3. ExErcisE
Is the period of enhanced energy
expenditure
This energy is provided by increased
fuel consumption which is reflected
as increased O2 consumption and
increased CO2 production
4. incrEasEd o2 dElivEry to thE
tissuEs and incrEasEd rEmoval
of co2from thE tissuEs is
achiEvEd by
cardiovascular responses to exercise
respiratory responses to exercise
changes at tissue level during
exercise
5. tyPEs of ExErcisEtyPEs of ExErcisE
SStatictatic exerciseexercise = constant muscle
length and increased tension
Dynamic exerciseDynamic exercise = rhythmic cycles of
contraction and
relaxation; change in muscle length
6. tyPEs of ExErcisEtyPEs of ExErcisE
Anaerobic exerciseAnaerobic exercise
weight-lifting) –
short duration,
great intensity
(fast-twitch muscle
fibers); creatine
phosphate +
glycogen (glucose)
from muscle
o2
Aerobic exerciseAerobic exercise
running, swimming)-
prolonged but at lower
intensity (slow-twitch
mucle fibers) fuels
stored in muscle,
adipose tissue and liver
(glucose – early, FFA –
later)
o2
7. oxygEn consumPtion
during ExErcisE
The increase in ventilation during exercise
prevents large changes in the partial
pressure of O2 or CO2.
The increase in ventilation occurs before
there is a change in blood chemicals.
Neuronal signals are sent to the
respiratory center during exercise,
possibly at the same time signals are being
sent to the skeletal muscles.
9. OXYGEN CONSUMPTION (VO2) AT
REST = 250 ml and increases with
severity of exercise
MAXIMAL OXYGEN CONSUMPTION
(VO2 MAX)= level of O2 consumption
beyond which no further increase in O2
consumption occurs with further
increase in severity of exercise
10. vo2 max
Average VO2 max in
adults=3L/min
trained athletes=5L/min
So VO2 max represents the max
attainable rate of aerobic metabolism
during performance of rhythmic
muscular work that exhausts the
subject in 5-10 minutes
11.
12. AlveolAr ventilAtion And
ArteriAl PCo2 during exerCise
The decrease PCO2 at the
onset of exercise
demonstrates that
increasing blood CO2
does not trigger the
increase in ventilation
during exercise.
However, chemical
changes do fine-tune
the ventilation rate.
Notice the decrease in
ventilation associated
with the decrease in PCO2
at the onset of
exercise.
13. o2 defiCit And o2 debt
Period of muscular exercise can be
divided into 3 phases
Adaptation phase
Steady phase
Recovery phase
14.
15. AdAPtion PhAse
First 2-4 min after beginning
exercise
O2 consumption reaches VO2 max
VO2 max is less than O2 demand….O2
deficit develops
Anaerobic respiration begins
16. steAdy PhAse
Plateau phase of work done and O2
consumption
Anaerobic respiration continues
Built up of lactic acid which is
buffered by bicarbonate buffer
system
H+ + HCO3-……..H2CO3….H2o + CO2
Extra CO2 evolved is removed by
hyperventilation
17. reCovery PhAse
After cessation of exercise extra
amount of O2 is consumed called
oxygen debt
Oxygen debt is proportional to extent
to which oxygen deficit occurred
during exercise
19. MusCle fAtigueMusCle fAtigue
Lactic acid
↓ATP (accumulation of ADP and Pi,
and reduction of creatine phosphate)
Ca↓ ++
pumping and release to and
from SR↓ ccontraction and
relaxation
Ionic imbalances muscle cell is less
responsive to motor neuron
stimulation
20. ↓ the rate of ATP hydrolysis,
↓ efficiency of glycolytic enzymes,
↓Ca2+
binding to troponin,
↓ interaction between actin and myosin
(muscle fatigue)
during rest is converted back to pyruvic acid
and oxidized by skeletal muscle, or converted
into glucose (in the liver)
21.
