into the matrix of the mitochondria.
A complex cyclical series of reactions occurs:
1. Carbon dioxide is formed
2. Oxidation takes place to remove hydrogen (H) from the compound
3. Sufficient energy is released to synthesize 2 molecules of ATP.
Stage 3: The electron transport chain/ electron transport system
The hydrogen atoms that were removed in stage 2 are transported by coenzymes to the
inner membrane of the mitochondria.
The electrons are passed along by electron carriers combining oxygen and hydrogen
ions to form water.
Energy is released which combines ADP with phosphate to form ATP.
The energy yield from the electron transport chain forms 34 molecules of ATP.
The total yield of ATP from aerobic respiration is 28 molecules of ATP.
13. Describe the principle of oxygen deficit.
Is the difference between oxygen supply and demand.
Occurs at the onset of exercise
Energy sources other than the aerobic system that facilitates ATP production.
Increased ADP and P with increased energy need.
Amount of oxygen needed to breakdown glucose and restore PC stores.
Slow rate of oxygen utilization by cells.
14. What is steady state?
Where energy supply matches energy demand.
Oxygen consumption matches the energy needs of the task
Occurs at submaximal constant load exercise (where the work load does not
increase or change)
15. Describe the recovery from exercise (EPOC).
Also called oxygen debt
Excess post –oxygen consumption.
Elevated VO2 for several minutes immediately after exercise
“Fast” portion of EPOC:
Resynthesize of PC stores
Replacing muscle and blood O2 stores
“Slow” portion of EPOC:
Elevated HR and breathing rate – which requires more energy to be expended
Elevated body temperature = increased metabolic rate
Elevated epinephrine and norepinephrine = increased metabolic rate
Conversion of lactic acid to glucose (gluconeogenesis)
16. What are the physiological differences between prolonged exercise, prolonged
exercise in a hot environment and short term exercise?
Prolonged exercise: (exercise >10mins)
APT production is primarily from aerobic metabolism
Steady state oxygen consumption can generally be maintained
Prolonged exercise in a hot environment:
Steady state not achieved – blood circulation doesn’t go to muscles only – goes to skin
to try and lose heat through sweating
Upward drift in ventilation and oxygen uptake over time
Short term exercise:
High intensity <20sec – ATP from ATP/PC system
High intensity >20sec – ATP from ATP/PC system and glycolysis
High intensity >45sec – ATP from all energy systems
17. What are the metabolic responses to incremental exercise?
Oxygen uptake increases linearly until VO2max is reached – then no further increase
in VO2 even with increased workload
Influenced by ability of cardiorespiratory system to deliver oxygen to muscles and
the ability of muscles to use oxygen and produce ATP aerobically
18. Discuss the use of the lactate threshold in exercise and the factors that contribute to
an increase in lactic acid.
The exercise intensity at which lactate (lactic acid) starts to accumulate in
the blood stream – above baseline. Used as a predictor of endurance performance and
marker of exercise intensity.
Factors that add to an increase in lactic acid:
Increased glycolytic rate (increased from increased epinephrine and norepinephrine)
Decreased removal of lactate
Increased recruitment of fast twitch muscle fibres
Other mechanisms:
Failure of mitochondrial hydrogen shuttle to keep up with the rate of glycolysis – excess
NADH in sarcoplasm favours conversion of pyruvic acid to lactic acid.
Type of LDH – enzyme that converts pyruvic acid to lactic acid + LDH in fast twitch fibres
favours formation of lactic acid.
19. Explain the different fuel selections during different exercise intensities.
Low intensity (<30% Vo2max) – fats are the primary fuel
High intensity (>70%vo2max) – Carbs are primary fuel
20. Explain the cross over concept.
Describes shift from fats to carb metabolism as exercise intensity increases.
i.e. as exercise intensity increases, fats will no longer be used and carbohydrates will
be used for ATP.
This is because of the recruitment of fast twitch fibres and increasing blood levels of
21. How does the duration exercise affect fuel selection?
During prolonged exercise there is a shift from carb metabolism to fat metabolism.
Therefore increased rate of lipolysis: breakdown of triglycerides into glycerol and
This is due to rising blood levels of epinephrine.
22. How do fats and carbohydrates interact with each other during exercise?
Fats burn a carbohydrate flame.
Glycogen is depleted during prolonged high intensity exercise.
Therefore results in a reduced rate of glycolysis and reduced amount of pyruvate
Reduction in krebs cycle intermediates
Reduced fat oxidation (fats are metabolised by krebs cycle)
23. Discuss the different sources of fuel during exercise.
Carbohydrates – Blood glucose & muscle glycogen
Fat – Plasma FFA (from adipose tissue lipolysis) & intramuscular triglycerides
Protein – Only small contribution to total energy production (2%) – can increase up to 5
– 15% during prolonged exercise
Blood lactate – gluconeogenesis via Cori cycle.
24. Describe the ‘crossover concept’ with regard to exercise intensity and duration.
The crossover concept describes the shift in substrate utilisation.
