Basic Anatomy - Heart
Normal Cardiorespiratory
p
to Exercise
Responses
KINE 5335
Coronary Arteries
Muscle
‹ Myocardium
„ Protective Covering
‹ Pericardium
 Epicardium
 Endocardium
‹ Circulatory System
„
In one cardiac
cycle…
from Brubaker, 2002
ACSM Resource Manual, 2001
1
Review - The Fick Equation
Basic Principles in Exercise Physiology
1.
Fick Principle
‹
‹
(Total body oxygen consumption)
Q =
Total Body demand
VO2 = C
Cardiac
d c Output
Ou pu (Q) X a-v O2 difference
d e e ce
VO2
a-vO2 difference
OR
2.
Myocardial oxygen consumption
‹
“Heart” demand
‹
(mVO2) = heart rate (HR) X systolic BP
VO2
(L O2•min -1)
= Q (L blood • min -1) X a-vO2 diff (mL O2 • L -1 blood)
VO2
(L O2•min -1)
= (HR x SV)
X a-vO2 diff (mL O2 • L -1 blood)
VO2
(L O2•min -1)
= (HR x SV)
X
(
?
X
?
)
Rest and Exercise Q (typical)
„
Rest
„ Q = SV x HR
„ = 0.07 L•beat -1 X 60 bts•min -1
„
„
= 4.2 L•min -1
Exercise
„ Q = SV x HR
„ = 0.16 L•beat -1 X 190 bts•min -1
„
= 30.4 L•min -1
Froelicher and Myers, 2000
2
Heart Rate (control of)
Autonomic nervous system (ANS)
‹ Sympathetic (SNS) (“cardioaccelerator
nerves”)
 Adrenergic (general),
(general) norepinephrine,
norepinephrine
epinephrine
‹ Parasympathetic(PNS)
 Acetycholine (muscarinic)
„ Exercise?
„
Opie, 1998
HR response to dynamic exercise
ANS
influence
Predominant
PNS
withdrawal
60
80
100
SNS
increases
influence
120
140 160 180 200
HR
(bts/min)
3
SV response to dynamic exercise
Stroke Volume (SV)
EDV
Stroke volume = end
end--diastolic volume
(EDV) - end
end--systolic volume (ESV)
„ Ejection fraction (EF)
(EF)-- percentage of EDV
blood ejected with each beat
„ = EDV - ESV
X 100
EDV
„ = stroke volume
X 100
EDV
„
-
ESV
= SV
Rest
(ejection fraction = 50%)
70 ml
120 ml
50 ml
Peak Exercise
(ejection fraction = 75%)
90 ml
120 ml
30 ml
Fox, ‘98
LVEDV (ml)
70
60
50
40
30
20
10
SV (ml)
LVEDV = left ventricular
end-diastolic volume
LVESV = left ventricular
end-diastolic volume
SV = stroke volume
200
180
160
140
120
100
80
LV
VESV (ml)
Fox, ‘98
Factors Affecting EDV
Athletes
1. Heart rate (chronotropic)
Sedentary
Athletes
3. Filling Pressure (inotropic effect)
„
Sedentary
160
140
120
100
80
60
40
2. Ventricular Compliance - stretch placed on the heart
just before contraction (Starlings Law)
Athletes
Sedentary
Rest
110
130
Heart rate (bts/min)
150
„
Frank-Starling mechanism (length
Frank(length--tension
relationship) – venous pressure is a result of
venous return (amount of blood returning to the
heart)
Venous return (preload) is affected by
„ Skeletal muscle pump
„ Respiratory and abdominal pumps
„ Venoconstriction (body position)
4
Factors affecting ESV
SV and Cardiovascular Disease
During exercise the FrankFrank-Starling curve will shift upward and to
the left due to an increase in circulating NE causing contractility to
i
increase
SV andd Cardiovascular
C di
l Disease
Di
„
2.
