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Biomedical subjects

H H Dickhuth

Publications and source records attributed to H H Dickhuth.

At least 55 records · Page 3Linked to original sources
PubMed1996

Breath-by-breath measurements for the analysis of exogenous glucose oxidation during intense endurance exercise using [13C]-isotopes.

Up to now only the analysis of 13CO2 in separate breath-gas samples after administration of [13C]-labelled carbohydrates with intervals of several minutes in between has been available for analyses of the exogenous glucose oxidation during exercise. Our studies show the use of rapid respiratory mass spectrometry for breath-by-breath analysis to determine exogenous glucose utilization. Six male triathletes performed two exercise tests of 100-min duration each on a cycle ergometer. In both tests 5 min after the beginning of cycling glucose was administered. In test 1 30 g natural glucose was given, in test 2 a mixture of 1.5 g [13C1]-glucose and 28.5 g natural glucose. The work rate was regulated to keep constant 90% of the VO2 at the VO2 levelling off (VO2max) measured in a short ramp test. The resulting work rate was at 260.2 +/- 9.5 watts in test 1 and at 276.3 +/- 12.1 watts in test 2. Respiration gases and the end-tidal concentrations of 12CO2 (12C) and 13CO2 (13C) were calculated breath-by-breath online. The course of the ratio [13C/12C] reflects the course of exogenous glucose utilization. Onset of utilization was 10.5 +/- 5.5 min following oral administration. Maximum utilization was attained at 53.1 +/- 9.8 min with a maximal rate of oxidation of 0.36 +/- 0.05 g/min. The beginning of the energy supply of exogenous glucose could be determined quite soon after oral administration.

Adult↗
PubMed1996

The echocardiographic determination of volume and muscle mass of the heart.

One- and two-dimensional echocardiography permits assessment of left ventricular size and muscle mass, whereas the validity and reliability differ. It is comparable to other methods, such as angiography, scintigraphy and magnetic resonance imaging, but has the advantage of being noninvasive and of lower cost. It therefore appears particularly well-suited for applications in sports medicine. However, changes of 10%-20%, depending on the parameter, are necessary in individual cases to permit assumption of a proven change. A further methodical improvement, especially in respect to reliability but also to validity may be expected in the future from three-dimensional, computer-supported examination techniques. Enlargement of the heart due to endurance sports is harmonic and affects all four cardiac chambers. Limits to the increase in left ventricular volume and muscle mass can be recognized in relation to body weight. They usually do not exceed 70% of the baseline value or the value obtained for untrained persons. Power training, even in extreme forms, results in no or only minimal dimensional changes.

Adaptation, Physiological↗
PubMed1996

Effect of combined parasympathetic and sympathetic blockade on left ventricular relaxation at rest and during exercise in trained and untrained men.

We investigated the influence of autonomic blockade (AB) on the left ventricular (LV) diastolic function at rest (R) and during bicycle exercise (EX) in eight endurance-trained (TR) and ten untrained subjects (UT). Two-dimensional and M-mode echocardiography at the parasternal long axis were performed at rest and during an exercise protocol, which consisted of two stages of 50 and 100 W. Using the digitized data from the M-mode echocardiogram, the normalized maximal increase in LV dimension during the rapid filling phase (nmD) was calculated according to Hörtnagl. Additionally the ECG was recorded at R and during Ex 60 min after this first test. 0.02 mg.kg body mass-1 propanolol and 0.04 mg.kg body mass-1 atropine were injected intravenously over a 5-min period and the test procedure was repeated as described above. Before AB nmD increased significantly from resting values to 100 W in both groups, whereas nmD tended to be lower in UT compared to TR. During AB nmD of UT was rather unchanged at R and during EX compared to pre-blockade conditions. In contrast nmD of TR was slightly reduced and this difference was significant at 100 W. No major difference in nmD between the TR and UT group could be observed during AB. Before and during AB HR of TR were significantly lower at rest, 50 and 100 W compared to UT. We conclude that the enhanced diastolic relaxation observed in endurance athletes seems to be due to a training-induced adaptation of the autonomic nervous system.

Adaptation, Physiological↗
PubMed1995

Right ventricular apical view--a new window for Doppler echocardiography of aortic valve stenosis.

We studied a new Doppler echocardiographic approach in 56 patients with valvular aortic stenosis from the right ventricular apex (AS-RV) and compared the transvalvular gradients with the results of the standard view from the left ventricular apex (AS-LV). AS-RV resulted in good or acceptable velocity curves in 59% of patients. The correlation between the two apical views for the peak/mean gradients were close (r = 0.95/0.96). Using all typical positions for Doppler investigation of aortic stenosis, highest peak gradients were best recorded in five cases by AS-RV. In one woman with a narrow left ventricular cavum and severe aortic stenosis, only AS-RV yielded a technically good spectral curve. Thus, in selected patients--probably those with a small left ventricular cavity or an enlarged right ventricle--AS-RV may be the best window or even the only possibility in Doppler investigation of aortic valve stenosis.

Adult↗
PubMed1994

Relative functional buffering capacity in 400-meter runners, long-distance runners and untrained individuals.

