Stress Adaptation and Exercise

8/3/2019 Stress Adaptation and Exercise

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Stress Adaptation and

Exercise


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Stress

Nonspecific response of the body to any

demand placed on it.

Stressors, stress producing factors It may be pleasant or unpleasant and

induces different emotional or

psychological responses while eliciting

similar physiological reaction.


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The Stress response

Eustress, positive stress; Distress,

negative stress

It elicits the General Adaptation Syndrome(GAS; the syndrome of just getting sick)

Enlargement of the adrenal glands, sympathetic

stimulation

Fatigue, malaise, loss of appetite, gastric upsetand other nonspecific complaints


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General Adaptation Syndrome

Alarm Stage

Stage of Resistance

Stage of Exhaustion


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Alarm Stage

Initial stimulation by a stressor hypothalamic

stimulation (release of CRH) pituitary

stimulation (release of ACTH) adrenal glands

release glucocorticoids (cortisol)

Sympathetic stimulation (fight-or-flight

mechanism) release of catecholamines

(epinephrine, norepinephrine) vasoconstriction

of the skin, GIT, kidneys; vasodilatation` of heart

vessels and skeletal muscles increase in heart

and respiratory rate; increase in blood pressure


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Alarm Stage

Sympathetic stimulation (fight-or-flight

mechanism) release of catecholamines

(epinephrine, norepinephrine)

vasoconstriction of the skin, GIT, kidneys;

vasodilatation` of heart vessels and

skeletal muscles increase in heart and

respiratory rate; increase in bloodpressure


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Stage of Resistance

Increase in blood sugar levels immune

suppression due to circulating excess

corticosteroids

delayed healing


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Stage of Exhaustion

Resistance to the stressors are depleted

and death ultimately occurs


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Local Adaptation Syndrome (LAS)

Local Adaptation Syndrome (LAS)

Localized reaction to stress

Similar to GAS but exhaustion lead to ageneralized response

Ex. Inflammation


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Physiologic Response to Stress

Neurologic Mechanisms

Motor nervous system (voluntary) and

Autonomic nervous system (involuntary)mediated via the sympathetic nervous

system


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Neurologic Mechanisms

Epinephrine and

Norepinephrine

Peripheral vasoconstriction

(skin, viscera, kidneys)GI motility and secretion

Vasodilatation of skeletal and

cardiac muscles

Bronchial dilatation Rate and force of cardiac

contraction

Glycogenolysis and

gluconeogenesis by the liver


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Endocrine Mechanism

Effects of Glucocorticoids

More fuel is made available for energy via

increase in gluconeogenesis,glucogenolysis, lipolysis and protein

catabolism


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Endocrine Mechanism

Suppresses the inflammatory response

Stabilizes lysosomal membrane which

decreases release of proteolytic enzymes

Decreases capillary permeability

Suppresses the immune system

Blocks interleukin 1


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Stress-Induced Disease

Cardiovascular disease

Coronary artery disease ( Atheroscelrosis)Hypercholesterolemia

high fat diet, stressful living conditions, personality

and genetics

AnginaEmotional stress


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Immune Deficiency

Excessive glucocorticoids

Physiologically and psychologicallystressful events precipitate a decrease in

lymphocyte and leukocyte activity

It is detrimental in certain conditions


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Gastrointestinal Diseases

Stress ulcers due to gastric mucosal

ischemia and acid secretionDuodenal ulceration (H. Pylori)


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Cancer

Increase in the production of abnormal

cells Inability of the body to destroy abnormal

cells


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Exercise

Physical exercise is essential to health

It promotes cardiovascular and other

systemic adaptaion to maintain physiologicfunction


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Effects on the Cardiovascular System

Heart Rate (HR)

Sympathetic stimulation of the autonomic

nervous systemRelease of epinephrine and nor

epinephrine


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Heart rate increases (maximal heart rate)

Influenced by age, gender, level of fitness,

pre-existing diseases, altitude, type ofexercise and true maximal exertion


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Stoke Volume (SV)

Amount of blood ejected from the ventricle

per each heartbeatFactors responsible for SV are venous

return, ventricular distensibility, ventricular

contractility, systemic and pulmonary

resistance

Resting SV range from 60 to 100ml


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Factors responsible for SV are venous

return, ventricular distensibility, ventricular

contractility, systemic and pulmonary

resistance

Resting SV range from 60 to 100ml


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Cardiac Output (CO)

Amount of blood pumped by the heart per

minuteCO = SV x HR in one minute

Resting CO is about 4 to 8 L/min

Cardiac Reserve, ability to increase COwhen needed


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Blood Pressure (BP)

BP = CO x systemic vascular resistance


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Although peripheral resistance decreases

during exercise there is a significant

increase in the CO which lead to an

increase in mean arterial pressure due to

an increase in the systolic blood pressure

Systolic blood pressure increase can

range from 20 to 80 mm Hg


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Blood Flow

Increased blood flow to the skeletal and

cardiac muscles Increased in nutrient, oxygen, carbon

dioxide and other waste exchange

between the circulation and muscles

Increased skin temperature


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Effects on the Respiratory System

Pulmonary ventilation increases with

exercise

Increase in the depth and frequency ofrespiration

Increased respiratory reserve


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Effects on the Endocrine System

Increased hormone secretion

Increased metabolic rate


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Effects on the Immune System

Moderate exercise boost functions of

natural killer cells, T and B lymphocytes

and macrophages

May have a reverse effect


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Effects on the Muscular System

Hypertrophy

Increase contractile force

Increase in power, strength andendurance


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Long Term Adaptation to Exercise

Decrease in resting HR and Increased SV

Cardiac muscle hypertrophy

Increase respiratory reserve Increase muscle mass and cell size

Efficient metabolism


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Thank You

Documents

Stress Adaptation and Exercise