Download Revision Questions What is the definition of energy and what are the

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
4.2kcal
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 muscle.
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 formed.
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 system.
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
phosphofructokinase.
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:
Hypoxia
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
epinephrine.
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 FFA
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 produced.
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. (4)
The crossover concept describes the shift in substrate utilisation.
Intensity:
As exercise intensity increases, there is a shift from fat metabolism as the primary fuel for
exercise to carbohydrate metabolism.
Duration:
During prolonged exercise, there is a shift from carbohydrate metabolism towards fat
metabolism as the rate of lypolysis increases.
25. What determines the blood hormone concentration?
Rate of secretion of hormone from endocrine gland
rate of metabolism or excretion of hormone
Quantity of transport protein
Changes in plasma volume
26. What does the magnitude of hormone receptor effect depend on:
Concentration of hormone
Number of receptors on the cell
Affinity of the receptor for the hormone
27. How do hormones bring about their effects?
By altering membrane transport
Stimulating DNA to increase protein synthesis
28. How does the hormone insulin interact with receptors to be transported around the body?
Insulin binds to receptors on the surface of the cell.
It mobilises glucose transporters located in the membrane of the cell.
The transporters link up with glucose on the outside of the cell membrane where the
concentration of the glucose is high
Glucose transporters diffuse into the inside of the cell to release glucose
29. How does diabetes occur?
There is not enough insulin in the body to help cells take up glucose.
Therefore glucose accumulates in the plasma/ blood
This is because glucose transporters in the cell membrane are not activated
30. What endocrine glands are there in the body?
Hypothalamus
Pituitary glands
Thyroid and Parathyroid glands
Adrenal glands
Pancreas
Testes and ovaries
31. What is the function of Growth Hormone?
Essential for normal growth – stimulates protein synthesis and long bone growth.
32. What are the effects of exercise on Growth Hormone?
Increases during exercise:
Decrease glucose uptake
Mobilizes fatty acids from adipose tissue
Aids in the maintenance of blood glucose and gluconeogenesis
33. How does Growth Hormone aid in the maintenance of blood glucose?
Opposes the action of insulin to reduce the use of plasma glucose
Increases the synthesis of new glucose in the liver (gluconeogenesis)
Increases metabolism of fatty acids from adipose tissue
34. What hormones are secreted by the posterior pituitary glans?
Antiduiretic hormone (ADH) or vasopressin
35. What are the functions of ADH?
Reduces water loss from the body to maintain plasma volume
36. What are the hormones released from the thyroid gland?
Triidothyronine (T3) and Thyroxine (T4)
Calcitonin
37. What is the function of the parathyroid hormone?
Regulate Ca++
38. What are the functions of the adrenal medulla?
Secretes catecholamines: epinephrine and norepinephrine which
increase heart rate
convert glycogen to glucose (glycogenolysis)
mobilise fatty acids from adipose tissue for lipolysis
39. What are the hormones secreted by the adrenal cortex?
Secrete Mineralcorticoids (Aldosterone) and Glucocorticoids (Cortisol)
40. What are the functions of Mineralcorticoids?
Maintain plasma sodium and potassium levels
Regulate blood pressure
41. What are the functions of Glucocorticoids?
- Stimulated by exercise and long term fasting
Promote use of FFA as fuel – block entry of glucose into tissues
Stimulate glucose synthesis in liver by glycogenolysis
Promote protein breakdown for gluconeogenesis and tissue repair
42. What hormones does the pancrease release?
Insulin – promote storage of glucose, amino acids, fats
Glucagon – promotes mobilization of fatty acids and glucose.
Somatostatin – control rate of entry of nutrients in circulation
43. What are the functions of testosterone?
Anabolic steroid – promotes tissue (muscle) building
Androgenic steroid – promotes masculine characteristics
44. What are the functions of estrogen?
Stimulate breast development
Stimulate fat deposition and other secondary sex characteristics
45. How does the intensity of exercise affect glycogen utilization?
Glycogenolysis – breakdown of glycogen.
High intensity – greater and more rapid glycogen depletion
Plasma epinephrine is stimulate glycogenolysis – Therefore higher intensity results in greater
increase/ stimulation of plasma epinephrine.