As exercise intensity increases, there is a shift from fat metabolism as the primary fuel
for exercise to carbohydrate metabolism.
During prolonged exercise, there is a shift from carbohydrate metabolism towards fat
metabolism as the rate of lypolysis increases.
25. How does the endocrine system regulate homeostasis during rest?
Chemicals that control and regulate cell/organ activity
Act on target cells
26. How does the endocrine system maintain homeostasis during exercise?
Controls substrate metabolism
Regulates fluid, electrolyte balance
27. What are the 3 types of hormones?
Steroid hormones
Non steroid hormones
28. Discuss how steroid hormones differ from non steroid hormones.
Steroid hormones:
Derived from cholesterol
Lipid soluble, diffuse through membranes
Secreted by four major glands:
Adrenal cortex (cortisol, aldosterone)
Ovaries (estrogen, progesterone)
Testes (testosterone)
Placenta (estrogen, progesterone)
Non steroid hormones:
Not lipid soluble, cannot cross membranes
Divided into two groups
Protein/peptide hormones
Most nonsteroid hormones
From pancreas, hypothalamus, pituitary gland
Amino acid-derived hormones
Thyroid hormones (T3, T4)
Adrenal medulla hormones (epinephrine, norepinephrine)
29. What triggers or regulates hormone bursts?
Secretion regulated by negative feedback
30. What determines the blood hormone concentration?
Determined by:
1. Rate of secretion of hormone from endocrine gland
-Magnitude of input
-Stimulatory versus inhibitory input
2. Rate of metabolism or excretion of hormone
-At the receptor and by the liver and kidneys
3. Quantity of transport protein
4. Changes in plasma volume
31. Discuss the difference between upregulation and downregulation.
Downregulation: decrease number of receptors during high plasma concentration =
Upregulation: increase number of receptors during high plasma concentration =
32. Describe prostaglandins.
Third class of (pseudo)hormones
Derived from arachidonic acid
Act as local hormones/ immediate area
Inflammatory response (swelling, vasodilation)
Sensitize nociceptor free nerve endings (pain)
33. Describe the main hormone secreted from the posterior pituitary gland and describe
the functional properties of this hormone.
Antidiuretic hormone (ADH)
Reduces water loss from the body to maintain plasma volume
Reabsorption of water from kidney tubules to capillaries
Release stimulated by low plasma volume
Due to sweat loss without water replacement = less water in urine
Increases during exercise >60% VO2 max
To maintain plasma volume
34. Describe the main hormone secreted from the anterior pituitary gland and describe
the functional properties of this hormone.
Releases growth hormone (GH)
Potent anabolic hormone
Builds tissues, organs
Promotes muscle growth (hypertrophy)
Stimulates fat metabolism
Essential growth of all tissues
– Amino acid uptake and protein synthesis
– Long bone growth
Spares plasma glucose
– Reduces the use of plasma glucose
– Increases gluconeogenesis
– Mobilizes fatty acids from adipose tissue
35. What is the effect of exercise on growth hormone?
Increase in plasma GH with increased intensity
Greater response in trained runners
*GH release proportional to exercise intensity
36. Discuss how thyroid hormones are regulated and how an increase in T3 and T4
affects the regulation of metabolism.
Secretes triiodothyronine (T3), thyroxine (T4)
Act in a permissive manner to allow other hormones to exert their full effect &
maintain metabolic rate
T3 enhances effect of epinephrine to mobilize free fatty acids from adipose tissue
T3 and T4 lead to increases in:
Metabolic rate of all tissues
Protein synthesis
Number and size of mitochondria
Glucose uptake by cells
Rate of glycolysis, gluconeogenesis
FFA mobilization
37. Which endocrine gland is calcitonin secreted from and how does it function?
Thyroid gland
Regulation of plasma Ca+2  bone building
When Ca+2 levels are high = stimulates Ca+2 excretion by kidneys  expelled in urine
Protects against calcium loss from skeleton during periods of calcium mobilization 
pregnancy & lactation
38. What is the function of the parathyroid hormone?
(opposes effects of calcitonin)
Primary hormone in plasma Ca+2 regulation
When Ca+2 levels are low = stimulates reabsorption of Ca+2 by kidneys
39. What are catecholamines and how are they secreted?
Releases catecholamines (fight or flight)
Increase during Exercise  Increase sympathetic nervous system 
Increase epinephrine and norepinephrine
40. What are the effects of an increase in catecholamine levels?
Catecholamine release increases:
Heart rate, contractile force, blood pressure, Glycogenolysis, FFA , Blood flow to
skeletal muscle
41. How is cortisol used to maintain plasma glucose?
Promotes protein breakdown for gluconeogenesis
Stimulates FFA mobilization from adipose tissue
Stimulates glucose synthesis
Blocks uptake of glucose into cells:
