Running Header: CARDIOVASCULAR RESPONSE AT REST AND DURING SUB- MAXIMAL WORK Cardiovascular Response at Rest and During Sub-Maximal work Exercise Physiology Lab 4 Kin 3010 Name: MariaCristina De Rose Student #: 0756618 Due: November 14 th 2013 Due To: Alison Ludzki
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 2 Abstract M De Rose. Cardiovascular Response at Rest and During Sub-Maximal Work of two Healthy Active Young Adult Females While performing sub-maximal work, blood pressure (BP) is calculated in response to exercise mode and their intensities. Two protocols, endurance and resistance, were done to investigate the increase in BP whereby further calculations were performed to establish systolic, diastolic and mean arterial pressures. An increase in work is proportional to the increase in BP. Systolic and diastolic pressures differ slightly with the different modes of exercise. All in all the cardiovascular response to work is an elevation in total BP. KEY WORDS: Sub-Maximal Work, Aerobic, Resistance, Blood Pressure, Heart Rate, Systolic, Diastolic, Mean Arterial Pressure, Total Peripheral Resistance
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 3 Introduction Cardiac output (Q) heart rate (HR), blood pressure (systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP)) and oxygen consumption (VO 2 ) are just a few physical changes that happen with an increased metabolic activity (Sprangers et al., 1991). These increases are crucial as they aid the body in regaining homeostasis. The responses of the body differ depending on the state in which the body is in; at rest or under a stress. Reactions within the body will happen regardless, yet the time in which they take, differs. Muscle sets the demand in terms of energy production, but this is not the only factor that regulates its production. The respiration and cardiovascular units must systematically respond to changes in concentrations, such as oxygen (PO 2 ) and carbon (PCO 2 ) concentrations. In order for quick product / by-product exchange to occur, the O 2 must be loaded into the blood at the lungs and unloaded at the muscle while CO 2 is ultimately undergoing the opposite reactions, loading of CO 2 into the blood at the muscular level and unloading it into the lungs to be expired. This happens by an increase in HR, Q, blood pressure and V E. Rate of gas exchange varies at different intensities of work, and this phenomenon is not fully understood, as there are many variables to account for when examining the flow of gas and blood. However, knowing the basic physiological adaptations at rest can help with better understanding the processes happening with increases in intensity. At rest, there is a required amount of energy that is said to be the basal metabolic rate (Nishimoto et al., 2012) therefore, with an increase in work there is an increased demand for energy which sends signs to increase regulation of the cardiorespiratory system; HR, blood pressure, VO 2. HR increases in order to deliver more oxygenated blood to the tissues, a climb in VO 2 is due to the increased O 2 demand, and overall blood pressure increases since there is greater pressure on the vessel walls. Blood pressure is an interesting variable to examine since there is
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 4 both vasodilation and vasoconstriction at the local and peripheral vessels, respectfully with a final outcome of overall increase in pressure (Brett et al.,2000, MacDougall et al., 1985). Through calculations, we are able to identify the rise of the different elements of the cardiorespiratory system by using the appropriate equations; Q (Q=5xVO 2 +5), stroke volume (SV) (SV= Q/HR), and total peripheral resistance (TPR). In knowing this information, better understanding of the differences at any given workload within body is gained, examples being sub-maximal vs maximal VO 2 test, and resistance vs1rm tests (MacDougall et al., 1985). During the laboratory performed, this concept was explored, cardiorespiratory difference at rest, during aerobic and resistance training. The rise of all variables is expected with a larger workload since there is a proportional relation. The opposite outcome is expected of TPR due to its inversely proportional relationship. Methods Subject The participants were healthy females, aged 20-22, with average height and weight. The subjects self-classified as being active individuals, which would suggest normal values for both HR and blood pressure. Testing Procedure MOXUS Metabolic Cart and On-line System is the main tool used to aid in the collection of data during the testing of the cardiorespiratory systems when performing sub-maximal VO 2 test. The headpiece, as a whole, consists of a mouthpiece, spit cylinder, two 2-way valves, and the headpiece, rests on the subjects head and is used to analyze inspired and expired air. The nose piece is essential as it ensures all airflow is to and from the mouth where no air is gained or
