based on gk pal practical physiology of mbbs 1st year ,effect of exercise and posture on blood pressure and heart rate

1. Effect of exercise and posture on blood
pressure and heart rate
Dr.G.Sandeep,MBBS,MD(Physiology)

2. Effect of exercise on blood pressure and heart rate
Introduction
• Regular exercise improves health
• It affects all body systems and improves functioning of all organs of body
Two types of responses
• Short term response to acute exercise
• Long term response to chronic exercise
• CVS response to exercise is different in trained and untrained persons

3. Immediate response to acute exercise depends on degree and
type of exercise and exercise training that the individual has
received
Three categories of degree of exercise
mild moderate severe
Oxygen
consumption/min
0.5-1 lit/min 1-2 lit/min >2 lit/min
Work done 150-350 watts 350-550 watts >550 watts
Rise in basal heart rate 25 percent 50 percent 75-100
percent

4. Types of exercise
Isotonic and isometric
Isotonic-change in muscle length is seen
• Exercise is phasic in nature
• Eg;walking ,jogging,running
Isometric-no change in muscle length
• Exercising muscle remains contracted through out maneover
• Eg;pushing against wall

5. cvs changes in isotonic and isometric exercise
isotonic isometric
Heart rate Increases proportionately Increases at start
Cardiac output Increases due to inc in HR and SV SV changes little
SBP increases Rises sharply
DBP Inc in mild,dec or normal in moderate,dec in
severe exercise
Rises sharply
Blood flow Increases to exercising muscle decreases
Peripheral resistance increases leading to incresed DBP in isometric exercise

6. Procedure;
principle c.v.s functions alter during exercise
pulse rate and b.p recorded before and after exercise
• Requirementsstethoscope and sphygmomanometer
• Procedure;
• Observation;
Pulse
rate
SBP DBP Pulse
pressure
Mean arterial
pressure
Basal (before exercise)
Immediately after exercise
Two minutes after exercise
4 minutes after exercise
10 minutes after exercise

7. Observation;
• HR and SBP rise significantly immediately after exercise
• DBP rises or may not change
• PP changes accordingly
• BP returns to normal within 5-7 minutes
• HR takes longer time to return to normal
• Precautions ;
• BP should be recorded in standing position only
• Subject should be encouraged for 5 minute exercise
• BP and PR should be recorded as quickly as possible

8. Discussion
Effect of acute exercise
• HR-----increases with severity
• CO-----marked increase due to increased HR and SV
• SBP-----increases markedly due to increased CO
• DBP-----remain unchanged or fall(due to decreased peripheral
resistance and due to vasodilation in exercising muscle)
• Muscle blood flow-----increases due to vasodilation in skeletal bed
vasoconstriction in cutaneous and splanchnic
circulation diverted to skeletal vascular bed.

9. Physiological basis of c.v.s changes
• Psychic stimuli and stimulation of receptors in muscles,joints,tendons Inc
activity of symp nerves to heart tachycardia,increase SV  CO increases
• Vagal tone inhibitiontachycardia
• SV increase due to--- inc myocardial contractility by symp stimulation
inc venous return
• Venous return inc due to –symp veno constriction
inc skeletal pump activity
inc thoracic pump and
vaso constriction of splanchnic and cutaneous beds

10. • SBP—inc due to inc in CO
• DBP---inc in mild exercise due to symp vaso constriction
• normal or falls in moderate exercise due to vasodilation in
exercising muscle
• falls in severe exercise due to vasodilation in exercising muscle
• Blood vessels in skeletal vascular bed receive symp vasodilator fibers
that leads to vasodilation in skeletal bed

11. • Systemic blood vessels dilate in severe exercise due to
• rise in body temp(thermal vasodilation)
• deposition of lactic acid ,potassium and carbondioxide in
active tissues(metabolic vasodilation)
• Total peripheral resistance decreases due to vasodilation
• therefore inspite of inc symp activity DBP falls during severe exercise
• Muscle blood flow:--inc to great extent ,neural and local mechanisms
cause vasodilation