Promotes use of free fatty acids as fuel
42. Explain the effect that exercise has on cortisol levels.
Decrease during low-intensity exercise
Increase during high-intensity exercise
Above ~60% VO2 max
43. Describe the 2 hormones secreted by adipose tissue.
Influences appetite
Enhances insulin sensitivity and fatty acid oxidation
Increases insulin sensitivity and fatty acid oxidation
44. How does increased fat mass (obesity) affect the hormones secreted by adipose
Higher leptin levels and lower adiponectin
Leads to type 2 diabetes and low-grade inflammation
45. Describe the characteristics of the hormone testosterone.
Released from testes
Anabolic steroid
Promotes tissue (muscle) building
Performance enhancement
Androgenic steroid
Promotes masculine characteristics
46. Describe the characteristics of the hormones released from the ovaries.
Estrogen and Progesterone
Released from ovaries
Establish and maintain reproductive function
Levels vary throughout the menstrual cycle
47. Describe the 4 hormones secreted by the pancreas and provide their functions.
Insulin (from  cells)
Promotes the storage of glucose, amino acids, and fats
Lack of insulin is called diabetes mellitus
Glucagon (from  cells)
Promotes the mobilization of fatty acids and glucose
Controls rate of entry of nutrients into the circulation
Digestive enzymes and bicarbonate
Into the small intestine
48. Explain the effect that insulin has on blood glucose.
Counters hyperglycemia, opposes glucagon
Increases glucose transport into cells
Increases synthesis of glycogen, protein, fat
Inhibits gluconeogenesis
49. Explain the effect that glucagon has on blood glucose.
Counters hypoglycemia, opposes insulin
Increases Glycogenolysis, gluconeogenesis
50. Explain how carbohydrates are adequately regulated during exercise.
Glucose must be available to tissues
Glycogenolysis (glycogen  glucose)
Gluconeogenesis (FFAs, protein  glucose)
Adequate glucose during exercise requires:
– Glucose release by liver
– Glucose uptake by muscles
Hormones secreted to increase circulating glucose:
(Glucagon, Epinephrine, Norepinephrine, Cortisol)
Circulating glucose during exercise also affected by
GH: Increase FFA mobilization, Increase cellular glucose uptake
T3, T4: Increase glucose catabolism and fat metabolism
Amount of glucose released from liver depends on exercise intensity & duration
51. Describe how intensity and duration of exercise affect carbohydrate metabolism.
As exercise intensity increases:
Catecholamine release increase
Glycogenolysis rate increases (liver, muscles)
Muscle glycogen used before liver glycogen
As exercise duration increases:
More liver glycogen used
Increase Muscle glucose uptake  increase liver glucose release
As glycogen stores increase, glucagon hormone levels increase
52. Explain the 4 processes that occur to maintain plasma glucose.
1. Mobilization of glucose from liver glycogen stores
2. Mobilization of FFA from adipose tissue
Spares blood glucose
3. Gluconeogenesis from amino acids, lactic acid, and glycerol
4. Blocking the entry of glucose into cells
Forces use of FFA as a fuel
53. Explain the role of insulin and glucagon as fast acting hormones.
Uptake and storage of glucose and FFA
Plasma concentration decreases during exercise
Decreased insulin response following training
Mobilization of glucose and FFA fuels
Plasma concentration increases during exercise
Decreased response following training
Insulin & glucagon secretion influenced by catecholamines
54. Explain the role of epinephrine and norepinephrine as fast acting hormones during
Maintain blood glucose during exercise
Muscle glycogen mobilization
Increasing liver glucose mobilization
Increasing FFA mobilization
Alter glucose uptake
Plasma E and NE increase during exercise
Also related to increased heart rate and blood pressure during exercise
Decreased plasma E and NE after training
55. Discuss how fat metabolism is regulated during exercise.
FFA mobilization and fat metabolism critical to endurance exercise performance
Glycogen depleted  need fat for energy
= release hormones accelerate fat breakdown (lipolysis)
Triglycerides  FFAs + glycerol
Fat stored as triglycerides in adipose tissue
Broken down into FFAs  transported to muscle
Rate of triglyceride breakdown into FFAs = determine rate of cellular fat metabolism
56. What causes the stimulation of lipolysis?
(Decreased) insulin
Stimulate lipolysis via lipase
57. What is power?
How much work is accomplished per unit time.
Describes the rate at which work is being done & therefore intensity of exercise.
58. What is the unit for power?
Watt (W)
59. What is the formula for power?
P = work/ time
60. How is work defined?
Work = product of force multiplied by distance.
61. What is the SI unit for work?
Newtons (N)
62. What is ergometry?
The measurement of work output
63. What is an ergometer?
An apparatus or device used to measure a specific type of work.
64. By what means can the immediate energy system be evaluated?
Short term muscular power: Sprinting up flight of stairs/ jumping (debatable – too
brief ATP & PCr)
65. Give an example of specificity.
A sprinter may not be the best repetitive volleyball leaper.
66. What are the best tests to evaluate glycolytic power and why?
Best tests are those that demand maximal work to be done for up to 3 minutes. This
is because glycogen depletion in specific muscles that are activated occurs during
that time frame, which indicates the contribution of glycolysis to exercise.