Buffering is a factor which influences performance in short and middle-term endurance by compensating exercise acidosis. The aim of the study was to establish whether respiration parameters are a relative measure of buffering capacity and to study the influence of buffering on specific performance parameters. Three groups (each of ten subjects) with defined degrees of adaptation [untrained (UT), aerobic-trained (AeT) and elite 400-m runners (AnT) with a best time of 48.47 +/- 0.98 s] were examined in an incremental multi-stage test on the treadmill. Breath-by-breath gas analysis was performed using mass spectrometry and computer routines. Serum lactate concentrations were determined at each exercise level until subjective exhaustion. A value for the relative functional buffering capacity (relFB) was calculated using exercise metabolic parameters. Running speed at the lactate threshold was used as the starting point of buffering. The start of respiratory compensation of acidosis (RCP) was taken as the endpoint of buffering. RCP was determined at the point of decrease in end-tidal CO2 content (CO2-ET). RelFB was given in percent of buffering to running speed at RCP. Group AnT attained the same maximum performance data (maximum running speed, maximum rate of O2 consumption) as group AeT. However, these values were attained in group AnT with a significantly higher relFB (AnT: 31.0 +/- 3.2% vs. AeT: 15.7 +/- 3.9%, P < 0.0001), while a higher lactate threshold indicated a greater oxidative capacity in AeT (AeT: 3.07 +/- 0.26 m.s-1 vs. AnT: 2.68 +/- 0.22 m.s-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Echocardiographic findings in endurance athletes with hypertrophic non-obstructive cardiomyopathy (HNCM) compared to non-athletes with HNCM and to physiological hypertrophy (athlete's heart).

Hypertrophic non-obstructive cardiomyopathy (HNCM) is one of the most frequent causes of sudden cardiac death in young athletes. Since the clinical findings in HNCM patients may be inconspicuous and the ECG changes found in endurance athletes may be similar to those of HNCM patients, echocardiography, as a non-invasive procedure, seems to take on an important role in differential diagnostics. To prove this hypothesis, conventional echocardiographic parameters were compared in three groups with confirmed diagnosis: Group I: HNCM (n = 9) without sports activity; Group II: HNCM (n = 9) with regular, intensive endurance training (3-5 hours/week). The diagnosis was invasively confirmed in both groups. Group III: healthy subjects (n = 9) with physiological hypertrophy and regular endurance training (3-6 hours/week). In the presence of HNCM, endurance sports activity appears to offset the reduction in the left ventricle and enlargement of the left atrium. The wall thickness of the septum and posterior wall do not differ in the two HNCM groups, but show a significant difference to the healthy athletes. The enddiastolic diameter, the absolute septum and posterior wall thickness and the ratio of septum+posterior wall/enddiastolic diameter can be taken as the most important differential diagnostic criterium in physiological hypertrophy, but not the ratio between septum/posterior wall. It is concluded that conventional echocardiographic examination can be considered a valuable non-invasive method for differentiating HNCM from athlete's heart, even in patients with HNCM who participate in endurance sports. However, a reliable diagnosis may not be possible in individual cases.

Adolescent↗
PubMed1994

Normal values of isokinetic maximum strength, the strength/velocity curve, and the angle at peak torque of all degrees of freedom in the shoulder.

Many acute and chronic complaints in the shoulder joint are due to a reduced active stabilization capacity. Procedures to measure isokinetic strength are used to objectify the muscle deficits and imbalances of various muscle groups. In this study, standard values and reference ranges were determined for peak torque (PT), strength/velocity curve, and range of motion (ROM) at peak torque in the shoulder in 19 untrained women and 32 men. Differentiation was made by the individual degrees of freedom of the shoulder joint and the various types of work (concentric, isometric, eccentric). Moreover, the influence of height, body weight, and body mass index on isokinetic maximum strength development was investigated. It was found that it is necessary to distinguish between the various movements and types of work in development of peak torque. A decrease in maximum strength is observed in the sequence extension, adduction/flexion, abduction/internal rotation, external rotation. The maximum strength of men was determined to be higher than that in women. ROM shows a wide fluctuation and does not possess high validity. Height, as well as body weight and body mass index have only slight influence on the isokinetic maximum strength in the shoulder of untrained men and women.

Adult↗
PubMed1994

Reproducibility of isokinetic peak torque and angle at peak torque in the shoulder joint.

Adequate reliability studies of knee flexion and extension are currently available for isokinetic measurements, but not for the shoulder joint. For this reason, this study examines the variability (%) in the determination of peak torque (PT) and the angle at peak torque (AP) in the test-retest procedure. Differentiation is made between the various types of work (concentric, isometric, eccentric) and the degrees of freedom in the shoulder joint (flexion/extension, abduction/adduction, external rotation/internal rotation). The results show a variability of PT for concentric measurements of 15.0%-19.0% for all degrees of freedom; for flexion/extension and abduction/adduction in isometric and eccentric work, the variability is 17.5%-25.3%. External and internal rotation show generally greater deviation (29.0%-35.3%), except in concentric work. The angle at peak torque can only be reproduced to a limited degree (25.1%-41.1% variability). It is concluded that lower reproducibility can be attained for the shoulder joint compared to the knee joint, depending on the degree of freedom and exercise form tested. It appears meaningful to cite only ranges for the angle at peak torque.

