Cardiovascular Responses To Exercise
Cardiovascular – Respirator y System UnitChapter 13CardiovascularResponses toExerciseAfter studying the chapter, you should be able to Graph and explain the pattern of response for themajor cardiovascular variables during short-term, lightto moderate submaximal aerobic exercise. Graph and explain the pattern of response for themajor cardiovascular variables during long-term,moderate to heavy submaximal aerobic exercise. Graph and explain the pattern of response for themajor cardiovascular variables during incrementalaerobic exercise to maximum. Graph and explain the pattern of response for themajor cardiovascular variables during dynamicresistance exercise. Graph and explain the pattern of response for themajor cardiovascular variables during static exercise. Compare and contrast the response of the majorcardiovascular variables to short-term, light tomoderate submaximal aerobic exercise; incrementalaerobic exercise to maximum; dynamic resistanceexercise; and static exercise. Discuss the similarities and differences between thesexes in the cardiovascular response to the variousclassifications of exercise. Discuss the similarities and differences between youngand middle-aged adults in the cardiovascular responseto the various classifications of exercise.351
352 Cardiovascular–Respiratory System UnitIntroductionAll types of human movement, no matter what themode, duration, intensity, or pattern, require an expenditure of energy above resting values. Much of thisenergy will be provided through the use of oxygen. Inorder to supply the working muscles with the neededoxygen, the cardiovascular and respiratory systemsmust work together. The response of the respiratorysystem during exercise was detailed in Chapter 11.This chapter describes the parallel cardiovascular responses to dynamic aerobic activity, static exercise,and dynamic resistance exercise.Cardiovascular Responsesto Aerobic ExerciseAerobic exercise requires more energy—and, hence,more oxygen (and thus the use of the term aerobic,with oxygen)—than either static or dynamic resistanceexercise. How much oxygen is needed depends primarily on the intensity at which the activity is performedand secondarily on the duration of the activity. Like thediscussion on respiration, this discussion will categorize the exercises performed as being short-term(5–10 min), light (30–49% of maximal oxygen consumption, VO2max) to moderate (50–74% of VO2max)submaximal exercise; long-term (greater than 30min), moderate to heavy submaximal (60– 85% ofVO2max) exercise; or incremental exercise to maxi mum, increasing from 30% to 100% of VO2max.Short-Term, Light to Moderate SubmaximalAerobic ExerciseAt the onset of short-term, light- to moderate-intensityexercise, there is an initial increase in cardiac output(Q) to a plateau at steady state (see Figure 13.1a). Cardiac output plateaus within the first 2 min of exercise,reflecting the fact that cardiac output is sufficient totransport the oxygen needed to support the metabolicdemands (ATP production) of the activity. Cardiac output increases owing to an initial increase in bothstroke volume (SV) (Figure 13.1b) and heart rate (HR)(Figure 13.1c). Both variables level off within 2 min.During exercise of this intensity the cardiorespiratory system is able to meet the metabolic demandsof the body; thus, the term steady state or steady rateSteady State A condition in which the energyexpenditure provided during exercise is balanced with the energy required to performthat exercise and factors responsible for theprovision of this energy reach elevated levelsof equilibrium.is often used to describe this type of exercise. Duringsteady state exercise, the exercise is performed at anintensity such that energy expenditure is balancedwith the energy required to perform the exercise. Theplateau evidenced by the cardiovascular variables (inFigure 13.1) indicates that a steady state has beenachieved.The increase in stroke volume results from anincrease in venous return, which, in turn, increasesthe left ventricular end–diastolic volume (LVEDV)(preload). The increased preload stretches the myocardium and causes it to contract more forcibly inaccordance with the Frank-Starling law of the heartdescribed in Chapter 12. Contractility of the myocardium is also enhanced by the sympathetic nervous system, which is activated during physical activity. Thus, an increase in the left ventricularend–diastolic volume and a decrease in the leftventricular end–systolic