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8. Markovic, G. (2007). Does plyometric training improve vertical jump height? A metaanalytical review. British Journal of Sports Medicine, 41, 349-355 p.
9. Yu, B., Gabriel, D., Noble, L., and An, K. (1999). Estimate of the optimal cutoff frequency for the Butterworth low-pass digital filter. J Appl Biomech 15: 318-329 p.
10. Jensen R.L., Ebben WP. (2005). Ground and knee joint reaction forces during variation of plyometric exercises.”In: Proceedings of the XXIII International Symposium of the Society of Biomechanics in Sports, (K. E. Gianikellis, ed.) Beijing, China: 222-225 p.
Spahiu Elton, Erindi Altin, Sports University of Tirana PhD student at Sport Sciences E-mail: eltonsph@yahoo.it
Gender differences responses in isometric exercise
Abstract: Gender differences in cardiovascular responses to isometric exercise for sitting position and spine.The purpose of this study was to 1) determine whether cardiovascular responses to isometric exercise differ between genders, and 2) to determine if the behavior affects cardiovascular responses to isometric hand tightening (IHG) exercise.Sixteen women and sixteen men (age 22.6 ± 4.2 years) performed two tests (seated or spine) IHG maximum trials at 40% MVC a week away.Blood pressure (BP) and heart rate (HR) measurements were collected at rest (RT), the first minute of exercise (M1), before failure (PF), and 30 s of recovery after failure (RC).Mean arterial pressure (MAP), pulse pressure (PP), and the rate of pressure produces (RPP) were calculated from BP and HR data.Tests showed considerable time by gender interactions for diastolic blood pressure (DBP) and MAP. Males had DBP significantly higher than women in M1 (105.46 ± 14.97 vs. 92.59 ± 13:14 mmHg), PF (122.46 ± 11.23 vs 109.50 ± 13.72 mmHg) and RC (85, 83 ± 4.11 vs. 73.46 ± 8.35 mmHg) and higher MAP measurements that women in M1 (120.32 ± 13.76 vs 105.43 ± 13.76 mmHg), PF (136.44 ± 8.65 vs. 24.31 ± 13:34 mmHg), and RC (100.44 ± 8.21 vs. 87.67 ± 8.26 mmHg).DBP, MAP, and HR were significantly higher in the sitting position than in the spine position for both sexes.
Conclusions: 1) men significantly increase MAP and DBP after starting the exercise submaximal IHG through recovery regardless of position, 2) women have significantly lower measurement of blood pressure than men along the submaximal despite exercising attitude and 3) The attitude has important effects on the cardiovascular response during exercise submaximal IHG.4) The force exerted varies significantly in standing position compared to other positions.
Keywords: Cardiovascular responses, Isometric Handgrip, The force at different positions.
Introduction
Evaluation of isometric force in general average is about thirty percent greater in men than in women [1, 1-44]. With the initiation of isometric tension, increased heart rate, systolic blood pressure and diastolic blood pressure occurs [2,229-244] [3,120-135]. Then, Mitchell et al. [4, 45-54] suggested that cardiovascular responses to isometric exercise are greater when large muscle groups are in-
volved. So the gender differences in cardiovascular responses to static exercise is believed to be due to differences in the sympathetic-adrenal interactions pre sympathetic or cardiac level [7,245-251] [8,147-154]. While heart rate responses in stable submaximal static contractions tend to not be very different before, during or after exercise, blood pressure responses to exercise were significantly elevated before, during, and after exercise [6,863-868]. The
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proposed mechanisms that try to explain gender differences in cardiovascular responses to isometric training have been numerous and most of the time contradictory. Even Sanchez et al. [8, 147-154] found differences in patterns of adrenergic between the sexes in response to isometric exercise. Ettinger et al. [7, 245-251] found an attenuated increase in blood pressure and muscle sympathetic nerve activity compared with men. Jones et al. [9, 350-357] found that gender did not influence the sympathetic nervous reactivity to stressors such as hand shaking in isometric exercise. Changes in behavior often experienced during exercise or sports activities, have also shown extracting various adaptations circulatory [10, 523-530]. Sagiv et al. [11, 170-174] and Borst et al. [12, 676-681] both noted changes in cardiovascular regulation as a result of postural changes. Only a few studies have investigated the cardiovascular adaptations to exercise when performed attitude did not change over the course of the time of the exercise.
