共查询到20条相似文献,搜索用时 375 毫秒
1.
Matthew A. Marcus Jack Wang John C. Thornton Ruimei Ma Santiago Burastero Richard N. Pierson 《Obesity (Silver Spring, Md.)》1997,5(2):122-130
Dual-energy X-ray absorptiometry (DXA) is now a commonly used method for the determination of bone mineral status and body composition in humans. The purposes of this study were to compare fat mass by in vivo neutron activation analysis (FMIVNA) with that by DXA (FMDXA) in an anthropometrically heterogeneous sample of healthy adult men (n=33) and women (n=36) (19=≤BMI≤39), and to determine whether differences in fat mass estimates between the two methods (ΔFM) were attributable to subject anthropometry as defined by several circumference (waist, iliac crest, thigh) and skinfold thickness (umbilical, suprailiac, abdominal) measurements. No significant differences between FMDXA and FMIVNA were observed in men (p=0.46) or women (p=0.09). The two methods were very highly correlated in both sexes (women r2=0.97, p<0.001, men r2=0.91, p<0.001), although the regression line for men was significantly different from the line of identity (p=0.043). These results suggest modest trends toward underestimation of FMDXA in men when FMIVNA<18 kg, and overestimation in men when FMIVNA>18 kg. ΔFM (IVNA-DXA) was not significantly related to any combination of skinfold thicknesses and circumferences in either gender. Age explained 27% of the variance in ΔFM for the men (p=0.008). Furthermore, ΔFM was not significantly related to inter-method disparity in total-body bone mineral measurements in men or women (p<0.05). The present study demonstrates strong correlation in fat measurements between IVNA and DXA in men and women ranging from normal to markedly obese. Correction for subject anthropometry does not significantly improve this relationship. 相似文献
2.
David Ben-Sira Michael Sagiv 《European journal of applied physiology and occupational physiology》1997,75(6):549-553
The effect of gender on left ventricular systolic function and exercise haemodynamics in healthy young subjects was studied
during 30-s all-out sudden strenuous dynamic exercise. A group of 22 men [19.3 (SD 1) years] 20 women [19.1 (SD 1) years]
volunteered to participate in this study. Two-dimensional direct M-mode and Doppler echocardiograph studies were performed
with the subject in the sitting position. The Doppler examination of flow was located with continuous-wave, interrogating
ascending aorta measurements. The subjects completed the study without showing any electrocardiograph abnormalities. An interaction
effect with stroke volume (P < 0.05) was characterized by a decrease in the men and an increase of stroke volume in the women. Cardiac output rose significantly
(P < 0.05) up to 14.5 (SD 6) l · min−1) for the men and 12.1 (SD 4) l · min−1 for the women compared to the rest values [5.8 (SD 0.4) and 4.7 (SD 0.5) l · min−1, respectively]. Flow velocity integral and acceleration time differed significantly between the two groups at rest (P < 0.05). During exercise these differences showed an interaction effect (P < 0.05). These results would indicate that normal men and women respond to sudden strenuous exercise by reducing their left
ventricular systolic function, with a significantly greater decrease in women (P < 0.05). The gender differences in the haemodynamic responses during the present study, may, as suggested by others, be attributable
to differences in energy metabolism. In addition, changes in Doppler parameters of aortic flow, haemodynamics and blood pressure
responses during sudden strenuous exercise differed markedly from those seen before with endurance exercise.
Accepted: 8 January 1997 相似文献
3.
Responses of 21 women and 29 men (29-56 yr of age) to -50 Torr lower body negative pressure (LBNP) were examined for differences due to sex or age. Responses to LBNP were normal, including fluid shift from thorax to lower body, increased heart rate and peripheral resistance, and decreased stroke volume, cardiac output, and Heather index of ventricular function. Mean arterial blood pressure did not change. Comparison of responses of the women to responses of an age-matched subset of the men (n = 26) indicated the men had larger relative increases in calf circumference and greater increases in peripheral resistance during LBNP than the women, whereas the women experienced greater increases in thoracic impedance and heart rate. Analyses of responses of the 29 men for age-related differences indicated older subjects had greater increases in peripheral resistance and less heart rate elevation in response to LBNP (P less than 0.05 for all differences, except sex-related heart rate difference, where P less than 0.10). Based on these data and the data of other investigators, we hypothesize the age-related circulatory differences in response to LBNP are due to a reduction in vagal response and a switch to predominant sympathetic nervous system influence in older men. We cannot exclude the possibility that diminished responsiveness in the afferent arm of the baroreceptor reflex also plays a role in the attenuated heart rate response of older men to LBNP. 相似文献
4.
