Download Respiratory System

NASM Chapter 3RESPIRATORY SYSTEM and
CHRONIC ADAPATATIONS TO
EXERCISE OF THE
CARDIORESPIRATORY SYSTEM
Learning Objectives
 This lesson covers how the Respiratory System
responds to the demands of exercise and the
physiological adaptations that occur with specific training
programs.
 Upon completion of this chapter, you will be able to:
– Describe the anatomy and physiology of the respiratory system
– Describe the acute and chronic responses to aerobic training
Respiratory System: Introduction
 The functions of the respiratory
system include:
– Replacing oxygen and removing
carbon dioxide from the blood
– Vocalization
– Regulation of the acid-base balance
during exercise
 Components of the respiratory
system include the nose,
nasal cavity, pharynx, larynx,
trachea, bronchi, and lungs.
– They form a passage that filters air
and transports it to the lungs.
– Gas exchange occurs in the lungs in
the alveoli.
– Lungs contain an estimated 300
million alveoli providing a surface area
about the size of a tennis court).
Respiratory System: Pulmonary Ventilation
 Pulmonary ventilation is the process by which air is
moved into and out of the lung (inspiration, expiration)
 Inspiration is an active process in which the diaphragm
and intercostal muscles contract, increasing
dimensions and volume of the thoracic cage
 Expiration at rest is normally passive; the inspiratory
muscles relax, decreasing the thoracic cage
 Forced inspiration and expiration are active processes
involving accessory muscles
 The air exchange rate increases from 5 to 6 liters of air
per minute at rest to 20 to 30 liters per minute during
exercise.
Dysfunctional Breathing
 If there is a dysfunction in the cardiorespiratory system, this can
directly impact the components of the HMS and perpetuate into
further dysfunction.
 Alterations in breathing patterns are a prime example of this
relationship:
– During shallow breathing patterns, the secondary respiratory muscles are
used more predominantly.
– If this shallow, upper-chest breathing pattern becomes habitual, it can
cause overuse of muscles, including the scalenes, sternocleidomastoid,
levator scapulae, and upper trapezius.
– These muscles also play a major postural role in the kinetic chain, as they
all connect directly to the head and neck.
– Their increased activity and excessive tension often result in headaches,
lightheadedness, and dizziness.
Physiology of the Cardiorespiratory System
 For muscles to contract, they need energy in the form of
adenosine triphosphate (ATP).
 The cardiorespiratory system is responsible for the three
basic processes to produce this energy:
– Get oxygen into the blood (oxygen-carrying capacity)
– Deliver oxygen to the muscles (oxygen delivery)
– Extract the oxygen from the blood to form ATP (oxygen
extraction)
 Oxygen-carrying capacity is affected by two primary
factors:
– The ability to adequately ventilate the alveoli in the lungs
– The hemoglobin concentration in the blood
Oxygen Extraction
 Oxygen extraction from the blood at the cellular level
depends on muscle-fiber type and the availability of
specialized oxidative enzymes.
– Slow-twitch muscle fibers are specifically adapted for oxygen
extraction and utilization.
– Aerobic production of ATP occurs in the mitochondria of the
cells.
– The circulatory system increases blood flow to the active
muscles and decreases blood flow to non-active areas such as
the viscera, allowing a higher concentration of O2 to be
extracted.
– Oxygen extraction can be measured by a-v-O2 difference (i.e.
the difference between oxygen in the arteries versus the veins).
Oxygen Consumption
 The usage of oxygen by the body is known as oxygen consumption
– At rest = 3.5ml∙kg·min
– Approximately 5 kcal of energy are burned for every liter of oxygen
consumed.
 VO2max, or maximal oxygen consumption is generally accepted as
the best means of gauging cardiorespiratory fitness.
– Submaximal testing procedures have been established to estimate
maximal oxygen consumption.
– The more oxygen a person can take in, deliver, and utilize, the more work
he or she can perform.
– It is expressed in either “relative” terms (mL/kg/min) or “absolute” terms
(L/min).
Oxygen Consumption during exercise

As soon as aerobic exercise begins, the sympathetic nervous system
stimulates an increase in cardiac output and the release of epinephrine and
norepinephrine.

Oxygen Deficit: It takes two to four minutes for the body to meet the increased
metabolic demand of oxygen.
– During this time, the anaerobic energy systems take over.

Steady State: When the cardiorespiratory system has fully taken over, a new
level of steady-state oxygen consumption is achieved.

