you are deserved to read this for further knowledge.

1. Energy expenditure at rest and during exercise
 Basal metabolic rate is a measurement of the number
of calories needed to perform your body's most basic
(basal) functions, like breathing, circulation and cell
production.
 Resting metabolic rate is a measurement of the
number of calories that your body burns at rest.
 Resting metabolic rate is usually measured in the
morning before you eat or exercise and after a full night
of restful sleep.

2.  Human consumption and expenditure of energy,
alongside any change in the body’s macronutrient stores
(fat, protein, and carbohydrate) is summarized by the
energy balance equation:
 Change in macronutrient stores = Energy consumed
– Energy expended
 The parts of the equation can be expressed as
kilocalories (kcal), equivalent to 4.2 kilojoules (kJ), and
are usually expressed per unit of time, for example kcal
per day
 The kJ is a measure of energy

3. Factors affect BMR are the followings:
 Age: BMR gradually decreases with increasing age.
 Body temperature: BMR increases with increasing
temperature.
 Stress: Stress increases activity of the sympathetic
nervous system, which increases the BMR.
 Hormones: Thyroxine from the thyroid gland and
epinephrine from the adrenal medulla both increase the
BMR.

4. Calculating Metabolic Rate
Harris-Benedict BMR Equations (calories/day):
 Male:(88.4 + 13.4 x weight) + (4.8 x height) – (5.68 x age)
 Female: (447.6 + 9.25 x weight) + (3.10 x height) – (4.33 x
age)
weight in kilograms, height in centimeters, age in years

5.  E.g, calculate for a 48-year-old man who is 180 cm and
weighs 80 kg using several popular RMR equations.
 Harris-Benedict BMR Equations (calories/day):
Male:(88.4 + 13.4 x weight) + (4.8 x height) – (5.68 x
age)
 Female: (447.6 + 9.25 x weight) + (3.10 x height) – (4.33
x age)
 By substituting H and W Calculate for the male and
female.

6. Chapter
Three
Systems
response
to
Exercise

7. Exercise Effect on the Respiratory System
 The respiratory system and the circulatory system are
both necessary for the transport of oxygen to the
body’s tissues for use in aerobic metabolism and to
remove carbon dioxide from tissue and eventually
from the body.
 Respiration can be divided into two major types:
Pulmonary ventilation and pulmonary diffusion
are referred to as pulmonary respiration because
these two processes occur at the lungs.
7

8. Respiratory System Functions
The function of the lungs is to exchange gases between the air
and the blood.
1. supplies the body with oxygen and disposes of
carbon dioxide
2. filters inspired air
3. produces sound
4. contains receptors for smell
5. rids the body of some excess water and heat
6. helps regulate blood pH
8

9. Respiratory events
 Pulmonary ventilation = exchange of gases between
lungs and atmosphere.
-Pulmonary ventilation refers to the amount of air moved
in and out of the lungs during a particular timeframe,
such as 1 minute.
 External respiration - exchange of gases between alveoli
and pulmonary capillaries
 Internal respiration - exchange of gases between
systemic capillaries and tissue cells
9

10. Phases of pulmonary ventilation
 Two phases of pulmonary ventilation
 Inspiration, or inhalation - a very active process that
requires input of energy.
The diaphragm, contracts, moving downward and
flattening, when stimulated by phrenic nerves.
The phrenic nerve provides the primary motor supply
to the diaphragm, the major respiratory muscle.
 Expiration, or exhalation - a passive process that
takes advantage of the recoil properties of elastic fiber.
･The diaphragm relaxes.
 The elasticity of the lungs and the thoracic cage allows
them to return to their normal size and shape.
10

11. Mechanism of breathing
 The diaphragm and intercostal muscles, two mechanisms
control the volume of the chest cavity to increase and
decrease, causing air to flow in and our of the lungs.
 Inspiration – Increase in the volume of chest cavity,
diaphragm moves down and ribs move up, the pressure
decreases and is lower than atmospheric pressure, air
moves from atmosphere into the lungs.
 Expiration – Decrease in the volume of the chest cavity,
ribs move down and diaphragm moves up, higher
pressure in lungs than atmosphere, air moves from
lungs into the atmosphere.

