This document provides an introduction to exercise physiology. It defines exercise physiology as the study of physiological responses and adaptations to exercise. The importance of exercise physiology is discussed, including its role in areas like physiotherapy, understanding muscle structure and function, bioenergetics, and sports performance. The origins of exercise physiology as a discipline that evolved from its parent field of physiology are also noted. Key topics covered include the different types of muscle fibers, muscle contraction, the role of calcium, energy systems, and the sliding filament theory of muscle contraction.

1. MIZAN-TEPI UNIVERSITY
COLLEGE OF NATURAL AND COMPUTATIONAL SCIENCE
DEPARTMENT OF SPORT SCIENCE
EXERCISE PHYSIOLOGY(SPSC 3545)
By MillionD.
2022

2. CHAPTER ONE
Introduction to Exercise Physiology
• Definition of exercise physiology
• Importance’s of exercise physiology
• Origins of exercise physiology

3. Definition of exercise physiology
Exercise:
• Exercise represents a subset of physical activity that is planed with a goal
of improving or maintaining fitness.
• Series of muscular work or movement that is carried out in a sequential
manner are called exercise .
• This is economical, skillful, coordinated and graceful manner in order to
fulfill a particular task.
Physiology
• Physiology can be defined as one of the branches of natural science,
which deals with; functional aspect of living organism.

4. • Exercise physiology has evolved from its parent discipline, physiology.
• Exercise physiology is an applied science that deals with various interaction
and adjustment physiologically before, after and during exercise.

5. Importance of exercise physiology:
• Exercise physiology provides the physiological basis of therapeutic exercise
which is mostly important for physiotherapy.
• Exercise physiology gives us the knowledge about structure and function of
various types of muscle of human body.
• It gives us knowledge about Bio-energetic system.
• It provides information about nervous control of muscular movement.
• It is helpful for understanding of the functional aspect of respiratory and
cardiovascular system.
• Exercise physiology is informative for sports and nutritional effect on sports
performance.
• It gives the knowledge about work and environment such as summer, winter
humid and high altitude.

6. What do exercise physiologists do?
Educators
Health
center
Fitness
center
Rehabilitati
on center
Physical
therapy
Personal
trainers
Managers
Athletic Trainers
Massage therapy
Occupational therapy
Nursing
Nutrition
Medicine
Sports Therapy Entrepreneurs
Governmental agencies

7. Exercising Muscle
• Human body contains over 400 skeletal muscles
• 40-50% of total body weight
• Functions of skeletal muscle
• Force production for locomotion and breathing
• Force production for postural support
• Heat production during cold stress
Skeletal muscle is a collection of long thin cells called fibers.
These fibers has surrounded by a dense layer of connective tissue called fascia that
holds the individual fibers together and separates muscle from surrounding tissues.
Muscles are attached to bone by connective tissues known as tendons.
Muscular contraction causes the tendons to pull on the bones, thereby causing
movement.

8. Slide 8 of 16
• Muscles move your eyes as you read.
The Muscles in Your Body
• Muscles in your chest allow you to
breathe.
• Muscles in your heart pump your blood.
• Every time your body moves, muscles
are at work.
How Muscles Work
• All muscles do work by contracting,
or becoming shorter and thicker.
• Many skeletal muscles work in
pairs.
• One muscle in the pair
contracts to move the bone in
one direction.
• Then, the other muscle in the pair
contracts to move the bone back.

