Cardiovascular-Responses-to-Acute-Exercise-1.pptx

r Responses to Acute Exercise

Cardiovascular response: response : heart rate anticipatory response; activity response; increased blood pressure; vasoconstriction; vasodilation

The Goal of the CV system is  To  T o meet the incr increased eased demands demands needed to perform perform exercise  To  T o meet such demands demands the following following come into play: play: Heart rate (HR)- beats per minutes tro!e volume (") # $mount of blood pumped from the ventricles in one beat %ardiac output (&) - The - The amount of blood blood that is pumped by the heart per unit time' measured in litres per minute (lmin) *lood pressure (*+) - is the pressure exerted by circulating blood upon the walls of blood vessels *lood ,ow

Restin# Heart Rate (RHR"  Typically RHR  ./-0/ bpm (beats per minute) +re-exercise HR usually increases above normal resting values  This is an anticipatory rise and is not a reliable estimate of RHR - RHR must be ta!en sometime before exercise Increases in HR are due to the sympathetic nervous system (!" releasin# adrenaline$ %nce exercise has started the increase in car&on dioxide (C%" and lactic acid in the &ody is detected &y the chemoreceptors' si#nals are then sent &ac to the ! and more adrenaline is released this further increases HR

teady,tate HR HR increases until it reaches a plateau' when rate of wor! is held constant at sub-maximal intensity 1ptimal HR for meeting the circulatory demands at that rate of wor!  The lower the steadystate HR at each exercise intensity' the greater the cardiorespiratory 2tness

.aximum HR (.HR" Hi#hest HR value achieved in an all,out e-ort to the point of exhaustion Remains constant from day to day but decreases with age $pproximated by: HRmax 33/-age or HRmax  3/0- (/4 x age)

troe Volume (V" " is the amount of blood pumped from the ventricles in one beat (speci/cally the left one) " is a ma5or determinant of cardiorespiratory endurance capacity at near-maximal and maximal exercise intensities The /tter you are the #reater your

V #enerally0 Resting " is normally around 4/-6/ml (//4 -//67) 8n general males have a bigger " than females " values are determined by: "olume of venous blood returned to the heart "entricular dispensability

troe Volume (V" stroe volume rises during the initial stages of wor! and then levels o9 until near maximal levels where it slightly declines due to decreased ventricular 2lling time in early exercise the increase is related to increases in &oth HR and V$ 1ater increases are due to HR only assumin# that V

troe Volume Trained Vs 2ntrained • Trained individuals have a larger " then untrained as you can see from the graph

venous return

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8ncreased (preload) (the muscle pump and respiratory pump help with venous return during exercise):

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extent to which ventricle flls with blood and stretches and subsequently contracts more orceully: FrankBlood is returned through the veins to Starling mechanism the heart and enters the atria

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The greater the venous return the more blood that enters the ventricles, the greater the myocardium is stretched. The

further it is stretched the stronger and more forceful the contract will

2. Blood then moves from the atria to the ventricles causing the myocardium (cardiac muscle) in the ventricles to stretch

 3ou can mimic preload &y stretchin# an elastic &and4 the further the stretch the elastic &and the #reater the distance it 5ill travel 5hen

The .uscle thoracic 8ump Helps Venous Return uring exercise the muscle pump functions to return blood to the heart' or increase venous return' the muscles contract and s6uee7e the veins to push &lood &ac up to the heart

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the thoracic or respiratory pump serves the same function' ie' as you breath in and out this

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9hat causes V to increase durin# exercise " values can also increase due to increased ventricular contractility from neural stimulation from the sympathetic nerve (from the Central !ervous ystem C!)  " values can increase also due to decreased total peripheral resistance in the blood vessels due to vasodilation of blood vessels in exercising s!eletal muscle

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Cardiac %utput (;"

; is the amount of &lood pumped from the heart every minute (litres per minute" and is the product of: HR x V $s HR and " increase therefore so does & during exercise' to a maximum Resting & is about