Chapter 8: Cardiorespiratory Responses to Acute Exercise
The ratio of volume of air expired (VE) to the volume of CO2 produced (VCO2) is the ___________. a. Anaerobic threshold b. Lactate threshold c. Ventilatory equivalent for CO2 d. Ventilatory equivalent for O2 e. Ventilatory threshold
c. Ventilatory equivalent for CO2
What statement is supported by scientific research? a. During exercise, stroke volume increases above resting values. b. SV continues to increase beyond 50% of VO2max, even up to maximal exercise intensity. c. There is no clear pattern of SV increases beyond the 40 to 60% work rate range. d. All of these statements are supported by scientific research.
d. All of these statements are supported by scientific research.
Increases with increased exercise intensity until exhaustion, when it begins to level off. Plateaus with constant work rate at submaximal exercise levels. a. Blood flow b. Blood pressure c. Cardiac output d. Heart rate e. Stroke volume
d. HR
The ratio between the volume of air expired or ventilation (VE) and the amount of oxygen consumed by the tissues (VO2) in a given amount of time is the __________. a. Anaerobic threshold b. Lactate threshold c. Ventilatory equivalent for CO2 d. Ventilatory equivalent for O2 e. Ventilatory threshold
d. Ventilatory equivalent for O2
Frank-Starling Mechanism
The mechanism by which an increased amount of blood in the ventricle causes a stronger ventricular contraction to increase the amount of blood ejected.
How does Frank-Starling mechanism work during exercise?
The mechanism by which an increased amount of blood in the ventricles causes a stronger ventricular contraction to increase the amount of blood ejected. During exercise, this mechanism appears to have its greatest influence at lower exercise intensities and improved contractile force becomes more important.
Lactate Threshold
The point at which blood lactate production exceeds lactate clearance during a graded exercise test
Preload
The precontraction pressure in the heart as the volume of blood builds up; degree of stretch of the cardiac muscle fibers at the end of diastole; depends on venous tone and circulating blood volume.
Valsalva Maneuver
The process of holding the breath and attempting to compress the contents of the abdominal and thoracic cavities, causing increased intra-abdominal and intrathoracic pressure.
Ventilatory equivalent for oxygen
The ratio between the volume of air expired or ventilated (VE) and the amount of oxygen consumed by the tissues (VO2) in a given amount of time.
Ventilatory equivalent for carbon dioxide
The ratio of the volume of air expired (VE) to the volume of carbon dioxide produced (VCO2 )
Total Peripheral Resistance
The resistance to the flow of blood through the entire systemic circulation.
How do kidneys influence pH balance?
They maintain a constant buffer reserve and help remove accumulated H+ from the body through urination
What are the functions of the lungs?
To replace oxygen, to remove carbon dioxide, to regulate acid-base balance during exercise
Define the term: The resistance of the flow of blood through the entire systemic circulation
Total Peripheral Resistance
Altered breathing patterns and sensations associated with exercise include ____________. a. Dyspnea b. Hyperventilation c. Performance of Valsalva maneuver d. All of these
d. all of these
Define the term: The mechanism by which an increased amount of blood is the ventricle causes a stronger ventricular contraction to increase the amount of blood ejected.
Frank-Starling Mechanism
Describe how heart rate, stoke volume, and cardiac output respond to increasing rates of work.
-Heart Rate: Increases directly in proportion to the increase in exercise intensity until near maximal exercise is achieved. At max exercise intensity approaches, HR begins to plateau even if intensity continues to increase. -Stroke Volume: Increases with increasing exercise intensity up to intensities somewhere between 40-60% of VO2 max. At that point it plateaus, remaining essentially unchanged up to and including the point of exhaustion. -Cardiac Output: Increases in proportion to exercise intensity to match the need for increased blood flow to exercising muscles. Also, as HR and SV combine and increase cardiac output.
What happens as a result of sweating with regards to fluid portion of blood and its concentration?
As a result of sweating, there is a decrease in blood plasma volume which combines to the decrease ventricular filling which affects EDV/preload since plasma volume is more vicious which results in SV reducing in order to maintain cardiac output and increasing heart rate
SBP can exceed _______________ mmHG at maximal exercise intensity, the result of an increase in ________________.
200-250; Q
How do we determine HRmax?
208 - (0.7 - age)
Stroke volume increases proportionately with an increase exercise intensity but usually achieves a maximal value at __________ % of VO2max.