9. Slide 9 of 16
Muscle Pairs
Biceps contracted
Biceps relaxed
Triceps relaxed
Triceps contracted

10. Slide 10 of 16
1
2
3
4
5
6
7
8
9
10
11
12
13
The Muscular System
1) Frontalis
2) Temporalis
3) Trapezius
4) Deltoid
5) Pectoralis major
6) Sartorius
7) Tibialis anterior
8) Biceps
9) Triceps
10) External oblique
11) Rectus abdominus
12) Quadriceps muscles
13) Gastrocnemius

11. Types of muscle
Muscles cause movement, help to maintain posture, and produce
heat.
There are 3 types, classified according to function and appearance:

12. 3 types of muscle Skeletal muscles are elastic and work in
pairs - one flexing while the other is
extending.
They are striated, with horizontal
markings, and are stimulated to contract
by electrical impulses from the nervous
system.
Fast, white muscle fibers contract rapidly, have poor blood supply,
operate without oxygen, and tire quickly.
Slow, red muscle fibers contract more slowly, have better blood
supplies, operate with oxygen, and do not tire as easily.
They are used in ongoing movements, such as maintaining
posture.

13. Smooth muscles contract slower than
skeletal muscles, but can remain
contracted longer, and are not as
dependent on oxygen.
They are stimulated by electrical
impulses or hormones, and use
carbohydrates for energy.
Smooth muscle lines most
hollow organs of the body,
such as the intestines,
stomach, and uterus.
They help move substances
through tubular areas such as
blood vessels and the small
intestines, contracting
automatically and
rhythmically.

14. They are stimulated to contract by electrical impulses sent out
from small clumps of specialized tissue in the heart… the
sinoatrial and atrioventricular nodes.
The cardiac muscle or
myocardium are striated like
skeletal muscles, but are
smaller and shorter.

15. A tendon is a means of
attachment, connecting the
muscle to the bone. They vary in
length, from less than an inch to
more than a foot.
A wide sheet-like
tendon is called an
aponeurosis
Each muscle consists of a group of fibers held together by
connective tissue, and enclosed in a fibrous sheath or fascia.

16. Tonicity
Muscles are continually
working to maintain
posture.
This passive muscle
contraction known as
residual muscle tension
is called tonicity.
Tonicity is not the same as achieving muscle tone through
exercise.

17. Slide 17 of 16
• Even when a skeletal muscle is not contracting to cause
movement, a few of its individual muscle fibers are still
contracting.
Muscles that cannot contract due to injury, or are not used
often, will weaken and shrink, a condition known as atrophy.
Hypotonia can happen from damage to the brain, spinal cord, nerves, or
muscles. The damage can be the result of trauma, environmental factors,
or genetic, muscle, or central nervous system disorders.
Hypertonia is a condition in which there is too much muscle tone
so that arms or legs, for example, are stiff and difficult to move.

18. parts of Skeletal Muscle:
• Epimysium: Surrounds entire
muscle
• Perimysium: Surrounds bundles
of muscle fibers
-Fascicles
• Endomysium: Surrounds
individual muscle fibers

19. Structure of Skeletal Muscle
• Sarcolemma
• Muscle cell membrane
• Myofibrils
• Threadlike strands within muscle
fibers
• Actin (thin filament)
• Troponin
• Tropomyosin
• Myosin (thick filament)

20. The Sarcomere
• Further divisions of
myofibrils
• Z-line
• A-band
• I-band
• Within the sarcoplasm
• Sarcoplasmic reticulum
• Storage sites for calcium
• Transverse tubules
• Terminal cisternae

22. Fiber Type and Athletic Success
Power athletes
• Sprinters- Possess high percentage of fast
fibers
Endurance athletes
• Distance runners
Have high percentage of slow fibers
Others
• Weight lifters and nonathletes
Have about 50% slow and 50% fast fibers
• Endurance and resistance
training
• Cannot change fast fibers to
slow fibers
• Can result in shift from Type
IIb to IIa fibers
• Toward more oxidative
properties

23.  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

24. 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
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

25.  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

26.  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

27.  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

29. Fiber types
Characteristic Type I Type IIa Type IIx
Motor neuron size Small Large Large
Nerve conduction velocity Slow Fast Fast
Contraction speed Slow Fast Fast
Relaxation speed Slow Fast Fast
Fatigue resistance High Intermediate/Low Low
Force production Low Intermediate High
Power output Low Intermediate/High High
Endurance High Intermediate/Low Low
Aerobic enzyme content High Intermediate/Low Low
Anaerobic enzyme content Low High High
Capillary density High Intermediate Low
Myoglobin content High Low Low
Mitochondria size / density High Intermediate Low
Fiber diameter Small Intermediate Large
Color Red White/red White
slow fast