Ventricular Perfoormance
1. Inotropic effect - refers to the contractility of the
heart (force of contraction of LV)
LV)
Afterload – measure of the force resisting the
ejection of blood by the heart
„
Example: hypertension
Increased Contractility
Normal
Heart Disease
End-diastolic Volume
from Brubaker, 2002, pg 43
Factors affecting ESV
Plasma
epinephrine
Activity of parasympathetic
Nerves to myocardium
stroke volume
heart rate
Cardiac output
Cardiac output
=
stroke volume
x
heart rate
From Vander et al. Human Physiology. 7th ed, 1998
30
30
T
25
25
20
20
150
UT
100
100
0
0
15
10
10
5
5
Rest
Max/Pk
Exercise Intensity
200
200
UT
15
200
T
150
Rest
Max/Pk
Exercise Intensity
Heart Rate
(bt•min-1)
Sympathetic activity of
Nerves to myocardium
Cardiac Outp
put (l•min-1)
REST (start)
End-diastolic
Ventricular volume
Stroke Volume
(ml•bt-1)
200
Cardiovascular Responses to Exercise
150
UT
T
150
100
100
0
0
Rest
Max/Pk
Exercise Intensity
(Fox, ‘98)
5
Peripheral Factors
„
„
„
Arterial-venous oxygen difference (a
Arterial(a-vO2 diff
diff))
‹ Diff. in oxygen content between arteries (18 to 20 ml
O2/ 100 ml blood, rest) and veins (13 to 15 mlO2/100 ml
blood) rest = 4 -5 mlO2/100 ml blood
‹ Exercise a
a--vO2 diff = 16 to 18 ml O2/ 100 ml blood
Arterial O2 content
‹ Related to partial pressure of O2
 Alveolar ventilation
 Hemoglobin
Venous O2 content
‹ Ability of muscle to extract O2 from blood (capillary
density)
‹ Determined by regional blood flow
Froelicher and Myers, 2000
Pulmonary System - Ventilation
VE
Minute Ventilation
(L•min-1)
„
=
VT
=
tidal volume
(L)
x
x
Ventilatory Responses to Exercise
f
respiratory
frequency
(breaths / min)
Air moving into and out of the lungs is measured
in liters per minute (volume x frequency), called
minute
i
ventilation, VE
‹
Rest: VE = 8 to 12 L/min
Peak exercise: VE ~ 150 L/min (highly fit)
Determined by:
‹ Gas exchange in the lungs
‹ Ventilatory requirements for exercise
‹
„
ACSM Resource Manual, 2001
6
Minute Ventilation
=
VT
=
tidal volume
(L•min-1)
VE (L•min-1, STP
PD)
„ Increase in maximal minute
ventilation (VE )
‹Increase TV and f
„ Increase in ventilatory efficiency
through a decrease in ventilatory
equivalent for oxygen
„ Increased diffusion capacity during
exercise
VE
Minute Ventilation
180
160
140
120
100
80
60
40
20
5
180
160
140
120
100
80
60
40
20
5
untrained
trained
REST
f
respiratory
frequency
(breaths / min)
untrained
trained
REST
MAX
VO2 (L•min-1, STPD)
How do O2 and CO2 move in and out of the
tissues between the air and the blood
(extraction)?
x
x
(L)
VE (L•min-1, ST
TPD)
Respiratory responses to
exercise (training)
MAX
VCO2 (L•min-1, STPD)
Blood flow distribution during exercise
Diffusion of a gas across tissues is dependent upon the area and thickness of the
tissue, diffusability of the gas, and the difference in P between 2 tissues.
Cardiac Output = 25 l/min
Heavy
Exercise
100%
3-5%
2-4%
3-4%
80-85%
Rest
100%
20-25%
20%
15%
15-20%
Cardiac Output = 5 l/min
From Powers and Howley, Exercise Physiology.p 186
7
Hemodynamics
Change in BP and TPR during exercise
200
Blood pressurre (mmHg)
150
15
100
2. Total peripheral
resistance
TPR = MAP/ Q
Diastolic
BP
50
0
MAP - mean arterial pressure
TPR - total peripheral resistance
Rest
Pk Ex
10
5
0
Rest
Pk Ex
Fox. Physiological Basis for Exercise and Sport, 98
Bottom Line:
Components of oxygen transport
system at rest and during exercise in untrained and in trained
= Stroke volume X Heart rate X a-vO2 diff
VO2
(mL•min-1)
20
Systolic
BP
TPResistance (mmH
Hg•L •min-1)
1. Blood pressure MAP = Q x TPR
Or
MAP = .3(DBP – SBP)
+ DBP
(L•bt-1)
UT
Rest
300 = 0.075
M E 3100 = 0.112
MaxEx
0 112
Endurance
Athletes
MaxEx 5570 = 0.189
(bt•min-1)
X
X
82
200
(mlO2•L-1)
X
X
Focus on the cardiovascular system
„
48.8
138.0
138
0
Myocardial oxygen consumption (mVO2)
„ Also called RateRate-Pressure Product (RPP)–
(RPP)–
„ Estimated by the following calculation:
RPP = HR (bts
(bts••min-1) X SBP (mmHg)
„
X
190
X
155.0
100
Important when exercise testing those with history of
CVD (specifically angina, hypertension)
Fox. Physiological Basis for Exercise and Sport, 98
8
Exercise Responses: RPP
„
„
„
Those who are of a high fitness level will
have lower RPP for any given submaximal
VO2 compared to sedentary
Those with cardiovascular disease could
have higher, lower, or the same RPP for any
given submax workload compared to
healthy counterparts
Goal in clinical populations is to push the
RPP up as high as possible (safe levels)
without inducing signs or symptoms of
CVD
RPP: Hemodynamic Responses to Exercise
Variable
Q
HR
SV
TPR
SBP
DBP
MAP
LV Work
Dynamic
Static
++++
+
++
+
++
0
+++
+++
++++
0++++
0++++
Volume Load Pressure Load
ACSM, Resource Manual. P 143, 1998
RPP: Arm Vs. Leg Exercise
HR x SB
BP/100
260
220
arm
180
140
leg
100
0
0
50
150 300 450
Workload (kgm/min)
600
9