Craig R. White Lesley A. Alton Taryn S. Crispin Lewis G. Halsey 《Ecology and evolution》2016,6(18):6712-6720
The energetic costs for animals to locomote on land influence many aspects of their ecology. Size accounts for much of the among‐species variation in terrestrial transport costs, but species of similar body size can still exhibit severalfold differences in energy expenditure. We compiled measurements of the (mass‐specific) minimum cost of pedestrian transport (COTmin, mL/kg/m) for 201 species – by far the largest sample to date – and used phylogenetically informed comparative analyses to investigate possible eco‐evolutionary differences in COTmin between various groupings of those species. We investigated number of legs, ectothermy and endothermy, waddling, and nocturnality specifically in lizards. Thus, our study primarily revisited previous theories about variations in COTmin between species, testing them with much more robust analyses. Having accounted for mass, while residual COTmin did not differ between bipedal and other species, specifically waddling bipeds were found to have relatively high COTmin. Furthermore, nocturnal lizards have relatively low COTmin although temperature does not appear to affect COTmin in ectotherms. Previous studies examining across‐species variation in COTmin from a biomechanical perspective show that the differences between waddling birds and nonwaddling species, and between nocturnal lizards and other ecotherms, are likely to be attributable to differences in ground reaction forces, posture, and effective limb length. 相似文献
5.
Hilda Ahnstedt Lei Cao Diana N. Krause Karin Warfvinge Hans S?veland Ola G. Nilsson Lars Edvinsson 《PloS one》2013,8(4)
Background and purpose
Male-female differences may significantly impact stroke prevention and treatment in men and women, however underlying mechanisms for sexual dimorphism in stroke are not understood. We previously found in males that cerebral ischemia upregulates contractile receptors in cerebral arteries, which is associated with lower blood flow. The present study investigates if cerebral arteries from men and women differ in cerebrovascular receptor upregulation.Experimental approach
Freshly obtained human cerebral arteries were placed in organ culture, an established model for studying receptor upregulation. 5-hydroxtryptamine type 1B (5-HT1B), angiotensin II type 1 (AT1) and endothelin-1 type A and B (ETA and ETB) receptors were evaluated using wire myograph for contractile responses, real-time PCR for mRNA and immunohistochemistry for receptor expression.Key results
Vascular sensitivity to angiotensin II and endothelin-1 was markedly lower in cultured cerebral arteries from women as compared to men. ETB receptor-mediated contraction occurred in male but not female arteries. Interestingly, there were similar upregulation in mRNA and expression of 5-HT1B, AT1, and ETB receptors and in local expression of Ang II after organ culture.Conclusions and Implications
In spite of receptor upregulation after organ culture in both sexes, cerebral arteries from women were significantly less responsive to vasoconstrictors angiotensin II and endothelin-1 as compared to arteries from men. This suggests receptor coupling and/or signal transduction mechanisms involved in cerebrovascular contractility may be suppressed in females. This is the first study to demonstrate sex differences in the vascular function of human brain arteries. 相似文献6.
Heinrich Vierhapper Peter Nowotny Werner Waldhusl 《Obesity (Silver Spring, Md.)》2004,12(9):1421-1425
Objective: To determine the metabolic clearance rates (MCRs) and endogenous production rates (PRs) of cortisol (F) in grades 2 and 3 obese men (n = 9) and women (n = 6). Research Methods and Procedures: The MCRs and the endogenous PRs of cortisol (F) were determined in grades 2 and 3 obese men (n = 9) and women (n = 6) using the stable isotope dilution technique and mass spectrometry. Results: In obese women, endogenous PRs of F (0.6 ± 0.4 mg/h) were similar to those of nonobese women, but MCRs of F were higher in obese women (9 ± 4 L/h) compared with nonobese women (5 + 2 L/h; p < 0.05). The MCR of F was correlated with the ratio of excreted cortisone to F metabolites. Furthermore, obese women were characterized by an increased ratio of androsterone to etiocholanolone (p < 0.01). In obese men, the MCRs (11 ± 6 L/h) and the endogenous PRs of F (0.6 ± 0.3 mg/h) were both similar to those of nonobese men, but the MCR of F was directly correlated with the ratio of excreted cortisone to F metabolites (r = 0.7833, p = 0.012). Discussion: These data demonstrate sex‐specific differences in F metabolism in obesity. The rise in MCRs of F is more pronounced in obese women than in men. However, the increase in the MCR of F is moderate in both genders and exceeds the normal range only in a subgroup of obese individuals. 相似文献
7.