30. Event Type I Type II
100 m sprint Low High
800 m run High High
Marathon High Low
Olympic weightlifting Low High
Soccer, hockey High High
Basketball Low High
Distance cycling High Low
Baseball pitcher Low High
Boxing High High
Cross-country skiing High Low
Tennis High High
The relative proportion of different types of muscle
fibers in different sports
Hypertrophy: fiber Increase in
size
Hyperplasia : fiber Increase in
number

31. Properties of Muscle Fibers
• Biochemical properties
• Oxidative capacity
• Type of ATPase
• Contractile properties
• Maximal force production
• Speed of contraction
• Muscle fiber efficiency
Types of Muscle Contraction
1. Isometric(static)
• Muscle exerts force without
changing length
• Pulling against immovable object
• Postural muscles
ex. pushing the wall
2. Isotonic (dynamic)
A. Concentric- Muscle shortens
during force production
B. Eccentric- Muscle produces
force but length increases
ex, lifting a dumbbell.
C. Isokinetic- are concentric or eccentric
contractions performed at a constant
speed.

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

33. • 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.
Skeletal Muscle Energy
Metabolism
• 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
Skeletal Muscle Contraction –Force
Generation

34. Energy for Muscle Contraction
 Energy currency for muscle contraction is ATP
• Myosin ATPase breaks down ATP as fiber contracts
• Hydrolysis of ATP by Myosin ATPase energizes cross bridges
prior to cycling.
• Binding of ATP to myosin dissociates cross bridges bound to
actin allowing the bridges to repeat their cycle of activity.
• Hydrolysis of ATP by Ca –ATPase provides energy for active
transport of Ca into sarcoplasmic reticulum thus ending the
contraction and allowing the muscle fiber to relax.

35. • 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.
 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

36.  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
• 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.

37. 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.

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

39. 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
Cross-bridge cycling continues as long as there is an adequate supply of ATP
and if there is stimulation from a motor neuron

40. Muscular Contraction:The
• Muscle shortening occurs due to the movement of the actin filament over
the myosin filament
• Formation of cross-bridges between actin and myosin filaments
• Reduction in the distance between Z-lines of the sarcomere
 Rest – uncharged ATP cross-bridge complex
 Excitation-coupling – charged ATP cross-bridge complex, “turned on”
 Contraction – actomyosin – ATP > ADP & Pi + energy
 Recharging – reload cross-bridge with ATP
 Relaxation – cross-bridges “turned off”

41. Excitation-Contraction Coupling

42. Actin Filament
Myosin
Filament
ADP
+ P Myosin head
cocked up
The cocked up myosin molecule rapidly binds to the Actin: this
link is a “cross bridge”

43. • Myosin head then undergoes a conformational change causing a “rachet
action” and pulls the actin filament to the centre of the sarcomere.
• ADP and Pi are released by this process
• This is called the “power stroke” which causes the sliding action
• An ATP binds to the Actomyosin complex
- This causes the affinity of myosin for actin to decrease
• The myosin head changes its position to close around the ATP and
hydrolyze it.
-This change in conformation of the Myosin head releases the
myosin from the actin.

44. ATP hydrolysed
Myosin returns to cocked up position
Fresh cycle starts
ADP
+ P

45. • Cycling continues until cytosolic Ca levels remain high
• One Ca ion releases one Troponin which covers 7 active sites.
• All myosin molecules do not move simultaneously but sequentially
like oars on a boat and cause the myosin slide along the Actin
filament
Calcium pumped out of cytosol: active sites covered
ADP
+ P

46. Bioenergetics and Muscle Metabolism
Bioenergetics or the flow of energy in a biological
system, concerns primarily the conversion of
macronutrients-
carbohydrates,
proteins and fats, which contain chemical energy.

