Cardiovascular and Respiratory Physiology in Exercise Flashcards
what are the effects of increased thermogenesis
sweating -> loss of water and electrolytes
skin vasodilation
what are the intramuscular effects of increased metabolism
increased substrate consumption and generation of by products
increased thermogenesis
increased O2 consumption and CO2 production
what is the phosphagen system
what type of exercise uses it
ATP generation from creatine phosphate
few seconds of anaerobic high intensity
depletion of glycogen in exercise
glycogen acts as glucose source for 20-30 mins of exercise
once depleted, fatty acids become the substrate of aerobic metabolism
what type of exercise is most suitable for fat burning
aerobic for a longer period of time
CO increase in exercise
resting ~ 5 L/min
increase up to ~ 20 L/min for sedentary
~ 40 L/min for trained
SV increase in exercise
in general plateaus at 40-60% CO max
resting ~ 65 mL/beat
untrained ~ 120 mL/beat
trained ~ 180 mL/beat
EDV and ESV responses to exercise
why
EDV increases and ESV decreases
sympathetic stimulation increases contractility and decreased ESV
muscle pump, respiratory pump and redistribution of blood
increase venous return and EDV
SV in supine exercise
increased venous return and EDV
increased SV
SV in supine vs upright
SV max is the same in supine and upright exercise
action of the muscle pump in high intensity overcomes the increased EDV from supine
HR increase in response to exercise
linearly with intensity
calculating HR max
208 - (0.7 x age)
will heart rate stay the same when you exercise at fixed intensity for a long period
cardiovascular drift: HR gradually increases with time despite fixed intensity
explanation of cardiovascular drift
increased heat generation causes sweating and reduced body fluid volume as well as skin vasodilation
leads to reduced EDV and SV
HR increases to maintain CO
what happens to blood vessels supplying muscle during exercise
reduced muscle O2 concentration
endothelium releases NO and prostacyclin
vasodilation
blood flow redistribution during exercise
away from other organs to muscle
heart remains the same
how does the body increase ventilation during exercise
by how much
peripheral and central chemoreceptors sense changes in blood gases and chemistry
pain and emotional stimuli through hypothalamus
receptors inn muscles and joints
all cause medullary respiratory centre to increase ventilation
can increase up to 25 times
what causes the O2 deficit at the start of exercise
due to mismatch in supply and demand
what is excess post exercise O2 consumption
phosphocreatine restoration
lactate removal
support ventilatory muscles
VO2 max
the maximum rate at which an individual can take in and use oxygen during maximal exercise
factors affecting VO2 max
genetics
age (typically declines with age)
training status
altitude (lower at higher altitudes)
VO2 equation
factors that affect it
VO2 = CO x (a-v) O2 difference
cardiac output: delivery by CVS
HR, SV, contractility, volume, composition
atrial-venous oxygen: O2 utilisation
muscle vascularisation, mitochondria density, oxphos, muscle type and enzymes
adaptions to chronic exercise training
endurance and strength
improves exercise performance and capacity to resist fatigue and efficiency of energy utilisation
endurance improves maximal oxygen consumption
strength improves muscles size and strength
CVS adaptions to chronic endurance exercise:
blood volume
ventricles
afterload
EDV
LV compliance
EF
resting HR
blood volume - increased
ventricles - remodelling
afterload - decreased
EDV - increased
LV compliance - increased
EF - increased
resting HR - decreased
why does blood volume increase post training
one of the earliest training adaptions
due to increase in both plasma and RBCs
greater increase in plasma than RBCs to prevent larger hematocrit and viscosity
what does increased erythropoietin lead to increased blood volume
increases RBCs leading to increased O2 carrying capacity
what does increased albumin synthesis lead to increased blood volume
increases oncotic pressure leading to increased plasma volume
why does left ventricle size increase post training
increased diameter and wall thickness
not pathological
how does stroke volume increase with training
increased EDV by LV compliance, size and blood volume
decreased ESV by decreased peripheral resistance, increased LV muscle mass and contractility
why does resting HR decrease post training
increased resting SV leads to increased parasympathetic activity
respiratory adaptions to training
increased respiratory muscle strength
increased efficiency and lung diffusion capacity
increased V/Q matching and reduced dead space
how does the respiratory rate change with training
decreases due to more efficient O2 use
is training of the respiratory system critical to endurance performance
overbuilt to withstand peak exercise
may not be as important as training other systems
usually does not limit endurance performance
CVS and muscle are more likely to limit
