1. Exercise Physiology

3. MAP = CO x TPR Structure of the heart Cardiac output
Cardiac cycle
Control of heart rate
Control of stroke volume
Total peripheral resistance
Functions of vessels
Local control of resistance
Central control of resistance
Regulation of CO and TPR
Cardiovascular changes during exercise

4. The Cardiac Cycle Systole ___________ phase Diastole _________ phase
Fig 9.5

5. Definitions
Systolic Blood Pressure (SBP) pressure measured in brachial artery during systole (ventricular emptying and ventricular contraction period)
Diastolic Blood Pressure (DBP) pressure measured in brachial artery during diastole (ventricular filling and ventricular relaxation)
Mean Arterial Pressure (MAP) "average" pressure throughout the cardiac cycle against the walls of the proximal systemic arteries (aorta)
estimated as: MAP = DBP + 1/3(SBP – DBP)
Total Peripheral Resistance (TPR) - the sum of all forces that oppose blood flow
Length of vasculature
Blood viscosity
Vessel radius
TPR = ( MAP - MVP) CO

6. Factors That Influence Arterial Blood Pressure
Fig 9.8

7. ISOMETRIC VENTRICULAR
THE CARDIAC CYCLE
LATE DIASTOLE
DIASTOLE
ISOMETRIC
VENTRICULAR
RELAXATION
ATRIAL
SYSTOLE
VENTRICULAR
EJECTION
ISOMETRIC VENTRICULAR
CONTRACTION

8. PRELOAD AND AFTERLOAD IN THE HEART
INCREASE IN FILLING PRESSURE=INCREASED PRELOAD
PRELOAD REFERS TO END DIASTOLIC VOLUME.
AFTERLOAD IS THE AORTIC PRESSURE DURING THE EJECTION PERIOD/AORTIC VALVE OPENING.
LAPLACES’S LAW & WALL STRESS, WS = P X R / 2(wall thickness)
A preloaded muscle is one in which some tension has been applied before the muscle performs any work. In the case of the heart this tension is provided by the End Diastolic Volume (EDV). Afterload refers to the load that the preloaded muscle has to work against. In the heart it refers to the aortic pressure present just at the instant that the aortic valve opens. Thus, the higher the aortic diastolic pressure, the more work the heart has to perform to pump blood into it. A higher aortic pressure means more afterload. Afterload is also defined as the Ventricular Wall Stress that develops during systolic ejection. It can be estimated using Laplace’s Law:
VWS = Pressure x radius / 2 (wall thickness)
The pressure can be estimated from arterial systolic pressure. In heart failure the dilated heart increases its thickness to reduce wall stress. This is a compensatory measure.

9. THE HEART AS A PUMP REGULATION OF CARDIAC OUTPUT
Heart Rate via sympathetic & parasympathetic nerves
Stroke Volume
Frank-Starling “Law of the Heart”
Changes in Contractility
MYOCARDIAL CELLS (FIBERS)
Regulation of Contractility
Length-Tension and Volume-Pressure Curves
The Cardiac Function Curve

10. Autoregulation
(Frank-Starling “Law of the Heart”)
CARDIAC OUTPUT = STROKE VOLUME x HEART RATE
Contractility
Sympathetic
Nervous System
Parasympathetic
Nervous System

11. Exercise

12. Cardiorespiratory System At Rest and With Exercise
Heart Rate
Rest bpm
Exercise Up to bpm
Respirations
Rest breathes per minute
Exercise breathes per minute
Blood Pressure (Systole=Contraction Diastole=Relaxation)
Rest 110/70
Exercise 175/65
Cardiac Output (SV x HR)
Rest 5 quarts/min.
Exercise 20 or more quarts/min.

13. Blood flow during exercise
CO is redirected due to:
local metabolic autoregulation in working muscle causing arteriolar dilation
offset by centrally mediated generalised sympathetic
arteriolar constriction
circulating epinephrine causes
- arteriolar constriction in most tissues
(ie those expressing a receps)

14. Redistribution of Blood Flow During Exercise
Fig 9.24

15. The Effects of Exercise
Immediate Effects:
*Increase in HR, since higher demand for oxygen.
*Increase in BP, as a result of ↑ blood flow.
*Increase in supply, delivery, and use of oxygen by muscle.
*Increase in body temperature.
*Increase in certain hormones/ neurotransmitters , especially epinephrine which stimulates a rise in all body functions.
*Increase in metabolism.