22. How does tHeHow does tHe
respiratory systemrespiratory system
respond to exercise?respond to exercise?
23. major factors wHicH stimulatemajor factors wHicH stimulate
increased ventilation duringincreased ventilation during
exercise include:exercise include:
neural input from the motor areas of the cerebral
cortex
proprioceptors in the muscles and joints
↑ body temperature
circulating NE and E
pH changes due to lactic acid
Rest Exercise intensity V02max
Arterial blood
pH
24. Before expected exerciseBefore expected exercise
Begins,Begins, ventilationventilation risesrises
emotional
hyperventilation‘
at any rate, impulses
descending from the
cerebral cortex are
responsible
25. During the exercise,During the exercise, stimulistimuli
from the muscles, joints andfrom the muscles, joints and
perhaps such sensoryperhaps such sensory
receptors as pressurereceptors as pressure
endings in the feet,endings in the feet,
contribute to the elevationcontribute to the elevation
ofof ventilationventilation
so do chemicals, originating
in the active muscles.
26.
27. increase oxygen uptake
By lungs
Increases from 250ml at rest to
4L/min
This is achieved by
*increased ventilation
* increased alveolar capillary PO2
* increased pulmonary diffusion
capacity
28. cHanges at tHe tissue
level
Increased blood flow to the
exercising muscles
Increased PO2 gradient between the
systemic capillaries and tissues
Rightward shift of oxygen Hb
dissociation curve (increased 2,3DPG
and temperature)
29. How does tHeHow does tHe
cardiovascular systemcardiovascular system
respond to exercise?respond to exercise?
30. cardiovascular
responses to exercise
Increase in cardiac output (COP)
Increase in heart rate
Increase in blood pressure
Increase in skeletal muscle blood flow
Changes in blood volume
31. Increased CO can be achieved by raising either
stroke volume (SV) or heart rate (HR)
steady-state HR rises essentially linearly with
work rate over the whole range from rest to
VO2max :
increased sympathetic and decreased
parasympathetic discharge to the cardiac
pacemaker + catecholamines
reflex signals from
the active muscles
blood-borne metabolites
from these muscles
temperature rise
CCardiaC output (Cop)ardiaC output (Cop)
inCreaseinCrease
33. BloodBlood ppressureressure (Bp)(Bp) also rises inalso rises in
exerCiseexerCise
systolic pressure
(SBP) goes up to
150-170 mm Hg
diastolic scarcely
alters
in isometricisometric (heavy
static) exercise, SBP
may exceed 250
mmHg, and diastolic
(DBP) can itself reach
180
34. CardiovasCularCardiovasCular
adaptations toadaptations to eexerCisexerCise
trainingtraining
Adaptations that increase muscle
oxidative capacity and delay lactate
production
↓↓ muscle chemoreflexmuscle chemoreflex influence on
cardiovascular system
As a result sympathetic activity is
decreased, which lowers BP and HR
(trained people)
35. inCrease in skeletal
musCle Blood flow
It is 2-4ml/100gm/min of muscle tissue
Increases 20 times i.e.50-80
ml/100gm/min
Achieved by
* arteriolar dilatation
* opening up of dormant capillaries
38. during exerCiseduring exerCise
Norepinephrine rises again ('fight or flight'). Increases
glycogen breakdown and elevates free fatty acids; also
cardiovascular effects as in anticipatory phase
Glucagon rises (to keep up blood sugar). Increases glucose
release from liver
Cortisol rises (response to the stress). Increases use of
fatty acids, reinforces glucose elevation
Growth hormone begins to rise (damage repair). Stimulates
tissue repair, enhances fat use instead of glucose
39. ADH is released in considerable quantities.
It's not just socially inconvenient to have to
urinate during exercise - it's a waste of fluid
which will probably be needed as sweat.
Testosterone/estrogen increase with
exercise - probably, over many repetitions,
promoting increased muscle bulk
Aldosterone also rises, reducing Na+ loss in
sweat (and in such urine as is still produced).