volume (LVESV) account forthe increase in stroke volume during light to moderate dynamic exercise (Poliner, et al., 1980). Heartrate increases immediately at the onset of activityas a result of parasympathetic withdrawal. As exercise continues, further increases in heart rate aredue to the action of the sympathetic nervous system(Rowell, 1986).Systolic blood pressure (SBP) will rise in a pattern very similar to that of cardiac output: There isan initial increase and a plateau once steady state isachieved (Figure 13.1d). The increase in systolicblood pressure is brought about by the increase incardiac output. Systolic blood pressure wouldbe even higher if not for the fact that resistancedecreases, thereby partially offsetting the increasein cardiac output. When blood pressure (BP) ismeasured intra-arterially, diastolic blood pressure(DBP) does not change. When it is measured byauscultation it either does not change or may godown slightly. Diastolic blood pressure remains relatively constant because of peripheral vasodilation,which facilitates blood flow to the working muscles.The small rise in systolic blood pressure and thelack of a significant change in diastolic blood pressure cause the mean arterial pressure (MAP) to riseonly slightly, following the pattern of systolic bloodpressure.Total peripheral resistance (TPR) decreasesowing to vasodilation in the active muscles (Figure13.1e). The vasodilation of vessels in the active muscles is brought about primarily by the influence oflocal chemical factors (lactate, K , and so on), whichreflect increased metabolism. The decrease in TPRcan be calculated using Equation 12.8:TPR MAPQ
Chapter 13 Cardiovascular Responses to Exercise 353(a)201510505Time (min)180SBP140MAP100010(b)DBP1401006005Time (min)10(e)25TPR (units)SV (mL)1806002015105005Time (min)1005Time (min)010(c)220(f)400180RPP (units)HR (b·min 1)(d)220BP (mmHg)Q (L·min 1)25Figure 13.1Cardiovascular Responses toShort-Term, Light to ModerateAerobic Exercise14010030020010060005Time (min)10005Time (min)ExampleCalculate TPR by using the following information fromFigures 13.1a and 13.1d:MAP 110 mmHgQ 15 L·min 1The computation isTPR 110 mmHg 7.33 (TPR units)15 L·min 1Thus, TPR is 7.33 for light dynamic exercise. The decrease in total peripheral resistance hastwo important implications. First, the vasodilation inthe active muscle that causes the decrease in resistance has the effect of increasing blood flow to the active muscle, thereby increasing the availability of oxygen and nutrients. Second, the decrease in resistancekeeps mean arterial pressure from increasing dramatically. The increase in mean arterial pressure is10determined by the relative changes in cardiac outputand total peripheral resistance. Since cardiac outputincreases more than resistance decreases, mean arterial pressure increases slightly during dynamic exercise. However, the increase in mean arterial pressurewould be much greater if resistance did not decrease.Myocardial oxygen consumption increases duringdynamic aerobic exercise because the heart mustdo more work to pump an increased cardiac output tothe working muscles. The rate-pressure product willincrease in relation to increases in heart rate andsystolic blood pressure, reflecting the greater myocardial oxygen demand of the heart during exercise(Figure 13.1f ). The Question of Understanding box onpage 354 provides an example of normal responses toexercise. Refer back to it as each category of exerciseis discussed and check your answers in Appendix D.The actual magnitude of the change for each ofthe variables shown in Figure 13.1 depends on the
354 Cardiovascular–Respiratory System UnitThe following measurements were obtained on a 42year-old man at rest and during light aerobic exercise,during heavy aerobic exercise, during maximal dynamicaerobic exercise, and during sustained static contractions at 50% MVC.ConditionRestHR(b·min 1)SBP(mmHg)DBP(mmHg).Q(L·min 008Calculate MAP, TPR, and RPP for each condition.workload, environmental conditions, and the geneticmakeup and fitness level of the individual.Blood volume decreases during dynamic aerobicexercise. Figure 13.2 shows the percent reduction ofplasma volume during 30 min of moderate bicycle exercise (60–70% VO2max) in a warm environment(Fortney, et al., 1981). The largest changes occur during the first 5 min of exercise, which is consistent withshort-term exercise. Following the initial rapid decrease, plasma volume stabilizes. This rapid decreasein plasma volume suggests