A. M. P. M. Bovens M. A. van Baak J. G. P. M. Vrencken J. A. G. Wijnen F. T. J. Verstappen 《European journal of applied physiology and occupational physiology》1993,66(3):281-284
The purpose of this study was to investigate criteria for maximal effort in middle-aged men and women undertaking a maximal exercise test until they were exhausted if no measurements of oxygen uptake are made. A large group of 2164 men and 975 women, all active in sports and aged between 40 and 65 years, volunteered for a medical examination including a progressive exercise test to exhaustion on a cycle ergometer. In the 3rd min of recovery a venous blood sample was taken to determine the plasma lactate concentration ([la–]p, 3min). Lactate concentration and maximal heart rate (f
c, max) were lower in the women than in the men (P<0.001). Multiple regression analyses were performed to assess the contribution of sex to [la–]p, 3 min, independent of age and f
c max, It was found that [la–]p,3 min was about 2.5 mmol·l–1 lower in women than in men of the same age and f
c, max. In our population 88% of the men and 85% of the women met a combination of the following f
c, max and [la–]p, 3min criteria: f
c, max equal to or greater than 220 minus age beats·min–1 and/or [la–]p, 3min equal to or greater than 8 mmol·l–1 in the men and f
c, max equal to or greater than 220 minus age beats·min–1 and/or [la–]p, 3min equal to or greater than 5.5 mmol·1–1 in the women. 相似文献
8.
G H Stevens T E Graham B A Wilson 《Canadian journal of physiology and pharmacology》1987,65(2):165-171
This study was conducted because of the paucity of information concerning gender differences in the cardiovascular and metabolic responses to cold stress. Lightly clad men (n = 8) and women (n = 8) were tested in 21 and 5 degrees C environments during a 20-min rest, followed by 20 min each of 50, 100, and 150 W of exercise. At 21 degrees C there was no gender differences in VO2 or cardiac output. Cold lowered skin temperature more in women than in men, but women demonstrated no differences in heart rate, stroke volume, or VO2 at 5 and 21 degrees C. The women's noradrenaline levels in the cold were higher than comparable 21 degrees C data at rest and 50 W and increased with work intensity in both tests. In contrast, men had a lower heart rate, higher stroke volume, and higher VO2 throughout the 5 degrees C treatment compared with 21 degrees C. The men's noradrenaline response to 5 degrees C was similar to that of women at rest and 50 W, but the level subsequently declined at 100 and 150 W. Thus, the women do not show a heart rate-stroke volume shift in either resting or exercising states in cold environments. Furthermore, the data fail to support that either skin cooling or changes in noradrenaline cause the bradycardia and enhanced stroke volume seen in men. 相似文献
9.
Yang H Cooke WH Reed KS Carter JR 《Journal of applied physiology (Bethesda, Md. : 1985)》2012,112(10):1744-1751
Recent evidence suggests that young men and women may have different strategies for regulating arterial blood pressure, and the purpose of the present study was to determine if sex differences exist in diastolic arterial pressure (DAP) and muscle sympathetic nerve activity (MSNA) relations during simulated orthostatic stress. We hypothesized that young men would demonstrate stronger DAP-MSNA coherence and a greater percentage of "consecutive integrated bursts" during orthostatic stress. Fourteen men and 14 women (age 23 ± 1 yr) were examined at rest and during progressive lower body negative pressure (LBNP; -5 to -40 mmHg). Progressive LBNP did not alter mean arterial pressure (MAP) in either sex. Heart rate increased and stroke volume decreased to a greater extent during LBNP in women (interactions, P < 0.05). DAP-MSNA coherence was strong (i.e., r ≥ 0.5) at rest and increased throughout all LBNP stages in men. In contrast, DAP-MSNA coherence was lower in women, and responses to progressive LBNP were attenuated compared with men (time × sex, P = 0.029). Men demonstrated a higher percentage of consecutive bursts during all stages of LBNP (sex, P < 0.05), although the percentage of consecutive bursts increased similarly during progressive LBNP between sexes. In conclusion, men and women demonstrate different firing patterns of integrated MSNA during LBNP that appear to be related to differences in DAP oscillatory patterns. Men tend to have more consecutive bursts, which likely contribute to a stronger DAP-MSNA coherence. These findings may help explain why young women are more prone to orthostatic intolerance. 相似文献
10.