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 5 lost through the nose. Heart rate (HR) is measured via a monitor that is worn by the subjects, which then transmits data onto a watch that is then read and recorded. Blood pressure is measured via a blood pressure cuff, which is taken manually. Responses of the cardiovascular system during aerobic exercise. A cycle ergometer is used to perform this part of the test. This test is only sub-maximal meaning the subject never reaches a VO 2max/peak. The protocol designed increases workloads (50 Watts each time) over a series of stages that last for 5 minutes each while maintaining a cadence of 70 RPM. Increasing workload increases the cardiovascular response. Values for HR and blood pressure (systolic and dystonic (SBP, DBP) were recorded at rest, at the end of each workload (5, 10, 15, 20 mins of the protocol), and 1 minute after as recovery (26 min); from this further calculation can be done (See Appendix). Ensure that subject does not grip the handlebars or hold their breath as this may cause data to be inaccurate. Responses of the cardiovascular during resistance exercise. Dumbbells are used to perform this part of the test (choose appropriate weight. Ensure that the completion of 15 repetitions and 5 sets can be performed). Exercise is performed with weight in the left hand and blood pressure calculated on the right arm. This protocol is designed to increase blood pressure during the series of 5 sets. HR and blood pressure values were recorded just before the completion of each set of 15 repetitions (at approximately the 9 th repetition). Ensure that the subject does not hold their breath or grip too tightly to the weight as this may cause data to be inaccurate.
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 6 Results SBP, DBP, MAP vs Time for Aerobic Exercise Sub- maximal test SBP, DBP, MAP vs Time for Resistance Exericse (Time mins) Figure 1 a) 1b) HR vs Time for Aerobic Exercise HR vs Time for Resistance Figure 2 a) 2b)
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 7 Figure 3 Figure 4 Figure 4
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 8 Radial Carotid Auscultation HR SBP DBP Pulse Pulse (BPM) monitor (mmhg) (mmhg) (BPM) (BPM) (BPM) Rest 80 76 76 76 120 80 Table 1. Resting HR and BP for Aerobic Subject Power Time HR SBP DBP VO 2 VCO 2 Output (W) (min) (BPM) (mmhg) (mmhg) (L/min) (L/min) Rest 0 76 120 80 0.289 0.338 Sit on Bike 5 103 120 84 0.369 0.377 50 W 10 95 128 84 0.592 0.469 100W 15 133 148 94 1.598 1.564 150W 20 170 154 88 2.374 2.512 Recovery 1 123 138 60 1.531 1.719 Table 2. Measured Cardiovascular Responses to Graded Sub-Maximal Aerobic Exercise Power Output (W) Time MAP CO SV TPR (min) (mmhg) (L/min) (ml/beat) (mmhg/l/min) Rest 0 93.33 6.445 62.57 14.48 Sit on bike 5 96 6.845 66.46 14.02 50 W 10 106 7.96 83.79 13.32 100W 15 121 12.99 97.67 9.31 150W 20 121 16.87 99.24 7.17 Recovery 1 99 12.655 102.89 7.82 Table 3. Calculated Cardiovascular Responses to Graded Sub-Maximal Aerobic Exercise Weight selected (lbs) Set # HR (BPM) SBP (mmhg) DBP (mmhg) Table 4. Cardiovascular Responses to Constant Load Resistance Exercise MAP (mmhg 3 min Rest 84 116 84 94.67 1 93 116 84 100 2 91 120 86 103 5 lbs 3 97 122 92 107 4 101 126 96 111 5 94 124 92 108 1 min Recovery 92 108 82 95
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 9 Aerobic Exercise Linear increases in HR, Q, SBP, DBP, and MAP during sub-maximal aerobic exercise was easily observed during this protocol. The decrease in total peripheral resistance (TPR) is also evident, due to local vasodilation (Fig. 1a, Tab.1, 2,3). As time goes on, workload increases, the changes in SBP, DBP and MAP are amplified. This demonstrates an escalated demand by the muscle tissue due to increased blood flow ultimately caused by an increase in intensity. Conversely, TPR, seems to lower with the increase in intensity demonstrating increase local vasodilation in the working tissues. Resistance Training HR, SBP, DBP and MAP all seem to have a similar effect when the stress is changed to resistance training (Fig. 1b, Tab. 4). These values all increase as expected, but since the weight use was very light the amplified changes are not seen. Also, due to the fact that BP was taken manually during a very quick bout of resistance exercise, the changes that may have occurred might not have been fully gathered. However, muscle contraction is likely to be the factor for increase in overall BP, including SBP, DBP, MAP and TPR. Discussion During both the aerobic and resistance exercise bouts there was an apparent increase in SBP DBP and MAP when being compared to the resting state of the subject; the change between types of exercise however differed. A larger increase in pressures was achieved during the aerobic protocol and this may be due to the difference in 1) lengthen of protocol, 2) percent increase in workload or 3) change in subject. During the resistance bout only 5 pounds was used and it seemed to be very easy for the subject. Since the work done was at a low intensity the changes in pressure will be proportional thus, being low. The slight increase that was observed