12.  Dyspnea – shortness of breath or sense of difficulty in
breathing during exercise;
Due to elevated CO2 and [H+] which cause you to breathe
faster – from poorly conditioned ventilatory muscles.
 Hyperventilation – increased ventilation (fast breathing)
causes CO2 to be expired quickly; accompanied by
decrease in [H+].

13. Pulmonary Diffusion
 There is always some air in the nasal cavity, larynx,
trachea, and bronchi, so not all of the air inspired
reaches the alveoli, where gas diffusion takes place.
 The air that never reaches the alveoli is termed as
anatomical dead space, whereas air that does
reach the alveoli is termed alveolar ventilation.
 So, VE can be divided into these two components:
VE = VA + VD
where
VD = anatomical dead space
VA = alveolar ventilation.
13

14.  Pulmonary diffusion is aided by the large surface area
created by the tremendous number of alveoli and the
wrapping of alveoli by capillaries.
 The diffusion of oxygen and CO2 into and from the body
occurs at the interface between the alveoli and the
pulmonary capillaries.
14

15.  Partial Pressures of gasses
the individual pressures from each gas in a mixture
together create a total pressure.
air we breathe = 79% (N2), 21% (O2), and .03%
(CO2) = 760mmHg
differences in the partial pressures of the gases in the
alveoli and the gases in the blood create a pressure
gradient.
15

16. Oxygen diffusion capacity- Oxygen’s rate at which it
diffuses from the alveoli into the blood is referred to as
the oxygen diffusion capacity.
- it can be affected by training and body size
untrained (45 ml/kg/min) vs trained (80 ml/kg/min)
 The variations b/n the trained and untrained is due
to increased cardiac output, alveolar surface area,
and reduced resistance to diffusion across the
respiratory membranes.
large athletes (males) vs. small athletes (females)
 due to increased lung capacity, increased alveolar
surface area, and increased blood pressure from
muscle pumping.
16

17. Transport of Oxygen by the Blood
O2 transported in 2 ways:
 In physical solution – dissolved in fluid portion of blood
 Combined with hemoglobin – connects to iron-protein
component of red blood cell
 – Has O2 carrying capacity that is 65-70 times higher than
dissolving in blood
 – Average hemoglobin in men = 15-16 grams/100 ml blood
 – “ “ “ women = 14 grams/100 ml blood
(this is 5-10% less than men)*
* contributes to lower aerobic capacity in women
17

18.  Athletes with larger aerobic capacities often have
greater oxygen diffusion capacities due to:
 increased cardiac output,
 Increased blood pressure,
 Increased alveolar surface area, and
 reduced resistance to diffusion across
respiratory membranes.
18

19. Transport of Carbon Dioxide in the Blood
 There are three methods by which carbon dioxide is
transported in the blood:
1. 7% - 10% is dissolved in plasma,
2. approximately 20% is bound to hemoglobin
(Deoxyhemoglobin).
3. approximately 70% is transported as bicarbonate.
CO2 + H2O  H2CO3  H+ + HCO3
-
19

20. Gas Exchange at the Muscles
 The arterial-venous oxygen difference as the rate of oxygen
use increases as the a-vO2 difference increases.
 Factors influencing oxygen delivery and uptake
under normal conditions hemoglobin is 98% saturated
with O2.
increased blood flow increases oxygen delivery and
uptake
 because of increased muscle use of O2 and CO2 productions
 because of increased muscle temperature (metabolism)
 Carbon dioxide exits the cells by simple diffusion in response
to the partial pressure gradient between the tissue and the
capillary blood.
20

21. The Influence Of Exercise On Breathing
 Exercise increases the
breaths/minute
 Exercise increases the
amount of air in each
breath (tidal volume)
How is increased ventilation accomplished?