67. What methods can be used to measure anaerobic capacity?
No clear method
Accepted methods include:
Maximal accumulated O2 deficit
Wingate anaerobic test
Critical power test
68. What does the Wingate test measure?
Peak power, average power output, anaerobic fatigue.
69. What is anaerobic fatigue?
Percentage decline in power relative to work power.
70. Why is the lactate threshold a good predictor of potential endurance exercise?
Lactate production rate > lactate clearance rate which reflects exercise intensity.
71. How does a higher lactate threshold contribute towards endurance performance?
Higher lactate threshold = higher sustained exercise intensity = better endurance
performance as athlete can exercise hard without accumulating lactate over that
which the body can clear/ utilize, which ultimately delays fatigue.
72. What is direct calorimetry?
Process of measuring metabolic rate via measurement of heat
73. What is the theory behind direct calorimetry?
When the body uses energy to do work, heat is given off. If we measure heat
production (calorimetry) = direct measure of metabolic work.
74. What is the theory behind indirect calorimetry?
Since direct relationship between O2 consumed and amount of heat produced by
body. Therefore measurement of O2 consumption rate provides estimate of
metabolic rate (measurement of O2 consumption is indirect since heat is not
measured directly).
75. Define Respiratory Quotient
Ratio of volume of carbon dioxide produced to volume of oxygen consumed.
76. Define Respiratory Exchange Ratio
Ratio of carbon dioxide exhaled to oxygen consumed when CO2 and O2 exchange
77. How is RER different to RQ?
RER does not represent food oxidation. RQ represents food oxidation (RQ for Carbs
is 1.0)
78. What are the 2 general criteria needed to for tests that measure maximal oxygen
1. Test that is independent of muscle strength, speed, body size, skill
2. Test that consists of graded exercise to point of exhaustion (without muscular
79. What are the criteria for determining if VO2max has been obtained?
1. Criteria for true max VO2 is leveling off or peaking in oxygen uptake.
2. Oxygen uptake fails to increase by some value
3. Maximum lactic acid
4. Maximum predicted HR
5. R > 1.0
80. Explain the factors that affect maximal oxygen uptake.
State of training
Body composition
81. What 4 characteristics assist athletes to become successful in endurance events?
1. High VO2max
2. High lactate threshold (as % VO2max)
3. High economy of effort
4. High percentage of type I muscle fibers (Slow, oxidative, fatigue resistant)
82. Describe the different components found in the circulatory system.
Pumps blood
Arteries and arterioles:
Carry blood away from the heart
Exchange of nutrients with tissues
Veins and venules:
Carry blood toward the heart
83. What are the acute cardiovascular responses to exercise?
 heart rate
 stroke volume
 cardiac output
 blood pressure
 blood flow
 blood plasma volume
84. What 3 factors influence the circulatory response to exercise?
Type, intensity, and duration of exercise
Environmental condition
Emotional influence
85. Describe the changes in cardiac output during exercise.
CO increases during exercise in direct proportion to metabolic rate required to
perform the exercise task.
The increase is from an increase in SV and HR
In untrained and moderately trained subjects at work rates >40% to 60% VO2max –
the increase in cardiac output is from only and increase in HR
CO increases during exercise in direct proportion to metabolic rate required to
perform the exercise task.
 due to an increase in HR & SV
[CO = SV x HR]
BUT: In untrained & moderately trained, at work rates >40% - 60% VO2max the
increase in CO is from increase in heart rate only.
86. Explain how the arteriovenous oxygen difference is affected with exercise.
The extent to which O2 is extracted from the blood as it passes through the body
Calculated as the difference between the oxygen content of arterial blood and right
atrial blood
Arteriovenous difference increases with increasing exercise intensity:
more oxygen being extracted from the blood and used for oxidative production of
ATP by skeletal muscle
87. Explain how the blood pressure is affected with exercise.
As work rate increases, BP also increases (as more blood is pumped to working muscle from
the heart):
Mean arterial pressure (MAP)
Average pressure in the arteries
Maximal CO tends to decrease in linear fashion after 30years of age.
This is due to decrease in heart rate with age.
88. Explain how blood flow is redistributed around the body during exercise.
During maximal exercise, 80% to 85% of total cardiac output goes to contracting
This is necessary to meet the increase in muscle oxygen requirements during intense
Increases in blood flow to the muscles is due to redistribution of blood flow from
inactive organs to the contracting skeletal muscle.
Vasodilation occurs in the arterioles to the contracting skeletal muscle.
Vasodilation reduces the vascular resistance and therefore increases blood flow to
skeletal muscles.
Capillaries in skeletal muscle are also recruited: at rest 50% - 80% are open
compared to intense exercise, where they are almost all open.
89. Describe the circulatory responses that occur with incremental exercise.
Heart rate and cardiac output increase in direct proportion to oxygen uptake.
This ensures that there is enough O2 available for ATP synthesis.