that it is fluid shifts, ratherthan fluid loss, that accounts for the initial decrease inplasma volume (Wade and Freund, 1990). The magnitude of the decrease in plasma volume is dependentupon the intensity of exercise, environmental factors,and the hydration status of the individual.Figure 13.3 illustrates the distribution of cardiacoutput at rest and during light exercise. Notice thatcardiac output increases from 5.8 L·min 1 to9.4 L·min 1 in this example (the increase in Q is illustrated by the increased size of the pie chart). The mostdramatic change in cardiac output distribution withlight exercise is the increased percentage (47%) andthe actual amount of blood flow (4500 mL) that is directed to the working muscles. Skin blood flow alsoincreases to meet the thermoregulatory demands ofexercise. The absolute amount of blood flow to thecoronary muscle also increases although the percentage of cardiac output remains relatively constant. Theabsolute amount of cerebral blood flow remains constant, which means that the percentage of cardiacoutput distributed to the brain decreases. Both renalChange in plasma volume (%)A Question of Understanding0 3 6 9 12 1505101520Time (min)2530Figure 13.2Percent Reduction of Plasma Volume during 30-minModerate Bicycle Exercise to MaximumSource: S. M. Fortney, C. B. Wenger, J. R. Bove, & E. R. Nadel. Effect of bloodvolume on sweating rate and body fluids in exercising humans. Journal ofApplied Physiology. 51(6):1594–1600 (1981). Reprinted by permission.and splanchnic blood flow are modestly decreasedduring light exercise.Long-Term, Moderate to HeavySubmaximal Aerobic ExerciseThe cardiovascular responses to long-term, moderateto heavy exercise (60–85% of VO2max) are shown inFigure 13.4. As for light to moderate workloads, cardiac output increases rapidly during the first minutesof exercise and then plateaus and is maintained at arelatively constant level throughout exercise (Figure13.4a). Notice, however, that the absolute cardiac output attained is higher during heavy exercise than itwas during light to moderate exercise. The initial increase in cardiac output is brought about by an increase in both stroke volume and heart rate.Stroke volume exhibits a pattern of initial increase, plateaus, and then displays a negative (downward) drift. Stroke volume increases rapidly duringthe first minutes of exercise and plateaus at a maximal level after a workload of approximately 40–50%of VO2max has been achieved (P. Åstrand, et al.,1964) (Figure 13.4b). Thus, during work that requiresmore than 50% of VO2max, the stroke volume response is not intensity dependent. Stroke volume remains relatively constant during the first 30 min ofheavy exercise.As for light to moderate exercise, the increase instroke volume results from an increased venous return, leading to the Frank-Starling mechanism, andincreased contractility owing to sympathetic nerve
Chapter 13 Cardiovascular Responses to Exercise 355(b) Light Exercise (Q 9.4 L·min 1)(a) Rest (Q 5.8 L·min 1)Skin(500 mL)9%Other(600 mL)10%Other(400 mL) 4%Skeletal 21%muscle(1200 mL)4%Coronary 13 %Cerebralmuscle(250 mL) (750 mL)12% Splanchnic(1100 mL)Skin(1500 mL) 16%Splanchnic(1400 mL)24 %9%Renal(900 mL)8% Cerebral(750 mL)4%Coronarymuscle(350 mL)19 %Renal(1100 mL)47%Skeletal muscle(4500 mL)Figure 13.3Distribution of Cardiac Output at Rest and during Light ExerciseSource: Data from Anderson (1968).(a)20BP (mmHg)Q (L·min 1)251510220(d)180SBP140MAP1005DBP600153045Time (min)600153045Time (min)(e)25(b)20TPR (units)SV (mL)1801401006015106050153045Time (min)0153045Time (min)60(c)220(f)400180RPP (units)HR (b·min 1)60140100300200100600153045Time (min)600153045Time (min)60Figure 13.4Cardiovascular Responses to LongTerm, Moderate to HeavySubmaximal Aerobic Exercise
356 Cardiovascular–Respiratory System UnitCardiovascular Drift The changes in observed cardiovascular variables that occurduring prolonged, heavy submaximal exercisewithout a change in workload.