Exercise II

Question 1

describe sex differences in CV response to exercise

Answer 1

• WOMEN

–> lower cardiac index

–> lower stroke volume index

–> high HR responses (to correct for lower cardiac index)

–> high AVO2 differences

–> Lower SNA

–> Lower SBP/DBP

• potential mechanisms for lower VO2 (related to estrogen)

–> lower hemoglobin content

–> lower CaO2 and SOT

Question 2

Describe difference in blood flow, SNA, oxygen delivery and functional sympatholysis in men vs women

Answer 2

• Blood flow responses to exercise are greater in pre-menopausla women
• SNA during exercise is lower in pre-menopausal women
• Oxygen delivery is lower in pre-menopausla women due to lower Hgb
• Functional sympatholysis is impaired in post vs. pre menopausal women and reversed with exog. estorgen

Question 3

describe sex differences in PULMONARY response to exercise in regards to women

Answer 3

• Reduced airway diamter leading to expiratory flow limitation during exercise (relative to men)
• working of breathing (WOB) is greater due to expiratory flow limitation and increased end expiratory and inspiratory lung volumes (relative to men)
• Airway hyperresponsiveness may predispose exercise-induced asthma
• Increase susceptibility to exercise-induced arterial hypoxemia at high workloads due to reduced airway diamter and higher WOB

Question 4

describe estrogens role in response to EX

Answer 4

• Estrogen is a major sex steroid hormone produced by ovaries in women

–> targt tissues include brain and cardiovascular system

• estrogen plays a cardioprotective role in part by acting through estrogen receptors to INCREASE production of NO, and inhibit release of other inflammatory and vasoconstrictor peptides in heart, vasculature and CNS

Question 5

describe mechanisms for age effects on muscle blood flow

Answer 5

• sympathetic nerve activity to skeletal muscle increases with aging
• sympathetic responses to exercise increase with aging
• decreased sensitivity to sympathetics so decrease response
• MECHS
• vascular constriction to endothelin increase
• vascular relaxation to NO decreased
• Decreased ATP production/decreased purnergic receptor expression

Question 6

describe the structural changes to chronic exercise

Answer 6

• increased atrial dimensions = improved diastolic function and cardiac filling
• increase size and thickness of left ventricle = increased cardiac contracitlity
• increased ventricular compliance (faciliates diastolic filling) = increased SV/CO
• Increased red cell mass and plasma volume = increased oxygen carrying capcity and ability to increase cardiac output
• Increased capillary density and increase mitochondrial content of muscle fibers = greater O2 extraction and wider arterio-venous oxygen difference
• increased expression of anti-inflammatory/vasodilatory/antioxidant gene programs in vasculature= healthy vascular phenotype, lower blood pressure at sub-max intensity (improved muscle blood flow)

Question 7

describe physological adaptations in chronic exercise

Answer 7

• reduction in blood flow in response to sympathetic stimulation during exercise is improved with EX tranining
• contraction induced-ATP release and purinergic receptor (P2Y2) expression is also improved in training

Question 8

benefits of physical activity/exercise

Answer 8

• impoves muscular and cardiorespiratory fitness
• improves bone health
• reduces risk of hypertension, CHD, stroke, diabetes, breast and colon cancer
• reduces risk of falls and hip fracture in elderly populations
• improves morbidity, mortality, and quality of life in clinical populations (CHF, Post-MI)
• regular exercise may decrease psychosocials tress and indices of depression

Question 9

describe impaired/improved matching of blood and the effects of physical actiity

Answer 9

Question 10

describe heat effects on exercise

Answer 10

• hemodynamic respones to exercise are altered in hot environments
• ecercise capacity is signficantly affected by ehat and humidity
• redistribution of cariac output is altered during exercise in the heat
• PROLONG EXERCISE:

–> reduced SV, CO, BP

–> reduced Blood flow to muscle and skin

–> reduced blood volume

–> reduced time to exhaustion

–> increase plasma catecholamines, plasma lactate, fatigue

Question 11

heat strok and heat exhaustion

Answer 11

• Heat exhaustion: plasma volume is reduced due to sweat losses, reduce CO/perfusion of viscera
• Heat stroke: blood flow to vital organs will be preserved at the expense of skin blood flow and thermoregulation