Transcript Assessment of Cardiorespiratory Fitness Heart Rates and Blood

Assessment of Cardiorespiratory
Fitness
Heart Rates and Blood Pressures
KNR 240
Fall 2004
Cardio-respiratory Endurance
“The ability of the body to perform
prolonged, large muscle, dynamic exercise
at moderate-to-high levels of intensity”
This is the most important health related
component of physical fitness.
A healthy heart is essential to high levels
of fitness and wellness, as well as to a
long and healthy life.
CRE training results in a general
improvement in the ability to perform
aerobic exercise.
Aerobic and Anaerobic
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“Aerobic” means “with air”, “using oxygen”. The term aerobic
relates to the energy processes that occur in the presence of
adequate oxygen.
“Aerobic Fitness” is the ability of the heart and lungs to
provide the oxygen needs of the body (muscular system)
over a sustained period of time.
Aerobic Fitness may be limited by:
The ability of the lungs to intake O2 and transport to the blood
The ability of the heart to pump oxygenated blood to the tissues, the ability of the
blood vessels to carry the blood, or the ability of the blood to completely
saturate with oxygen.
The ability of the muscles to extract oxygen and to utilize it.
“Anaerobic” refers to an inadequate supply of oxygen to meet the
demands of physical work; the body starts accumulating lactic
acid, which is unable to reduce without adequate oxygen. In other
words, because there is not enough O2 present, pyruvate is not
allowed to enter into Krebs cycle in the cell’s mitochondria. Due to
the lack of ample O2, pyruvate converts to Lactic acid, and
accumulates in the cell.
“Anaerobic threshold” refers to the point when oxygen availability
is not sufficient to meet the demands of the workload. The AT is
the point at which blood lactate concentrations start to rise above
resting values.
Oxygen Consumption
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The most accepted index of work capacity is maximal oxygen
consumption (VO2max). (“V”= volume of oxygen used per minute,
“O2”=oxygen, and “max”=maximal exercise conditions).
VO2max represents the maximal rate of delivery of oxygen from the inspired
air to the working tissues (skeletal muscle). In other words, VO2max is the
greatest rate at which oxygen can be consumed during exercise or the
maximal rate at which oxygen can be taken up, distributed, and used by the
body during physical activity.
Remember, “Uptake, Distribution, and Utilization.”
Physiologically, VO2max is the product of maximal cardiac output and
maximal (a-v O2) difference. This is the amount of O2 extracted from the
blood.
Exercise training can significantly improve the oxygen transport system and
increase VO2 max by increasing both the maximal cardiac output and the
maximal (a-v O2) difference.
These improvements are one or a combination of improvements in the systems of
respiration, cardiac function, central circulation, peripheral circulation, and skeletal
muscle metabolism.
The extent of improvement is determined, in part, by the net training work
rate performed, and thus, depends on the frequency, intensity, and duration
of each exercise session. The initial level of fitness also dictates the amount
of fitness improvements (The lower the level of initial fitness, the greater
possible gains.)
MEASUREMENT OF VO2MAX
The measurement of max VO2 is a
measurement of aerobic or cardiorespiratory fitness.
Direct measurement of oxygen
uptake during max exercise is
considered the best measure of
heart and lung endurance.
However, direct laboratory measurement
is expensive and time consuming,
requires highly trained personnel, and
therefore is not practical for most testing
situations.
MEASUREMENT OF VO2MAX
Therefore, various formulas and tests
have been developed as substitutes.
They include:
– Non-exercise test VO2max prediction
equations
– Field tests of cardio-respiratory
endurance
– Sub-maximal laboratory tests
– Maximal laboratory tests.
Blood Pressure
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BP is the force of blood against the walls of the arteries and
veins created by the heart as it pumps blood to every part of
the body.
Go to:
http://www.mayoclinic.com/invoke.cfm?objectid=AF528CAA72A4-4A5A-B65D37511AE58FE2 for new BP classifications.
When taking a BP, one needs a sphygmomanometer and a
stethoscope.
A sphygmomanometer is an inflatable compression bag enclosed
in an unyielding covering called the cuff, plus an inflating bulb, a
manometer from which the pressure is read, and a controlled
exhaust valve to deflate the system.
