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SPS2201 – Exercise Physiology Laboratory Report 3 Cardiovascular Response to Exercise Greg Levin Student Number: 2011360 Edith Cowan University 1.0 Introduction The added stress placed on the body during exercise causes many changes to occur within the body. In fact Laughlin (1999,p. 244) explains that dynamic exercise places more stress on the cardiovascular system than anything else. One of the most important changes is the response of the cardiovascular system to deal with the increased amount of blood and oxygen required by the working muscles (Wilmore & Costill, 1994, p. 176). The way in which the system responds can be seen by changes in heart rate, blood pressure, and ECG. 1.1 Aim To view if changes in the heart rate, blood pressure, and ECG are a direct result of varying workloads. 2.0 Method 2.1 Participants In order to test for any variation between males and females, two participants took part in the test. ‘Subject 1’ was a male in his early to mid-twenties and ‘subject 2’ a younger female in her late teens. Neither of the subjects were elite athletes although both exercise regularly. 2.2 Materials The equipment that was required to carry out the test included a Repco cycle ergometer, a PE 4000 heart rate monitor and IBM computer interface, a sphygmomanometer and stethoscope, and a stopwatch. 2.3 Procedure The participant was seated and a resting blood pressure (BP) and resting heart rate (HR) was recorded. A three lead ECG was attached to the subject in order to take recordings of the heart activity. The ergometer was then adjusted to suit the physique of the subject. Once seated on the ergometer another set of BP and HR readings were recorded. The participant then began cycling at a workload of 50 watts. At the completion of three minutes the workload was increased to 100 watts and then again at the end of the next three minutes the workload was increased to 150 watts. The participants HR was monitored and recorded every minute while ECG and BP were only recorded at the end of every three-minutes. Upon completion of the 9 minutes the participant was instructed to continue cycling for a further three minutes, a cool down period, at a decreased workload of 50 watts. As before the HR was recorded at every minute of the cool down and the BP and ECG were recorded only at the end of the three minutes. This was repeated for both participants. Due to a testing fault the male subject’s workloads increase was greater than 50 watts. 3.0 Results As expected there was an increase in both heart rate and blood pressure of both subjects. Systolic blood pressure increased by 74mmHg and 59mmHg in the two subjects (see Table 1) and there was also a constant increase in heart rate as the workload increased (Figure 1). Initial heart rates were 65bpm and 70bpm while the maximal heart rates were 177bpm 184bpm respectively. The initial blood pressure of subject 2 was taken three times because of difficulty in hearing both the systolic and diastolic pressures and therefore the figures might be slightly inaccurate. Table 9 Blood Pressure Responses to Increasing Workloads Workload (Watts) 0 0ª 50 100 150 50 Subject 1 Subject 2 124/90 114/76 124/68 176/68 188/72 164/70 110/55 111/60 150/65 160/65 170/70 140/60 ª Second blood pressure taken while sitting on the bike. Heart Rate (bpm) Heart Rate: Subject 1 (bpm) Heart Rate: Subject 2 (bpm) 200 180 160 140 120 100 80 60 40 20 0 0 0 50 100 150 50 Workload (watts) Figure 1. Heart rate responses to varying levels of exercise 4.0 Discussion The heart rate and blood pressure were recorded twice while the subject was not doing any work. The first recordings were a the subjects true resting heart rate and blood pressure, whereas the second set of recordings were taken once the subject had already seated him/herself on the bike. Usually increases are seen between resting heart rates and the newer rates recorded just prior to exercising (Wilmore & Costill, 1994, p. 177). Unfortunately neither of the subjects showed any signs of the anticipatory increases. This could be as a result of the subjects knowing that they were going to partake in the tests. Both subjects exhibited similar signs and responses to the exercise. Despite subject 1’s workload increasing more than the desired 50 watts a comparison could still be drawn between the two subjects. The systolic blood pressure increased slowly and then climbed steeply as the intensity levels became harder. This was similar to what Man-I and Imachi (1981, p. 103) described when they said, “the measurement of both blood pressure and heart rate react greatly but slowly to exercise in untrained subjects.” Even though both subjects do exercise regularly neither of them is trained in cycling, and therefore fall into the category of untrained athletes. Diastolic blood pressure on the other hand was almost unchanged. This is consistent with previous findings and studies on the effects of exercise on blood pressure (Laughlin, 1999, p. 249). Heart rate increases matched the increase in workload and appeared at near maximal levels for both subjects. Maximal levels were calculated at 220 minus participant’s age (Wilmore & Costill, 1994, p. 177). An increase in the amount of blood needed in the body causes an increase in blood pressure. This is because the heart must pump more blood out of the heart at each contraction increasing the systolic pressure (Wilmore & Costill, 1994, p. 169). Although the use of a manual sphygmomanometer during exercise has caused concern about its accuracy, it is still a suggested method (Griffin, Robergs, &Heyward, 1997, p. 153). A problem that does arise however is that manual sphygmomanometry takes approximately 50 seconds, a time period that was too long, and caused an overlap in intensity differences. Resting ECG’s showed a large gap between the ‘P’ and ‘T’ complexes. This gap symbolises the amount of time that the heart takes between ventricular repolarisaion and atrial depolarisation. When the exercise intensity was raised the gap between the two became shorter signifying that the heart was working at a much faster rate. The contracting of this gap was visible best the rest and commencement of exercise. This indicates that the body needs to adjust as quickly as possible. Another clear indication on the ECG was that the returning of the heart to rest patterns, during the cool down period. Recovery rates of the 2 subjects varied. Some cause of this might be because of the fact that subject 1 worked at greater intensities and therefore was more fatigued. However both subjects showed declines in their systolic blood pressures and their heart rates. The rate at which these decline may be attributed to the level of fitness and level of training of the athlete but neither was relevant in this case. In conclusion, the test performed was successful in attaining the goals that were set out. However due to the levels of inexperience amongst the testers not all information can be regarded as being extremely accurate. Therefore while this test does show the changes associated with the cardiovascular system in response to exercise, past and future results are more reliable. References Griffin, S.E., Robergs, R.A., & Heyward, V.H. (1997). Blood pressure measurement during exercise: a review. Medicine and Science in Sport and Exercise, 29(1), 149 – 158 Laughlin, M.H. (1999). Cardiovascular response to exercise. American Journal of Physiology, 277, S244 – S259 Man-I, M., & Imachi, I. (1981). Effect of training on blood pressure and heart rate measured continuously during exercise. The Journal of Sports Medicine and Physical Fitness, 21(2), 102 – 111 Wilmore, J.H., & Costill, D.L. (1994). Physiology of sport and exercise. USA: Human Kinetics