ch6 - adaptations to aerobic endurance training programs Flashcards
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.
diatsolic blood pressure?
used to estimate pressure against the arterial walls when no blood is being forcefully ejected through the vessels (diastole)
what is a secondary function of diastolic blood pressure?
indicator of peripheral esistance and can decrease with aerobic exercise due to vasodilation.
with maximal aerobics, systolic can rise to what?
as much as 220 to 260mmgh, while diastolic remains at resting or sightly decreases
how do arterioles affect blood flow to organs and muscles during aerobics?
blood flow to active muscles is considerably increased by the dilation of local arterioles, while blood flow to other organ systems is reduced by constriction of the arterioles
percent of cardiac output distributed to skeletal muscle at rest and during exercise?
15-20% at rest, and up to 90% during exercise
what is minute ventilation?
volume breathed per minute
how are alveolar gas concentrations provided for during aerobic exercise?
significant increases in oxygen delivered to the tissue, carbon dioxide returned to lungs, and minute ventilation
how is breathing rate affected during strenuous exercise?
increases from 12-15 breaths per minute at rest to 35-45 breaths per minute, while tidal volume (amount of air inhaled with each breath)
tidal volume?
amount of air inhaled with each breath
how is tidal volume affected during strenuous exercise?
increases from resting values to 3L or greater
how is minute ventilation affected during strenuous exercise?
can increase to 15 to 25 times the resting value (or 90-150L of air per minute.)
what is ventilatory equivalent?
ratio of minute ventilation to oxygen uptake
does tidal volume or minute ventilation influence low-moderate intensity exercise more?
tidal volume is more of an influence on increase in ventilation than minute ventilation b/c minute ventilation (at intense exercise) parallels the rise in blood lactate
anatomical dead space?
air occupying areas of nose, mouth, trachea, bronchi, and bronchioles
what is the area of anatomical dead space?
normally 150ml and increases with age. anatomical dead space increases as tidal volume increases.
physiological dead space?
alveoli where poor blood flow, ventilation, or other problems impair gas exchange
what populations is physiological dead space seen in?
usually negligible in healthy people. seen in chronic obstructive lung disease or pneumonia – can increase physiological dead space 10x.
gas transfer during exercise?
large amounts of oxygen go from capillaries into tissues. CO2 goes from blood into alveoli
does minute ventilation increase or decrease during exercise, and why?
minute ventilation increases to maintain appropriate alveolar concentrations of gases.
diffusion?
movement of oxygen and co2 across a cell membrane; a function of gas concentrations and partial pressure by molecular gas motions
what does diffusion result from?
movement of gas from high–>low concentration.
how much oxygen can be carried per liter of plasma?
only about 3ml of oxygen per liter of plasma; this limited amount still contributes to the partial pressure of oxygen in blood and other body fluids, thus regulating breathing and and diffusion of oxygen
how is the majority of blood carried?
by hemoglobin
how much hemoglobin do men and women have per 100ml?
men have about 15-16g of hemoglobin per 100ml, and women have about 14g
how much oxygen does one gram of hemoglobin carry?
about 1.34ml of oygen, so 100ml of blood is about 20ml of oxygen in men and a little less in women
what causes the greatest amount of carbon dioxide removal?
70% is from combination with water and delivery to the lungs as bicarbonate (HCO3)
an athlete wants to train lactic threshold with low-medium exercise. why will this not work?
lactic acid buildup doesn’t happen in low-medium exercise b/c the removal rate is greater than or equal to the production rate
when does lactate undergo gluconeogenesis?
in the cori cycle, when muscle-derived lactate is removed to be transported via the blood to the liver, thereby undergoing gluconeogenesis
why is OBLA a significant metric for athletes?
measures how much erobic metabolism can or can’t keep up with formation of lactic acid
changes in cardiovascular function with aerobics?
increased maximal cardiac output, increased stroke volume, reduced heart rate at rest and during submaximal exercise, increased muscle fiber capillary density (as a result of aerobic endurance training)
most significant increase over long-term (6-12 mo) aerobic training?