(a)FluidreplacementQ (L·min 1)242220No fluid18020406080Time (min)100120(b)Fluidreplacement160SV (mL)150140130No fluid120020406080Time (min)100120(c)160No fluid155HR (b·min 1)stimulation. Thus, changes in stroke volume occur because left ventricular end–diastolic volume increasesand left ventricular end–systolic volume decreases(Poliner, et al., 1980). Left ventricular end–diastolicvolume increases because of the return of blood to theheart by the active muscle pump, increased venoconstriction (which decreases venous pooling, thereby increasing venous return), and increased cardiac output. Left ventricular end–systolic volume decreasesowing to augmented contractility of the heart, whicheffectively ejects more blood from the ventricle, leaving a smaller residual volume.However, if exercise continues beyond approximately 30 min, stroke volume gradually drifts downward although it remains elevated above resting values. The downward shift in stroke volume afterapproximately 30 min is most likely due to thermoregulatory stress; plasma loss and a redirection of bloodto the cutaneous vessels in an attempt to dissipate heat(Rowell, 1986). This effectively reduces venous returnand thus causes the reduction in stroke volume.Heart rate displays a pattern of initial increase,plateaus at steady state, and then shows a positive drift.Heart rate increases sharply during the first 1–2 min ofexercise, with the magnitude of the increase dependingon the intensity of exercise (Figure 13.4c). The increasein heart rate is brought about by parasympathetic withdrawal and activation of the sympathetic nervous system. After approximately 30 min of heavy exerciseheart rate begins to drift upward. The increase in heartrate is proportional to the decrease in stroke volume, socardiac output is maintained during exercise.The changes observed in cardiovascular variables, notably in heart rate and stroke volume, duringprolonged, heavy submaximal exercise without achange in workload are known as cardiovasculardrift. Cardiovascular drift is probably associated withrising body temperature during prolonged exercise.The combination of exercise and heat stress producescompeting regulatory demands—specifically, competition between skin and muscle for large fractions ofcardiac output. Stroke volume decreases as a result ofvasodilation, a progressive increase in the fraction ofblood being directed to the skin in an attempt to dissipate heat from the body, and a loss of plasma volume(Rowell, 1974; Sjogaard, et al., 1988).The magnitude of cardiovascular drift is heavilyinfluenced by fluid ingestion. Figure 13.5 presentsdata from a study in which subjects cycled for 2 hrwith and without fluid replacement (Hamilton, et al.,150Fluidreplacement145140135020406080Time (min)100120Figure 13.5Cardiovascular Response to Long-Term, Moderateto Heavy Exercise (70–76% VO2max) with andwithout Fluid ReplacementSource: M. T. Hamilton, J. G. Alonso, S. J. Montain, & E. F. Coyle. Fluid replacement and glucose infusion during exercise prevents cardiovascular drift.Journal of Applied Physiology. 71:871–877 (1985). Reprinted by permission.1991). Values are for minutes 20 through 120; thus,the initial increase in each of the variables is notshown in this figure. When subjects consumed enoughwater to completely replace the water lost through
Chapter 13 Cardiovascular Responses to Exercise 357IntervalSteady State25IntervalSteady StateLV Volumes (mL)1501401301201101009080706050047Time (min)121520MAP (mmHg)Throughout this book, we examinethe exercise response to various categories of exercise, with this chapterlooking specifically at the cardiovascular responses. Most studies thathave examined the cardiovascular response to exercise have used continuous activity. Yet many clinical populations (for example, peopleundergoing cardiac rehabilitation)and many athletic populations utilizeinterval training. So how do these activities compare in terms of cardiovascular responses?Foster and colleagues set out toanswer this question by comparingthe cardiovascular responses of agroup of adults (mean age 52.9 yr)in two separate 15-minute cycling trials—one involving steady state exercise, the other utilizing interval exercise. Participants cycled at 170 W forthe full 15 minutes in one trial and alternated 1-min “hard” (220 W) and“easy” (120 W) periods in the secondtrial, resulting in an equal power output (170 W) for both trials. Cardiovascular measurements were obtained before exercise (0 minutes)and after minutes 4, 7, 12, and 15.As can been seen from the results,no significant difference was notedbetween the steady state exerciseand the interval exercise for any ofthe variables. The authors concludedthat heart function during intervalexercise is remarkably similar toCardiac Output (L·min–1)Foster, C., K. Meyer, N. Georgakopoulos, A. J.Ellestad, D. J. Fitzgerald, K. Tilman, H. Weinstein, H. Young, & H. Roskamm: Left ventricularfunction during interval and steady stateexercise. Medicine and Science in Sports andExercise. 