Hemodynamic indices of the cardiovascular system in children as related to their constitutional characteristics

In children five to seven years of age, the adaptation of their cardiovascular system to a high physical activity as related to their individual somatic characteristics was studied. The methods of rheography and bicycle ergometry were used under physical loads with the power increasing from 1 and 1.5 W/kg body weight. During exercises, load grading according to the body’s somatic characteristics led to a significant increase in the degree of the children’s functional training. In children of different somatotypes, the indices of absolute physical efficiency and of both cardiac output (Q) and stroke volume (SV) increased significantly. The increase in hemodynamic indices in girls was higher than in boys of the same age.     

Involvement of the growth hormone and insulin in gastric secretion regulation in wrestlers during sport and post-sport ontogeny

The roles of gastrin, somatotropic hormone, insulin, and glucose in the formation of long-term and acute adaptation of gastric secretion in wrestlers during sport and post-sport ontogeny are discussed. The basal secretion of hormones and the blood glucose level have been found to change with age in a wavelike manner. Ascents and declines of different waves of their time course correspond to sensitive stages of ontogeny. Changes in hormone secretion and the glucose level under bicycle ergometry are statistically nonsignificant in 90% of cases, but these changes are enough to obtain a final result, namely, an adequate level of protein hydrolysis as a result of physical activity.     

Interhemispheric Differences in Indices of α Activity Spectral Power Electroencephalogram during Bicycle Ergometry

An EEG study during bicycle ergometry in the prone position with the load growing stepwise to submaximal heart rate was carried out in 30 volunteers in order to investigate the spectrum parameters and interhemispheric differences in α activity on the encephalogram. Comparative analysis of EEG data showed a statistically significant increase in α power indices in both hemispheres at the final stage of aerobic exercise and in the course of recovery period with the highest power values recorded in the left hemisphere. Analysis of interhemispheric differences demonstrated right-hemisphere activation during the entire period of the research.     

Plasma renin system during exercise in normal men

The exercise-related increase in plasma renin activity (PRA) and in the plasma concentration of angiotensin II (ANG II) and aldosterone (Aldo) was studied in 43 healthy volunteers whose 24-h urinary sodium excretion (UVNa) ranged from 10 to 250 mmol. Arterial blood samples were obtained at rest and during bicycle ergometry. Compared with rest, PRA, ANG II, and Aldo rose to a similar extent during light and moderate exercise. However, at peak exercise ANG II increased significantly more (P less than 0.001) than PRA and Aldo. Thus, with increasing intensity of exercise, the slope of the linear regression of ANG II on PRA became significantly (P less than 0.001) steeper, whereas at maximal exercise the Aldo response did not follow the acute rise in ANG II. At rest as well as during exercise, Aldo rose with increasing ANG II, but the stimulatory effect of ANG II on Aldo was attenuated with higher sodium intake, as estimated from UVNa. Finally, independent of the level of physical activity, UVNa was negatively correlated with PRA, ANG II, and Aldo.     

Metoclopramide decreases baroreflex sensitivity in patients with essential hypertension

The effect of metoclopramide (10 mg, iv.) or physiological saline on the exercise-induced (standardized bicycle ergometry) increase in blood pressure and heart rate of patients with essential hypertension was investigated in a double blind, randomized, self controlled study. Metoclopramide had no effect on the exercise-induced increase in blood pressure but significantly enhanced the tachycardia due to ergometry after 4-6 min exercise. The mean slope of linear regression lines calculated from the systolic blood pressure and the corresponding heart rate measured before and during (at 1,2,3,4,5 min) exercise after metoclopramide was significantly steeper than after physiological saline (1.1 +/- 0.12 vs 0.79 +/- 0.09; mean +/- SEM), indicating the decrease in baroreflex sensitivity after metoclopramide. On the basis of results the possible role of endogenous dopaminergic mechanisms in suppressing some components of pressor effect of physical exercise can be hypothesized.     

The entrainment of ventilation frequency to exercise rhythm

To investigate whether ventilation frequency could be entrained to a sub-harmonic of the exercise rhythm, 19 experimentally naive male volunteers were tested during steady state bicycle ergometry and arm cranking under conditions of constant applied workload. Each exercise was performed at two separate ventilatory loads, one within the linear range and the other in the curvilinear range of ventilatory response to exercise. A preferred exercise rhythm was initially adopted (4 min.) followed by forced incremented and decremented rhythm changes each lasting 3 min during a 12 min exercise period. Ventilation, pedal pulse train and heart rate were sampled at 17 Hz on a PDP 11/23 computer. Ratios of limb frequency to dominant respiratory frequency were determined following Fourier analysis of these signals. Data that lay within +/- 0.05 of an integer and half-integer ratio were accepted as indices of entrainment, provided that the observed entrained scores were statistically significant. Ventilation frequency showed a clear, but intermittent tendency to entrain with limb frequency. This tendency was greater during bicycle ergometry, possibly as a consequence of task familiarisation, although both exercise entrainments were independent of workload. No difference between preferred versus varied exercise rhythm was evident, but more entrainment (p less than 0.01) was observed during a decremental change in exercise rhythm. These responses do not appear to support an appreciable role for limb-based afferents in the control of entrainment. The results of this study provide evidence that exercise rhythm has some regulatory role in the control of breathing during moderate rhythmical laboratory-based exercise ergometry.     