40-60%
How much is venous O2 content during exercise? Greater than or equal to ___________ mL O2 / 100 mL blood
5 mL O2 / 100 mL blood
Hyperventilation
A breathing rate or tidal volume greater than necessary for normal function.
Exercise-inducedaertial hypoxemia
A decline in arterial PO2 and arterial oxygen saturation during maximal or near-maximal exercise.
Valsalva Maneuver
A harmful increase in blood pressure when a person holds his breath during resistance training
Hemoconcentration
A relative (not absolute) increase in the cellular content per unit of blood volume, resulting from a reduction in plasma volume.
Define the term: Resistance to blood being ejected from the left ventricle.
Afterload
Which of the factors that influence stoke volume, cause an increase in filling capacity?
Amount of blood (venous return to heart) and Ventricular distribution
Which of the factors that influence stoke volume, determine preload?
Amount of blood (venous return to heart) and Ventricular distribution
What factors influence stroke volume?
Amount of blood (venous return to heart), Ventricular distribution, Ventricular contractility, Aortic or pulmonary artery pressure
Cardiovascular Drift
An increase in HR during exercise to compensate for a decrease in SV. This compensation helps maintain a constant cardiac output, progressive increase in cardiac output directed to vasodilation skin for purpose of: cooling the body to attenuate the increase in core temperature.
Cardiovascular Drift
An increase in heart rate during exercise to compensate for a decrease in stroke volume.
The increased VCO2 thought to result from excess carbon dioxide being released from bicarbonate buffering of lactic acid. (A number of scientists objected to the use of this term to describe this respiratory phenomenon.)
Anaerobic Threshold
How does increased ventilation influence pH balance?
Any increase in H+ in blood stimulates the respiratory center to increase ventilation which facilitates binding of H+ to bicarbonate and removes CO2 which results in a decrease in H+ and increase in blood pH
How much oxygen is present during exercise? (arterial blood and venous blood)
Arterial Blood: 20 ml of O2/100 ml Venous Blood: 15 ml of O2/100 ml
What happens to blood flow redistribution during exercise?
Blood flow is redistributed during exercise from inactive tissues of the body to meet the increase metabolic needs of active muscle.
What are the primary buffers in blood? In muscles?
Bicarbonate, inorganic phosphates, proteins, Hb
Define the term: Increases during exercise to active muscles and decreases to kidneys, live, stomach, and intestines.
Blood flow
Define the term: Increases with increased exercise, though systolic and diastolic pressure measures do not both increase to a similar degree.
Blood pressure
Define the term: Increases with increased exercise intensity to ensure adequate oxygen and nutrients reach muscles and waste products are cleared away. Probably plateaus when cardiac output approaches maximal exercise intensities.
Cardiac Output
Define the term: An increase in heart rate during exercise to compensate for a decrease in stroke volume.
Cardiovascular Drift
What happens to the integration of exercise response?
Cardiovascular responses to exercise fast and becomes finely tuned. Highest priority of cardiovascular system is to maintain blood pressure by maintaining blood flow (only as long as BP remains stable) and by prioritizing it before other needs (thermoregulation)
What happens to blood pressure during upper body exercise?
Causes a greater BP response than leg exercise at the same exercise intensity, attributed to smaller muscle mass of upper body, plus energy demand increases to stabilize upper body during arm exercise
Define the term: Information originating in the brain that is transmitted to the cardiovascular, muscular, or pulmonary system.
Central command
What keeps blood pH within a relatively narrow range?
Chemical buffers in blood, pulmonary ventilation, and kidney function
What do bicarbonates combine with? What does it form?
Combine with H+ to form carbonic acid
Dyspnea
Difficult and labored breathing, shortness of breath
What changes occur in the plasma volume and red blood cells with increasing levels of exercise? With prolonged exercise in the heat?
During prolonged exercise, plasma volume is reduced 10-15% which impairs exercise performance. Impaired performance is caused by blood flow to active muscle is reduced to allow more blood to be diverted to skin to lose body heat; blood viscosity is increased which is what impedes blood flow, limiting oxygen transport
Define the term: Labored or difficult breathing.
Dyspnea
Define the term: A decline in arterial PO2 and arterial oxygen saturation during maximal or near - maximal exercise.
Exercise-inducedaertial hypoxemia
True or false: During exercise, the initial, immediate rise in ventilation is caused by chemical stimulation and not neural stimulation.
False
What is the Fick principle, and how does this apply our understanding of the relationship between metabolism and cardiovascular function?