The purpose of this study was to 1) determine whether cardiovascular responses to isometric exercise differ between genders, and 2) to determine if the behavior affects cardiovascular responses to handgrip exercise isometric (IHG). 3) The force exerted at different positions varies according to sex and body mass.
Methods
Subjects
Sixteen women and sixteen men volunteers have participated as subjects. Before participating in the study, subjects were asked to sign a statement of acceptance voluntarily participating in the experiment. Subjects were valuated medically pathology had not displayed or hidden in the moment of performing the tests.
Procedures
Before experimental testing each subject was assessed medically for blood pressure, to provide normative measurements of blood pressure (<140/90 mmHg). Maximum voluntary isometric contraction (MVCs) with handshakes were obtained using the dominant hand participants in both positions: sitting and spine. Maximal voluntary contraction (MVC) that were taken as the final evaluation are determined by the contraction of the best single ofthe
subject voluntary previous three times tested. Within three days, the subjects returned for testing. Subjects were tested with both the positions ofsitting and spine. Sitting and spine tests alternated in subsequent visits approximately a week away, to prevent possible effects of previous testing. Subjects initially were sitting or standing tested were made quietly in the spine position for 15 min before experimental testing to stabilize the heart rate and blood pressure and make adaptation to the position. Spine measurements were taken with the subject placed on a horizontal surface with arms extended parallel between the line of the body. Measurements were taken using reduced vertical stand. The wings were stretched perpendicular to the floor with hands positioned under the surface where the subject is seated. In both trials the sitting and spine hand, the subject was positioned 90 o toward the middle ofthe body. Subjects were instructed to maintain normal breathing patterns during all trials to avoid any influence of Valsalva maneuver.Isometric handgrip contractions were performed using a camera handgrip isometric associated with a load cell and force the monitor. Force monitoring was associated with a linear graph recorder. (LB 200 Baseline Hydraulic Hand Dynamometer Lite). MVC initial measurements are taken with the chart recorder out of the field ofvision of the subject to help this issue in focusing attention on the handgrip. Heart rate measurements were taken during the test sessions using a heart rate monitor Lifepak (Physio-Control Lifepak 7).
Blood pressure measurements were taken in the brachial artery of the arm that was not being used for contraction (non-dominant arm). Systolic blood pressure was determined after hearing the first of two or more Korotkoffsounds. Diastolic blood pressure was determined before the disappearance of Korotkoff sounds. Blood pressure and heart rate measurements were taken after stabilization, every minute of exercise, and 30 s after the end of exercise. These values are used to calculate the pulse pressure mean arterial blood pressure, product norms that pressure. In all trials, subjects were instructed to refrain from muscular contractions other than those involved in contraction handshake. During the trials, the subjects save 40% MVC contraction isometric handgrip individuality observing their 40% MVC in the chart recorder. Subjects maintained this intensity until failure. All
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subjects were able to complete two min of exercise, but none to exceed four minutes. During this period, blood pressure and heart rate measurements were obtained at every minute of exercise. When 40% MVC will not be held in 10% of the predetermined value of the subject, the test was terminated. Subjects were asked to stay at the appointed following the completion test to allow recovery ofblood pressure and heart rate measurements to 30 s post-workout. All blood pressure measurements were performed by an experienced laboratory technician.
Statistical Analysis
A repeated measures Anova is used to analyze the data by time, gender, and position to determine whether significant changes in variables were due to experimental evaluation. Statistical significance was accepted at p>0.05. Due to the different length
Diastolic pressure of the
of the trial between the groups, cardiovascular measurements were taken during the period before the exercise, in the first minute of exercise, in the end, and after 30 seconds of restoring functional physiologic parameters.
Results
Men had values significantly larger than females in all conditions for cardiovascular measurements: MAP (112.25 ± 101.17 ± 19.07 vs 19:27 mmHg), SBP (143.58 vs 128.45 ± ± 20:38 22.8 mmHg) and DBP (97.50 ± 87.25 ± 18.82 vs 21:36 mmHg). When the data were combined, cardiovascular variables during the exertion were significantly lower compared with the spine position: MAP (108.40 ± 19.55 vs 104.66 ± 20.18 mmHg), DBP (95.05 ± 20.86 ± 89.37 mmHg vs. 20:21), HR (82.82 ± 1.19 vs. 78.75 ± 19:54 mmHg), blood during the Handgrip
DiastolicPressureof Blood (mmHg)
160 —I
140
Rest Before Maximum Rest after exertion
* Significant changes
Figure 1. shows changes in arterial blood pressure during IHG by gender
Figure 2. shows changes in diastolic blood pressure during IHG-than by gender
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Gender differences responses in isometric exercise
Men have resulted in greater values of MAP than women (Figure 1) in all the positions ofexercise, before the failure, and following the 30 seconds of recovery. Men also had DBP significantly larger than females (Figure 2) at all positions in the first minute of exercise, before failure, and following the 30 seconds of
rest. There were no significant differences between men and women following the rest period before exercise. Mean arterial pressure, SBP, SBP, HR, and RPP values significantly increased for women and men in all positions. Recovery values were significantly greater than resting values and heart rate was normal.
