CH. 8 - Cardiorespiratory Responses to Acute Exercise Flashcards
cardiovascular response to acute exercise
- > increased BF
- > involves altered heart function, peripheral circulatory adaptations (HR,SV,Q,BP)
normal resting HR (RHR) ranges
Untrained
- > 60-80bpm
Trained
- > 30-40 bpm
*affected by neural tone, temp, altitude
what is the anticipatory cardiovascular response to exercise
- > HR increases above RHR just before start of exercise
- > response is mediated by norepinephrine (for SNS) and epinephrine (adrenal medulla)
- > vasal tone decreases
what happens to HR during exercise
- > HR will increase at a rate that is directly proportional to exercise intensity
HRmax
highest HR achieved in all out effort to volitional fatigue
- > declines slightly with age
- > highly reproducible
- > 220 - age (207 - 0.7xage is more precise)
steady state HR
the point of plateau
- > optimal HR for meeting circulatory demands at given sub-maximal intensity
- > if intensity increases, so does steady state HR
- > adjustments to new intensity take 2-3 minutes
- > SSHR is a basis for simple exercise tests that estimate aerobic fitness
stroke volume (SV) during maximal exercise
- > SV increases above resting values during exercise
- > increase with increased intensity up to 40-60% of VO2max then will typically plateau (possible exceptions for elite athletes)
- > SV during maximal exercise = double normal standing SV
SV in a supine vs upright position
SV during max exercise is only slightly higher than supine SV
- > resting SV is much higher than standing SV
- > supine EDV > standing EDV
- > frank sterling mechanism
frank starling mechanism
to eject a greater volume of blood, the ventricle must respond by contracting more forcefully
Factors that increase SV
- > increased preload (end diastolic ventricular stretch); inc stretch = inc contraction stretch
- > increased contractility (inherent ventricle property caused by inc nor/epi)
- > decrease afterload (aortic resistance (R))
- > increased preload at lower intencities (inc venous return will inc EDV and therefore increase preload)
- > increase HR (means dec. filling time=dec EDV = decrease SV
- > inc contractility at higher intensities
- > decrease afterload via vasodilation
normal Cardiac output (Q) values
Q = HR x SV
- > increase with inc. intensity, plateaus near VO2max
Resting
- > 5L/min
Untrained Qmax
- > 20L/min
Trained Qmax
- > 40L/min
- Qmax is a function of body size and aerobic fitness*
fick principle
states that the O2 consumption of a tissue is dependant on BF to that issue and the amount of O2 extracted from the blood by the tissue
VO2 = Q x (a-v) O2 difference
VO2 = HR x SR x (a-v) O2 difference
what happens to BP during endurance exercise
- > systolic BP will increase proportionally to the intensity of the exercise
- > diastolic BP does not change significantly, slight decrease or increase (at max exercise)
- > mean arterial pressure (MAP) increases
MAP
MAP = Q x total peripheral resistance (TPR)
- > resistance exercise will cause a periodic large increase in MAP
valsalva maneuver
a breathing method that may slow your heart when it’s beating too fast