Fick's Law states that the net diffusion rate of a gas across a fluid membrane is proportional to the difference in partial pressure, proportional to the area of the membrane, and inversely proportional to the thickness of the membrane
Afterload
Force against which the heart pumps when ejecting blood (is the pressure or resistance against flow); resistance to left ventricular ejection; the pressure that must be exceeded before ejection of blood from the ventricles can occur
What is the difference between HR max, steady state heart rate, and resting heart rate?
HR Max: The highest HR value achieved in an all-out effort to the point of volitional fatigue SS HR: When the exercise intensity is held constant at any sub maximal workload, HR increases rapidly until it plateaus; optimal HR for circulatory demands and rate of work. RHR: Mainly due to an increase in parasympathetic (Vagal Tone) that accompanies endurance exercise training
What are the major cardiovascular adjustments that the body makes when someone is overheated during exercise?
HR increases during exercise to compensate for a decreased SV in order to help maintain cardiac output; there is a decline in arteria BP which causes CV drift
Bicarbonates
Helps to maintain the pH in one or more of the fluid compartments; a salt of carbonic acid, containing the HCO 3 −1group; an acid
Define the term: A relative (not absolute) increase in the cellular content per unit of blood volume, resulting from a reduction in plasma volume.
Hemoconcentration
Define the term: A breathing rate or tidal volume greater than necessary for normal function.
Hyperventilation
Why does heart rate increase during cardiovascular drift?
In order to compensate for the drop of SV which the compensation helps maintain cardiac output
What are some explanations for increases in stroke volume?
Increase in preload, increase in contractility, and decrease in after load
Frank-Starling Law
Increased EDV results in increased contractility and thus increased stroke volume; Degree of stretch is directly related to the face of the contraction (systole)
Acidosis
Increased acidity in the blood and occurs when the blood pH falls below 7.35.
Hyperventilation
Increased pulmonary ventilation in excess of metabolic demand
Blood Flow
Increases during exercise to active muscles and decreases to kidneys, live, stomach, and intestines.
Stroke Volume
Increases during exercise. Probably plateaus at exercise intensities between 40-60% of maximal capacity, and remains unchanged up to exhaustion.
How does pulmonary ventilation respond to increasing intensities of exercise?
Increases immediately in proportion to the metabolic needs of muscle. Low exercise intensity: only tidal volume increases. High exercise intensity: rate also increases.
Cardiac Output
Increases with increased exercise intensity to ensure adequate oxygen and nutrients reach muscles and waste products are cleared away. Probably plateaus when cardiac output approaches maximal exercise intensities.
Blood pressure
Increases with increased exercise, though systolic and diastolic pressure measures do not both increase to a similar degree.
Central Command
Information originating in the brain that is transmitted to the cardiovascular, muscular, or pulmonary systems.
Dyspnea
Labored or difficult breathing.
Define the term: The point at which blood lactate production exceeds lactate clearance during a graded exercise test
Lactate Threshold
What is ventilatory threshold associated with?
Lactate threshold
What happens during a decreased after load?
Left ventricles expels blood against less resistance, greater emptying of the ventricle which causes SV to increase resulting in a reduced mean arterial pressure.
Define the term: The highest heart rate value attainable during an all - out effort to the point of exhaustion.
Maximum Heart Rate
What factors of blood are influenced the most during exercise?
Oxygen content, plasma volume, hemoconentration
Define the term: The degree to which the myocardium is stretched before it contracts, determined by factors such as central blood volume.
Preload
Afterload
Resistance to blood being ejected from the left ventricle.
During rest and maximal exercise, how much is stroke volume at per beat?
Rest: 60 - 70 ml/beat Maximal: 110-130 ml/beat
Define the term: The heart rate at rest, averaging 60 to 80 bpm.
Resting Heart Rate
What two pumps contribute to the Frank-Starling Law?
Skeletal muscle pump and respiratory pump
Alkalosis
State of abnormally low hydrogen ion concentration in the extracellular fluid; pH above 7.45
Define the term: Increases during exercise. Probably plateaus at exercise intensities between 40-60% of maximal capacity, and remains unchanged up to exhaustion.
Stroke Volume
Ventricular Distensibility
The capacity to enlarge the ventricle, to allow maximal filling
Preload
The degree to which the myocardium is stretched before it contracts, determined by factors such as central blood volume.
Frank-Starling Mechanism
The force of contraction is a function of the length of the fibers of the muscle wall
Maximum Heart Rate
The highest heart rate value attainable during an all out effect to the point of exhaustion.
