Lab 8: Graded Exercise Testing Flashcards
best indicator of overall cardio respiratory function
VO2 max
potential reasons for using a graded exercise test
can be used for a young, healthy individual to measure changes in cardio respiratory function before and after a training program
could also be used for a 60 yo with multiple risk factors as a diagnostic for heart disease
common measurements for all graded exercise procedures
cardiac electrical conduction through 12-lead ECGs, ratings of perceived exertion (RPE), oxygen consumption, and blood pressure
one of the most valuable and convenient indicators of cardiovascular health
blood pressure measurements
what is systolic blood pressure
pressure in the arteries when the heart contracts
what is diastolic blood pressure
pressure in arteries when the heart is filling between beats
what is the pulse pressure
difference between systolic and diastolic blood pressure
healthy blood pressure is defined as:
less than 120/80 mm Hg
how does blood pressure change with age?
rises steadily with age due to arterial stiffness and plaque buildup
what is the mean arterial pressure
average pressure in the arteries during a cardiac cycle
why is MAP important?
it determines the rate of blood flow through the vasculature
equation for MAP
MAP = dBP + 1/3PP
why is MAP calculated using 1/3 of the pulse pressure? how does this affect MAP measurements during exercise?
because the heart is in diastole for two thirds of the cardiac cycle at rest; MAP measurement loses accuracy during exercise because the heart is in systole for a relatively greater amount of time compared to rest
how is MAP determined during exercise?
by using cardiac output (Q) and total peripheral resistance (TPR)
(MAP = Q x TPR)
what is total peripheral resistance (TPR)?
sum of resistance to blood flow in the vasculature
why does blood pressure increase during exercise?
because of large increase in cardiac output
factors that contribute to increased cardiac output during exercise?
elevated heart rate and increased ventricular contractility (due to sympathetic activity) and increased venous return
what is MAP also referred to?
afterload: the barrier to the ejection of blood from the ventricles
stroke volume must increase more than ___ to pump blood to the body
blood pressure
what helps attenuate increases in afterload during exercise?
vasodilation of arterioles supplying blood to active muscles
how do systolic and diastolic blood pressure change during exercise?
systolic blood pressure increases due to increased cardiac output and diastolic blood pressure does not change (or may decrease slightly) due to vasodilation
how does aerobic exercise training affect blood pressure?
decrease resting and submaximal exercise blood pressure
how does aerobic training affect heart rate?
decreased resting and submaximal heart rate
how does aerobic training affect TPR?
vascular tone (TPR) is diminished through a variety of factors
do diastolic, systolic, and MAP change during max exercise?
systolic and MAP typically do not change at max, but diastolic can
how does aerobic training indirectly affect blood pressure via weight loss?
weight loss has favorable influences on blood pressure
besides directly evaluating for cardiorespiratory fitness, why else might a GXT be performed?
extending the medical history and physical, evaluating exertional discomfort, evaluating the presence of hidden coronary artery disease, stratifying risk in patients with known cardiovascular disease, and prescribing exercise
prior to a GXT, how are subjects classified?
into three different risk categories based on age, known disease, and risk factors
low risk individuals:
do not need physician supervision during a GXT
moderate risk individuals:
are recommended to undergo a medical exam prior to maximal exercise testing
high risk individuals:
are recommended to undergo a medical exam before max exercise testing and must be supervised by a physician
when is a GXT stopped?
a predetermined point (based on percent of HR max), volitional exhaustion, or chest pain/breathlessness
how does heart rate change during a GXT? stroke volume?
heart rate increases linearly until max, stroke volume increase linearly until a certain intensity where it plateaus
when does SV plateau in untrained individuals? trained individuals?
untrained: 50% VO2 max
trained: much greater intensities, maybe not at all
how does cardiac output change over a GXT?
increases greatly at first, then less as stroke volume plateaus
what affect does altered action potential duration, conduction velocity, and contractile velocity (all due to increased HR) have on a normal ECG?
reduced RR intervals, minor QRS and P wave changes
cardiovascular dysfunctions not apparent at rest that can present during exercise
arrhythmias, conduction disturbances, and myocardial ischemia (reduced blood flow)
most common sign of myocardial ischemia during a GXT
ST segment depression
describe the procedure generally
two groups: one performs the GXT and the other does BP measurements, then switch
BP measurements: take 2 seated BP and 2 standing BP measurements
GXT: measure BP in the exercise posture, determine speed on treadmill that elicits HR of 70% max (speed constant for duration of test), increase treadmill grade 2% every 2 minutes (do not exceed 10% —> if subject completes 2 mins at 10%, increase speed by 1 mph every 2 mins) record HR every minute, record BP and RPE during the second min of each stage, stop when subject reaches exhaustion or termination criteria is met, record HR and BP immediately post exercise and then every minute until stabilized near baseline level