Edgell H Robertson AD Hughson RL 《Journal of applied physiology (Bethesda, Md. : 1985)》2012,112(9):1482-1493
Increased incidence of orthostatic hypotension and presyncopal symptoms in young women could be related to hormonal factors that might be isolated by comparing cardiovascular and cerebrovascular responses to postural change in young and older men and women. Seven young women, 11 young men, 10 older women (>1 yr postmenopausal, no hormone therapy), and 9 older men participated in a supine-to-sit-to-stand test while measuring systemic hemodynamics, end-tidal Pco(2), and blood flow velocity of the middle cerebral artery (MCA). Women had a greater reduction in stroke volume index compared with age-matched men (change from supine to standing: young women: -22.9 ± 1.6 ml/m(2); young men: -14.4 ± 2.4 ml/m(2); older women: -17.4 ± 3.3 ml/m(2); older men: -13.8 ± 2.2 ml/m(2)). This was accompanied by offsetting changes in heart rate, particularly in young women, resulting in no age or sex differences in cardiac output index. Mean arterial pressure (MAP) was higher in older subjects and increased with movement to upright postures. Younger men and women had higher forearm vascular resistance that increased progressively in the upright posture compared with older men and women. There was no difference between sexes or ages in total peripheral resistance index. Women had higher MCA velocity, but both sexes had reduced MCA velocity while upright, which was a function of reduced blood pressure at the MCA and a significant reduction in end-tidal Pco(2). The reductions in stroke volume index suggested impaired venous return in women, but augmented responses of heart rate and forearm vascular resistance protected MAP in younger women. Overall, these results showed significant sex and age-related differences, but compensatory mechanisms preserved MAP and MCA velocity in young women. 相似文献
11.
Sabrina G. V. Dutra Ana Paula M. Pereira Geisa C. S. V. Tezini José H. Mazon Marli C. Martins-Pinge Hugo C. D. Souza 《PloS one》2013,8(10)
Background
Aerobic physical capacity plays an important role in reducing morbidity and mortality rates in subjects with cardiovascular diseases. This action is often related to an improvement in the autonomic modulation of heart rate variability (HRV). However, controversies remain regarding the effects of physical training on cardiac autonomic control in healthy subjects. Therefore, our objective was to investigate whether aerobic capacity interferes with the autonomic modulation of HRV and whether gender differences exist.Methods
Healthy men and women (N=96) were divided into groups according to aerobic capacity: low (VO2: 22-38 ml/kg-1 min-1), moderate (VO2: 38-48 ml/kg-1 min-1) and high (VO2 >48 ml/kg-1 min-1.) We evaluated the hemodynamic parameters and body composition. The autonomic modulation of HRV was investigated using spectral analysis. This procedure decomposes the heart rate oscillatory signal into frequency bands: low frequency (LF=0.04-0.15Hz) is mainly related to sympathetic modulation, and high frequency (HF=0.15-0.5Hz) corresponds to vagal modulation.Results
Aerobic capacity, regardless of gender, determined lower values of body fat percentage, blood pressure and heart rate. In turn, the spectral analysis of HRV showed that this parameter did not differ when aerobic capacity was considered. However, when the genders were compared, women had lower LF values and higher HF values than the respective groups of men.Conclusion
The results suggest that aerobic physical capacity does not interfere with HRV modulation; however, the cardiac modulatory balance differs between genders and is characterized by a greater influence of the autonomic vagal component in women and by the sympathetic component in men. 相似文献12.