16. Effects of Aerobic Training on Cardiovascular Function
Heart rate
Stroke volume
a-v O2 difference
Cardiac output
VO2
Systolic blood pressure
Diastolic blood pressure
Coronary blood flow
Brain blood flow
Blood volume
Plasma volume
Red blood cell mass
Heart volume

17. Myocardial Hypertrophy
Aerobic training. Thicker walls and greater volume
Strength training. Thicker walls only
Pathological. Thicker but weaker walls

18. CV Function and Endurance Training
Increase in EDV (increase chamber size)
Endurance training
Increase myocardial mass (increase force of contraction)
Strength training

19. CV Function and Endurance Training
Increase in parasympathetic inhibition of the SA node (mostly at rest)
Decrease in sympathetic stimulation (mostly during exercise)

20. BLOOD PRESSURE Greatest effect on high blood pressure
Systolic: lower resting and submax
10 mm Hg decrease
Diastolic lower maximum
Why?
Weight loss
Reduce sympathetic stimulation
Other

21. BLOOD FLOW Blood flow Coronary: higher at rest, submax, and max.
Greater SV and lower HR cause a reduction in mVO2.
Greater vascularity only in diseased hearts

22. Redistribution of Blood Flow During Exercise
Fig 9.24

23. BLOOD FLOW Skeletal blood flow Increase vasularity (capillaries)
Increased O2 and fuel delivery
Decrease resistance → decrease afterload → increase Q
Decrease flow at submax exercise
Compenstated by an increase O2 extraction
Greater blood flow to skin
Increase flow at maximal exercise (10%)
Due to greater Q and vasularity

24. Causes venous distension in legs
20mmHg
0mmHg
+80mmHg
-40mmHg
-20mmHg
100mmHg
20mmHg
0mmHg
Causes venous distension in legs
 VR,  EDV,  preload,  SV,  CO,  MAP
causes orthostatic (postural) hypotension

25. Chronic adaptations to Aerobic training WITHIN THE MUSCLE TISSUE
The following tissue changes occur:
Increased O2 utilisation
increased size and number of mitochondria
Increased myoglobin stores
Increased muscular fuel stores
Increased oxidation of glucose and fats
Decreased utilisation of the anaerobic glycolysis (LA) system
Muscle fibre type adaptations

26. Chronic adaptations to Aerobic training
Cardiac hypertrophy (increased ventricular volume)
Increased capillarisation of the heart muscle
Increased stroke volume
Lower resting heart rate
Lower heart rate during sub max workloads
Improved heart rate recovery rates

27. Chronic adaptations to Aerobic training
Increased cardiac output at max. workloads
Lower blood pressure
Increased arterio-venous oxygen difference (a-VO2 diff)
Increased blood volume and haemoglobin levels
Increased capillarisation of skeletal muscle

28. Chronic adaptations to Aerobic training
Changes to blood cholesterol, triglycerides, lipoprotein levels (L.D.L’s and H.D.L’s)
Increased lung ventilation
Increased max. oxygen uptake (VO2 max)
Increased anaerobic threshold

29. Cardiovascular Adjustments to Exercise
Fig 9.23

30. LACATE LEVELS
Lactic acid comes to blood from muscles, in which aerobic resynthesis of energy stores cannot keep pace with their utilization and a oxygen debt is being incurred.
With increased production of Lactic acid, the increase in ventilation and production of carbon-dioxide remains proportionate, to an extent.
If lactic acid accumulates further , it causes metabolic acidosis
Accumulation in skeletal muscles causes pain.

31. The respiratory rate after exercise does not reach basal levels until the oxygen debt is paid.
This may take as long as 90 minutes.
Stimulus: elevated lactic acid in blood
When the oxygen debt is paid,
-ATP & phosphorylcreatine resynthesized
-lactic acid is removed – 80% converted to glycogen, 20% metabolised in to CO2 & H2O

32. The athlete can work harder for longer
INCREASED ANAEROBIC OR LACTATE THRESHOLD
As a result of improved O2 delivery & utilisation a higher lactate threshold (the point where O2 supply cannot keep up with O2 demand) is developed.
Much higher exercise intensities can therefore be reached and LA and H+ ion accumulation is delayed.
The athlete can work harder for longer

33. Blood Lactate Levels

34. Effects of Exercise on Respiration
When talking about the respiratory system we are talking about the lungs, air passages and our breathing (ventilation).

36. Respiratory Capacities
Figure 13.9 36

37. Lung capacities
Total lung capacity: The volume lation in the lungs at maximal in
Tidal volume: The amount of air inhaled in or exhaled out of the lungs during quiet breathing
Inspiratory reserve volume: The maximal volume that can be inhaled from the end inspiratory level
Expiratory reserve volume: The maximal volume of air that can be exhaled from end expiratory position
Residual volume: The volume of air that remains in the lung after a maximal expiration
Vital capacity: the volume of air exhaled out after the deepest breathing

38. Chronic adaptations to Aerobic training RESPIRATORY ADAPTATIONS
Just as there are cardiovascular adaptations to AEROBIC training there are also respiratory adaptations. These include:
Increased lung ventilation
Increased oxygen uptake
Increased anaerobic or lactate threshold

39. Chronic adaptations to Aerobic training RESPIRATORY ADAPTATIONS
INCREASED LUNG VENTILATION
Aerobic training results in a more efficient and improved lung ventilation.
At REST and during SUB MAX. work ventilation may be decreased due to improved oxygen extraction (pulmonary diffusion), however during MAX. work ventilation is increased because of increased tidal volume and respiratory frequency.