47. Energy emerges with the decomposition of high-energy bonds in such
macronutrients which release energy needed to carry out mechanic work.
Catabolism is the breakdown of large molecules into smaller
molecules, associated with the release of energy (e.g. breakdown
of glycogen into glucose).
Anabolism is opposite of catabolism.
It is the synthesis of larger molecules from smaller molecules (e.g.
synthesis of proteins from amino acids).
Anabolism requires energy to grow and build. Catabolism uses energy to break
down.

48. • ATP storage limited
• Body must constantly synthesize new ATP
Three ATP synthesis pathways
1) ATP-PCr system (anaerobic metabolism)
2) Glycolytic system (anaerobic metabolism)
3) Oxidative system (aerobic metabolism)

49. Creation of energy, capacity
In general, there is an inverse relationship between a given energy
system’s maximum rate of ATP production (i.e., ATP produced per unit of
time) and the total amount of ATP it is capable of producing over a long
time.
As a result, the phosphagen energy system primarily supplies ATP
for high-intensity activities of short duration (e.g., 100 m dash), the
glycolytic system for moderate to high intensity activities of short
to medium duration (e.g, 400m dash), and the oxidative system for
low intensity activities of long duration (e.g., marathon).
The extend to which each of the three energy system contributes to ATP
production depends primarily on the intensity of muscular activity and
secondarily on duration. At no time, during either exercise or rest does any
single energy system provide the complete supply of energy.

50. Carbohydrate
• All carbohydrate converted to glucose
• 4kcal/g; ~2,500 kcal stored in body
• Primary ATP substrate for muscles, brain
• Extra glucose stored as glycogen in liver,
muscles
• Glycogen converted back to glucose when
needed to make more ATP
• Glycogen stores limited (2,500 kcal), must
rely on dietary carbohydrate to replenish
• Efficient substrate, efficient storage
– 9kcal/g
– +70,000 kcal stored in body
• Energy substrate for prolonged,
less intense exercise
– High net ATP yield but slow ATP
production
– Must be broken down into free fatty
acids (FFAs) and glycerol
– Only FFAs are used to make ATP
Fat

51. • Energy substrate during starvation
– 1g = 4 kcal/g
– Must be converted into glucose
(gluconeogenesis)
• Can also convert into FFAs
(lipogenesis)
– For energy storage
– For cellular energy substrate
Protein

53. intensity
low high
How
?
aerobic anaerobic
Where?
Mitochondria Sarcoplasm
substrate
Carbohydrates
Fats
Proteins
Carbohydrates
Energy system
Slow glycolysis
Oxidative system
Fast glycolysis
ATP-CP system
(phosphagen)

54. Phosphagen system (ATP-CP)
The phosphagen system provides ATP primarily for short-term,
high-intensity activities.
(e.g., resistance training and sprinting) and is active at the start
of all exercise regardless of intensity.

55. Glycolysis
Glycolysis is the breakdowns of carbohydrates-either
glycogen stored in the muscle and in the liver or glucose
delivered in the blood-to resynthesize ATP.
Pyruvate is the end result of glycolysis, may proceed in one of two
directions:
1. Pyruvate can be converted to lactate
2. Pyruvate can be shuttled into the mitochondria

56. Oxidative system
The oxidative system, the primary source of ATP at rest
and during low-intensity activities, uses primarily
carbohydrates and fats as substrates.
Following the onset of activity, as the intensity of
exercise increases, there is a shift in substrate
preference from fats to carbohydrates.