Anaerobic Threshold
The increased VCO2 thought to result from excess carbon dioxide being released from bicarbonate buffering of lactic acid. (A number of scientists objected to the use of this term to describe this respiratory phenomenon.)
Ventricular Contractility
The inherent capacity of the ventricle to contract forcefully
Which of the factors that influence stoke volume, determine after load?
Ventricular contractility and Aortic or pulmonary artery pressure
What are the primary functions of blood?
Transportation, temperature regulation, acid-base (pH) balance
True or false: During whole body endurance exercise, mean arterial blood pressure increases by an increase in systolic blood pressure, with only small changes in diastolic pressure
True
Ventilatory Threshold
Up to a certain point, ventilation increases during exercise in direct proportion to the rate of work being performed. Beyond this point, ventilation increases disproportionately as the body tries to clear excess CO2.
Define the term: The process of holding the breath and attempting to compress the contents of the abdominal and thoracic cavities, causing increased intra-abdominal and intrathoracic pressure.
Valsalva Maneuver
Describe important mechanisms for returning blood back to the heart during exercise in an upright position.
Valves in the veins, muscle pump, respiratory pump
Ventilatory Threshold
Ventilation increases more than oxygen uptake, swtich from aerobic to anaerobic; the point at which this happens should happen around the same time as lactate threshold.
Define the term: Up to a certain point, ventilation increases during exercise in direct proportion to the rate of work being performed. Beyond this point, ventilation increases disproportionately as the body tries to clear excess CO2.
Ventilatory Threshold
Define the term: The ratio of the volume of air expired (VE) to the volume of carbon dioxide produced (VCO2 )
Ventilatory equivalent for carbon dioxide
Define the term: The ratio between the volume of air expired or ventilated (VE) and the amount of oxygen consumed by the tissues (VO2) in a given amount of time.
Ventilatory equivalent for oxygen
Which of the factors that influence stoke volume, cause an increase in emptying capacity?
Ventricular contractility and Aortic or pulmonary artery pressure
What role does the respiratory system play in acid - base balance?
Whenever hydrogen concentration starts to increase, inspiratory center responds by an increase rate and depth of breathing. Removing carbon dioxide is an essential means for reducing hydrogen concentration.
What is cardiovascular drift? What two theories have been proposed to explain cardiac drift?
With prolonged aerobic exercise or aerobic exercise in a hot environment at a steady-state intensity, SV gradually decreases and HR increases. Cardiac output is well maintained, but arterial blood pressure also declines. These alterations are called cardiovascular drift. One theory: With more blood in the skin for the purpose of cooling the body, less blood is available to return to the heart, thus decreasing preload. There is also a small decrease in blood volume resulting from sweating and from a generalized shift of plasma across the capillary membrane into the surrounding tissues. These factors combine to decrease ventricular filling pressure, which decreases venous return to the heart and reduces the EDV. Second Theory: As HR increases, there is less filling time for the ventricles. This exercise tachycardia may lower SV under the conditions of prolonged exercise even without peripheral displacement of blood volume
What happens to the hemoconcentration during exercise?
With sweating fluid portion of blood is reduced which causes blood to become more concentrated. Hematocrit increases up to 50% or more.
The Valsalva maneuver is a potentially dangerous respiratory procedure that frequently accompanies certain types of exercise, in particular lifting of heavy objects. One step in the Valsalva maneuver is when a person _________________. a. Closes the glottis (the opening between the vocal cords) b. Decreases her intra -abdominal pressure by forcibly contracting the diaphragm and the abdominal muscles c. Decreases her intrathoracic pressure by forcibly contracting the respiratory muscles
a. Closes the glottis (the opening between the vocal cords)
Stoke volume is determines by all of these EXCEPT ___________. a. The volume of venous blood pumped from the heart b. The capacity to enlarge the ventricle for maximal filling c. The inherent capacity of the ventricle to contract d. The pressure against which the ventricles must contract
a. The volume of venous blood pumped from the heart
What is NOT a normal response to exercise? a. Venous return decreases b. Ventricular contractility increases c. HR increases in proportion to the increase in exercise intensity until you are near the point of exhaustion, at which point it levels off d. Cardiac output increases to meet the muscles' increased demand for oxygen
a. Venous return decreases
The increased VCO2 thought to result from excess CO2 being released from bicarbonate buffering of lactic acid is the __________. (A number of scientist objected to the use of this term to describe the respiratory phenomenon.) a. Anaerobic threshold b. Lactate threshold c. Ventilatory equivalent for CO2 d. Ventilatory equivalent for O2 e. Ventilatory threshold
a. anaerobic threshold
Increases during exercise to active muscles and decreases to kidneys, liver, stomach, and intestines. a. Blood flow b. Blood pressure c. Cardiac output d. Heart rate e. Stroke volume
a. blood flow
Blood flow is redistributed during exercise from inactive tissues of the body to meet the ______________ metabolic needs of active muscle. a. increase b. decrease
a. increase
For Frank-Starling mechanism to increase stroke volume → Left ventricular must __________. Requires _________ venous return to heart. a. increase; increase b. increase; decrease c. decrease; increase d. decrease; decrease
a. increase; increase
As exercise intensity increases, what happens to the a-vO2 difference? a. Increases b. Decreases c. Stays the same
a. increases
Mean arterial BP _____________ immediately in response to exercise and the magnitude of the increase proportional to the increase in exercise intensity. This is accomplished primarily by an ____________ in SBP, with minimal changes in diastolic pressure. a. increase; increase b. increase; decrease c. decrease; increase d. decrease; decrease
a. increases; increases
An increase in heart rate and stroke volume combine to increase cardiac output (Q). Thus, more blood pumped during exercise to ensure...