22. During light exercise
 Ventilation increases linearly
with oxygen uptake and carbon
dioxide production
 This increase in ventilation is
accomplished more by
increased tidal volume
(breathing deeper in and out)

23. During higher exercise levels
 Ventilation is increased
more by increased
breathing frequency
 This will keep the blood
saturated with oxygen
because the blood is in
the alveoli capillaries
long enough for
complete diffusion of
gases

24. Steady rate (moderate) exercise
 sufficient oxygen is supplied to muscles
 due to increased oxygen up take, there is little, or no,
build up of lactic acid in the muscles
 some lactate will be produced and removed by the blood
stream
 lactic acid is neutralized in the blood (this reaction
produces carbon dioxide as a by-product)
 increased carbon dioxide in the blood will stimulate
increased ventilation
 Increased ventilation is accomplished by both
increased tidal volume and frequency

25. How does pulmonary ventilation
(breathing) increase during exercise?
1. During light exercise (walking)?
By increasing the tidal volume (breathing deeper)
2. During intense exercise (sprinting)?
By increasing the frequency of breathing
3. During steady state exercise (jogging)?
By increasing both the tidal volume and the
frequency of breathing

26. The Energy Cost of Breathing at rest
and with light exercise
At rest:-
 the energy cost of
breathing is minimal (4%
of energy)
 During exercise:-
 the energy use may
increase from 10-20% of
total energy expenditure

27. The neuromuscular system and exercise
 Exercise has beneficial effects on the nervous system,
including at the neuromuscular junction (NMJ).
 Exercise causes hypertrophy of NMJs and improves
recovery from peripheral nerve injuries, whereas
decreased physical activity causes degenerative
changes in NMJs.

29. Neural activity during exercise
 The response of the ANS during exercise is much more
complex and involves many different target cells.
 In essence the primary role is taken by the sympathetic
nervous system although the withdrawal of
parasympathetic activity is also important (the analogy is
taking the brake off at the same time as pushing down
on the accelerator to get a car moving).

30. Skeletal Muscle Energy Metabolism
 Metabolic processes are responsible for generating
adenosine triphosphate (ATP), the body’s energy source
for all muscle action.
 ATP is generated by three basic energy systems: the
ATP-phosphocreatine (ATP-PCr) system, the glycolytic
system, and the oxidative system.
 Each system contributes to energy production in nearly
every type of exercise.

31. Skeletal Muscle Contraction
 The chemical components and reactions that occur
when a muscle is stimulated by a motor nerve result
in the sliding of the myofibrils past one another.
 The sliding of each myofibril within a muscle fiber
cause the muscle fiber to shorten.
 When many muscle fibers shorten, the result is
contraction of the skeletal muscle.
31

32. Skeletal muscle and exercise

34.  Role of Actin and Myosin
These myofilaments are responsible for muscle
contractility
 Arrangement of actin and myosin
Cross bridges are oriented around the myosin
myofilament in rows so that they may interact with
actin molecules
The purpose of this complex structure is the
production of tension (pulling force) within the
muscle causing the muscle to shorten, thus causing
movement
34

35. Skeletal Muscle Contraction –Force
Generation
 Chemical or heat energy in the body is converted to
mechanical work or movement.
 A nerve impulse arrives at the neuromuscular junction
(NMJ) and stimulates the beginning of the contraction
process
 NMJ = synapse between a motor neuron and a skeletal
muscle cell
 Stimulation of the skeletal muscle cell triggers the
release of calcium ions from the terminal cisternae of
the sarcoplasmic reticulum
 Calcium catalyzes the contraction process
35

36.  Calcium ions bind to troponin causing a
conformational(structure,shape) change
 Troponin then pushes tropomyosin away thus exposing
the active site that it is covering on actin
 Myosin crossbridges have a strong affinity for the exposed
active site on the actin molecule
 Myosin binds to the exposed active site
 Myosin cross-bridges pull
 the actin myofilament pulling it toward the center of the
sarcomere
 This motion physically shortens the sarcomere, the
myofibril, and the muscle fiber.
36

37.  After the sarcomere is shortened, the calcium ions are
pumped back into the sarcoplasmic reticulum
 Calcium ions are stored until another nerve stimulus
arrives at the NMJ
 Tropomyosin moves back to its original position of
covering the active site
 This causes the myosin crossbridges to release their
hold on the actin myofilament
 The actin myofilaments slide back to their original
position
37