EPOC: Excess Post-exercise Oxygen Consumption: Oxygen consumption
slowly declines, but remains elevated above resting level, a.k.a “afterburn”
Anaerobic Threshold
 The anaerobic threshold (AT) is reached when exercise
intensity increases above steady-state aerobic
metabolism and anaerobic production of ATP occurs.
 Anaerobic threshold or lactate threshold is generally
when a person becomes “out of breath” and cannot
sustain that level of intensity for more than a few
minutes.
– Lactate accumulates progressively in the blood and the oxygen
deficit and corresponding EPOC are extremely high.
– At this point, the body attempts to rid excess CO2 (a by-product
of acid metabolites) through increased ventilatory rate.
Summary
 The respiratory system gathers oxygen from the
environment, inhales it through the nose and mouth, and
processes it to be delivered to the tissues of the body.
 As cells use oxygen, they produce carbon dioxide, which
is transported back to the heart and lungs in the
deoxygenated blood to be released through exhalation.
 The collection and transportation of oxygen is made
possible by the respiratory pump and the respiratory
airways.
 If there is a dysfunction in the cardiorespiratory system,
this can directly impact the components of the HMS and
perpetuate into further dysfunction.
Acute Responses to Exercise
 Going from rest to exercise requires the circulatory and respiratory
systems to increase oxygen delivery.
 To meet the increased demands of the muscles, two major
adjustments in blood flow occur:
– Redistribution of blood flow from the inactive organs to the active skeletal
muscles
– Increased cardiac output (Q = SV x HR)
 Regulation of heart rate is controlled:
– Intrinsically by the sinoatrial node (SA node)
– Extrinsically by the nervous and endocrine systems
– Changes in heart rate are influenced by the parasympathetic and
sympathetic divisions of the autonomic nervous system (ANS).
Blood Pressure During Exercise
 Systolic blood pressure has a
much higher increase during
exercise than diastolic blood
pressure due to:
– Increased contractility of the heart
– Increased stroke volume
– The muscular need for greater force
and pressure to deliver blood to the
exercising muscles
– Vasodilation within the exercising
muscle, which results in more blood
draining from the arteries, through the
arterioles, and into muscle capillaries
Ventilatory Regulation
 Aerobic exercise results in:
– An increase of oxygen to the working tissues
– Increased return of carbon dioxide to the lungs
– An increase in the volume of air breathed per minute (minute
ventilation—VE)
 During submaximal exercise, ventilation increases
proportionately with increased oxygen consumption and
carbon dioxide production.
 As intensity increases to near maximal, the minute
ventilation increases disproportionately to oxygen
consumption.
Ventilatory Response to Exercise
 Ventilatory response to exercise
increases linearly, with the
exception of two distinct
deflection points at the first and
second ventilatory thresholds
(VT1 and VT2).
– VT1 represents the increased
respiratory response to remove
extra CO2 produced by the buffering
of lactate as it begins to accumulate
in the blood.
– VT2 represents the blood buffering
systems becoming overwhelmed by
rapidly increasing blood lactate.
Chronic Adaptations: Muscle-buffering Capacity
 Muscle-buffering capacity refers to the muscles’ ability to
neutralize the lactic acid that accumulates in them during
high-intensity activity.
– Delays the onset of fatigue
– Allows the exerciser to perform at a higher intensity and duration
before “hitting the wall”
 Training at the lactate threshold will enhance buffering
capacity and delay muscle fatigue for subsequent training
sessions.
 Ventilatory threshold is an indirect representation of lactate
threshold.
– Endurance training improves the ability to sustain high levels of
submaximal ventilation.
Chronic Adaptations: CV Changes
 Regular, consistent exercise leads to several adaptations that allow
the body to improve performance.
 Cardiorespiratory changes
– Cardiorespiratory endurance capacity is determined by the ability of the
cardiovascular and respiratory systems to deliver oxygen to active
tissues, and the ability of those tissues to extract and use the oxygen
during prolonged bouts of exercise.
Chronic Adaptations: Blood Volume
 Increase in blood volume
– An initial, rapid adaptation to exercise
– Increase is due primarily to plasma and, to a lesser extent, red
blood cells
– Plasma volume can increase 12 to 20% after three to six
aerobic-training workouts.
– The number of red blood cells may increase, but the ratio of red
blood cell volume to total blood volume may decrease.
Chronic Adaptations: Heart Size and Volume
 Heart size and volume
– Increase as an adaptation to increased work demand, but return to
pre-training levels within several weeks if training ceases
– Characterized by an increase of the left ventricular cavity and slight
thickening of the walls
– Increase in size is due to endurance training and an increase in
blood volume
– These adaptations lead to an increase in cardiac force and the
amount of blood pumped per beat.
– Decreased resting heart rate (RHR) and exercise heart rate for a
given intensity allow for longer diastolic filling and a reduced work
requirement for the heart.
– Improved maximal oxygen uptake (VO2max) and decreased cardiac
stress
Chronic Adaptations: CV Components
 Improvements in VO2max are due to increases in one or
more of the following variables:
–
Stroke volume
• Increases at rest and during exercise result from regular training
–
Heart rate
• Regular training typically yields:
– Decreased RHR of more than 10 bpm
– Decreased submaximal heart rate of 10–20 bpm
–
a-vO2 difference
•
Increases with training, particularly at maximal exercise
•
Reflective of greater oxygen extraction at the tissue level and more
effective distribution of blood flood to active tissue
Cardiorespiratory Changes: Blood Flow and Pressure
 Blood flow
– Increased blood flow to working muscles is enhanced through
regular endurance training due to:
• Increased capillarization of trained muscles
• Greater recruitment of existing capillaries in trained muscles
• More effective blood flow redistribution from inactive areas to active
tissues
• Increased blood volume
 Blood pressure
– In response to regular endurance training, a decrease in resting
SBP and DBP is noted.
– Resistance training may also reduce SBP.
Cardiorespiratory Changes: Oxidative Enzymes
 Oxidative enzymes
– Responses to regular endurance training include:
• Increase in the size and number of mitochondria in skeletal
muscle
– Enhances the muscle’s ability to use oxygen and produce ATP
via oxidation
• Increase in the activity of the mitochondrial oxidative
enzymes
– Slower rate of muscle glycogen utilization
– Enhanced reliance on fat as fuel at any given exercise intensity
Summary
 Understanding the transition from rest to exercise
and the adaptations that occur in response to
regular training is essential for proper exercise
selection and program design.
 This lecture covered:
– Respiratory System, Cardiorespiratory interaction
– Acute responses to exercise
– Chronic adaptations to exercise