an adequate supply of oxygen is reaching active muscle and waste products of metabolism.
Amber is a swimmer on her high school swim team. Her specialty is the 500-yd freestyle. After a long drive, her team finally arrived at an away meet, and Amber was very hungry. She and a few friends found a fast food place, and Amber downed a burger, fries, and a shake 30 to 45 min before her event. She figured that the food would give her energy to compete. To her surprise, she finished a distant sixth, instead of her usual top-three finish. Which of the following explains Amber's sixth-place finish? a. Reduced gravity in the water caused blood to pool in Amber's legs, reducing the volume of blood returning to her heart. b. Blood was diverted to Amber's gastrointestinal system to aid digestion and absorption of her lunch. Less blood was available to supply oxygen to Amber's muscles during this endurance event. c. The Valsalva maneuver that occurred each time Amber did a flip turn caused an increase in intrathoracic pressure and a reduction in venous return. d. The supine position reduced Amber's cardiac output and lowered her skin blood flow, resulting in less oxygen transport to her muscles and a higher core temperature that caused premature fatigue. e. More blood was directed to Amber's skin prior to her event. Therefore, less blood was left for her muscles, thereby hindering performance.
b. Blood was diverted to Amber's gastrointestinal system to aid digestion and absorption of her lunch. Less blood was available to supply oxygen to Amber's muscles during this endurance event.
As part of a research study, Kassee's stroke volume was measured in different situations. Her resting stroke volume in a reclining position was 75 ml. After swimming five laps, Kassee's stroke volume was measured at 90 ml. Her resting stroke volume in an upright position was 55 ml. While running on a treadmill, Kassee's stroke volume was measured at 100 ml. Kassee wonders why her stroke volume increased so much, almost doubling, while running on a treadmill as compared with swimming. Which of the following explains Kassee's increased stroke volume? a. Gravity caused blood to pool in the legs, reducing the volume of blood returning to the heart. Heart rate responds by increasing to maintain cardiac output. b. Blood was diverted to the system that was placing a high demand. Less blood was available to supply oxygen to muscles during this long-distance event. c. Use of the Valsalva maneuver causes enormous increase in intrathoracic pressure. Subsequent blood pressure increase occurs because of body's effort to overcome high internal pressure. d. Blood does not pool in the lower extremity in a supine position, allowing for easy blood flow return to the heart and resulting in a higher stroke volume. Performing upright exercise, stroke volume must increase to compensate for the force of gravity. e. More blood is directed to the skin. Less blood was left for muscles, thereby hindering performance.
b. Blood was diverted to the system that was placing a high demand. Less blood was available to supply oxygen to muscles during this long-distance event.
