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Respiratory System
under stress
AIMS:
 1.
What physiological changes
occur with exercise in the
respiratory cardiovascular and
muscular systems?
 2.
What are the limitations to
exercise in health and disease?
 3.
What are the effects of
altitude, O2 toxicity, diving &
foetal environments on the
lungs?
EXERCISE
 Aerobic


(dynamic, isotonic)
Non-aerobic ( isometric, static) Isokinetic
Short or long term
 Successful



exercise
muscular, CVS, respiratory
Adequate gas exchange- O2 & CO2
Availability of fuel- oxidation of
glycogen, glucose, fatty acids
STEPS IN EXERCISE
3
STAGES
 1. Anticipation- preparatory, HR, C.O.
 2. During- main changes- metabolic,
respiratory,CVS, blood flow redistribution
 blood flow to muscles
 1 to 22-33 l.min-1
 SNS, metabolic hyperaemia, indirect PNS
 3. Recovery- return to resting conditions,
payback of O2 debt, metabolic replenishment
Physiological changes
 Respiratory



VE, Pulmonary blood flow, bronchial
dilation, VO2,VCO2
PaO2 ,PaCO2, anaerobic metab., pH, RQ
O2 extraction- intensity, capillary density,
Bohr shift to right, aerobic enzyme activity
CVS

SP, DP, C.O. SV, H.R
Muscular

muscular contraction




motor cortex
action potential
Ca2+ release
cross-bridges
 Metabolic
 Anaerobic
- creatinephosphate (CP),
glycolysis of glucose, lactic acid
 Aerobic- ATP, glycogen (muscle),
carbohydrates and fats, glycogen (liver)
 Intensity of exercise - CP, glycogen,
pH, K+; lactate, ADP, AMP, Pi
 replenishment


Fatty acids- from lipolysis, lipases, A,
Glucagon,cortisol
Glucose- from glycogenolysis, A, GH,
Glucagon
LIMITATIONS TO EXERCISE
 RESPIRATORY

DISORDERS
Ventilation, gas exchange, exercise
capacity; exercise responses variable &
difficult to predict from resting values
 COPD

VE varies, weak skel. Muscle, aerobic
capacity & PaO2, lactate & dead space,
high V/Q
 RESTRICTIVE

high f, stiff lungs, PaO2, low V/Q, high
dead space
 Symptoms


during exercise
sense of effort in breathing, inspiratory
muscle strength - dyspnoea
PaO2 & PaCO2 - dyspnoea
 Cardiovascular

disorders-
exercise capacity, Hrmax, SV, muscle
weakness & blood flow, lactate
CONCLUSIONS

1.Excercise involves changes in
respiratory (VE, VT, f, VCO2, VO2),
cardiovascular (C.O., SV, HR,BP) &
muscular ( blood flow, ATP, force
generation) systems.
 2.Limitations  health- inadequate fuel, delivery of O2, removal
of CO2
 disease- perceived effort, weak muscles, poor gas
exchange

3. Other environments




Altitude- HV leads PaCO2, alkalosis, loss of
bicarbonate, further increase of ventilation &
polycythemia.
high O2 - toxic, can damage lungs by impairing
gas exchange, oedema, atelectasis.
Diving descent- increase in gas density,
compression of gas cavities, N2 dissolves into
body tissues. Ascent causes expansion of gas
cavities, Bends.
Fetal respiration- placenta, no air, shunting of
oxygenated blood from RA to LA & then to
aorta, also to RV & then to aorta. Following birth,
air enters, lung liquid removed, loss of shunts.
TRAINING


Repeated physical exercise (frequency,
type, intensity)
training effect
‘Large muscle rhythmic activity for 20-30
min, 3-5 days/week at 60-80% (55-60%
VO2 max) age adjusted maximum heart
rate’ for 6-10weeks. - ACSM
 Isometric



advantages- I lean tissue, strength, flexibility,
Psychological benefits
small changes- H.R, cholesterol, chamber size,
VO2max
disadvantages- anaerobic energy used, S.P & D.P,
blood flow at high workloads

Advantages of exercise

strength of bones, ligaments, cartilage & muscle,
 fibrinolysis, HDL, lean tissue, weight loss
 osteoporosis, risk of Diabetes Mellitus, mortality of
post MI patients
 blood flow, faster recovery from illness, pulmonary
rehabilitation
 ? Slow ageing, psychological benefits
Disadvantages



Injury (tendons, cartilage), osteoarthritis, Ischaemia, strokes,
exercise induced asthma
sudden death, weakens immune system, addiction to
DETRAINING
 Prolonged
bed rest, inactivity
 Space
 ‘Ageing’
 decrease heart response, elasticity of blood
vessels, increased B.P
 stiffness of rib cage, vital capacity, work of
breathing
 speed and muscle strength, earlier fatigue, bone
loss
 reaction times, sensory loss, ANS
 BMR, lean tissue, body fat, glucose tolerance
 Reversal of training effects
 autonomic response
 body fat, cholesterol
 osteoporosis, muscle atrophy
 joint mobility, metabolism
 O2 extraction, VO2max
 heart size, HR, C.O.