intensities on blood pressure, heart rate and rate pressure product (an index of myocardial oxygen consumption). An increased understanding of this issue has ...
Kufa Med. Journal 2008. Vol. 11. No.1
Heart Rate and Blood Pressure Changes After Exercise In Normal Adolescent In Relation To Body Mass Index. )Yesar M.H.Al-ShammaMBChB,Ph.D(U.K. Ahmed Jumah Mhous BSc,Msc,Ph.D Ali M. M.Al Mousawi MBChB,MSc.
اﻟﺧﻼﺻﺔ:
َن ﺗَﺗﺣـ ّـرى اﻟﻌﻼﻗ ـ َﺔ ﺑـ ن اﻟﻠ ﺎﻗ ـ ِﺔ اﻟﻘﻠﺑ ــﺔ اﻟرﺋو ـ ِﺔ ﺑﺎﺳــﺗﺧدام ﻣؤﺷــر اﻹﺟﻬـﺎد ﺑﻌــد ﺧﻣــس دﻗــﺎﺋق ﻫـدف ﻫــذ اﻟد ارﺳــﺔ ﻛـﺎن أ ْ
وﻣﻌدل ﻧﺑﺿﺎت اﻟﻘﻠب. دم اﻻﻧﻘﺑﺎﺿﻲ ّ ودﻟ ل ﻛﺗﻠﺔ اﻟﺟﺳم )ﺑﻲ أم آي( ،ﺿﻐط اﻟ ّ ﻣﺗطوﻋﺎً ﺳﺎﻟﻣﺎً ) ٧٨ذﻛر ٦٦ ،أﻧﺛﻰ(ِ ، ﺑﻌﻣر ٢٢-١٨ﺳﻧﺔ. ﺗم اﻟﺑﺣث ﻓﻲ ﻣﺟﻣوﻋﺔ ١٤٤ ّ
ﻓﻲ ﻣﺟﻣوﻋـﺔ اﻟـذﻛور ،ﺑﻠـﻎ ﻣﺗوﺳـط دﻟ ـل ﻛﺗﻠـﺔ اﻟﺟﺳـم )ﺑـﻲ أم آي( ٠.٥١٧ -/+ ٢٧.٦٧ﻛ ﻠـوﻏرام ) m 2 /اﻟﻣـدى
ﺑ ن ١٧.٧و (٤٦.٤واﻧﺣراف ﻣﻌ ﺎري ،٤.٥٦٧ﺑ ﻧﻣﺎ ﻓﻲ ﻣﺟﻣوﻋﺔ اﻹﻧﺎث ،ﺑﻠﻎ ﻣﺗوﺳط دﻟ ل ﻛﺗﻠﺔ اﻟﺟﺳم )ﺑـﻲ أم آي( ٠.٦٧٧ -/+ ٢٩.٧١ﻛ ﻠوﻏرام ) m 2/ﺑ ن ١٦.٩و (٤٤.٤واﻧﺣراف ﻣﻌ ﺎري .٥.٤٩٨
أدى ُﻛ ّل ﻣﺗطوع ﺗﻣر ن اﺧﺗﺑﺎر ﻟﺧﻣس دﻗﺎﺋق ﻋﻠﻰ دورة َﻣ ْﻛُﺑوﺣﺔ ﺑﺎﻟﻛﻬروﻣﻐﻧﺎط ﺳ ﺔ. ّ اﻟدم اﻹﻧﻘﺑﺎﺿﻲ ﻗﺑل اﻟﺗﻣـرن ﺷـ ّﻛل ﻣﻌـدل اﻟﺧـط ﺣﺎﺻل ﺿرب ّ ﻣﻌدل ﻧﺑﺿﺎت اﻟﻘﻠب ﻗﺑل اﻟﺗﻣرن ﻣﺿروب ﺑﺿﻐط ّ
اﻷﺳــﺎس اﻟــذي ﻋﻧــد ﻣﻘﺎرﻧﺗــﻪ ﺑﻣﻌــدل اﻟﻧــﺎﺗﺞ اﻟــذي وﺟــد ﻣ ـن ﺧــﻼل ﺿــرب ﺿــﻐط اﻟــدم اﻹﻧﻘﺑﺎﺿــﻲ ﺑﻌــد اﻟﺗﻣــرن ﺑﻣﻌـ ّـدل ﻧﺑﺿﺎت اﻟﻘﻠب اﻟذروة اﻟذي أَﺧذ ﻓﻲ ﻧﻬﺎ ﺔ اﻟﺗﻣرن.