Erratum to: Weather-induced ischemia and arrhythmia in patients undergoing cardiac rehabilitation: another difference between men and women

Given the accumulating evidence that people with underlying heart disease are a particularly vulnerable group for triggers like changing meteorological parameters, the objective of this longitudinal study was to analyze the influence of weather parameters on blood pressure, arrhythmia and ischemia in cardiovascular patients. A panel study with repeated measurements was conducted in a rehabilitation clinic in Timmendorfer Strand (Baltic Sea, Germany) with 872 cardiovascular patients. Heart rate, blood pressure and electrocardiography changes were measured during repeated bicycle ergometries. Generalized Estimating Equations were used for regression analyses of immediate, delayed and cumulative influences of the daily measured meteorological data. For men, a decrease in air temperature and in water vapor pressure doubled the risk of ST-segment depression during ergometry [odds ratio (OR) for 1 day delay: 1.88 (1.24; 2.83) for air temperature] with a delay of 1-2 days. For women, an increase of their heart rate before the start of the ergometry [same day: 4.36 beats/min (0.99; 7.74) for air temperature] and a 2- to 3-fold higher risk for ventricular ectopic beats [1 day delay: OR 2.43 (1.17; 5.05) for air temperature] was observed with an increase in temperature and water vapor pressure in almost all analyzed time-windows. The study indicates that meteorological parameters can induce changes in heart function which may lead to adverse cardiovascular events especially in susceptible, diseased individuals. The observed effect on ST-segment depression could be a link between the association of weather changes and cardiovascular morbidity and mortality.     

Effects of experimental weight perturbation on skeletal muscle work efficiency in human subjects

Maintenance of reduced or elevated body weight results in respective decreases or increases in energy expended in physical activity, defined as 24-h energy expenditure excluding resting energy expenditure and the thermic effect of feeding, beyond those attributable to weight change. We examined skeletal muscle work efficiency by graded cycle ergometry and, in some subjects, rates of gastrocnemius muscle ATP flux during exercise by magnetic resonance spectroscopy (MRS), in 30 subjects (15 males, 15 females) at initial weight and 10% below initial weight and in 8 subjects (7 males, 1 female) at initial weight and 10% above initial weight to determine whether changes in skeletal muscle work efficiency at altered body weight were correlated with changes in the energy expended in physical activity. At reduced weight, muscle work efficiency was increased in both cycle ergometry [mean (SD) change = +26.5 (26.7)%, P < 0.001] and MRS [ATP flux change = -15.2 (23.2)%, P = 0.044] studies. Weight gain resulted in decreased muscle work efficiency by ergometry [mean (SD) change = -17.8 (20.5)%, P = 0.043]. Changes in muscle efficiency at altered body weight accounted for 35% of the change in daily energy expended in physical activity.     

Adenosine triphosphate concentration and beta-D-glucuronidase activity as indicators of sea bass semen quality

The most common parameters used to evaluate sperm quality are motility rate and duration and fertilization ability. In this study, chemical and biochemical parameters of sea bass (Dicentrarchus labrax) sperm were investigated to find an alternative method for evaluating sperm fertilization ability before and after cryopreservation. The biochemical and chemical analyses were performed with fresh and frozen-thawed sperm and seminal plasma. To cryopreserve sperm, 250-microl straws were used. Fertilization ability was evaluated by inseminating eggs (obtained from hormonally stimulated females) with fresh and cryopreserved sperm. The results revealed a linear relationship (P < 0.05) between semen fertilization capacity and some seminal plasma (beta-D-glucuronidase activity, potassium concentration) and sperm (ATP concentration, aspartate aminotransferase activity) parameters. Variations in semen fertilization rate could be best described by two multiple regression models: one including the sperm parameters and another including the seminal plasma parameters. For practical application, the use of simple regression models is of value. Fertilization rate in both fresh and cryopreserved sperm was reliably predicted by determining the ATP concentration or the beta-D-glucuronidase activity or both.     