Man
118 117 116 115 114 113 112 111
MF Exerted
■ MF Standing BMP Sitting IMF Lying
Figure 3. shows changes in the pressure exerted on dynamometer in positions standing, sitting and lying in men
Women
68 67 66 65 64 63 62 61 60 59
MF Exerted
BMFStanding — MF Sitting IMF Lying
Figure 4. shows changes in the pressure exerted on dynamometer in positions standing, sitting and lying on women
So the force exerted on dynamometer is higher in the force in sitting and lying position does not differ
the upright position, statistically significant, while statistically although a decline in lying position.
Women
Men
■ Age - High
■ Weight
Figure 5. shows the information age, length and weight by sex
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There is a statistically significant relation between the force exerted on dynamometer and body weight but not the length ofleverage or age between the sexes.
Discussion
Before in the research done by a lot of scientific staf for a considerable time there were not shown gender interactions in MAP and DBP response to isometric handgrip exercise. In some of the investigations has been measured the cardiovascular response to isometric exercise between the sexes [7, 245-251; 8, 147-154; 9, 350-357] with very good results. Jones et al. [9, 350-357] found that blood pressure responses to various forms of laboratory stressors, to include IHG, are constantly influenced by gender.Systolic blood pressure and HR were not found to be significantly higher among males during the first minute of exercise till the recovery. These results indicate that there are gender differences in cardiovascular responses to isometric handgrip exercise. Sanchez et al. [8,147-154] found that continuous isometric contractions showed similar response to blood pressure between genders. It was observed that the average systolic blood pressures were lower in women at rest and during isometric contraction that, but these differences were not significant. Even Ettinger et al. [7, 245-251] showed a small increase blood pressure in women. In these investigations the subjects had an IHG performance in 30% MVC while in the present study was used 40% MVC. Exercise in the isometric form below 40% MVC may not have been sufficient enoght to evoke diastolic and mean arterial response in males as it is shown in the present study. Average blood pressure was greater for people in all positions when the isometric handgrip (IHG) was performed, there were no significant differences in DBP and MAP between the sexes during the time in each position. Mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and the degree of pressure (RPP) increased in both sexes and in all the subjects. Analysis showed no gender differences based on position.
The explanation why men experience DBP and MAP at the beginning of the exercise is difficult to explain because there are a lot of mechanisms that lay behind. These changes will undergo significant
changes in each cardiac output or total peripheral resistance at the start of isometric exercise while women may not have such a change in the blood flow. There are many possible explanations for such responses. Based on Sanchez et al. [8, 147154] there is an increase in sympathetic outflow to increase circulating levels catecholamine. This study investigated the changes in blood pressure response to exercise catecholamine isometric handgrip at 40% MVC. The force produced was of nearly half in the women instead of man in all possitions but the differences were of the same level in the different possitions with no significant differences in both sexes.Ettinger et al. [7, 245-251] measured gender differences in blood pressure and muscle sympathetic nerve activity (MSNA) in response to low intensity (non-ischemic) static exercise. They concluded that this type of exercise static leakage produced less sympathetic nerve among women due to an attenuated metabolic reflex in the women. Claustre et al. [13, 147-153] suggested gender differences adrenergic may result from changes in the central mechanisms for activating sympathetic extrusion. The gender differences in adrenergic response may be due to gender-specific hormones [14, 195-210]. An analysis of gender comparison twelve investigations revealed two together existence males have greater SBP and catecholamine of acute stress response [15, 127-131]. This analysis did not focus on responses to IHG exercise, but it has shown an advantage of greater cardiovascular reactivity to stressors in men. The study of gender differences in isometric exercise has less definitive conclusions, which make it difficult to identify a precise mechanism or mechanisms to explain gender differences in cardiovascular responses to isometric exercise. Current data show a significant increase in HR, MAP, DBP, and rate-pressure product (RPP) all genders in response to isometric work performed in sitting position compared with the spine position. Position of the body can be responsible for changes in blood pressure during isometric exercise [11, 170-174]. In the vertical position postural muscle tension can be increased within the thoracic and abdominal pressures contributing to increased blood pressure. Interruption in flow pressure values venous system, and increased systemic venous resistance are
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usually attributed to the effect of gravity. As a result of isometric exercise in a standing position, increases the blood collection in the distant part extremities reducing the load before the left ventricle. In vertical position the gravity reduces the central volume of blood in body and the heart output. This causes difficulty in increasing or maintaining an adequate systolic volume [16, 51-55]. To maintain adequate cardiac production in an upright position, heart rate should be increased [11, 170-174]. In this experiment there is a situation where we have mans with a significant difference in body weight compared with women, while the differences in length are statistically not significant.