31(8):1157–1162 (1999).151050TPR (units)Interval Exercise versusSteady State ExerciseHeart Rate (b·min–1)Focus on Research181614121086420047Time 009080706050xxxx0xxxInterval–EDVSteady State–EDVInterval–ESVx Steady State–ESVx Interval–SVSteady State–SVx47Time (min)xx12151215IntervalSteady State047Time (min)IntervalSteady State047Time (min)continuous steady state exercise atthe same average power output,when moderate duration and evenlytimed hard and easy periods are utilized. The results provide good newsfor individuals with low levels of fitness who may not be able to performsweat, cardiac output remained nearly constantthroughout the first hour of exercise and actually increased during the second hour (Figure 13.5a). Cardiac output was maintained in the fluid replacement15 minutes of continuous activitywhen starting an exercise program.Fitness professionals can assure suchclients that alternating periods of“hard” and “easy” work results in cardiovascular responses similar to thoseresulting from sustained exercise.trial because stroke volume did not drift downward(Figure 13.5b). Heart rate was significantly lowerwhen fluid replacement occurred (Figure 13.5c).This information can be used by coaches and fitness
358 Cardiovascular–Respiratory System Unit(a) Rest (Q 5.8 L·min 1)(b) Heavy Exercise (Q 17.5 L·min 1)Other(400 mL)Skin(500 mL)9%Other(600 mL)10%Splanchnic(1400 mL)24 %Skeletal 21%muscle(1200 mL)4%Coronary 13 %Cerebralmuscle(250 mL) (750 mL)Skin12%(1900 mL)Splanchnic (600 mL)Renal (600 mL)Cerebral (750 mL)2% 3% 3%4%Coronary4% muscle(750 mL)19 %Renal(1100 mL)71%Skeletal muscle(12,500 mL)Figure 13.6Distribution of Cardiac Output at Rest and during Heavy ExerciseSource: Data from Anderson (1968).leaders. If your clients exercise for prolonged periods,they must replace the fluids that are lost during exercise, or performance will suffer.Refer back to the cardiovascular responses illustrated in Figure 13.4. Systolic blood pressure responses to long-term, moderate to heavy dynamic exercise are characterized by an initial increase, aplateau at steady state, and a negative drift. Systolicblood pressure increases rapidly during the first1–2 min of exercise, with the magnitude of the increase dependent upon the intensity of the exercise(Figure 13.4d). Systolic blood pressure then remainsrelatively stable or drifts slightly downward as a resultof continued vasodilation and a resultant decrease inresistance (Ekelund and Holmgren, 1967). Diastolicblood pressure does not change or changes so littlethat it has no physiological significance during prolonged exercise in a thermoneutral environment. But itmay decrease slightly when exercise is performed in awarm environment owing to increased vasodilation asa result of heat production. Because of the increasedsystolic blood pressure and the relatively stable diastolic blood pressure, mean arterial pressure increasesmodestly during prolonged activity. Again, as in light tomoderate exercise, the magnitude of the increase inmean arterial pressure is mediated by a large decrease in resistance that accompanies exercise.Total peripheral resistance exhibits a curvilineardecrease during long-term heavy exercise (Figure13.4e) because of vasodilation in active muscle and because of vasodilation in the cutaneous vessels in orderto dissipate the heat produced by mechanical work(Rowell, 1974). Finally, because both heart rate andsystolic blood pressure increase substantially duringheavy work, the rate-pressure product increasesmarkedly (Figure 13.4f ). The initial increase in ratepressure product occurs rapidly with the onset of exercise and plateaus at steady state. An upward drift inrate-pressure product may occur after approximately30 min of exercise as a result of heart rate increasingto a greater extent than systolic blood pressure decreases. The high rate-pressure product reflects thelarge amount of work the heart must perform to support heavy exercise.During prolonged exercise, particularly if performed in the heat, there is continued loss of totalbody fluid owing to profuse sweating. Total bodywater loss during long-duration exercise varies from900 to 1300 mL·hr 1, depending on work intensityand environmental conditions (Wade and Freund,1990). If fluid is not replaced during long-duration exercise, there is a continued reduction in plasma volume throughout exercise.Figure 13.6 illustrates the distribution of cardiacoutput at rest and during heavy exercise. Notice thatcardiac output increases from 5.8 L·min 1 at rest to17.5 L·min 1 in this example. The most dramaticchange in cardiac output distribution with heavy exercise is the dramatic increase in blood flow to the working muscle, which now receives 71% of cardiac output.Skin blood flow is also increased to meet the thermoregulatory demands of exercise. The absoluteamount of blood flow to the coronary muscle again increases although the percentage of cardiac output remains relatively constant. The absolute amount of cerebral blood flow remains constant, which means that the