Heart rate and perceptual response to exercise with different pedalling speed in normal subjects and patients

The perceived exertion rating (RPE) scale of Borg was used to investigate the relationship between perceived exertion and pedalling rate. Normal subjects and patients with chronic obstructive lung disease (Cold) were studied in repeated test series. Work load, applied in a random order, varied from 2.5 to 10 mkp/s (patients) and 5 to 20 mkp/s (normals). Pedalling rate varied from 2.5 to 10 mkp/s (patients) and 5 to 20 mkp/s (normals). Pedalling rate varied from 40 to 60, 80, 100 rpm. At constant work load, RPE decreases during increasing pedalling rate. With respect to validity, RPE, showing a closer relationship to work load than to heart rate, seems to reflect perception of physical stress rather than perception of physiological strain. In addition, the results raise the question of standardization of pedalling rate in bicycle ergometry.     

Circadian Variation of Cardiac Performance in Coronary Heart Disease

To study the circadian variation of cardiac performance in patients with coronary heart disease, three exercise tests on a bicycle crgometer were performed during the active part of the day (10 a.m., 2 p.m. and 6 p.m.), recording ST-segment depression and pulmonary capillary wedge pressure. Ten male patients with angiographically documented coronary heart disease underwent bicycle ergometry during placebo and during nitrate therapy (placebo controlled, double-blind crossover 2 × 20 mg IS-5-MN and 1 × 120 mg ISDN sustained release). During placebo as well as during nitrate therapy there was a gradual decrease of cardiac performance during the day, documented by the increase in ST-depression and pulmonary capillary wedge pressure at equal work loads. High nitrate concns led to a significant reduction of both ST-depression and preload with a marked circadian-phase dependency of cardiovascular effects.     

Circadian Variation of Cardiac Performance in Coronary Heart Disease

To study the circadian variation of cardiac performance in patients with coronary heart disease, three exercise tests on a bicycle crgometer were performed during the active part of the day (10 a.m., 2 p.m. and 6 p.m.), recording ST-segment depression and pulmonary capillary wedge pressure. Ten male patients with angiographically documented coronary heart disease underwent bicycle ergometry during placebo and during nitrate therapy (placebo controlled, double-blind crossover 2 × 20 mg IS-5-MN and 1 × 120 mg ISDN sustained release). During placebo as well as during nitrate therapy there was a gradual decrease of cardiac performance during the day, documented by the increase in ST-depression and pulmonary capillary wedge pressure at equal work loads. High nitrate concns led to a significant reduction of both ST-depression and preload with a marked circadian-phase dependency of cardiovascular effects.     

Correlation between the dopamine-beta-hydroxylase activity and the level of plasma catecholamines during muscular exercise]

The plasma dopamine-beta-hydroxylase activity was measured in 10 healthy untrained volunteers during a graded physical exercise on a bicycle ergometer. The authors have shown a good correlation between the DbetaH activity and the noradrenaline content in plasma. It can therefore be concluded that the DbetaH activity could be a true measure of the sympathetic activity.     

Relationships of inflammatory activity with biochemical parameters of the blood and sympathovagal balance of young athletes

Results of numerous studies show that a specific combination of biochemical parameters is formed in a trained body. The systemic inflammatory activity is supposed to be an integral factor involved in the formation of such a specific biochemical profile. The measurements of biochemical parameters of athletes’ blood and sympathovagal balance (via the assessment of the heart rate variability) performed in this study show that a decreased level of C-reactive protein is correlated with the count of red blood cells, hematocrit, levels of neutrophils and lymphocytes, total concentration of cholesterol and its concentration in low-density lipoproteins, activity of creatine phosphokinase, time of heart rate recovery from 170 to 120 beats/min (the HR_170-120 index), and the LF/HF ratio (regarded as a marker of the sympathovagal balance). Hence, a decreased inflammatory activity can be involved in the regulation of some biochemical parameters and affect the sympathovagal balance of a trained body.     

Electrocardiographic chest wall mapping in the diagnosis of coronary artery disease.

Chest wall mapping of ST segment changes, inverted U waves, and Q waves using 16 electrocardiographic electrodes was performed at rest and during and after bicycle ergometry in 150 patients presenting with chest pain suggestive of angina. All patients underwent coronary angiography. The presence or absence of appreciable coronary artery disease (greater than or equal to 50% stenosis) was detected with a sensitivity of 98% and a specificity of 88%. The identification of lesions in individual coronary arteries was also possible with a sensitivity and specificity of 87% and 85% respectively for the territory of the left anterior descending and diagonal artery, 71% and 85% respectively for the right coronary artery, and 85% and 80% respectively for the circumflex artery. This test appears to be a reliable non-invasive screening method for selecting patients for angiography.     