The stethoscope is made of rubber tubing attached to a device
that amplifies the sound of blood passing through the vessels.
4. Refer to p. 81-83 for step-by-step instructions on
blood pressure taking.
Heart Rate
Heart rate refers to the number of times the heart contracts in
1 min.
True resting heart rate should be taken upon awakening, and
averaged from measurements taken on at least 3 separate
mornings.
Sites of palpation: best determined during rest at the radial
artery. During exercise, it is easier to feel the carotid artery,
but remember to use caution!!
Resting heart rate can be affected by medications, level of
conditioning, stress, season of the year, gender, and smoking.
– See Appendix A, Table 21 for norms
Max heart rate is the maximum number of times per minute
the heart could beat.
– Estimated max beats equation is 220-age.
– Max heart rate can be affected by medications.
Polar Heart rate monitors are great for measuring exercise
heart rate.
Assessment of VO2 max
Houston Non-exercise Test Prediction
of VO2
– Developed by the University of Houston
to estimate or predict VO2 based on
age, physical activity status, and BMI or
%BF.
It is felt that the %BF equation is slightly
more accurate.
– Refer to handout and pp. 85-86 for
instructions.
Assessment of VO2 max
Field Tests of CRE
– 1-mile run
– 1.5 mile run
– 1-mile walk
These are practical, inexpensive, less time
consuming than laboratory tests, are easy to
administer for large groups, and quite accurate
when properly administered.
Refer to pp. 86-89 text, or ACSM pp. 71 and 307
for procedures and equations to determine VO2.
VO2 max norms are found on p. 697, Table 24.
Assessment of VO2 max
Sub-maximal Laboratory Tests
– Less risky, less expensive, and requires less
motivation than maximal stress tests.
– Makes 3 assumptions:
A linear relationship exists between heart rate, oxygen
uptake, and workload.
That the maximum heart rate at a given age is
uniform.
That the mechanical efficiency (oxygen uptake at a
given workload) is the same for everyone.
– The reasoning underlying sub-maximal lab tests
is that the person with the higher VO2 is able to
accomplish a given amount of exercise with less
effort (or more exercise at a particular heart
rate).
Assessment of VO2 max
Sub-maximal Laboratory Tests
– Oxygen uptake at any given workload can vary
by 15% among different people. In other
words, people vary in the amount of oxygen
they require to perform a certain exercise work
load.
– Some people are more efficient than others,
and thus the average O2 consumption
associated with a given workload may differ
significantly from one person to another.
Sub-max stress tests tend to overestimate VO2 for
those who are highly trained, and underestimate VO2
for the untrained (those with a high heart rate for a
given workload).
Assessment of VO2 max
Sub-maximal Laboratory Tests
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Step tests
1) Modified Canadian Aerobic Fitness Test
2) YMCA 3-minute step test
3) Queens College Step Test
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Treadmill tests
1)Typical cut-off point is 85% predicted max HR
2) See p. 94 text
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Bike tests
YMCA (p. 96 text, p. 75 ACSM)
Astrand (p. 72 ACSM)
Assessment of VO2 max
Maximal Laboratory Testing
– Treadmill
Bruce-most popular, followed by the Balke. See Table
4.8, p. 100 for equations to estimate VO2 from these
tests.
Naughton-used for cardiac patients.
Arizona State Univ. test for college students-see p.
101.
See p. 98 ACSM for VO2’s associated with different
stages of various protocols, also see Box 4.4 p. 101
text for ACSM walking and jogging VO2 formulas.
– Cycle
Astrand
Storer-Davis
Wingate Anaerobic
– Refer to p. 102
Termination of Maximal GXT-EKG test
Know Table 4.10, p. 104, or Box 5-3, p. 104 ACSM
Criteria utilized in the laboratory which determines
whether an individual’s true VO2 max has been
achieved includes the following
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Oxygen consumption plateaus during the last minutes of
a graded exercise test (defined as a rise of less than 2
ml/kg/min between the final test stages
The respiratory exchange ratio (RER) (ratio of the volume
of carbon dioxide produced to the volume of oxygen
consumed) increases to 1.15 or higher
The subject’s heart rate increases to within 10 beats of the
age-predicted maximum (MHR-220)
Blood lactate levels rise above 8 mmol/liter