Conclusions
In conclusion, the present study shows that cardiovascular responses and hemodynamical-lyin submaximal levels of isometric exercises with handshake differ by gender specifically in the onset of exercise and the attitude affects cardiovascular responses to isometric exercise. The factors responsible for differences in cardiovascular responses due to gender appear to be numerous and the need for further studies to definitely clarify specific mechanisms. There is a significant difference in the force produced in dynamometer lying or sitting position compared to the upright position in both sexes.
References:
1. Petrofsky J, Phillips C. The Physiology of Exercise static. Med Sci Sports Exerc 1986; 14: 1-44.
2. Lind A, Taylor S, Humphreys P, Kenelly B, Donald K. The circulatory volum- Effects of sustained muscle contraction. ClinSci 1964; 27: 229-244.
3. Humphreys P, Lind A. The blood flow through active and inactive muscles of the forearm up during sustained handgrip contractions. J Physiol London 1963; 166: 120-135.
4. Mitchell J, Payne F, Salti B, Schibye B. The role of muscle mass in the cardiovascular response to static contractions. J Physiol London 1980; 309: 45-54.
5. Seals D, Washburn R, Hanson P, Painter P, Nagle F. Increased cardiovascular response to static contraction of larger muscle groups and. J ApplPhysiol 1983; 54 (2): 434-437.
6. Petrofsky J, Grant-R, Lind A. Comparison of physiological Responses ofWomen and men to Isometric Exercise. J ApplPhysiol 1975; 38 (5): 863-868.
7. Ettinger S, Silber D, Collins B, Gray K, Sutliff G, Whisler S, McClain J, Smith M, Yang Q, Sinoway L. influence of gender on sympathetic Nerve Responses to Exercise static. J ApplPhysiol 1996; 80: 245-251.
8. Sanchez J, Pequignot J, Peyrin L, Monod H. Gender Differences in the sympatho-adrenal response to Isometric Exercise. Eur J ApplPhysiol 1980; 45: 147-154.
9. Jones P, Spraul M, Matt K, Seals D, Skinner J, Ravussin E. Gender does not influence the neural sympathetic reactivity to stress in Healthy Humans. Am J Physiol 1996; 270: 350-357.
10. Sprangers R, K Wesseling, Imholz A Wieling W. Initial Blood Pressure fall on stand up and Exercise Explained by Changes in Total Peripheral Resistance. J Appl Physiol 1991; 70 (2): 523-530.
11. Sagiv M, Rotstein A, Watkins J, Climor L, Ben-Sira D. Effect ofbody position on the afterload up during sustained response Exercise. J Sports Med Phys Fitness 1992; 32: 170-174.
12. Borst C, Wieling W, Van BREDERODE J, Honda A, De Rijk L, Dunning A. Mechanisms of initial heart rate response to postural Change. Am J Physiol 1982; 243: 676-681.
13. Claustre J, Peyrin L, Fitoussi R, Mornex R. Sex Differences in the adrenergic Responses to hypoglycemic stress in Humans.Psychopharmacology 1980; 67: 147-153.
14. Wiechman B, Borowitz J. Effects of steroid hormones and diethylstillbestrol on adrenomedullary catecholamine secretion. Pharmacology 1979; 18: 195-210.
15. Stoney C, Davis M, Matthews K. Sex Differences in Response to physiological stress and in coronary Heart Disease: a causal link? Psychophysiology 1987; 24: 127-131.
16. Ehsani A, Heath G, Hagberg J, Schechtman K. Noninvasive assessment of left ventricular function Change in induced by graded Isometric Exercise in Healthy subjects. Chest 1981; 80: 51-55.
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