Both then reach a plateau at approximately 100% VO2max
This point represents a maximal ceiling for O2 transport to exercising muscles
The elevation in mean arterial blood pressure during exercise is due to increase in
systolic pressure.
Diastolic pressure remains fairly constant during incremental work
Increase in exercise intensity result in an elevation of both heart rate and systolic
blood pressure; each of these factors increases the work load placed on the heart.
90. Describe the circulatory recovery response to intermittent exercise.
Discontinuous exercise (e.g. interval training) the extent of recovery of heart rate
and blood pressure between bouts of exercise depends on the subject, level of
fitness, environmental conditions (temperature, humidity) and the duration and
intensity of exercise.
Light effort in a cool environment, there is generally complete recovery within bouts.
Intense exercise in a hot/ humid environment there is a cumulative increase in heart
rate between efforts and recovery is not complete.
91. What does the recovery of HR and BP between exercise bouts depends on?
1. Level of fitness
2. Environmental conditions
(temperature, humidity)
3. Duration and intensity of exercise.
92. Explain what is meant by ‘cardiovascular drift’.
The ability to maintain a constant cardiac output (Q) in spite of a declining SV.
Heart rate increases parallel to the decline in SV to ensure Q is maintained at a
constant work rate.
Ability to maintain a constant CO despite a decreasing SV which is due to the
increase in HR being equal in magnitude to the decline in SV
93. What is the influence of body temperature on cardiovascular drift?
Progressive increase in the amount of CO directed to the vasodilated skin to
facilitate heat loss
 More blood in skin to cool the body
 Less blood available to return to heart = decreases SV
94. How does a reduction in plasma volume affect cardiovascular drift?
Reduces venous return to the heart & therefore reduces SV
If prolonged exercise is performed in a hot/humid environment, the increase in
heart rate and decrease in stroke volume is exaggerated
95. From a cardiovascular perspective, how does arm exercise compare with leg
At any given level of oxygen consumption both HR and BP are higher during arm
work compared to leg work
Higher HR from greater sympathetic stimulation (SNS) to the heart during arm work.
The relatively large increase in BP for arm work is due to a vasoconstriction in the
inactive muscle groups (e.g. legs)
96. What is the amount of haemoglobin found in a normal male and female? (2)
Normal, healthy men = 150g/L of blood
Normal, healthy women = 130g/L of blood
97. What is the amount of oxygen carried in a normal male and female? (2)
Healthy male can transport 200ml of O2
Healthy female can transport 174ml of O2
98. What is partial pressure? (2)
Defined as the pressure that any one gas would exert on the walls of the container if
it were the only gas present
99. Explain the oxyhemoglobin dissociation curve, focusing on the use, flat and steep
portions. (10)
The flat portion of the curve shows that the PO2 can fall from 100 to 60 mmHg and the
hemoglobin will still be 90% saturated with O2.
This means the O2 content does not change much (even with large changes in the partial
pressure of oxygen).
E.g. PO2 can fluctuate between 90 – 100mmHg without a large drop in the percentage of
hemoglobin that is saturated with O2.
This is important because there is a drop in PO2 with aging and with climbing high altitudes.
Significance of the steep portion
PO2 reductions below 40 mm Hg produce a rapid decrease in the amount of O2 bound to
When the PO2 falls below 40 mm Hg, the quantity of O2 delivered to the tissue cells may be
significantly reduced.
As PO2decrease in this steep area of the curve, the O2 is unloaded to peripheral tissue as
hemoglobin’s affinity for O2 diminishes.
Therefore, small changes in PO2 will release large amounts of O2 from hemoglobin.
This is critical during exercise when O2 consumption is high.
What factors affect the oxghemoglobin dissociation curve? (3)
Increased pH
Increased temperature
Increased PCO2
How does exercise affect the oxghemoglobin dissociation curve? (3)
During exercise, the oxyhemoglobin dissociation curve will shift to the right to allow for more
oxygen to be unloaded into active muscles.
This is because the pH in the body is decreased (from increased lactic acid) and an increase in body
temperature from exercise.
What is myoglobin and where is it found? (4)
Protein that binds with O2
Found in Skeletal and Cardiac muscle fibers (not in blood)
Acts as a shuttle to transport O2 from muscle cell membrane to the mitochondria
How is myoglobin different to hemoglobin? (4)
Myoglobin has a similar structure to hemoglobin, but is ¼ weight
Difference in structure = difference in affinity for O2
Myoglobin has a greater affinity for O2:
Therefore the myoglobin-O2 dissociation curve is much steeper
= myoglobin releases O2 at very low PO2 values
What are the differences in myoglobin and oxygen at the start and end of
exercise? Why does this happen? (8)
Myoglobin stores O2 = reserve O2 for transition from rest to exercise
At the start of exercise there is a lag time from the onset of muscular contraction
and increased O2 delivery to the muscles
Therefore O2 bound to myoglobin before exercise acts as a buffer
so that muscles can receive O2 until the cardiopulmonary system can meet the
new O2 demand
At the end of exercise:
myoglobin- O2 stores must be replenished to ensure O2 is available for the next time
exercise begins
Therefore O2 consumption above rest contributes to the O2 debt
i.e. O2 consumption continues after exercise has stopped  leading to an O2 debt (O2
(Anaerobic metabolism of lactate – also called EPOC  Post Exercise Oxygen Consumption)
What are the way in which carbon dioxide is transported? (3)
1. Dissolved CO2 (±10%)
2. CO2 bound to haemoglobin (±20%)
3. Bicarbonate (HCO3¯)(±70%)
How is carbon dioxide converted to bicarbonate? (5)
A high PCO2 causes CO2 to combine with water, forming carbonic acid.