ﻛﺎن اﻹرﺗﺑﺎط ﺑ ن ﻣﻌدل اﻟﻧﺎﺗﺞ و ﻣﻌدل اﻟﺧـط اﻷﺳـﺎس ﻟﻠﻣﺟﻣوﻋـﺔ اﻟﻛﻠ ـﺔ اﻋﺗﺑﺎرـﺎً َ◌ ) (r = 0.32وأ ﺿـﺎً ﻟﻠﻣﺟﻣوﻋـﺔ اﻟﻧﺳﺎﺋ ﺔ ) (r =525ﻟﻛﻧﻪ ﻏ ر اﻋﺗﺑﺎري ﻟﻣﺟﻣوﻋﺔ اﻟذﻛ ور ) .(r 0.213 ِ اﻷﺳﺎس ﻓﻲ ﻛﻠﺗﺎ اﻟﻣﺟﻣوﻋﺎت. وﻛﺎن ارﺗﺑﺎط دﻟ ل ﻛﺗﻠﺔ اﻟﺟﺳم )ﺑﻲ إم آي( ﺳﻠﺑ ًﺎ ﺑﻣﻌدل اﻟﺧطّ
ﻧﺗﺎﺋﺞ اﻟدراﺳﺔ اﻟﺣﺎﻟ ﺔ ﺗﺷـ ر إﻟـﻰ ّأﻧـﻪ وﺑﺳـﺑب اﻹرﺗﺑـﺎط اﻟﻌﻛﺳـ ِﻲ ﺑـ ن دﻟ ـل ﻛﺗﻠـﺔ اﻟﺟﺳـم )ﺑـﻲ أم آي( وﻣﻌ ّـدل ﻧﺑﺿـﺎت اﻟﻘﻠـب ﺑﻌــد اﻹﺟﻬـﺎد )واﻻﺣﺗ ــﺎطﻲ( ﻟـذﻟك ﻗــد ﻛـون ﻣــن اﻟﻣﻔ ـد اﻋﺗﺑــﺎر دﻟ ـل ﻛﺗﻠــﺔ اﻟﺟﺳـم )ﺑــﻲ أم آي( ﻓـﻲ ﺗﻣــﺎرن اﻟﻠ ﺎﻗــﺔ اﻟﻘﻠﺑ ﺔ اﻟرﺋو ﺔ ﻓﻲ اﻟﻣواﺿ ﻊ اﻟﻣﺧﺗﻠﻔﺔ.
Abstract: The aim of this study was to investigate the relationship between cardiopulmonary fitness as indicated by 5minutes (5min.) work rate (W5min.) production, body mass index (BMI), systolic blood pressure and heart rate reserve. A total of 144 sedentary volunteers (78 males, 66 females), aged 18-22 years were enrolled in the study. For male group the average BMI was 27.67+/-0.517 kg/m2 (range between 17.7 and 46.4) with standard deviation 4.567, while in female group the average BMI was 29.71+/0.677 kg/m2 (between 16.9 and 44.4) with standard deviation 5.498. Each subject performed an exercise test (15 W/min) for five minutes on an electromagnetically-braked cycle ergometer. Heart rate at rest multiplied by systolic blood pressure (SBP) at rest formed the base line figures compared to the output figures found by multiplying SBP by the peak heart rate taken at the end of exercise. 437
Kufa Med. Journal 2008. Vol. 11. No.1 Correlation between base line and output figures for all the group was significant (r=0.32) and also for the female group(r=525) but insignificant for the male group (r0.213). BMI was negatively correlated with baseline figures in both groups. The results of the present study have suggested that, due to the inverse correlation between BMI, W5min. and heart rate reserve, it may be useful to consider BMI in establishing cardiopulmonary fitness in various subjects.