38. Excitation-Contraction Coupling
 Depolarization of motor end plate(excitation) is coupled
to muscular contraction
 Sequence of events that links the nerve impulse and
skeletal muscle contraction
 Motor Neurons – stimulates skeletal muscles
Excitatory effect
 When a skeletal muscle cell receives input from a motor
neuron, it depolarizes
Depolarization causes the muscle cell to fire an action
potential
38

40.  Action Potentials
 Large changes in cell membrane potential (charge)
 Inside of the cell becomes to the outside of the cell more
positive relatively
 Function to transmit information over long distances
 Neuromuscular Junction (NMJ)
 The synapse between the motor neuron and the muscle
cell
 Synaptic Cleft
 The extra-cellular space between the motor neuron and
the muscle cell
40

41.  The NMJ releases a neurotransmitter from the motor
neuron into the synaptic cleft
o The neurotransmitter is acetylcholine (Ach).This
neurotransmitter is synthesized by the nerve cell and
stored in synaptic vesicles
o When a nerve impulse reaches the NMJ, the
synaptic vesicles release acetylcholine into the
synaptic cleft.
41

42. o Acetylcholine rapidly diffuses across the synaptic
cleft to combine with receptors on muscle cell
membrane (sarcolemma)
o The muscle cell is also called the motor end plate
membrane
o ACh causes depolarization of the muscle cell
membrane
 Generates an action potential
o Acetylcholine bound to the receptor is rapidly decomposed
by acetylcholinesterase (enzyme) preventing continuous
stimulation of the muscle fiber.
42

43.  Stimulation of Contraction
o Action potential propagates along the sarcolemma and
down the T-tubules to reach the sarcoplasmic
reticulum
o Sarcoplasmic reticulum releases calcium
o Calcium is actively pumped into and stored in the
SR leaving a small concentration of calcium ions in
the sarcoplasm
o The action potential causes the calcium ions to be
released from the SR into the sarcoplasm
43

44. o When calcium released from the SR, it travels toward
the Myofilaments
o Calcium binds with troponin on the actin myofilament
causing a conformational change, which results in
moving tropomyosin off the active site
o Myosin heads are then able to bind to the G-actin on
the active sites. This begins the contraction process of
crossbridge cycling

45. Excitation-Contraction Coupling
Skeletal muscle and
exercise
45

46. o Cross-bridge cycling continues as long as there is an adequate
supply of ATP and if there is stimulation from a motor neuron
o Cross-bridge cycling stops if there is an inadequate supply of ATP
or if the motor neuron impulse stops
 When the motor neuron impulse stops, calcium ions are rapidly
pumped back into the sarcoplasmic reticulum for storage
 Tropomyosin returns to its original position blocking the
myosin binding site on actin
 The muscle cell relaxes

47. Types of Skeletal Muscle Fibers
 Not all muscle fibers are the same physiologically
 Muscle fibers vary depending on:
 The predominant pathway utilized to synthesize ATP
 Oxidative fibers - predominantly aerobic
pathways
Oxidative phosphorylation in the
mitochondria
Fatigue-resistant fibers
 Glycolytic fibers – predominantly anaerobic
pathways
Glycolysis in the sarcoplasm
Fatigable fibers

48. The amount of myoglobin
 Red fibers - high amounts of myoglobin
 White fibers - small amounts of myoglobin
Efficiency of ATPase
 Fast twitch fibers - decompose ATP rapidly
 Slow twitch fibers - decompose ATP slowly

49.  Slow-twitch fibers
- fatigue-resistant fibers
 Slow oxidative fibers, or red muscle fibers.
 Contain abundant myoglobin giving them their red color.
 Slow acting ATPase enzymes
 Abundant mitochondria: Depend upon aerobic pathways
for production of ATP
 Endurance type muscles: Able to deliver strong, prolonged
contractions.
 Examples:
 Postural muscles - spinal extensors
 Anti-gravity muscles - calf muscle

50.  Fast-twitch fibers
 fatigable fibers
 Fast glycolytic fibers, or white muscle fibers.
 Contain small amounts of myoglobin
 Fast acting ATPase enzymes
 Allows the muscle fiber to contract rapidly
 Few mitochondria
 Contract for limited periods of time because fatigue rapidly
 Plenty of glycogen: Depends on anaerobic metabolism
 Extensive sarcoplasmic reticulum
 Rapidly releases and stores calcium ions contributing to rapid
contractions
 Best suited for short duration, high intensity contractions