40. Respiratory Adaptations From Aerobic Training
Respiratory system functioning usually does not limit performance because ventilation can be increased to a greater extent than cardiovascular function.
Slight increase in Total lung Capacity
Slight decrease in Residual Lung Volume
Increased Tidal Volume at maximal exercise levels
Decreased respiratory rate and pulmonary ventilation at rest and at submaximal exercise
(RR) decreases because of greater pulmonary efficiency
Increased respiratory rate and pulmonary ventilation at maximal exercise levels
from increased tidal volume

41. Cardiorespiratory Endurance
VO2MAX is the best indicator of cardiorespiratory endurance.

42. VO2MAX Maximal O2 consumption by tissues
VO2max = COmax * maximum O2 extraction by the tissue
Absolute and relative measures.
absolute = l . min-1
relative = ml . kg-1 . min-1
VO2 = SV x HR x a-vO2diff

43. Effects on Oxygen Uptake or Volume of Oxygen Consumed (VO2)
Oxygen uptake (VO2) is the amount of oxygen taken up and used by the body. It reflects the total amount of work being done by the body.
During strenuous exercise there can be a twenty-fold increase in VO2 which increases linearly with increases in the intensity of the exercise.

44. VO2 Training has little effect on resting VO2
Training has little effect on submaximal VO2
Example, running at 8 mph at a 0% grade is always at VO2 of ~24.9 ml/kg/min
Training increases maximal VO2 (VO2max)
15-20% (but as high as 50%) increase.

45. Effects on Oxygen Uptake or Volume of Oxygen Consumed (VO2)
As a person approaches exhaustion, his or her VO2 will reach a maximum above which it will not increase further.
This figure is his or her VO2 Maximum; that is, the largest amount of oxygen that a person can utilize within a given time (for example, 50 litres per minute).

46. VO2max Training to increase VO2max Expected increases in VO2max
Large muscle groups, dynamic activity
20-60 min, 3-5 times/week, 50-85% VO2max
Expected increases in VO2max
15% (average) - 40% (strenuous or prolonged training)
Greater increase in highly deconditioned or diseased subjects
Genetic predisposition
Accounts for 40%-66% VO2max

47. VO2max
Higher Q at max
High a-v 02 difference

48. Chronic adaptations to Aerobic training RESPIRATORY ADAPTATIONS
INCREASED MAXIMUM OXYGEN UPTAKE (VO2 MAX)
VO2 max is improved as a result of aerobic training – it can be improved between 5 to 30 %. (LIU page 255)
Improvements are a result of:
-Increases in cardiac output
-red blood cell numbers
-a-VO2 diff
- muscle capillarisation
- greater oxygen extraction by muscles

49. Chronic adaptations to Aerobic training RESPIRATORY ADAPTATIONS VO2 MAX

50. Respiratory Adaptations From Aerobic Training
Unchanged pulmonary diffusion at rest and submaximal exercise.
Increased pulmonary diffusion during maximal exercise.
from increased circulation and increased ventilation
from more alveoli involved during maximal exercise
Increased A-VO2 difference especially at maximal exercise.

51. Chronic adaptations to Aerobic training RESPIRATORY ADAPTATIONS
WORDS to KNOW
Arterio-venous oxygen difference
Pulmonary diffusion
Lung ventilation
Tidal volume
Respiratory frequency
VO2 max
Lactate threshold

52. Pulmonary Adaptations:
Most static lung volumes remain essentially unchanged after training.

53. Pulmonary Adaptations:
Tidal volume, though unchanged at rest and during submaximal exercise, increases with maximal exertion.

54. Pulmonary Adaptations:
Respiratory rate remains steady at rest, can decrease slightly with submaximal exercise, but increases considerably with maximal exercise after training.

55. Pulmonary Adaptations:
The combined effect of increased tidal volume and respiration rate is an increase in pulmonary ventilation at maximal effort following training.

56. Pulmonary Adaptations:
Pulmonary diffusion at maximal work rates increases, probably because of increased ventilation and increased lung perfusion.

57. Pulmonary Adaptations:
a-vO2diff increases with training, reflecting an increased oxygen extraction by the tissues and more effective blood distribution.

58. Cardiorespiratory Adaptations From Anaerobic Training
Small increase in cardiorespiratory endurance
Small increase in VO2 Max
Small increases in Stroke Volume

59. Cardiorespiratory Adaptations From Resistance Training
Small increase in left ventricle size
Decreased resting heart rate
Decreased submaximal heart rate
Decreased resting blood pressure is greater than from endurance training
Resistance training has a positive effect on aerobic endurance but aerobic endurance has a negative effect on strength, speed and power.
muscular strength is decreased
reaction and movement times are decreased
agility and neuromuscular coordination are decreased
concentration and alterness are decreased

60. Aerobic Training
The minimum period for chronic adaptations to occur is 6 weeks.
Adaptations from aerobic training can occur at the muscle site and in the cardio-respiratory systems.

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