Introduction: Exercise tests are commonly used for assessing the cardiopulmonary system functions in subjects with a different health status. It is well established that cardiopulmonary responses to exercise can be used to define pathophysiological processes that limit exercise and diagnose various diseases.(39,42) Although an acute bout of submaximal exercise can cause important cardiovascular changes, there are few and controversial published data on the effect of different exercise intensities on blood pressure, heart rate and rate pressure product (an index of myocardial oxygen consumption). An increased understanding of this issue has clinical implications, in addition to being important in prescribing exercise intensities for humans. Most studies dealing with post-exercise blood pressure responses have demonstrated that exercise reduces blood pressure during the recovery period.(1-3,5-7,13,15,17-19,21,28,3032,36,38,43)
A progressively increasing work rate exercise testing which provides a smoothly graded stress to the subjects is considered to be one of the most objective methods providing relevant information in impairment disability evaluation compared to resting cardiopulmonary measurements.(39,42) During exercise, cardiopulmonary system functions are associated with increased metabolic demands. When the oxygen providing capacity of the cardiopulmonary system to exercising muscles falls behind their demands during high intensity exercise، increased energy demands are compensated by the anaerobic metabolism.(39) During exercise, the metabolic transition point from aerobic to anaerobic metabolism, which is called the anaerobic threshold, is a widely used concept for determining the level of aerobic fitness, muscular strength and endurance in clinical medicine and sporting activities.(39) Importantly, it has been reported that reduced cardiopulmonary fitness is associated with an increased mortality rate.(24,40) Reduced aerobic fitness and exercise capacity are closely related with the level of cardiopulmonary fitness and commonly observed findings in patients with high body mass index (BMI).(33,35) A reduced aerobic fitness expressed as decreased work production capacity is an important factor affecting the energy intake to consumption ratio and leading to a positive energy balance and excess fat mass.(20) In addition, studies in young children and adolescents showed that high aerobic fitness is associated with a reduction in risk factors related to later cardiovascular system diseases.(11,44) Thus, it is important to determine the 438
Kufa Med. Journal 2008. Vol. 11. No.1 relation between BMI, aerobic fitness and exercise capacity in young subjects, which can be useful as a marker of cardiopulmonary system functions. Nevertheless, the magnitude and the time course of blood pressure changes after exercise are inconsistent. In normotensives, the magnitude ranges from no change(5,8,15,30,31) to falls as great as 30 mmHg.(38) In hypertensive humans, Somers et al.(38) observed that blood pres-sure levels are significantly lower than pre-exercise levels only during the first hour of recovery, while Pescatello et al.(30) found a significant blood pressure fall up to 12 h after exercise. In relation to post-exercise heart rate responses, the results are also controversial and less conclusive. Some investigators(2,5,6,13,18,19,21,31,43) have observed an increase in heart rate levels during the recovery period. In contrast, others have reported no change(1,3,7,8,15,21,30) or even decreases(17,28) in post-exercise heart rate responses. The experimental protocol, the initial levels of blood pressure, and the type، duration and intensity of exercise may explain، in part, these discrepancies in post-exercise blood pressure and heart rate responses.(22) It has been well established that the magnitude of neural and hemodynamic responses during exercise is directly related to exercise intensity.(25,36) Thus, it is possible that different exercise intensities have also distinct effects on cardiovascular changes after exercise. Hagberg et al.(17), in a study of older hypertensive men, observed that hypotension after exercise performed at 70% of maximal oxygen consumption (VO2 max) was greater and lasted longer than after exercise performed at 50% of VO2 max. Piepoli et al.