EXPH 2115: Lecture 9

ways to express exercise intensity

RPE or power output, %VO2 max, %HRR and %HRmax

%HRR

HRex - HRrest / HRrange, favored and matches %VO2max

%HRmax

HR/HRmax, not favored, does not take into consideration resting HR

what is better %HRR or %HRmax

%HRR because it accounts for differences in resting heart rates and measures of the space/range what % are you doing whereas %HRmax is never close to a low number and compresses a range

true/false: people doing a lot of resistance training often have low resting HRs

true

what changes would you expect to see to HR after endurance training?

after training you would expect to see lower HR at any exercise workload

does max HR change after endurance training?

no, because the only factor being taken into consideration for HR max is age which will be unaffected by endurance training

stroke volume

is the amount of blood ejected by the heart with each beat

true/false: stroke volume can also be represented as EDV-ESV

true, because stroke volume is the amount of blood ejected with each beat

stroke volume _________ with endurance training

increases

what factors impact stroke volume?

EDV, contractility, MAP

EDV is the period of time at the end of ________ when the ___________ has the most ______ in it and is completely full, before the next beat is completed

diastole, ventricle, blood

why is it that if you put more blood into the heart, more comes out?

only 2/3 of blood comes out with each beat from a typical healthy person meaning 1/3 stays behind, this is the ESV

what mechanisms are responsible for venous return?

muscle pump and respiratory pumps to facilitate venous return

contractility is the

forcefulness of the contraction

true/false: contractility is independent of how much blood is loaded

true

how is contractility regulated?

by catecholamines coming to the heart and Ca2+

When _____________ come to the heart, they cause the heart cells to put more _____ out with each beat, this is how ________ is regulated

catecholamines, Ca2+, contractility

contractility ________ during exercise

increases

why does SV eventually reach max and begin to plateau?

as HR increases and contractility increase, there is a limit on how much time the heart has to fill which prevents SV from going much higher

describe the length-tension relationship of the heart

when heart is done beating the sarcomeres tend to be short, so when the short sarcomeres are lengthened to a more intermediate length, the force production is greater

when the heart is filling and filling the __________ cells are being _________ at ____ and the heart can now beat ___________, this is the _______ _________ mechanism

muscle cells, stretched, EDV, harder/more forcefully, frank starling mechanism

describe the frank starling mechanism

the more blood being loaded in, the more forceful the beat, which means more cardiac output

true/false: during exercise, both the frank-starling mechanism and contractility will increase, which promotes the increase in SV

true

true/false: MAP decreases during exercise

false, it increases slightly

true/false: the increase in MAP counteracts the increases in EDV and contractility

true

why does the increase in MAP counteract the increase in EDV and contractility

the higher the pressure in the arterial system, the more the ventricle must work against to eject blood

what is cardiac output at rest roughly?

5 L/min

how can you find the resting SV

take the volume of Q or CO at rest / resting HR

what is cardiac output during exercise roughly?

25 L/min

how can you find exercise SV

take the volume of Q or CO during exercise / exercise HR

true/false: Q increases because of the increase in HR

false, the increase in Q is because of SV

how does Q change with endurance training?

Q increase due to the increase in SV

when the heart does not have enough time to properly fill in cases of elite athletes, what is the mechanism for the blood?

limits the amount of time there is for the heart to fill, which in these cases the heart bounces out and vacuums the blood back into it allowing EDV to be so high

fick principle

determines oxygen consumption based on the relationship between blood flow, oxygen content, and oxygen extraction in the body.

O2 consumption of muscles is the result of __________ put out through the system and _______________

blood flow, O2 extraction

O2 extraction is the amount of ____ that gets ______________ from the blood

O2, extracted

true/false: if you increase flow or cardiac output, there is a increase in the likelyhood of having a high VO2 max

true because O2 delivery and utilization is improved

overall body O2 consumption (VO2) =

Q x (a-v) O2 difference

endurance training results in a ___________ stroke volume which _________ cardiac output, and a _________ skeletal muscle capillary and ____________ density which allows for _________ O2 _____________

greater, increases, higher, mitochondrial, greater O2 extraction

how does muscle capillary and mitochondrial density increase O2 extraction

capillaries start growing and the amount of mitochondria inside muscle starts increasing so the ability to extract O2 increases

does the O2 content in arterials or veins make up the difference during exercise?

O2 venous content

true/false: O2 arterial content stays the same with exercise

true

why does the O2 arterial content stay the same during exercise

because each time blood comes back, it gets sent to the lungs to get fully oxygenated so it gets sent out full opposed to the venous side

why does the amount of O2 change with exercise in veins compared to arteries?

at rest, it is at 75% full, at max exercise, about 25% full, it never comes back 100% full as when it was sent out

how would anemia affect O2 content in arteries?

anemia would mean there is low O2 carrying capacity in arteries, so when fully loaded, there is simply not as much O2, and therefore the red line of O2 content in arterials would shift down

how would blood doping impact O2 content?