Chapter 13 Cardiovascular Responses to Exercise 359(a)201510(e)220BP (mmHg)Q (L·min 1)25SBP180140MAP1005DBP600050% of maximal work0100050% of maximal work(b)20TPR (units)SV (mL)14010060050% of maximal work100100050% of maximal work(c)100(g)400180RPP (units)HR (b·min 1)155220140100300200100600100(f)1800Figure 13.7Cardiovascular Responseto Incremental MaximalExercise050% of maximal work1000050% of maximal work100(d)VO2 (mL·min 1)2500200015001000500050% of maximal work100percentage of cardiac output distributed to the neuraltissue decreases. Both renal and splanchnic blood floware further decreased as exercise intensity increases.Incremental Aerobic Exercise to MaximumAn incremental exercise to maximum bout consists ofa series of progressively increasing work intensitiesthat continue until the individual can do no more. Thelength of each work intensity (stage) varies from 1 to3 min to allow for the achievement of a steady state,at least at the lower workloads.Cardiac output displays a rectilinear increase andplateaus at maximal exercise (Figure 13.7a). The initial increase in cardiac output reflects an increase instroke volume and heart rate; however, at workloads
360 Cardiovascular–Respiratory System Unit120LVEDV110Ventricular volume (mL)100908070SV LVEDV LVESV6050403020LVESV10Rest300600 –750(kgm·min 1)PeakexerciseFigure 13.8Changes in LVEDV and LVESV That Account forChange in SV during Incremental ExerciseSource: Based on data from Poliner, et al. (1980).greater than 40–50% VO2max, the increase in cardiacoutput is achieved solely by an increase in heart rate.As shown in Figure 13.7b, in normally active individuals stroke volume increases rectilinearly initially andthen plateaus at approximately 40–50% of VO2max(P. Åstrand, et al., 1964; Higginbotham, et al., 1986).Stroke volume may actually decrease slightly near theend of maximal exercise in untrained and moderatelytrained individuals (Gledhill, et al., 1994).Figure 13.8 indicates the changes in left ventricular end–diastolic volume and left ventricular end–systolic volume that account for changes in stroke volumeduring progressively increasing exercise (Poliner, etal., 1980). Left ventricular end–diastolic volume increases largely because of the return of blood to theheart by the active muscle pump and the increasedsympathetic outflow to the veins causing venoconstriction and augmenting venous return. Left ventricularend–systolic volume decreases because of augmentedcontractility of the heart, which ejects more bloodfrom the ventricle and leaves less in the ventricle.Heart rate increases in a rectilinear fashion andplateaus at maximal exercise (Figure 13.7c). The myocardial cells are capable of contracting at over300 b·min 1 but rarely exceeds 210 b·min 1 becausea faster heart rate would not be of any benefit sincethere would be inadequate time for ventricular filling.Thus, stroke volume and ultimately cardiac outputwould be decreased. Consider the simple analogy of abucket brigade. Up to a certain point it is very useful toincrease the speed of passing the bucket; however,there is a limit to this speed because some time mustbe allowed for the bucket to be filled with water.The maximal amount of oxygen an individual cantake in, transport, and utilize (VO2max) is another variable that is usually measured during an incrementalmaximal exercise test (Figure 13.7d). AlthoughVO2max is considered primarily a cardiovascular variable, it also depends on the respiratory and metabolicsystems. As noted in Chapter 12, VO2max can be defined by rearranging the Fick equation (Eq. 12.9) to thefollowing equation, as described in Equation 12.14b.13.1VO2max (Q max) (a-vO2 diff max)The changes in cardiac output during a maximal incremental exercise test have just been described (arectilinear increase). The changes in the a-vO2 diffwere discussed in Chapter 11 (an increase plateauingat approximately 60% of VO2max). Reflecting thesechanges, oxygen consumption (VO2) also increases ina rectilinear fashion and plateaus at maximum(VO2max) during