(31) reported that maximal exercise provoked an increase, while low to moderate exercise caused no change in post-exercise heart rate levels in normotensive subjects. Never the less, it is possible that low intensity exercise induces a reduction in sympathetic nerve activity to the heart and blood vessels during the recovery period. Chen et al.(3) observed a decrease in sympathetic tone to the heart after mild exercise in spontaneously hypertensive rats and Floras et al.(13) and Halliwill et al.(18) found a significant decrease in muscle sympathetic nerve activity after acute exercise in hypertensive and normotensive humans. Despite the fact that both moderate and high intensity exercise decreased blood pressure, no reduction in rate pressure product was observed. Halliwill et al.(18) observed that after an acute bout of moderate exercise,baroreflex control of heart rate and blood vessels is distinctly regulated. In other words, sympathetic drive to the heart increases, while sympathetic drive to blood vessels decreases. Thus, it is possible that different exercise intensities may distinctly affect the baroreflex control of heart rate, but not the baroreflex control of blood vessels. Moreover, the vasodilatory response(31) and/or the decrease in blood volume(28) may play a role in the post-exercise blood pressure fall. The absence of a blood pressure fall during the non-exercise control trial shows that, in fact, the decreased blood pressure levels after exercise are due to the exercise effect and not to the normal diurnal blood pressure variations.(14) It is well understood that muscle metabolites and heat accumulation are directly related to exercise intensity, and sweating rate is greater during more intense exercise.(26) 439
Kufa Med. Journal 2008. Vol. 11. No.1 In addition, the increased local muscle metabolites(9,27) and/or heat production (15) are also potential stimuli for the increased heart rate responses after moderate and high intensity exercise. The extent to which age-associated changes in aerobic capacity and body composition modulate the age-associated decline in heart rate variability (HRV) is unknown. Byrne et al. found that there were no consistent independent contributions of BMI to HRV) in 164 healthy normotensive adults from the Baltimore Longitudinal Study on Aging.(5)
Methods: The aim of this study was to investigate the relationship between cardiopulmonary fitness as indicated by five minutes work rate (W5min.) production and body mass index (BMI) and heart rate and systolic blood pressure reserve in response to work rate exercise test in young sedentary male and female subjects. Seventy eight male (age 18-22 years) and 66 female (age 18-22 years) subjects were asked to perform a cardiopulmonary exercise test for 5 minutes. In the present study, to eliminate the age-related decline in work production capacity, the subjects’ age was limited to 18 to 22 years. The subjects had to be healthy, without known cardiac symptomatology (determined by personal history and by electrocardiography), lung disease and musculoskeletal impairment, not to be on regular medication, and to be able to complete safely a five minutes exercise test. Blood pressure was measured by experienced observers using a standard mercury sphygmomanometer, taking the first phases of Korotkoff sounds as systolic and diastolic values, respectively. Pulse rate was counted by the same experienced observer. BMI was calculated as the ratio of body mass/height2 (kg/m2). Body weight and height were measured, in light clothing without shoe, to the nearest 0.1kg and 0.5 cm, respectively, before the cycling test. The subjects were requested not to eat a heavy meal or smoke at least 2 h before the test and also refrain from taking any drug, or caffeine for a period of 12 h before the test. After becoming familiar with the testing equipment, a five minutes exercise test was performed by each subject to assess cardiopulmonary capacity. Each subject performed five minutes ramp test (Whipp et al. 1981) using a calibrated electromagnetically braked cycle ergometer. At the end of the test, the heart rate and lying systolic blood pressure was measured and recorded; these data were later downloaded to a computer for analysis. Data were expressed as mean ± S.E.M. For statistical comparison between the males and females Student’s t-test was used. P