12. • Respiratory changes—hyperventilation and inc oxygen supply to
tissues
resp.minute volume increases
pulmonary blood flow inc and perfusion of alveoli inc
• Other changes—body metabolism increases,temp increases
catecholamine sec and glucocorticoid sec inc
glycogenolysis in liver and muscles
lipolysis in prolonged aerobic exercise

13. Effect of regular exercise on health
• CVS—profound improvement in cvs seen
• basal heart rate dec due to inc vagal tone
• SV—inc due to inc myocardial muscle mass
trained subject achieves required CO during exercise by inc SV
untrained subject by inc heart rate
• BP ---usually maintained in normal range and hypertension usually
does not occur unless pathology occurs.
• Resp.system—inc in breathing capacity and ventilation
• Skeletal muscles—size and work capability inc
• Mind—memory and intellectual mental function improves

14. Clinical significance
• Exercise suggested in hypertension and mi
• Isotonic exercise (mild to moderate)done regularly dec BP(in
hypertension)
• exercise improves cardiac performances in mi patients and prevents
the risk
• Exercise improves joint function in chronic joint disease person

15. Effect of posture on blood pressure and
heartrate
• Change in body posture affects the functions of cvs
• CVS changes are different on immediate standing and prolonged standing
CVS changes on immediate standing
Effect:
Due to gravity 200-500ml blood is pulled to lower extremities on
standingdec CO due to dec venous returndec in BP on standing
Mean arterial pressure in feet in standing is 180-200mmhg
at head is 60-80 mmhg
Venous pressure at feet—85-90 mmhg
At head level –0 mmhg

16. Compensatory mechanisms
• Vasoconstriction,tachycardia and increased cardiac output are
immediate compensatory mechanisms
• Triggered by fall in BP and are mediated by baroreceptor reflex
Dec pressure in carotid and aortic sinus dec rate of baroreceptor
discharge
dec stimulation of nucleus tractus solitarius
dec vagal activity and inc symp activity
restoration of blood pressure

17. Cvs changes on prolonged standing
• Effects
• More than 500ml of blood is pulled into lower limbs
• Capillary hydrostatic pressure incfluid moves from intravascular
compartment into interstitial tissue spaces and accumulates
• Venous return dec,SV dec by 40%.
• CO decreases ,cerebral blood flow decreases
• Subject may become unconscious and fall.
• Fainting is homeostatic mechanism to restore venous return,CO and
cerebral blood flow in horizontal position by automatic change of
posture

18. Compensatory mechanisms
• Baroreceptor reflex restores BP to normal
• Symp fibres activate and release catecholamines from adrenal
medulla that increase HR,CO and BP
• Renin angiotensin aldosterone axis is activated
• Angiotensin causes vasoconstriction and inc BP
• Aldosterone inc reabsorption of sodium and water from kidneys and
maintains blood volume and BP
• If subject stands for longtime he may develop hypotension

19. METHOD
• Principle-on standing from supine changes occur in cvs
• Requirements—stethoscope and sphygmomanometer
• Procedure—
• Observation—
Posture Pulse rate SBP DBP PP MAP
Supine (after 5 min)
On
standing(immediate)
After 2 min
After 5 min
After 10 min

20. Discussion
• CO dec due to pooling of blood in lower limbs after immediate
standing
So BP falls immediately with in 15 seconds
Activation of baroreceptor reflex
Tachycardia,increase CO and vasoconstriction
With in 15-30 sec bp returns to normal
But because of vasoconstriction peripheral resistance increases inc
DBP,HR rises and SBP remains normal or slightly raised

21. Physiological significance
• Change in posture initiates changes in CVS
• These changes reflect integrity of autonomic nervous system
• Heart rate and BP response to standing is important test to assess
autonomic function

22. Clinical significance
• Postural hypotension—In some people sudden standing causes
significant fall in BP causing fainting k/a postural or orthostatic
hypotension
• Seen in autonomic neuropathy(diabetes,syphilis)primary autonomic
failure
• Thereupatic uses—Regular practice of yoga improves autonomic
functions and improves physiological functions
• Traffic personnel—Police should walk around so skeletal muscle pump
activity increases venous return and maintains CO and BP