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 10 however may have been due to the slight compression on the arteries caused by compression of the muscle during contractions and by the increase in HR during regular beating ( Q x TPR= MAP). In contrast, if a larger amount of weight was used an increase in both SBP and DBP would have been higher then resting values. During resistance and aerobic exercise SBP increase due to increase activation of the sympathetic nervous system (SNS), which signals vasoconstriction of peripheral vessels ultimately increasing pressure. DBP on the other hand does not increase drastically during aerobic exercise because the SNS also signals to the local blood vessels stimulation dilation. During resistance exercise the same signaling happens except that since the muscles are undergoing a large forceful contraction the working muscles compress on the vasodilated vessels causing more pressure, in turn increasing DBP. Another reason for increasing pressure with greater stress, is likely the effect of a larger request for O 2 at the muscle tissues as well as an increased need to remove metabolic waste CO 2 causing increase Q. During any type of exercise there is increase in SNS and the amount of activation will correlate to the change in pressure; easy work - low intensity - low pressure change rate, hard work - high intensity - high pressure change rate. The opposite is true during rest; very low work very low intensity, negligible pressure change rate. The body however is sensitive to change, so even the slightest movement can increase BP momentarily. Comparing BP values for rest and sitting on the bike are almost identical. The waiting time of 5 minutes at rest and 3 minutes sitting allows for the small spike in pressure to dissipate; therefore, since there are no physiological increases there is no difference at rest and sitting on the bike. All observations for this report as stated above were made on healthy females, that selfclassified as being active, however active does not assume trained. When comparing trained
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 11 individuals (TI) to untrained individuals (UTI) it is expected that the TI will have a slightly lower BP due to any or all of the listed factors; ability to maintain blood flow to non-active tissues, delayed responses to increase SV (stronger left ventricle), less metabolic activation needed to work, and ability to prolong endurance (Hambrecht et al., 2000, Levy et al., 1998). The following adaptations lower Q since HR and SV are lower; therefore, allowing the body to be more efficient at any given workload. With this said TI might also have lower BP at rest since they are less likely to experience SBP spikes with sudden movement since they have a reduced SNS. During exercise or at an absolute workload (example 150 watts) TI will also have a lower BP compared to UTI. This statement is valid because at any given workload TI will have a lower HR then an UTI. Since HR correlates to BP (CO= MAP/TPR) this shows that BP indeed will be lower. Knowing that BP increases with intensity and exercise we can precisely state that MAP also increases. MAP is the sum of the systolic phase and the diastolic phase. However, we are presented with two different equations to calculate MAP at rest and exercise. This is due to the fact that the percent of each phase changes with exercise. Understanding that at exercise both the systolic phase and the diastolic phase are about even helps us understand why the equation is half SBP plus half DBP. At rest the systolic phase accounts for one third of the equation because more time is taken to fill the ventricle then to eject blood from the ventricle. Therefore, the diastolic phase accounts for the larger part of the equation being two thirds (Rogers et al., 2000, Appendix 1). As mentioned above, small motions can cause a spike in pressure ultimately changing it. Movements such as kicking, making a fist, shoulder shrugs can cause slight increases to BP. When doing the aerobic protocol the subject is instructed to not grip the handle bars tightly while
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 12 BP is taken. The reasoning behind this is because gripping the bars can cause tension in the arm muscles, a miniature isometric contraction, causing a slight increase in pressure in the arm. The mechanical compression can potentially elevate BP as the cuff is placed around and BP is read using the arm (brachiocephalic artery). Similar to the gripping movement, during the resistance protocol the subject is told not to hold their breath but instead exhale as the weight is being lifted. This is done in attempt to ensure measurement accuracy. Intra-abdominal is increased when there is a change in breathing patterns. The intra-abdominal muscles push against the thoracic walls and ultimately decreasing the space that the heart has to complete its contraction (Paprika et al., 2011). MacDougall et al., shows that this can raise values during exercise and during the performance of muscle contraction (1985). Exploring the effects of BP with exercise of any type can help us investigate whether or not resistance training has an affect on causing hypertension, the chronic state of high BP. There are many factors to consider when trying to find an answer; duration, frequency. Some studies state that there is a positive change the hypertension can stem from resistance training (Collier et al, 2008), while others show insignificant effect (Fleck, 1988). When exploring the literature Kelley et al concluded resistance training, if done properly shows no increase to resting levels of BP (2000). Also, according to Canadian Society of Exercise Physiologists (CSEP) Physical Activity Guidelines adults 18-64 and older adults 65+ should engage in strengthening activities, at least 2 days per week as they provide numerous benefits (2013). With this research done, data suggests that weight/resistance exercise has no negative affects and if there are, they are positive helping lower BP.