51.  Intermediate Fibers
 Fast-twitch fatigue-resistant fibers
 Fast glycolytic fibers
 Pale muscle fibers
 Characteristics lie between the red and white fibers
 Most of the body's muscles contain a mixture of fiber
types.
 motor nerve that innervates the muscle cell determines
fiber type
 all of the muscle cells in a single motor unit are of the
same type
 Motor Unit – a motor neuron and all of the muscle
fibers it innervates

52. Fiber Types and Performance
 People are genetically predisposed to have relatively
more of one fiber type than another
 People who excel at marathon running have higher
percentages of slow twitch fatigue resistant muscle fibers
 People who excel at sprinting have higher percentages of
fast twitch fatigable fibers
 Power athletes -Sprinters
-Possess high percentage of fast fibers
 Endurance athletes-Distance runners
-Have high percentage of slow fibers
52

54. Hormonal Responses to Exercise
 The endocrine system, like the nervous system,
integrates physiologic responses and plays an important
role in maintaining homeostatic conditions at rest and
during exercise.
 This system controls the release of hormones from
specialized glands throughout the body, and these
hormones exert their actions on targeted organs and
cells.
 In response to an episode of exercise, many hormones,
such as catecholamines, are secreted at an increased
rate, though insulin is secreted at a decreased rate.

55. The Endocrine System response to exercise
 The magnitude of hormonal response to a standard
exercise load generally declines with endurance training.
 The Endocrine system and the Nervous system work
together to integrate in the brain and complement each
other, but they tend to work at different speeds.
Nerves respond within split-seconds but their action soon
fades

56.  Hormones carry essential messages that have far-
reaching effects.
 There are 50 of hormones, which are the body’s
chemical messengers and they are made by 12 different
Endocrine glands.
 These glands have no ducts but secrete their hormones
directly into the blood, by which means they reach every
cell in the body.

58. Hormonal response to exercise

59. CHAPTER FOUR
Thermal Regulation
 Stress of physical exertion complicated by environmental
thermal conditions
 Humans are homeothermic
 Internal body temperature regulated, nearly constant
despite environmental temperature changes
 Thermoregulation: regulation of body temperature
around a physiological set point

60. 60
Normal Body Temperature
 Normal resting core temperature in humans is
36.5oC to 37.5oC.
 During exercise body temp can exceed 40oC.
 There is considerable variation throughout the
body.
 The core is relatively constant while skin temp
is influenced by the environment.

61. 61
 The hypothalamus is the temperature regulatory center of
the body.
 Poikilotherms: body temperature varies with the
environment (lizards, insects).
 Homeotherms: maintain constant body core temperature
(humans, birds, bears).
 In homeotherms, various physiological processes depend
on normal body temperature to function properly.
 at temps above 41oC, the interior of many cells begin
to deteriorate.
 at temps below 34oC, cellular metabolism slows
greatly, leading to unconsciousness and cardiac
arrhythmias.

62. Temperature Regulation
 The hypothalamus acts as a thermostat and keeps
the body’s core temp within a normal range.
 Thermoreceptors are located in different regions
of the body and transmit nerve impulses to the
spinal cord and then up to the hypothalamus.
 The greatest density of thermoreceptors are in the
skin and hypothalamus, but there are also some in
the blood vessels and abdominal cavity.
 There are more cold than warm receptors in the
skin.
 When core temp goes above or below its set-
point, the hypothalamus initiates processes to 
heat production or heat loss.

63. Temperature Regulation
 The anterior hypothalamus stimulates sweat glands.
 Normally sweating begins at precisely 37oC.
 The set-point can change temporarily in response to
dehydration, starvation, or fever.
 When cold receptors in the skin and hypothalamus are
stimulated, various processes will  heat production.
 The hunting reflex maintains BF to the hands and feet.
 Vasoconstriction can  the effective core insulation.
 Stimulation of the shivering center causes shivering.
 The post hypo initiates release of norep and thyroxin.

64. Temperature Homeostasis
 Keep the body temp within a very narrow range
 Range of NBT (970F to 990F)
 Temperatures above this:
denature enzymes and block metabolic
pathways
 Temperatures below this:
slow down metabolism and affect the brain.