Serum biochemical values in fallow deer (<Emphasis Type="Italic">Dama dama</Emphasis> L.) from different habitats in Croatia

Serum biochemical values were determined in blood samples collected from 48 shot fallow deer from the Brijuni islands and 45 sedated fallow deer (Dama dama L.) from hunting grounds in the continental part of Croatia. The parameters were compared with regard to age, sex and habitat. Statistically significant differences were found for serum total protein concentration, alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase activity between young and adult island deer, as well as for total protein, triacylglyceride, cholesterol concentration and alkaline phosphatase activity between young and adult continental deer. In young animals, island males had higher albumin concentrations, while continental males had higher alkaline phosphatase values than females. In adult animals, island males had a higher blood urea nitrogen concentration, while continental males had higher albumin and cholesterol concentrations, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and creatine kinase activities. In this group, males exhibited lower bilirubin and triacylglyceride concentrations than females. Our results indicate that besides age, sex and sampling method, nutritional and environmental factors should be considered when evaluating serum biochemical parameters of fallow deer     

A pilot study of exercise-induced changes in mitochondrial oxygen metabolism measured by a cellular oxygen metabolism monitor (PICOMET)

Impaired tissue oxygenation is the key pathomechanism in the development of organ dysfunction in shock; mitochondrial impairment can aggravate the condition. However, measuring tissue oxygenation directly and non-invasively still poses a clinical challenge. A novel device (COMET) allows the assessment of mitochondrial oxygen metabolism using the Protoporphyrin IX Triplet State Lifetime Technique (PpIX-TSLT). Critically ill patients, especially in sepsis, often exhibit oedema which may interfere with the COMET measurement. Furthermore, patients' physical activity level differs significantly before and during hospitalisation. Thus, the aim of this study was to identify the effects of physical activity and body composition on mitochondrial oxygen tension (mitoPO₂) and consumption (mitoVO₂) in healthy controls (N = 40). Furthermore, the study tested the repeatability of the COMET variables and identified covariates. Multiple COMET measurements were performed before (T₁, T₂), during and after (T₃, T₄) ergometry. Body composition was assessed by bioimpedance analysis. Physiological variables (blood pressure, heart rate, oxygen saturation) were recorded. In the analytical sample (n = 26), physical activity significantly decreased mitoVO₂; other COMET variables remained unchanged between T₂ and T₃. During ergometry, mitoPO₂ increased significantly. The distribution of body water significantly influenced mitoVO₂. In our setting, the method demonstrated moderate repeatability. Variables of fitness (heart rate recovery, phase angle and physical activity level), signal quality and duration of exposure to 5-aminolevulinic acid (obligatory for PpIX-TSLT) were identified as significant covariates of mitoVO₂. Mitochondrial oxygen delivery (mitoDO₂) was established as a new variable of COMET analysis. Results of this pilot study should be validated in future studies.     

Plasma free and sulfate conjugated catecholamine levels during acute physiological stimulation in man

The responses of plasma free and sulfate-conjugated catecholamines to acute physiological stimulation was examined in normal male subjects. Catecholamines were measured with a sensitive radioenzymatic assay incorporating simultaneous hydrolysis of sulfate conjugates and O-methylation of free norepinephrine and epinephrine. Following 20 minutes recumbency after venepuncture 30 +/- 3% of norepinephrine and 16 +/- 5% of epinephrine was in thr free form. Free catecholamines generally increased during standing, cold immersion and isometric handgrip, but sulfates did not change. Bicycle ergometry markedly increased free catecholamines which rapidly returned to basal levels at the end of exercise. In contrast, sulfated norepinephrine decreased substantially with exercise in all subjects but returned to basal levels 3 minutes after stopping exercise. Epinephrine sulfate varied considerably between subjects but showed a similar, although smaller, fall with exercise. Thus, during physiological stimulation, which caused increases in free norepinephrine and epinephrine levels in plasma, the only consistent change in sulfated catecholamines was a marked fall in norepinephrine sulfate after bicycle exercise. This may indicate saturation of sulfotransferase activity, substrate inhibition or impaired tissue conjugation.     

Blood pressure changes during running in humans: the "beat" phenomenon

In 20 runners the intra-arterial blood pressure changes determined by a long-distance run and by a maximal bicycle ergometric test were recorded by means of the portable Oxford system. A peculiar pattern of the phasic waves was observed throughout the run: continuous rhythmic pulse pressure oscillations ranging in frequency between 4 and 28/min and unrelated to respiration were detected. The shape of these oscillations prompted us to investigate whether they were due to a "beat" phenomenon, that is, to the combined effect of two waves with a nearly equal frequency. To test this hypothesis, during the run 10 athletes carried a fluid-filled container around the chest. The pressure waves recorded in the container were added by computer to those recorded intra-arterially during bicycle ergometry. The resultant harmonic showed a pattern similar to that recorded in the athlete's radial artery during running. Conversely, by subtracting the pressure waves recorded in the container from those simultaneously recorded at the radial artery during running, nearly flat tracings were obtained. The source of the beat phenomenon has therefore been identified in the wave, which generates inside the aorta and the great vessels at each foot-strike shock.