IJCRR - 6(6), March, 2014
Pages: 62-70
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EFFECT OF AEROBIC EXERCISE ON CARDIOVASCULAR FUNCTIONS AND REACTIVITY IN NORMOTENSIVE OFFSPRINGS OF NORMOTENSIVE AND HYPERTENSIVE PARENTS
Author: Amruta Chauhan
Category: Healthcare
Abstract:Introduction: Hypertension is a major health problem and when untreated, predispose to cardiovascular morbidity and premature death. Cardiovascular reactivity is the pattern of an individual's hemodynamic response to stress On the basis of genetic factor and environmental components, first degree relatives of essential hypertensive patients are known to be at risk of developing hypertension. Objective: The objective of the study is to compare the effect of aerobic exercise on response of cardiovascular functions and reactivity in normotensive offsprings of normotensive and hypertensive parents. Methodology: 30 individual with parental history of hypertension and 30 individual without parental history of hypertension were taken. At the beginning, baseline measures included body weights, heights were taken and BMI was calculated. After 5 minutes of rest, blood pressure reading was taken with mercury sphygmomanometer and heart rate reading was taken. Subjects performed aerobic exercise start with warm up in the form of slow walking for 5 minutes. Circuit training was given in the form of upper limb exercise, trunk mobility exercise, treadmill walking for 30 minutes. Subject performed exercise on RPE 6 and as much as can go above it on modified Borg scale with their maximum speed. Post parameter of heart rate and blood pressure was taken at immediately after, after 3 minute. Subjects performed cool down period in the form of slow walking for 5 minutes and again parameters were taken. Results: The result shows that there is statistically significant difference in the reactivity and cardiovascular functions in normotensive offsprings of hypertensive parents compared to normotensive offsprings of normotensive parents. Conclusion: The normotensive offsprings of hypertensive parents have increased reactivity and cardiovascular functions with delayed recovery compared to normotensive offsprings of normotensive parents.
Keywords: aerobic exercise, reactivity, offsprings
Full Text:
INTRODUCTION
Hypertension is a major health problem and when untreated, predispose to cardiovascular morbidity and premature death.1 Seventh report of joint national committee on prevention, detection, evaluation, and treatment of high blood pressure (JNC 7 report) has introduced following classification for adults aged 18 and older 2 ? Normal: <120 ? <80 mmHg ? Pre hypertension: 120-139 ? 80-89 mmHg ? Stage 1 hypertension: 140-159 ? 90-99 mmHg ? Stage 2 hypertension : ≥160 ? ≥100 mmHg On the basis of genetic factor and environmental components, first degree relatives of essential hypertensive patients are known to be at risk of developing hypertension.5 Reactivity is measured as the difference between baseline and initial stress response.5 Acute aerobic exercise may be potent stressor to the cardiovascular system. Stress activates the sympathetic nervous system directly causes increase in cardiovascular function. High sympathetic nervous system activity may interact with genetic factor, high sodium intake, obesity and lead to development of hypertension. Evidence supports that increased sympathetic nervous system activity in early hypertension and normotensive offspring of hypertensive parents. Both physical and mental stress causes increase in sympathetic activity. Normotensive offsprings of hypertensive and normotensive parents have increased cardiovascular and sympathetic nervous system reactivity to stress, but offsprings of hypertensive parents respond grater increased in cardiovascular reactivity. There is controversy about whether normotensive offsprings of hypertensive parents have an increased sympathetic response to stress. Such a response could produce a hyperactive sympathetic reaction, lead to development of hypertension. Both genetic and environmental factor are thought to contribute to this hyperresponsiveness. There are many studies on effect of mental stress of normotensive offspring of hypertensive parents. Little attention has been given to the importance of altered cardiovascular response in normotensive offsprings of hypertensive parents caused by physical exercise. Aerobic exercise includes arm exercise, trunk exercise and leg exercise so the whole body cardiovascular response can be checked. So, the need of the study is to compare the effect of aerobic exercise on response of cardiovascular functions and reactivity in normotensive offspring of hypertensive and normotensive parents
MATERIALS AND METHODOLOGY
Study Design: Source of Data: The study was conducted in Physiotherapy College. Study Duration: Total duration of study was 5 month Sample Design: Random sampling Sample Size: Total 60 subjects were taken: Group A: 30 subjects with parental history of hypertension Group B: 30 subjects without parental history of hypertension Inclusion Criteria: Age: 20-25 years Gender: male and female BMI within normal limits People willing to participate GROUP A: Subjects with parental history of hypertension GROUP B: Subjects without parental history of hypertension Exclusion Criteria: Doing regular exercise Any associated systemic involvement Any musculoskeletal problem Any neurological problem Any respiratory and cardiovascular diseases Data collection and procedure Materials Used Consent form, Data collection sheet, Pen, pencil, paper, Chair, Stop watch, Measure tap Appartus: Motorized treadmill, Weighing machine, Cuff sphygmomanometer Outcome Measure: Heart rate (HR), Systolic blood pressure (SBP), Diastolic blood pressure (DBP) Procedure: The entire subjects of this study were evaluated as per assessment format. Those who fulfilled all inclusion criteria were taken up for the study. The procedure was explained to all subjects. A written consent of all participants was taken. At the beginning, baseline measures included body weight, height was taken and BMI was calculated. After 5 minutes of rest, blood pressure reading was taken with mercury sphygmomanometer and heart rate reading was taken. Subjects performed aerobic exercise start with warm up in the form of slow walking for 5minutes.Circuit training was given in the form of upper limb exercise, trunk mobility exercise, treadmill walking for 30 minutes. (photograph 1- 3). Subject performed exercise on RPE 6 as much as can go above it on modified Borg scale with their maximum speed. Post parameters of heart rate and blood pressure were taken at immediately after, after 3 minute. Subjects performed cool down period in the form of slow walking for 5 minutes and again parameters were taken. Statistical tests were used to compare the data of both groups. Level of significance was kept at 5%.