improved stroke volume; significantly lower heart rates in response to submaximal levels of work, plus heart rate increases more slowly in trained athletes than in sedentary people
what does increased muscle fiber capillary density do?
increase decreases the diffusion distance for oxygen and metabolic substrates
can an athlete make general ventilatory adaptations?
ventilatory adaptations appear to be highly specific to activities that involve the type of exercise used in training; that is, adaptations observed during lower extremity exercise primarily occur as a result of lower extremity training. if you focus on lower extremity training you will not get ventilatory adapation during upper extremity activities. so,
how does synergy improve neural adaptations?
improved aerobic performance may result in a rotation of neural activity among synergists, i.e. rather than being constantly active, synergistic muscles alternate between active and inactive to maintain low-level force production.
why might an athlete compete at 75% maximal oxygen one time but be able to maintain 80% due to training later?
some adaptations occur as a result of glycogen sparing and increased fat utilization (prolonging performance at the same intensity). may also be due to aerobic endurance fiber type, localied adaptations that reduce lactic acid production, changes in hormones (specif. catecholamine release at high intensity) and more rapid lactic acid removal
type II fibers are anaerobic but are they totally?
no, type II fibers do contribute aerobic effort, and their aerobic capacity can increase with training, but chronic aerobic endurance training reduces concentration of glycolytic enzymes and can reduce overall mass of these fibers
how does myoglobin affect missue tissue oxygen use?
when larger and more numerous mitochondria combine with quantity of oxygen that can be delivered to mitochondria by the greater concentration of myoglobin, the capacity of muscle tissue to extract and use oxygen is enhanced
an athlete works a very intense manual labor job. why might this be a problem for bone growth?
activity to stimulate bone growth must be more intense than daily activities
how do athletes tolerate and sustain prolonged high aerobic intensities?
through greater hormonal response patterns to maximal exercise
what kind of changes occur from very high intensity and very short (5-10 seconds) exercise?
only peripheral changes (e.g. in epinephrine and norepinephrine)
someone undertaking aerobic endurance training can expect what kind of aerobic power increase?
5% to 30%, depending on starting fitness level and genetics
when do most aerobic adaptations occur?
within 6-12mo training period
adaptations to aerobic endurance training?
reduced bodyfat, maximal oxygen uptake, running economy, respiratory capacity, lower blood lactate concentrations at submaximal exercise, increased mitochondrial and capillary densities, improved enzyme activity
effects that influence acute and chronic responses to aerobics?
altitude, hyperoxic breathing, smoking, blood doping, genetic potential, age, sex
improvements from aerobic exercise?
(1) respiratory: decreased submaximal respiration rate (2) cardiovasc: decreased heart rate for fixed submaximal workloads, blood volume is increased, supporting increased stroke volume and cardiac output (3) musculoskeletal: increased arterial-venous O2 difference associated with increased capillarization in muscle, increased oxidative enzyme concentrations, increased mitochondrial size and density (4) aerobic power: increased maximal oxygen uptake (vo2max), elite athletes may show minor changes in vo2 with training (5-10%), while untrained may increase vo2 by as much as 20%. high vo2 + high lactate threshold allows enhanced performance for running sports as well as sports with intermittent sprinting (5) lactate threshold: running at higher percentage of vo2max, covering more distance during a game, enhanced recovery for second half performance, working at higher exercise intensities throughout an event
if athletes with the same VO2Max have different lactate thresholds, who will win?
lowered lactate threshold = better movement economy. if one has a lactate threshold of 80% of VO2max whereas the other’s occurs at 70%, the first individual will be able to maintain a power output higher than the second individual despite same VO2max.
how does aerobic exercise affect energy substrates?
greater use of fat as a substrate for exercise with relative sparing of carbs.
at what elevation does physiology begins to adjust to partial pressure of atmosphere (altitude hypoxia)?
> 3900 feet (1189m). Denver and Albuquerque are in this threshold (5289ft/1612m)