65. Heat Production
(Thermogenesis)
 BMR
 Specific Dynamic Action of
food
 Activity of skeletal muscle
Shivering
Exercise
 Chemical Thermogenesis
Epinephrine
&Norepinephrine
Thyroxine
 Brown Fat-
Source of considerable heat
production
Abundant in infants
 Radiation
 Conduction
 Convection
 Evaporation
 Perspiration
 Respiration
 Loss through urine
& feces
Heat Loss
(Thermolysis)

66. Body Temperature Control System
 Hypothalamus
 Acts as a thermostat
 Receives nerve impulses from
cutaneous thermoreceptors
 Thermoreceptors Cold &Heat
 Hypothalamus- also has
thermoreceptors called central
thermoreceptors
 These detect changes in blood
temperature
Initiates the rate of heat production
when body temp falls, and  the rate
of heat dissipation when temp rises.

67. Thermoregulatory regulatory responses
Exposure to Cold
Shivering
Increase voluntary activity
Increase TSH secretion
Increase Catecholamine
Vasoconstriction
Horripilation
Curling up
Exposure to Heat
Vasodilatation
Sweating
Increase in Respiration
Anorexia
Apathy
Decrease TSH secretion

68. Effects of Clothing
Cold Weather Clothing
provide an air barrier
to prevent convection
and conduction.
 Layers provide more
trapped air
 Allow water vapor to
escape
Warm Weather
Clothing loose
fitting to permit free
convection.
 The less surface
covered the more
evaporative cooling.
 Clothing should be
loosely woven to
allow skin to
breathe.

69. Acclimatization
Acclimatization refers to physiological changes
that improve heat tolerance.
2 – 4 hours daily heat exposure produce complete
acclimatization 5-10 days.
Habituation: is the lessening of the sensation
associated with a particular environmental stressor.

70. Factors that Improve Heat Tolerance:
Acclimatization
Improved cutaneous blood flow Transports metabolic heat from
deep tissues to body’s shell
Effective distribution of cardiac
output
Appropriate circulation to skin &
muscles to meet demands.
Lowered threshold for start of
sweating
Evaporative cooling begins early
in exercise.
More effective distribution of
sweat over skin surface
Optimum use of surface for
effective evaporative cooling.
Increased rate of sweating Maximize evaporative cooling.
Decreased salt concentration of
sweat
Dilute sweat preserves
electrolyte in fluids.

71. Factors that Improve Heat
Tolerance
 Fitness Level
 Age (see FYI)
Aging delays the onset of sweating and blunts
the magnitude of sweating response
 Gender
 Body fatness

72. Evaluating Heat Stress
 Prevention remains
most effective way to
manage heat-stress
injuries
 Wet bulb-globe
temperature relies on
ambient temperature,
relative humidity, and
radiant heat.
 Heat stress index

73. Heat Illness

74. Heat Illness

75. 75
Dehydration Strategies
Dehydration: loss of body fluid.
 Moderate levels of dehydration (2%) will impair CV
and temperature regulation and  performance.
 Aggressive fluid replacement during ex in the heat.
 Regular fluid breaks.
 Drink fluids in proportion to sweat loss.
 Drink cold fluids (8 - 13oC) with moderate amounts of
carbohydrate (~7%) and electrolytes.
 Physical fitness helps prevent dehydration ( BV).

76.  Heat Syndromes- adverse reaction to heat exposure
a) Heat Cramps
b) Heat Exhaustion
c) Heat Syncope
d)Heat Stoke
 Heat Cramps: involuntary cramping and spasm in
muscles used during exercise.
 Originally thought to be due to electrolyte imbalance, may
be due a spinal neural mechanism.

77. 77
Heat Exhaustion: hypotension and weakness caused
by an inability of the circulation to compensate for
acute plasma volume loss and vasodilation.
 It is characterized by rapid weak pulse, hypotension,
faintness and profuse sweating.
 Occurs at core temperature below 39.5 oC.
 Treat individual with fluids and move to a cool
location.