Fujita S Rasmussen BB Bell JA Cadenas JG Volpi E 《American journal of physiology. Endocrinology and metabolism》2007,292(1):E77-E83
Sexual dimorphism in skeletal muscle mass is apparent, with men having more muscle mass and larger individual muscle cells. However, no sex-based differences have been detected in blood forearm phenylalanine turnover, although whole body leucine oxidation has been reported to be greater in men than in women. We hypothesized that sex differences in intracellular amino acid turnover may account for these discrepancies, with men having a higher intracellular turnover than women. We studied young, healthy women (women, n = 8) and men (men, n = 10) following an overnight fast. Phenylalanine, leucine, and alanine muscle intracellular kinetics were assessed using stable isotope methodologies, femoral arteriovenous blood sampling, and muscle biopsies. Muscle intracellular amino acid kinetics were reported relative to both leg volume and lean leg mass because of sex differences in leg volume and in muscle and fat distribution. When expressed per leg volume (nmol.min(-1).100 ml leg volume(-1)), phenylalanine net balance (women: -16 +/- 4, men: -31 +/- 5), release from proteolysis in the blood (women: 46 +/- 9, men: 75 +/- 10) and intracellular availability (women: 149 +/- 23, men: 241 +/- 35), and alanine production, utilization, and intracellular availability were higher in men (P < 0.05). However, when the kinetic parameters were normalized per unit of lean leg mass, all differences disappeared. Muscle fractional synthetic rate was also not different between women and men. We conclude that there are no sex-based differences in basal muscle intracellular amino acid turnover when the data are normalized by lean mass. It remains to be determined if there are sex differences in intracellular amino acid metabolism following anabolic or catabolic stimuli. 相似文献
13.
Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance. 总被引:3,自引:0,他引:3
About 20% of astronauts suffer postspaceflight presyncope. We studied pre- to postflight (5- to 16-day missions) cardiovascular responses to standing in 35 astronauts to determine differences between 1) men and women and 2) presyncopal and nonpresyncopal groups. The groups were presyncopal women, presyncopal men, and nonpresyncopal men based on their ability to stand for 10 min postflight. Preflight, women and presyncopal men had low vascular resistance, with the women having the lowest. Postflight, women experienced higher rates of presyncope (100 vs. 20%; P = 0.001) and greater losses of plasma volume (20 vs. 7%; P < 0.05) than men. Also, presyncopal subjects had lower standing mean arterial pressure (P < or = 0.001) and vascular resistance (P < 0.05), smaller increases in norepinephrine (P < or = 0.058) and greater increases in epinephrine (P < or = 0.058) than nonpresyncopal subjects. Presyncopal subjects had a strong dependence on plasma volume to maintain standing stroke volume. These findings suggest that postflight presyncope is greatest in women, and this can be ascribed to a combination of inherently low-resistance responses, a strong dependence on volume status, and relative hypoadrenergic responses. Conversely, high vascular resistance and postflight hyperadrenergic responses prevent presyncope. 相似文献
14.
Cardiac output and stroke volume were estimated for a 200 g largemouth blackbass (Micropterus salmoides) by a modified whole-body thermodilution method using the relation between thermal equilibration rates and heartbeat frequencies. The reciprocal of the thermal time constant, k (min–1), was related to the heartbeat frequency, F (beats min–1), by the equation k=0.00146 F + 0.309; the slope is the weight-specific stroke volume (ml g–1) and the intercept is the weight-specific heat transfer constant (cal °C–1 min–1 g–1). Stroke volume was 0.292 ml (0.00146 ml/g body weight), yielding cardiac output values ranging from 44 ml kg–1 min–1 (at 30 beats min) to 158 ml kg–1 min–1 (at 108 beats min–1), or 4.4 to 15.8% of body weight. Active (convective) heat transfer due to blood flow constituted an estimated 11 to 34% (mean 22.5%) of total heat transfer, depending on heartbeat frequency; this variability constitutes physiological thermoregulation. 相似文献
15.