an incremental exercise test to maximum. The plateauing of VO2 is one of the primary indications that a true maximal test has been achieved.The arterial blood pressure responses to incremental dynamic exercise to maximum are shown inFigure 13.7e. Systolic blood pressure increases rectilinearly and plateaus at maximal exercise, often reaching values in excess of 200 mmHg in very fit individuals. The increase in systolic blood pressure is caused bythe increased cardiac output, which outweighs the decrease in resistance. Systolic blood pressure and heartrate are two variables that are routinely monitoredduring an exercise test to ensure the safety of the participant. If either of these variables fails to rise with anincreasing workload, cardiovascular insufficiency andan inability to adequately profuse tissue may result,and the exercise test should be stopped.Diastolic blood pressure typically remains relatively constant or changes so little it has no physiological significance, although it may decrease at high levels of exercise. Diastolic pressure remains relativelyconstant because of the balance of vasodilation in thevasculature of the active muscle and vasoconstrictionin other vascular beds. Diastolic pressure is mostlikely to decrease when exercise is performed in a hotenvironment; under these conditions skin vessels aremore dilated, and there is decreased resistance toblood flow.An excessive rise in either systolic blood pressure(over 260 mmHg) or diastolic blood pressure (over115 mmHg) indicates an abnormal exercise responseand is also reason to consider stopping an exercisetest or exercise session (American College of SportsMedicine [ACSM], 2000). Individuals who exhibit anexaggerated blood pressure response to exercise are
Chapter 13 Cardiovascular Responses to Exercise 361(a) Rest (Q 5.8 L·min 1)(b) Maximal Exercise (Q 25 L·min 1)Other ( 100 mL) 1% Splanchnic (300 mL)Renal (250 mL)Skin1%Cerebral (900 mL)(600 mL)2% 1% 3%Coronary muscle4% (1000 mL)Skin(500 mL)9%Other(600 mL)10%Splanchnic(1400 mL)24 %Skeletal 21%muscle(1200 mL)4%Coronary 13 %Cerebralmuscle(250 mL) (750 mL)19 %Renal(1100 mL)88%Skeletal muscle(22,000 mL)Figure 13.9Distribution of Cardiac Output at Rest and during Maximal ExerciseSource: Data from Anderson (1968).two to three times more likely to develop hypertensionthan those with a normal exercise blood pressure response (ACSM, 1993).Total peripheral resistance decreases in a negative curvilinear pattern and reaches its lowest level atmaximal exercise (Figure 13.7f ). Decreased resistance reflects maximal vasodilation in the active tissuein response to the need for increased bl
Example Calculate TPR by using the following information from Figures 13.1a and 13.1d: MAP 111
INDEX PRESENTATION 5 THE THUMB 7 MECHANICAL EXERCISES 8 SECTION 1 THUMB Exercise 1 12 Exercise 2 13 Exercise 3 - 4 14 Exercise 5 15 Estudio 1 16 SECTION 2 THUMB WITH JUMPS Exercise 6 17 Exercise 7 - 8 18 Exercise 9 19 Exercise 10 20 Exercise 11 - 12 21 Estudio 6 22 SECTION 3 GOLPE Exercise 13 23 Exercise 14 24 Exercise 15 25 Exercise 16 - 17 26 Exercise 18 27 .
Chapter 1 Exercise Solutions Exercise 1.1 Exercise 1.2 Exercise 1.3 Exercise 1.4 Exercise 1.5 Exercise 1.6 Exercise 1.7 Exercise 1.8 Exercise 1.9 Exercise 1.10 Exercise 1.11 Exercise 1.12 Fawwaz T. Ulaby and Umberto Ravaioli, Fundamentals of Applied Electromagnetics c 2019 Prentice Hall
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assisted in data collection in the Cardiovascular Exercise Physiology Lab. 13. One undergraduate research assistant (2011/2012) who assisted in data collection in the Cardiovascular Exercise Physiology Lab. 14. Three undergraduate research assistants (2010) who assisted in data collection in the Cardiovascular Exercise Physiology Lab. 15.
1.1 Identify the principles of range of motion, resistive exercise and manual muscle testing. 1.2 State the general principles of exercise including endurance, power, cardiovascular effects, and psychomotor considerations. 1.3 State the indications and contraindications to therapeutic exercise. 1.4 Identify the effects of pain on therapeutic exercise. 1.5 Identify components of an exercise .
Sample Responses and Rubrics Two of the four expository clarification prompts and two of the four expository point-of-view prompts have sample responses. Both of the persuasive prompts have sample responses. The narrative prompt also has sample responses. The three sample responses for each prompt are all modeled after the same basic essay.