RESULT
The study comprises the two groups with 30 subjects in each. In this study, all the descriptive analysis was done using software graph pad prism - 5. Group A and group B shows no statistical difference in age and body mass index value. (Graph 1-2) In this study, both group A and B performed aerobic exercise. Reactivity is measured as the difference between baseline and initial stress response of HR, SBP and DBP5 . The reactivity of HR, SBP, and DBP were taken. For comparison of reactivity between group A and B Mann-Whitney U was used. Table 1-4 shows significant difference in reactivity compared to group B at 5% level of significance. The value of mean and mean differences of HR responses is as shown in table 5 & 6. The value of mean and mean differences of SBP responses are as shown in table 8 & 9. The value of mean andmean differences of DBP responses are as shown in table 11 & 12. For comparison between group A and B Mann-Whitney U was used at immediately after exercise and at 3 minute after exercise. Table 7, 10, 13 shows statistically significant difference in of HR, SBP and DBP compared to group B respectively at 5% level of significance. After cool down period again Mann-Whitney U was used between two groups. There was no significant difference in group A and group B. DISCUSSION The present study was done to compare the effect of aerobic exercise on response of cardiovascular functions and reactivity in normotensive offsprings of hypertensive parents (group A) with the normotensive offsprings of normotensive parents (group B). Both groups in this study consisted of age, sex, and BMI matched, young, normotensive subjects. They differed only in the genetic propensity. The result shows that physical stress causes enhanced reactivity and increased immediate response of HR and BP in normotensive offsprings of hypertensive parents compared to normotensive offspring of normotensive parents. Stress related cardiovascular reactivity is assumed to a marker of autonomic or sympathoadrenal functions.6 Enhanced reactivity reflects a more general hyperadrenergic state, with elevation of neurohormones leading to increased risk for hypertension. BP reactivity may be a measure of poor endothelial function or the inability of the endothelium to counteract adequately the vasoconstrictive force induced by sympathetic stimuli.7 Folkow hypothesized that repeated episodes of stress over time cause a change in the wall-tolumen ratio of arterioles in subjects with genetic predisposition to hypertension, ultimately eventuating in a fixed increase in peripheral resistance and future hypertension. Thus, both genetic predisposition and environmental interaction may play necessary roles in thi process.8 Increased sympathetic activity may probably have a key role in the pathogenesis of hypertension.9 In this study, normotensive individuals with a genetic predisposition for hypertension showed increased sympathetic activity in response to physical stress. Noll et al. found excessive sympathetic activation in response to mental stress in normotensive offsprings of hypertensive parents.10 In the study of EG Ciolac, young normotensive women offsprings of hypertensive parents had increased resting, exercise, and recovery norepinephrine, and also exercise and recovery epinephrine than women with normotensive parents11 which may result in increased sympathetic activity. Increased endothelin-1 secretion play important role in development of hypertension. The enhanced vasoconstrictor response to endothelin-1 during exercise may be the result of an attenuated release of NO, a potent inhibitor of vascular contraction evoked by endothelin1. Additional explanation for enhanced vasoconstrictor response to endothelin- 1 may involve abnormality in endothelin receptor. In this study, the BP response to physical stress was exaggerated. This is supporeted by Enrico Mangieri, et al. handgrip increases endothelin-1 secretion in normotensive young male offspring of hypertensive parents.12 In other study Carmel M. et al assessed response to handgrip exercise before and after infusion of endothelin receptor antagonist and found that vasodilator response to exercise was markedly enhanced in hypertensive but not in noremotensive.3 Folkow had proposed that peripheral vascular adaptation to stress is an initiating factor in the hypertensive disease process. He argued that cardiovascular response to stress place pressure on the arterial vessel walls, initiating hypertrophy of vascular smooth muscle. This increases the vessel wall/lumen ratio, causing a vascular hyperreactivity to vasoconstrictor agents released during stress.13 The kidney may play a crucial role in development of genetic hypertension, perhaps in response to alteration in renal sympathetic activity. The possible mechanism would be early changes in glomerular function and vasoactive hormone execretion.14,15 O´ Connor DT et al. found that early allteration in glomerular reserve in humans at genetic risk of essential hypertension. 