46. Explain the four ways by which plasma glucose is maintained during exercise.
Mobilisation of glucose from the liver
Mobilisation of FFA from adipose tissue to spare glucose
Synthesis of new glucose in the liver – gluconeogenesis.
Blocking of glucose entry into cells to force the use of FFA by the cells
* Slow acting hormones (Tyroxine, Cortisol, Growth hormone) assist
47. What are the 3 functions of cortisol?
Stimulates FFA mobilization from adipose tissue
Mobilise amino acids for gluconeogenesis
Blocks entry of glucose into cells
48. What are the effects of epinephrine and norepinephrine during exercise?
Catecholamines that allow the body to favour the mobilization of FFA
Maintenance of plasma glucose
Increases linearly during exercise
49. What are the factors that determine blood hormone concentration?
Rate of secretion of hormone from endocrine gland
Rate of metabolism or excretion of hormone
Quantity of transport protein
Changes in plasma volume
50. What are the effects of insulin at rest and during exercise?
(5)
At rest:
Insulin is the primary hormone involved in the uptake of and storage of glucose and FFA
Insulin during exercise:
Plasma insulin decreases during exercise;
Prevents rapid uptake of plasma glucose.
Favours mobilisation of liver glucose and lipid FFA
With trained subjects:
More rapid decrease in plasma insulin
Increase in plasma glucagon
51. 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
52. Explain how blood flow is redistributed around the body during exercise.
(7)
During maximal exercise, 80% to 85% of total cardiac output goes to contracting muscles.
This is necessary to meet the increase in muscle oxygen requirements during intense exercise.
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.
53. Describe the circulatory responses that occur with incremental exercise.
(7)
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.
54. 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.
55. 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.
56. 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
57. 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
58. 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
59. Explain the oxghemoglobin dissociation curve, focusing on the use, flat and steep portions
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 hemoglobin.
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.
60. What factors affect the oxghemoglobin dissociation curve? (3)
Increased pH
Increased temperature
Increased PCO2
61. 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.
62. 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
63. 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
64. 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 deficit)
(Anaerobic metabolism of lactate – also called EPOC  Post Exercise Oxygen Consumption)
65. 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%)
66. 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
67. 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)
68. Describe the changes in PO2 and PCO2 with different exercises.
(6)
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  steady-state
exercise
69. Describe the rest to work transitions to exercise in constant-load exercise.
(4)
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
70. 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
71. 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
72. Explain the Ventilatory Threshold
Reflects aerobic fitness without the need to directly measure maximal oxygen uptake
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).
73. How do trained and untrained athlete’s ventilatory responses differ?
Trained:
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
74. 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
75. 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 oxygen.
76. 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
77. Why is a significant increase in core temperature a threat to life?
May destroy proteins and enzymes and lead to death
78. Describe the voluntary and involuntary heat production mechanisms.
Voluntary - Exercise:
70–80% energy expenditure appears as heat
Involuntary:
Shivering
Increases heat production by ±5 times
Action of hormones: Thyroxine, Catecholamines
Called non-shivering thermogenesis
79. What are the 4 ways that heat can be lost?
Radiation
Evaporation
Convection
Conduction
80. 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
81. 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
82. 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
83. 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
84. 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
85. 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
86. What are the guidelines to prevent exercise related heat injuries.
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
87. 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
88. How does exercising in the heat accelerate muscle fatigue?
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
89. What differences do age and gender have on thermoregulation?
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
90. 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
91. What are the primary adaptations to heat acclimatization?
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
92. 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
93. Name the 3 principles of training and describe what each entails.
1. Overload
Training effect occurs when a system is exercised at a level beyond which it is normally
accustomed
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
94. 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 ml.kg-1min-1)
95. 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
dimensions
…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)
96. 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
97. What are the structural and biochemical adaptations to endurance training?
(5)
 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.
98. What are the effects of intensity and duration on mitochondrial adaptations?
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)
99. 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.
100.
How is the plasma glucose concentration affected by training?
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.
99. 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
Therefore:
Increased capillary density helps increase O2 availability = reduces anaerobic metabolism.
100. 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
more
103. What are the physiological effects of strength training?
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
Hypertrophy
May be due to increased number of fibers
Hyperplasia
104. 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/
ligament
Increased bone mineral content.
Increase mechanical stress on bone = increase bone formation/ density
105. 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
Specificity
Lack of rest
Genetics