Peter-Paul Henri Marie Delnoy Klaus-Jürgen Gutleben Niels Eske Bruun Sebastian K.G. Maier Hanno Oswald Christoph Stellbrink Jens Brock Johansen Stefan Paule Peter Søgaard 《Indian pacing and electrophysiology journal》2021,21(4):209-218
BackgroundIn patients with cardiac resynchronization therapy defibrillators (CRT-Ds), intracardiac impedance measured by dedicated CRT-D software may be used to monitor hemodynamic changes. We investigated the relationship of hemodynamic parameters assessed by intracardiac impedance and by echocardiography in a controlled clinical setting.MethodsThe study enrolled 68 patients (mean age, 66 ± 9 years; 74% males) at 12 investigational sites. The patients had an indication for CRT-D implantation, New York Heart Association class II/III symptoms, left ventricular ejection fraction 15%–35%, and a QRS duration ≥150 ms. Two months after a CRT-D implantation, hemodynamic changes were provoked by overdrive pacing. Intracardiac impedance was recorded at rest and at four pacing rates ranging from 10 to 40 beats/min above the resting rate. In parallel, echocardiography measurements were performed. We hypothesized that a mean intra-individual correlation coefficient (rmean) between stroke impedance (difference between end-systolic and end-diastolic intracardiac impedance) measured by CRT-D and the aortic velocity time integral (i.e., stroke volume) determined by echocardiography would be significantly larger than 0.65.ResultsThe hypothesis was evaluated in 40 patients with complete data sets. The rmean was 0.797, with a lower confidence interval bound of 0.709. The study hypothesis was met (p = 0.007). A stepwise reduction of stroke impedance and stroke volume was observed with increasing heart rate.ConclusionsIntracardiac impedance measured by implanted CRT-Ds correlated well with the aortic velocity time integral (stroke volume) determined by echocardiography. The impedance measurements bear potential and are readily available technically, not requiring implantation of additional material beyond standard CRT-D system. 相似文献
16.
Purpose
To provide a large reference material on key cardio-respiratory variables in a healthy population of Norwegian men and women aged 20–90 years.Methods
Sub maximal and peak levels of cardio-respiratory variables were measured using cardiopulmonary exercise testing during treadmill running.Results
The highest peak ventilation among men (141.9±24.5 L·min−1) and women (92.0±16.5 L·min−1) was observed in the youngest age group (20–29 years, sex differences p<0.001) with an average 7% reduction per decade. The highest tidal volumes were observed in the 30–39 and 40–49 year age groups among men (2.94±0.46 L) and women (2.06±0.32 L) (sex differences p<0.001), with a subsequent average 6% reduction per decade. Ventilatory threshold and respiratory compensation point were observed at approximately 77% and 87% of peak oxygen uptake (VO2peak) among men and women, respectively. The best ventilatory efficiency (EqVCO2Than) was observed in the youngest age group (20–29 years) in both men (26.2±2.8) and woman (27.5±2.7) (sex differences p<0.001) with an average 3% deterioration in ventilatory efficiency per decade.Conclusion
This is the largest European reference material of cardio-respiratory variables in healthy men and women aged 20–90 years, establishing normal values for, and associations between key cardio-respiratory parameters. This will be useful in clinical decision making when evaluating cardiopulmonary health in similar populations. 相似文献17.
Sex differences in running economy (gross oxygen cost of running, CR), maximal oxygen uptake (VO2max), anaerobic threshold (Than), percentage utilization of aerobic power (% VO2max), and Than during running were investigated. There were six men and six women aged 20–30 years with a performance time of 2 h 40 min over the marathon distance. The VO2max, Than, and CR were measured during controlled running on a treadmill at 1° and 3° gradient. From each subject's recorded time of running in the marathon, the average speed (v
M) was calculated and maintained during the treadmill running for 11 min. The VO2 max was inversely related to body mass (m
b), there were no sex differences, and the mean values of the reduced exponent were 0.65 for women and 0.81 for men. These results indicate that for running the unit ml·kg–0.75·min–1 is convenient when comparing individuals with different m
b. The VO2max was about 10% (23 ml·kg–0.75·min–1) higher in the men than in the women. The women had on the average 10–12 ml·kg–0.75·min–1 lower VO2 than the men when running at comparable velocities. Disregarding sex, the mean value of CR was 0.211 (SEM 0.005) ml·kg–1·m–1 (resting included), and was independent of treadmill speed. No sex differences in Than expressed as % VO2max or percentage maximal heart rate were found, but Than expressed as VO2 in ml·kg–0.75·min–1 was significantly higher in the men compared to the women. The percentage utilization of f
emax and concentration of blood lactate at v
M was higher for the female runners. The women ran 2 days more each week than the men over the first 4 months during the half year preceding the marathon race. It was concluded that the higher VO2max and Than in the men was compensated for by more running, superior CR, and a higher exercise intensity during the race in the performance-matched female marathon runners. 相似文献
18.