O2 content is arterials would increase because blood doping increases O2 carrying capacity

true/false: the guts/brain vary in amount of O2 being used

false, the guts/brain is always using the normal amount of O2

what are the 2 levels of the CV control center?

sympathetic and parasympathetic

the CV control center receives information from ____________ and feedback from ___________ and ____________

baroreceptors, chemoreceptors and mechanoreceptors

during exercise: the signal starts in the _________________ and gets sent to the _____________________ to start increasing __________ activity which therefore increase ___________, ______, ______, and ___________

motor cortex, CV control center, sympathetic, vasoconstriction, HR, SV, contractility

vasodilation comes from _______ _______________ near arteries coming out of the cell which ___________ brain signal and decrease ___________ and increases _________

local metabolites, overrides, resistance, flow

chemoreceptors gather info from ___________ which provides feedback to the _______________

metabolites, CV control center

chemoreceptors and mechanoreceptors are located in ______________

skeletal muscle

true/false: mechanoreceptors provide feedback to CV control center make sure muscles are active

true

central command is where the

signal to CV control center originates

is there a way we can have mechanoreceptor feedback and no central command?

yes, just means no voluntary activity by the person, but the mechanoreceptors are still active

explain the difference between the frank-starling mechanism and contractility

the frank starling mechanism is based on a length tension relationship, the heart is beating more forcefully because as more and more blood is being loaded resulting in higher EDV, the walls of the heart are being stretched, this mechanism is impacted based on how much blood is loaded, whereas contractility is independent of how much much blood is loaded and instead the heart is beating harder because there is more Ca2+ present and more cross-bridge cycling happening

why under the effects of a paralytic drug/substance will HR still increase when attempting exercise?

no signals are coming back to the heart from muscles, but the central command still exists because the motor cortex still sends out signals to CV control center, there is just no effect in the muscle, this is a feed-forward mechanism

when you sustain a contraction for a long time, why does your blood pressure go up (both SBP and DBP)?

as you sustain a contraction metabolites are building up so your metabolite feedback to the CV control center is getting stronger which will increase sympathetic activity, this is known as the pressor response, which increases blood pressure

what are the leading causes of death in mortality rates?

CV diseases, stroke are the leading cause and cancer is 2nd

what type of cancer is the leading cause of death amongst all cancers for both men and women?

lung cancer

true/false: coronary artery disease accounts for half of cardiovascular deaths

true

the fatty plaque formation in arteries is referred to as ___________________

atherosclerosis

true/false: the fatty plaque material hardens in the artery where blood is flowing

false, the fatty plaque hardens within the wall of the artery under the surface and will eventually burst, causing the body to create a blood clot

myocardial ischemia is when there is inadequate ____________ and ____________ which leads to __________ ________________

blood flow and oxygen, angina pectoris

angina pectoris can also be referred to as _______ ________

chest pains

atherosclerosis, myocardial ischemia, angina pectoris all lead to ___________ __________

myocardial infarction aka heart attack

true/false: myocardial infarctions occur when compromised blood flow cause damage, but that damage is reversible

false, the damage to the tissues is permanent and the tissue will not regenerate

how does atherosclerosis turn into clots/blockages in arteries?

eventually the fatty plaque will rupture and the body’s response to the rupture/injury to the blood vessel is to form a clot and could potentially stop blood flow downstream in an instant leading to a heart attack

how do you judge how hard the heart is working?

RPP (rate pressure product)

why do we use RPP to approximate how hard the heart is working?

RPP is HR x SBP, HR is how many reps the heart is doing, the higher the HR the harder the heart is working, SBP is generated by the heart, the heart has to get its pressure above the diastolic to send blood to the aorta and once blood is flowing the SBP is generated. therefore, the higher the SBP, the more pressure the heart has to generate to overcome diastolic pressure, indicating increased workload on the heart.

what is the percentage of O2 that gets extracted from the heart at rest?

about 75%

what is the percentage of O2 that gets extracted by the body?

about 25%

what is the best way to raise the VO2 of the heart?

deliver adequate blood flow

why is adequate blood flow so important for myocardial VO2?

O2 extraction is high at rest, this means the heart relies on an increase in flow to satisfy its needs during exercise

true/false: atherosclerosis begins late in life

false, atherosclerosis can appear in infancy and childhood

fibrous plaques begin to develop in 20s, these fibrous plaques are…

a hardened shell on the surface of the fatty streaks, which are a form of protection

what determines the rate at which CAD progresses?

a combination of genetics and lifestyle

what are the non-modifiable risk factors of CAD?

age, sex, family history (genetics)

true/false: women have more protection from CAD than men

true, due to hormonal differences.

what are the modifiable risk factors for CAD?

hypertension, smoking, obesity, sedentary lifestyle, hyperglycemia, dyslipidemia (high LDL)

true/false: “bad” diet and stress are considered traditional risk factors for CAD

false, these are not independent risk factors, they may play some role in those who have the other risk factors for CAD

how can CAD be prevented?

lifestyle changes, specifically living a non sedentary lifestyle, even taking a walk can decrease risk for CAD

how is exercise used for the diagnosis of CAD? what would you see on an ecg?

through stress testing to determine if someone has myocardial ischemia, this would be shown by the ST changes in the ecg either being elevated or depressed during exercise

how can exercise be used in the treatment of CAD?

there are surgical interventions that can be done, cardiac rehab/exercise, and staying active daily

what are some treatment options and surgical interventions for CAD?

angioplasty: uses balloon, less common

stent: more commonly used, uses a mesh tube

coronary artery bypass: takes section of vein from leg and stitches above or below diversion and allows blood to bypass the clot

a heart attack stemming from the _______________________ artery is known as the widower maker heart attack because ____________________

left anterior descending artery because is feeds the bulk of the left side of the heart, leading to a smaller chance of survival