This reaction is rapidly catalyzed by the enzyme Carbonic Anhydrase
The carbonic acid then dissociates into bicarbonate ion and hydrogen ion.
The hydrogen ion then binds with hemoglobin
The bicarbonate ion diffuses out of the red blood cell into the blood plasma
Explain bicarbonate exchange. (8)
Because bicarbonate carries a negative charge (anion), removal of a negatively
charged molecule from a cell = electrochemical imbalance
Therefore the negative charge must be replaced
Bicarbonate is replaced by chloride (Cl¯) which diffuses from the plasma into the red
blood cell
This is called chloride shift
 the shift of anions into red blood cells as blood moves through tissue capillaries
When blood reaches the pulmonary capillaries:
PCO2 of the blood is greater than that of the alveolus = CO2 diffuses out of the blood
across the blood-gas interface
At the lungs:
Binding of O2 to hemoglobin causes a release of the hydrogen ions (which are bound to
hemoglobin) to promote the formation of carbonic acid
In conditions where PCO2 is low (at the alveolus), carbonic acid then dissociates into
CO2 and H2O
The release of CO2 from the blood into the alveoli is removed from the body in expired
gas (CO2 we breathe out)
Describe the changes in PO2 and PCO2 with different exercises.
Transition from rest  constant-load-submaximal exercise
Arterial tensions of PCO2 and PO2 are relatively unchanged during transition during
submaximal exercise
BUT: arterial PO2 decreases & PCO2 increases slight in transition from rest  steadystate exercise
Describe the rest to work transitions to exercise in constant-load exercise.
At the onset of constant-load submaximal exercise:
Initially, ventilation increases rapidly
Then, a slower rise toward steady-state
Slight decrease in PO2 and increase in PCO2
What happens during prolonged sub maximal exercise? Why does this occur?
Ventilation tends to drift upwards
Little change in PCO2
Higher ventilation not due to increased PCO2
What happens during incremental exercise?
Linear increase in ventilation
- Up to 50 – 75% VO2max
Exponential increase beyond this point
Ventilatory threshold
- Point where minute ventilation increases exponentially
Explain the Ventilatory Threshold
Reflects aerobic fitness without the need to directly measure maximal oxygen
Point during exercise training at which pulmonary ventilation becomes
disproportionately high with respect to oxygen consumption during an incremental
exercise test
Used as a guide to determine exercise intensity
Therefore: Ventilatory threshold = intensity of exercise that shows a larger
ventilation than required to do work.
At this point, the contribution of anaerobic metabolism becomes significant to
produce larger concentrations of lactic acid.
Lactic acid accumulates, reducing pH & increasing metabolic acidosis.
Because one of the functions of the respiratory system is acid-base balance,
respiration must increase to compensate for the increased acidosis.
The point where ventilation deviates from linearity is termed the ventilatory
threshold (TVENT).
How do trained and untrained athlete’s ventilatory responses differ?
Decrease in arterial PO2 near exhaustion
pH maintained at a higher work rate
Ventilatory threshold occurs at higher work rate
Untrained: able to maintain PO2 in arteries within 10–12 mmHg of resting value
Trained: PO2 decreases by 30- 40 mmHg during heavy exercise
*low arterial PO2 vales during exercise = exercise induced hypoxemia
* Low arterial Po2 values are also seen in patients with severe lung disease
How do male and female ventilatory responses differ?
50% of highly trained male endurance athletes develop exercise induced hypoxemia
Females are suggested to have experience exercise induced hypoxemia more often
than males
What is hypoxemia and how does it relate to exercise?
Low arterial PO2 vales during exercise = exercise induced hypoxemia
Means that while exercising, the transport of oxygen throughout the body becomes
lower than optimal, resulting in earlier fatigue as muscle struggles to get enough
What are the suggested causes to hypoxemia in athletes?
Failure of pulmonary system?
Ventilation perfusion mismatch?
Indicates matching of blood flow to ventilation
Ideal: ~1.0
Light exercise improves
Heavy exercise = inequality
Diffusion limitations during exercise ?