57. Effect of Event Duration and Intensity on
Primary Energy System Used
Duration of event Intensity of event Primary energy system(s)
0-6 seconds Extremely high Phosphagen
6-30 seconds Very high Phosphagen and fast
glycolysis
30 second to 2 minutes High Fast glycolysis
2-3 minutes Moderate Fast glycolysis and oxidative
system
>3 minutes Low Oxidative system

58. ATP-PCr System
• Phosphocreatine (PCr): ATP recycling
• PCr + creatine kinase  Cr + Pi + energy
• PCr energy cannot be used for cellular work
• PCr energy can be used to reassemble ATP
• Replenishes ATP stores during rest
• Recycles ATP during exercise until used up (~3-15 s maximal
exercise)

59. Glycolytic System
• Anaerobic
• ATP yield: 2 to 3 mol ATP/1
mol substrate
• Duration: 15 s to 2 min
• Breakdown of glucose via
glycolysis
– Low ATP yield, inefficient use of
substrate
– Lack of O2 converts pyruvic acid to lactic
acid
– Lactic acid impairs glycolysis, muscle
contraction
– Allows muscles to contract when O2
limited
– Permits shorter-term, higher-intensity
exercise than oxidative metabolism can
sustain

60. Oxidative System (Aerobic)
• ATP yield: depends on substrate
• 32 to 33 ATP/1 glucose
• 100+ ATP/1 FFA
• Duration: steady supply for hours
• Most complex of three bioenergetic
systems
• Occurs in the mitochondria, not
cytoplasm
• Stage 1: Glycolysis
• Stage 2: Krebs cycle
• Stage 3: Electron
transport chain

61. Oxidation of Carbohydrate
• Glycolysis can occur with or without O2
• ATP yield same as anaerobic glycolysis
• Same general steps as anaerobic glycolysis but, in the
presence of oxygen,
• Pyruvic acid  acetyl-CoA, enters Krebs cycle

63. Oxidation of Fat
• Triglycerides: major fat energy source
• Broken down to 1 glycerol + 3 FFAs
• Lipolysis, carried out by lipases
• Rate of FFA entry into muscle depends on concentration gradient
• Yields ~3 to 4 times more ATP than glucose
• Slower than glucose oxidation

64. • Process of converting FFAs to acetyl-CoA before entering Krebs cycle
• Requires up-front expenditure of 2 ATP
• Number of steps depends on number of carbons on FFA
• 16-carbon FFA yields 8 acetyl-CoA
• Compare: 1 glucose yields 2 acetyl-CoA
• Fat oxidation requires more O2 now, yields far more ATP later

66. Oxidation of Protein
• Rarely used as a substrate
• Starvation
• Can be converted to glucose (gluconeogenesis)
• Can be converted to acetyl-CoA
• Energy yield not easy to determine
• Nitrogen presence unique
• Nitrogen excretion requires ATP expenditure
• Generally minimal, estimates therefore ignore protein metabolism

68. Interaction Among Energy Systems
• All three systems interact for all activities
• No one system contributes 100%, but
• One system often dominates for a given task
• More cooperation during transition periods

70. Oxidative Capacity of Muscle
• Not all muscles exhibit maximal oxidative capabilities
• Factors that determine oxidative capacity
• Enzyme activity
• Fiber type composition, endurance training
• O2 availability versus O2 need

71. Oxygen Needs of Muscle
• As intensity , so does ATP demand
• In response
• Rate of oxidative ATP production 
• O2 intake at lungs 
• O2 delivery by heart, vessels 
• O2 storage limited—use it or lose it
• O2 levels entering and leaving the lungs accurate estimate of O2
use in muscle

72. 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.

73. 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

74.  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.

75. 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
-

76. 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.

77. 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.

78. • 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

79. 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.

80. 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

81. Energy and Types of Physical Activities
Each physical activity or sport you undertake requires a different
energy system…
Track Events and their use of Aerobic Respiration
Basketball players
use both systems
 Some use mainly aerobic respiration.
 Others use mainly anaerobic respiration.
 Most use a combination of the two.
Event
Percentage of
Aerobic
Respiration
Less than 1%
100 m
10%
200 m
20%
400 m
50%
800 m
60%
1,500 m
83%
5,000 m
95%
10,000 m
100%
Marathon