This study investigated whether there are any gender differences in body-heating strategies during cold stress and whether the immune and neuroendocrine responses to physiological stress differ between men and women. Thirty-two participants (18 men and 14 women) were exposed to acute cold stress by immersion to the manubrium level in 14 °C water. The cold stress continued until rectal temperature (TRE) reached 35.5 °C or for a maximum of 170 min. The responses to cold stress of various indicators of body temperature, insulation, metabolism, shivering, stress, and endocrine and immune function were compared between men and women. During cold stress, TRE and muscle and mean skin temperatures decreased in all subjects (P < 0.001). These variables and the TRE cooling rate did not differ between men and women. The insulative response was greater in women (P < 0.05), whereas metabolic heat production and shivering were greater (P < 0.05) in men. Indicators of cold strain did not differ between men and women, but men exhibited larger changes in the indicators of neuroendocrine (epinephrine level) and in immune (tumor necrosis factor-α level) responses (both P < 0.05). The results of the present study indicated that men exhibited a greater metabolic response and shivering thermogenesis during acute cold stress, whereas women exhibited a greater insulative response. Despite the similar experience of cold strain in men and women, the neuroendocrine and immune responses were larger in men. Contrary to our expectations, the cooling rate was similar in men and women. 相似文献
19.
Wainstein RV Sasson Z Mak S 《American journal of physiology. Heart and circulatory physiology》2012,302(11):H2363-H2371
We aimed to determine whether sex differences in humans extend to the dynamic response of the left ventricular (LV) chamber to changes in heart rate (HR). Several observations suggest sex influences LV structure and function in health; moreover, this physiology is also affected in a sex-specific manner by aging. Eight postmenopausal women and eight similarly aged men underwent a cardiac catheterization-based study for force-interval relationships of the LV. HR was controlled by right atrial (RA) pacing, and LV +dP/dt(max) and volume were assessed by micromanometer-tipped catheter and Doppler echocardiography, respectively. Analysis of approximated LV pressure-volume relationships was performed using a time-varying model of elastance. External stroke work was also calculated. The relationship between HR and LV +dP/dt(max) was expressed as LV +dP/dt(max) = b + mHR. The slope (m) of the relationship was steeper in women compared with men (11.8 ± 4.0 vs. 6.1 ± 4.1 mmHg·s(-1)·beats(-1)·min(-1), P = 0.01). The greater increase in contractility in women was reproducibly observed after normalizing LV +dP/dt(max) to LV end-diastolic volume (LVVed) or by measuring end-systolic elastance. LVVed and stroke volume decreased more in women. Thus, despite greater increases in contractility, HR was associated with a lesser rise in cardiac output and a steeper fall in external stroke work in women. Compared with men, women exhibit greater inotropic responses to incremental RA pacing, which occurs at the same time as a steeper decline in external stroke work. In older adults, we observed sexual dimorphism in determinants of LV mechanical performance. 相似文献
20.
According to the literature, quality of life has been shown to be reduced in females compared with males with Inflammatory Bowel Disease (IBD). Psychosocial factors are also playing an important role in IBD, especially emotional lability. The aims of study was to investigate the sex differences in general and specific health-related quality of life (HRQoL), anxiety and depression in IBD patients. Hundred and twelve outpatients of the Gastroenterology Division, Clinical Hospital Centre Rijeka, were enrolled in our study and divided in two groups: 50 females (31 with ulcerative colitis, UC and 19 with Crohn disease, CD) and 62 males (30 with UC and 32 with CD), age range 19 to 74 (M = 41.46; SD = 13.06). Most patients have been in long clinical remission or with mild disease according to Clinical Disease Activity Index (CDAI) score for CD and Clinical Activity Index (CAI) score for UC. There were significant differences in physical (F = 13.96, p < .0001) and mental (F = 9.44, p < .001) component of the general HRQoL, emotional domain ((F = 9.26, p < .001) and bowel symptoms (F = 7.04, p < .001) of the Inflammatory Bowel Disease Quality of life (IBDQoL), as well as, in anxiety (F = 7.03, p < .001) and depression (F = 12.09, p < .0001) between men and women with IBD. Women have expressed significantly lower level of the general HRQoL and more emotional disturbances connected with their disease as well as more frequent bowel symptoms compared with men. Effect sizes of those differences were large. Results of this study confirm that women with IBD are more prone to the negative impact of the disease on their HRQoL than men. Women with higher level of depression and anxiety experienced more emotional disturbances, bowel and systemic symptoms and lower general HRQoL. These results should deserve more considerations in the clinical treatment of IBD patients. 相似文献