Reduced amount of time that red blood cells spend in the pulmonary
capillaries...caused by high cardiac outputs from athletes  less time for gas
equilibrium to be achieved
1. Why is a significant increase in core temperature a threat to life? (3)
May destroy proteins and enzymes and lead to death
2. Describe the voluntary and involuntary heat production mechanisms.
Voluntary - Exercise:
70–80% energy expenditure appears as heat
Increases heat production by ±5 times
Action of hormones: Thyroxine, Catecholamines
Called non-shivering thermogenesis
3. What are the 4 ways that heat can be lost?
4. Describe the evaporation rate & describe what factors this rate depends on.
Heat from skin converts water (sweat) to water vapor
Requires vapor pressure gradient between skin and air
Evaporation rate depends on:
Temperature and relative humidity
Convective currents around the body
Amount of skin surface exposed
5. What are the functions of the anterior hypothalamus?
Responds to increased core temperature
Begin to sweat:
Increased evaporative heat loss
Increased skin blood flow
Allows increased heat loss
6. What are the functions of the posterior hypothalamus?
Responds to decreased core temperature
Shivering and increased norepinephrine secretion
Increased heat production
Decreased skin blood flow
Decreased heat loss
7. Discuss the thermal events during exercise?
As exercise intensity increases:
Heat production increases
Linear increase in body temperature
Core temperature proportional to active muscle mass
Higher net heat loss
Lower convective and radiant heat loss
Higher evaporative heat loss
As ambient temperature increases:
Heat production remains constant
Lower convective and radiant heat loss
Higher evaporative heat loss
8. What is the heat index and how is it used?
Measure of body’s perception of how hot it feels
Relative humidity added to air temperature
9. Discuss exercise in the heat/ hot environments.
Inability to lose heat
Higher core temperature
Risk of hyperthermia and heat injury
Higher sweat rate
May be as high as 4–5 L/hour
Risk of dehydration
10. What are the guidelines to prevent exercise related heat injuries. (7)
Exercise during the coolest part of the day
Minimize exercise intensity and duration on hot/humid days
Expose a maximal surface area of skin for evaporation
Provide frequent rests/cool-down breaks with equipment removal
Avoid dehydration with frequent water breaks
Rest/cool-down breaks should be in the shade and offer circulating, cool air
11. What are the ways to prevent dehydration during exercise?
Dehydration of 1–2% body weight can impair performance
Hydrate prior to performance
400–800 ml fluid within three hours prior to exercise
Consume 150–300 ml fluid every 15–20 min
Volume adjusted based on environmental conditions
Ensure adequate rehydration
Consume equivalent of 150% weight loss
1 kg body weight = 1.5 L fluid replacement
Monitor urine colour
Sports drinks are superior to water for rehydration
12. How does exercising in the heat accelerate muscle fatigue? (6)
Rapid onset of muscle fatigue in hot/humid environments
Heat-related muscle fatigue due to:
High brain temperature reduces neuromuscular drive
Reduction in motor unit recruitment
Accelerated muscle glycogen metabolism and hypoglycemia
Increased free radical production
Damage to muscle contractile protein
13. What differences do age and gender have on thermoregulation? (4)
Women less heat tolerant than men
Lower sweat rates
Higher percent body fat
Age itself does not limit ability to thermoregulate
Decreased thermotolerance with age due to:
Deconditioning with age
Lack of heat acclimatization
14. How do we acclimatize to heat?
Requires exercise in hot environment
Adaptations occur within 7–14 days
Increased plasma volume
Earlier onset of sweating
Higher sweat rate
Reduced sodium chloride loss in sweat
Reduced skin blood flow
Increased cellular heat shock proteins
Acclimatization lost within a few days of inactivity
15. What are the primary adaptations to heat acclimatization? (4)
Increased plasma volume
Earlier onset of sweating
Higher sweat rate
Reduced sodium chloride in sweat
Reduced skin blood flow
Increased heat shock proteins in tissues
16. How do we adapt to cold environments?
Results in lower skin temperature at which shivering begins
Maintain higher hand and foot temperature
Improved peripheral blood flow
Improved ability to sleep in the cold
Due to reduced shivering
Adaptations begin in 1 week
1. Name the 3 principles of training and describe what each entails. (9)
1. Overload
Training effect occurs when a system is exercised at a level beyond which it is normally
2. Specificity
Training effect is specific to:
Muscle fibers involved
Energy system involved (aerobic vs. anaerobic)
Velocity of contraction
Type of contraction (eccentric, concentric, isometric)
3. Reversibility
Gains are lost when overload is removed
 2. How is VO2max improved with training?
Expected increases in VO2max
Average = 15%
2-3% in those with high initial VO2max
30–50% in those with low initial VO2max
Genetic predisposition
Accounts for 40%-66% VO2max
Prerequisite for high VO2max (60–80
1. 3. Discuss each training adaptation for VO2max.
1. Increased Svmax
 Preload (EDV):
End volumetric pressure that stretches the right or left ventricle of the heart to its greatest
…therefore preload = initial stretching of the cardiac muscles before contraction.
As ventricle contracts = develop greater pressure & eject blood more rapidly
(because the Frank Starling Mechanism = activated by the increased preload.)