78. 78
Heat Syncope: a person faints due to hypotension.
Occurs when blood pools in the legs following
exercise.
Heat Stroke: occurs when there is a failure of the
temperature regulatory function of the hypothalamus,
and represents a medical emergency.
 Results in an explosive  in core temperature (>
41oC) and is characterized by hot dry skin, confusion
and convulsions
 The patient should be treated in a hospital with a
spray of tepid water and a cool air stream.
 Outside of the hospital the patient can be cooled with
a fan and ice packs on the neck, axillae, and groin.

79. Prevention of Heat Illness
 Allow adequate time for acclimatization.
 Exercise during cooler parts of day.
 Limit/defer exercise if heat stress index is in high
risk zone.
 Hydrate properly prior to exercise and replace fluid
loss during and after exercise.
 Wear clothing that is light in color and loose fitting.

80. EXERCISE IN HYPOBARIC,
HYPERBARIC, AND MICROGRAVITY
ENVIRONMENTS

81. Conditions at Altitude
At least 1,500 m (4,921 ft) above sea level
Reduced barometric pressure (hypobaric)
Reduced partial pressure of oxygen (PO2)
Reduced air temperature
Low humidity
Increase in solar radiation intensity

82. Hypobaric•
 low atmospheric pressure
 low partial pressure of oxygen (PO2),
therefore low pulmonary diffusion & low
O2transport to tissue, hence HYPOXIA
(O2deficiency)
Hyperbaric
 High atmospheric pressure
• High partial pressure of certain gases which
is life-threatening
Microgravity
 Low gravitational force, i.e. environment in
the outer space.

83. Respiratory Responses to Altitude
Pulmonary ventilation increases.
Pulmonary diffusion does not change.
Oxygen transport is slightly impaired.
Oxygen uptake is impaired.
As the PO2 decreases, VO2max
decreases at a progressively greater rate.

84. Respiratory responses
 Pulmonary ventilation increases, therefore
hyperventilation occurs that increases CO2 clearance.
 Pulmonary diffusion is not affected but, O2transport is
slightly impaired because HbO2 saturation decreases.
 Gas exchange in the muscles decreases because
diffusion gradient between blood & active tissue is
lowered, therefore, O2uptake is affected
 Maximum O2consumption decreases since
PO2decreases.
 At sea level VO2max = 50ml/kg/min but, at Mt. Everest
peak, VO2max can be as low as 5ml/kg/min.

85. Cardiovascular Responses to Altitude
Initial decrease in plasma volume (more
red blood cells per unit)
Initial increase in HR, SV, and Q during
submaximal work to compensate for less
O2
Decrease in HR, SV, and Qmax during
maximal work, which limits oxygen
delivery and uptake.

86. Metabolic Responses to Altitude
Increase in anaerobic metabolism
Increase in lactic acid production
Less lactic acid production at maximal
work rates at altitude than at sea level

87. Performance at Altitude
 At altitude, endurance activity is affected the most due to
reliance on oxygen transport and the aerobic energy
system.
 Anaerobic sprint activities are the least affected by
altitude.
 The thinner air at altitude provides less aerodynamic
resistance and less gravitational pull, thus potentially
improving jumping and throwing events.
 Endurance athletes can prepare for competitions at
altitude by performing high intensity endurance training
at any elevation to increase their VO2max.

88. Acute Altitude Sickness
Nausea, vomiting, dyspnea, insomnia
Appears 6 to 96 h after arrival at altitude
May result from carbon dioxide
accumulation
Avoid by ascending no more than 300 m
(984 ft) per day above 3,000 m (9,843 ft)

89. HEALTH RISKS OF HYPERBARIC
CONDITIONS

90. Microgravity Environments
 Microgravity is the condition in which people or objects
appear to be weightless.
 "Micro-" means "very small," so microgravity refers to the
condition where gravity seems to be very small.
 Microgravity is sometimes called "zero gravity," but this
is misleading.

91. Exercise in Microgravity Env.ts
Muscle strength decreases
Cross-sectional areas of ST and FT fibers decrease
Bone mineral content in weight-bearing bones decreases
Plasma volume decreases
Transient cardiac output and arterial blood pressure
increases
Weight decreases (mostly from fluid loss)

92.  THE END