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 13 Conclusion In an attempt to explore the relationship between the cardiovascular system and exercise the conclusion is that an increase in intensity will also increase BP and HR independent of the mode chosen. Our results mirror similar studies such as that done by Hambrecht et al. (2000). Moreover, raised levels of SBP, DBP and MAP with both aerobic and resistance training run true with current literature. All in all subjects of this protocol experienced the effects of the cardiovascular system at sub-maximal exercise, which is an increase in total BP.
CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 14 References Brett, S. E., Ritter, J. M., & Chowienczyk, P. J. (2000). Diastolic Blood Pressure Changes During Exercise Positively Correlate With Serum Cholesterol and Insulin Resistance. Circulation, 101(6), 611 615. doi:10.1161/01.cir.101.6.611 Cameron, J. D., & Dart, A. M. (1994). Exercise training increases total systemic arterial compliance in humans. American Journal of Physiology - Heart and Circulatory Physiology, 266(2), H693 H701. Collier, S. R., Kanaley, J. A., Carhart, R., Frechette, V., Tobin, M. M., Hall, A. K., Fernhall, B. (2008). Effect of 4 weeks of aerobic or resistance exercise training on arterial stiffness, blood flow and blood pressure in pre- and stage-1 hypertensives. Journal of Human Hypertension, 22(10), 678 686. doi:10.1038/jhh.2008.36 CSEP- PATH (2013). Canadian Physical Activity Guidelines. Fleck, S. J. (1988). Cardiovascular adaptations to resistance training. Med Sci Sports Exerc, 20(5 Suppl), S146-51. Hambrecht R, Gielen S, Linke A, & et al. (2000). Effects of exercise training on left ventricular function and peripheral resistance in patients with chronic heart failure: A randomized trial. JAMA, 283(23), 3095 3101. doi:10.1001/jama.283.23.3095 Kelley, G. A., & Kelley, K. S. (2000). Progressive Resistance Exercise and Resting Blood Pressure A Meta-Analysis of Randomized Controlled Trials. Hypertension, 35(3), 838 843. doi:10.1161/01.hyp.35.3.838 Levy, W. C., Cerqueira, M. D., Harp, G. D., Johannessen, K.-A., Abrass, I. B., Schwartz, R. S., & Stratton, J. R. (1998). Effect of endurance exercise training on heart rate variability at rest
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CARDIOVASCULAR RESPONSE AT REST AND DURING SUB-MAXIMAL WORK 16 Appendix 1 Formulas: Resting MAP = 1/3 SBP + 2/3 DBP Exercise MAP = 1/2 SBP + 1/2 DBP Watts =Kg RPM CO = 5 VO 2 +5 CO = HR SV SV CO/HR CO= MAP/TPR TPR = MAP/CO Extra data: Estimated VO 2 (ml/kg) = Recreational individuals à 50 ml/kg Body Weight of subject doing the aerobic exercise protocolà 74kg Estimated VO 2 max (L/min): VO 2 =50 ml/kg x1000ml 74kg = 3.7L/min Estimated max wattage (W) = VO 2 L/min-0.435 3.7L-0.435 = 286.15W 0.01141 0.01141