Because  venous pressure:
(pressure exerted on the walls of the veins by the circulating blood)
 Plasma volume (yellowish solution ±91% water & other 9% = nutrients: glucose, amino
acids; sodium, potassium; antibodies)
 Venous return (volume of blood flowing back to the heart through the veins.)
 Ventricular volume
2.  Afterload (TPR):
Tension or stress developed in the wall of the left ventricle during ejection.
End load (pressure) against which the heart contracts to eject blood.
Afterload is broken into components:
aortic pressure and/or the pressure the ventricle must overcome to eject blood.
 Arterial constriction
 Maximal muscle blood flow with no change in mean arterial pressure
3.  Contractility
4. a-vO2max
 Muscle blood flow =  O2 to active muscles
Therefore  SNS vasoconstriction
[= vasodilation to  blood flow to muscles]
Improved ability of the muscle to extract oxygen from the blood
 Capillary density
 Mitochondial number (therefore  ATP produced)
4. How will detraining affect VO2max?
±50% of the increase in mitochondrial content lost after 1 week of detraining
All of the adaptations lost after 5weeks of detraining
4 weeks of retraining to regain the adaptations lost in the first week of detraining
5. What are the structural and biochemical adaptations to endurance training?
 capillary density
 number of mitochondria
 in oxidative enzymes
( catalysts in reactions that produce ATP):
 Krebs cycle (citrate synthase)
 Fatty acid cycle
 Electron transport chain
Increased NADH shuttling system (glycolysis)
 NADH from cytoplasm to mitochondria
Change in type of LDH (lactate dehydrogenase):
LDH catalyses oxidation of lactate to pyruvate & predominates in slow-twitch muscle fibres.
Endurance training  activity of LDH increases in slow-twitch fibres = improved the ability of
muscles to oxidize lactate.
6. What are the effects of intensity and duration on mitochondrial adaptations? (5)
Citrate Synthase (CS)
Marker of mitochondrial oxidative capacity
Found in Citric acid (Krebs cycle) – aerobic metabolism
Light to moderate exercise training
Increased CS in high oxidative fibers
Type I (slow) and IIa (intermediate fast/ fast twitch oxidative )
Strenuous exercise training
Increased CS in low oxidative fibers
Type IIx (fast glycolytic)
7. Why is oxygen deficit lower after training?
ADP stimulates mitochondrial ATP production
Increased mitochondrial number after training
Lower ADP needed to increase ATP production and VO2
Oxygen deficit is lower after training:
Same VO2 but lower ADP needed
Energy requirement can be met by oxidative ATP production at the onset of exercise
Faster rise in VO2 curve & steady-state reached earlier
= less lactic acid formed & less PC depletion
Therefore: rapid  in O2 uptake at the onset of exercise from  aerobic enzymes in the
mitochondria which have  in number.
8. How is the plasma glucose concentration affected by training? (6)
Increased utilization of fat = sparing of plasma glucose & muscle glycogen
Transport of FFA into the muscle:
Increased blood capillary density
= Slower blood flow and greater FFA uptake
Transport of FFA from the cytoplasm to the mitochondria
Increased mitochondrial number
Mitochondrial oxidation of FFA
Increased enzymes of -oxidation
Increased rate of acetyl-CoA formation
High citrate level inhibits PFK and glycolysis
Therefore: the  uptake of FFA from the blood circulation is from  capillary density and 
enzymes for metabolism of FFA.
9. How is the blood pH affected by training?
Lactate production during exercise
Increased mitochondrial number
Less carbohydrates used = less pyruvate formed
Increased NADH shuttles
= Less NADH available for lactic acid formation
Increased capillary density helps increase O2 availability = reduces anaerobic metabolism.
10. How is the lactate removal affected by training?
By nonworking muscle, liver, and kidneys
Gluconeogenesis in liver
Increased capillary density
Muscle can extract same O2 with lower blood flow
More blood flow to liver and kidney
Increased lactate removal
Increased enzymes in the increased number of mitochondria
= help with the metabolism of lactate
= lactate removal by increased capillaries to organs e.g. heart  which can metabolise lactate
11. What are the physiological effects of strength training? (8)
Strength training results in increased muscle size and strength
Neural factors:
Increased ability to activate motor units
Strength gains in first 8-20 weeks
Muscular enlargement
Mainly due enlargement of fibers
May be due to increased number of fibers
12. What are the adaptations to strength training?
Glycolytic enzymes:
Enhanced muscular storage of glycogen and increases in the levels of glycolytic enzymes –
especially with high volume resistance training
Intramuscular fuel stores
eg. Glycogen
Ligament and tendon strength
Increase in collagen content (only with high loads) to increase cross sectional area of tendon/
Increased bone mineral content.
Increase mechanical stress on bone = increase bone formation/ density
13. What are the limitations to strength training?
Hormones (testosterone, HGH)
Nutrition (Protein, Carbs)
Muscle size (smaller muscles have fewer muscle fibers)
Type and intensity of training
Lack of rest