ch6 - adaptations to aerobic endurance training programs
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what are the functions of the cardiovascular system?
(1) deliver oxygen and other nutrients to working muscles (2) remove metabolites and waste
cardiac output is what?
amount of blood pumped by the heart in liters per minute.
what is stroke volume?
the quantity of blood ejected with each beat
what is cardiac output determined by?
quantity of blood ejected with each beat (stroke volume)
what is cardiac output also determined by?
heart’s rate of pumping (heart rate)
what is the formula for cardiac output?
Q = stroke volume X heart rate, where Q is the cardiac output
what is the formula for stroke volume?
milliliters of blood per beat, where HR = BPM.
what is the maximum of cardiac output?
4x the resting level (resting is 5L/min, maximum is about 20-22L/min)
what is end-diastolic volume?
volume of blood available to be pumped by the left ventricle at the end of the filling phase or distastole
what are the effects of catecholamines on the cardiovascular system?
produce a more forceful ventricular contraction and greater systolic emptying of the heart
what physiological mechanisms are responsible for stroke volume?
end-diastolic volume and actions of catecholamines including epinephrine and norepinephrine
what is the maximal stroke volume sedentary college-aged men?
100-120ml of blood per beat; college women 25% less due to smaller body size + smaller heart
what is the maximal stroke volume of college-aged men?
up 150-160ml per beat and 100-110 for college-aged women
what is venous return?
the amount of blood that returns to heart
what increases venous return?
combination of venoconstriction (via sympathetic nervous system) and skeletal muscle pump (muscle contractions combine with venous valves to “push” more blood to heart during exercise) and respiratory pump (incr. respiratory frequency and tidal volume)
in athletes, the “stretch” of myocardial fibers and subsequent contraction will produce what?
greater systolic ejection and greater cardiac emptying – this is the frank-sterling mechanism, related to concept that the force of contraction is a function of the length of fibers of the muscle wall.
what is the heart rate effect of starting exercise?
just before and at beginning of exercise, heart rate increases in anticipatory manner of sympathetic nervous system
what is oxygen uptake?
amount of oxygen consumed by tissues.
an athlete with greater muscle mass or greater work would have what kind of oxygen uptake?
more total oxygen uptake. increased metabolic efficiency allows for greater oxygen uptake.
maximal oxygen uptake correlates with what?
degree of physical conditioning, and is recognized as the most widely accepted measure of cardiorespiratory fitness
for an average person, resting oxygen uptake is measured at what?
3.5ml of oxygen per kilogram of body weight per minute for an average person, this value is defined as 1 MET
how is oxygen uptake calculated?
with the fick equation
systolic blood pressure?
pressure exerted against arterial walls as blood forcefully ejected during ventricular contraction (systole)
what is a secondary function of systolic blood pressure?
can be used to describe myocardial oxygen consumption (work) of the heart.