16 Another possible mechanism of exaggerated BP response may be the altered baroreceptor sensitivity. The baro-receptor reflex is a negative feedback system acting to reduce BP variability, with the adaptive end of preserving transcapillary pressure for maintain vital tissues which may cause increased BP response.17 The study of L. R. Davrath, they found reduced baro-receptor sensitivity during the active change of posture from supine to standing position in the young adult normotensive offspring of hypertensive parents.18 In our study, exercise response causes enhanced reactivity & delayed recovery since exercise causes potent stress on the cardiovascular system. This is in supported by Harmer M that acute exercise & mental challenges causes blunted cardiovascular response in offspring of hypertensive parents.19 The long standing hypothesis that normotensive individuals who show large response to mental and physical challenge are at risk for hypertension. Karen A. tested this hypothesis on BP reactivity to psychological stress and concluded that larger BP response may be at risk for hypertension.7 In contrast, the study of Manuck found no difference in HR and BP reactivity between parental history groups.20 In our study, Group A showed statistically significant difference at 3 minute after exercise in HR, SBP, and DBP compared to group B. There is no significant difference found in HR, SBP, and DBP after cool down in between group A and group B. The result suggests that increased response and delayed recovery present in normotensive offsprings of hypertensive parents compared to normotensive offspring of normotensive parents. Reduced parasympathetic tone may have role in the etiology of hypertension. This is supported by G M Schneider, they found delayed recovery to repeated mental stress in HR, DBP and preejection period in positive family group compared to negative family group.21 In contrast Visser et al. found no difference in vagal activity between positive and negative family history group after giving mental stress but they used active coping tasks (shock avoidance and a memory search task).22 The studies by Borghi et al. and Falkner et al. suggest that reactivity in young borderline hypertensive subjects can be used to predict stable hypertension several years later.35,51 Frank A. conducted examining prospective studies and concluded that enhanced cardiovascular reactivity can predict the development of preclinical states & even new events in some patients of hypertension.23Evidence of elevated sympathetic activation at such an early stage of disease progression emphasizes the necessity of targeting reduction in sympathetic activation as primary goal in prevention in the treatment of hypertension. The limitations of the study were invasive cardiovascular measures were not used and different group of offspring of one &/or two hypertensive parents was not considered. Future research may be on response can be checked by isometric exercise and mental stress. Gender affection can be checked. Predicted age can be checked.
CONCLUSION
There is statistically significant difference in the reactivity and cardiovascular functions in normotensive offsprings of hypertensive parents compared to normotensive offsprings of normotensive parents. So clinically, early identification of these individuals with a prehypertensive profile is necessary. Life style modification such as weight reduction and moderate intensity aerobic exercise programme which may delay or prevent the onset of hypertension should be done.
ACKNOWLEDGEMENT
I am thankful to Dr. Pankaj Patel, Dean N.H.L. Medical College for giving me an opportunity to do the study. I am grateful to Dr. Neeta Vyas, Principal of S.B.B.College of Physiotherapy, for providing me all facilities for my work, without which it would not have been possible to complete this project. I would like to express my deep sense of gratitude to my respected teacher Dr. Sweety Shah, Lecturer; for her invaluable guidance. I also express my gratitude to all the staff members of S.B.B. College of Physiotherapy for their assistance & help in carrying out this project work I will be failing in my duty if I do not thank my all the subjects, who participated in my study and spent their valuable time. I owe thanks to my family &friends who shared my anxiety and believed in my abilities specially Foram Dhebar, Maharshi Trivedi for their support in carrying out this study. I acknowledge the great help received from the scholars whose articles cited and included in references of this manuscript. I am also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed. I am grateful to IJCRR editorial board members and IJCRR team of reviewers who have helped to bring quality to this manuscript.
References:
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