The limits of airway resistance will affect _________. a. Normal, healthy people during submaximal exercise b. Highly trained endurance athletes during maximal exercise c. Both a and b d. None of the above
b. Highly trained endurance athletes during maximal exercise
The limits of pulmonary ventilation and gas diffusion will affect __________. a. Normal, healthy people during submaximal exercise b. Highly trained endurance athletes during maximal exercise c. Both a and b d. None of the above
b. Highly trained endurance athletes during maximal exercise
Increases with increased exercise, though systolic and diastolic pressure measures do not both increase to a similar degree. a. Blood flow b. Blood pressure c. Cardiac output d. Heart rate e. Stroke volume
b. blood pressure
The point at which blood lactate production exceeds lactate clearance during a graded exercise test is the ___________. a. Anaerobic threshold b. Lactate threshold c. Ventilatory equivalent for CO2 d. Ventilatory equivalent for O2 e. Ventilatory threshold
b. lactate threshold
About 10% of the body's total oxygen consumption during heavy exercise can occur in the ____________ muscle(s). a. Thoracic b. Respiratory c. Leg d. Heart
b. respiratory
What equation more accurately estimates maximum heart rate? a. 220 - age in years b. 207 - (0.8 x age in years) c. 208 - (0.7 x age in years) d. 210 - age in years
c. 208 - (0.7 x age in years)
Increases with increased exercise intensity to ensure adequate oxygen and nutrients reach muscles and waste products are cleared away. Probably plateaus when cardiac output approaches maximal exercise intensities. a. Blood flow b. Blood pressure c. Cardiac output d. Heart rate e. Stroke volume
c. Cardiac output
Ben is a competitive weightlifter at his university. He is studying exercise physiology and asked a med student to take his blood pressure immediately after performing the clean and jerk at 80% of his 1RM. Ben was shocked when the blood pressure reading was 250/120. Which of the following explains Ben's blood pressure reading? a. Gravity caused blood to pool in the legs, reducing the volume of blood returning to the heart. Heart rate responds by increasing to maintain cardiac output. b. Blood was diverted to the system that was placing a high demand. Less blood was available to supply oxygen to muscles during this long-distance event. c. Use of the Valsalva maneuver causes enormous increase in intrathoracic pressure. Subsequent blood pressure increase occurs because of body's effort to overcome high internal pressure. d. Blood does not pool in the lower extremity in a supine position, allowing for easy blood flow return to the heart and resulting in a higher stroke volume. Performing upright exercise, stroke volume must increase to compensate for the force of gravity. e. More blood is directed to the skin. Less blood was left for muscles, thereby hindering
c. Use of the Valsalva maneuver causes enormous increase in intrathoracic pressure. Subsequent blood pressure increase occurs because of body's effort to overcome high internal pressure.
An explanation of what causes the cardiovascular system to be "turned on" at the onset of exercise and involves parallel activation of both the motor and the cardiovascular control centers of the brain is called the _____________. a. Frank - Starling mechanism b. Myocortical synchronization effect c. Cortex command theory d. None of these
d. none of these
According to the Fick equation, all but which of the following are necessary for calculating oxygen consumption? a. SV b. HR c. A - vO2 difference d. Respiratory rate
d. respiratory rate
Brandon is a 25-year-old recreational long-distance runner. He competes regularly, mostly for the fun of it and to keep himself motivated to train. Today he ran 10K in 35 °C (95 °F) heat. His time was unusually slow. Which of the following explains Brandon's unusually slow time? a. Gravity caused blood to pool in the legs, reducing the volume of blood returning to the heart. Heart rate responds by increasing to maintain cardiac output. b. Blood was diverted to the system that was placing a high demand. Less blood was available to supply oxygen to muscles during this long-distance event. c. Use of the Valsalva maneuver causes enormous increase in intrathoracic pressure. Subsequent blood pressure increase occurs because of body's effort to overcome high internal pressure. d. Blood does not pool in the lower extremity in a supine position, allowing for easy blood flow return to the heart and resulting in a higher stroke volume. Performing upright exercise, stroke volume must increase to compensate for the force of gravity. e. More blood is directed to the skin. Less blood was left for muscles, thereby hindering performance.
e. More blood is directed to the skin. Less blood was left for muscles, thereby hindering performance.
Increases during exercise. Most researchers agree that it plateaus at exercise intensities between 40% and 60% of maximal capacity, and remains unchanged up to exhaustion. a. Blood flow b. Blood pressure c. Cardiac output d. Heart rate e. Stroke volume
e. SV
Up to a certain point, ventilation increases during exercise in direct proportion to the rate of work being performed. Beyond this point, ventilation increases disproportionately as the body tries to clear excess CO2. This point is the _____________. a. Anaerobic threshold b. Lactate threshold c. Ventilatory equivalent for CO2 d. Ventilatory equivalent for O2 e. Ventilatory threshold
e. ventilatory threshold
True or false: RHR as low as 28 to 40 bpm reported in highly conditioned, endurance - trained athletes are mainly due to an increase in vagal tone that accompanies endurance exercise training.
true