Adult↗
PubMed1994

The cardiocirculatory reaction to isokinetic exercises in dependence on the form of exercise and age.

Although isokinetic training is gaining in importance in prevention and rehabilitation, even for older patients, there is hardly any information available on the extent of cardiocirculatory stress. This study was aimed, therefore, at examining the cardiocirculatory reaction to various isokinetic forms of exercise in dependence on age. Sixty-four subjects between 22 and 60 years of age were assigned to four age groups and the maximum torque measured in concentric and eccentric exercises with various angle accelerations. Moreover, all subjects underwent 1-min concentric and eccentric endurance stress and an isometric test. The cardiocirculatory reaction as reflected in heart rate and blood pressure patterns was determined, as well as the plasma catecholamines adrenaline and noradrenaline measured. The eccentric maximum torque was significantly above the concentric maximum torque; there was a significant inverse relationship to age only in the concentric mode of exercise (r = -0.48; p < 0.01). The cardiocirculatory reaction in endurance stress and isometry, like the behavior of heart rate, blood pressure, and plasma catecholamines, was greatest in concentric exercise, although the maximum strength values were lower, followed by eccentric exercise and isometry. Exercise values such as those attained in maximum ergometric forms of exercise were not reached. It is concluded that no special precautionary measures are required in isokinetic forms of exercise.

Adult↗
PubMed1991

[Fitness for swimming after myocardial infarct].

Standardized telemetry during swimming and blood pressure monitoring were performed on 25 consecutive patients (22 men and 3 women: mean age 59 +/- 7 years) after myocardial infarction, sustained on average 28 +/- 26 months ago. Mean exercise tolerance, as judged by symptoms during bicycle ergometry, was 1.31 +/- 0.5 W/kg (pulse limit 117 +/- 21 beats/min). The swimming test had to be discontinued in six patients because of severe arrhythmias, in two because of severe angina. Seven patients completed the full swimming distance, but were also considered unsuitable for swimming because of moderate angina and dyspnoea. Ten patients proved to be fit for swimming. Their average ergometrically determined exercise tolerance (1.27 +/- 0.51 W/kg, pulse limit 114 +/- 16 beats/min) was not different from that of unfit patients (1.34 +/- 0.50 W/kg; 119 +/- 24 beats/min). During swimming the unfit patients had a significantly higher heart rate and blood pressure rise than the fit ones. Only in the unfit patients the exercise tolerance limit determined by bicycle ergometry was exceeded during swimming. This indicates that postinfarction patients should undergo swimming telemetry before declared fit for swimming.

Angina Pectoris↗
PubMed1991

Training-overtraining. A prospective, experimental study with experienced middle- and long-distance runners.

Overtraining may be one frequent cause of stagnation or decrease in performance capacity of athletes. Israel (19) differentiates between addisonoid (parasympathetic) and basedowoid (sympathetic) overtraining, characterized by inhibition or excitation. We tried to induce an overtraining syndrome in 8 experienced middle- and long-distance runners, based on an increase in training volume from an average 85.9 km (week 1) to 115.1 km (week 2) and 143.1 km (week 3) to 174.6 km per week (week 4). The influence of this training on cardiovascular, metabolic and hormonal parameters was examined with special respect to plasma and urinary catecholamines. Laboratory testing including graded treadmill running was performed on the days 0, 14 and 28. Training was held six days each week, with nearly 30 km per day in the fourth week. A stagnation in endurance performance capacity (running velocity at the aerobic-anaerobic transition range) and a decrease in maximum working capacity were observed in 6 and a stagnation in 2 of the 8 sportsmen, indicated by a decrease in total running distance from 4719 + 912 m to 4361 + 788 m during incremental treadmill ergometry. The sportsmen could neither improve nor could they even approximately reach their personal records during the subsequent competitive season. Subjective complaints, classified on a four-point scale, increased from 1.2 (week 1) to 3.2 in week 4. Glucose, lactate, ammonia, glycerol, free fatty acids, albumin, LDL, VLDL cholesterol, hemoglobin level (transient), leukocytes, and heart rate (before and during exercise) decreased significantly. Urea, creatinine, uric acid, GOT, GPT, gamma-GT, serum electrolytes (except phosphate and calcium) remained constant at the measuring times, CPK was elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The relationship between heart rate and QT interval during atrial stimulation.

The relationship between heart rate and QT interval was investigated during atrial stimulation (intrinsic effect of heart rate) in ten healthy male volunteers prior to and after administration of sotalol. The QT interval in the ECG (paper speed 200 mm/s) was determined at rates of 70, 85, 100, 115, 130, 145, and 160 beats/min and at pacing periods of 180 s each at 30, 60, 120, and 180 s. After a 15-minute period, 2.0 mg sotalol/kg body weight were administered iv and the stimulation protocol was repeated. The analysis of QT interval behavior reveals contradictions to the mathematical implications of Bazett's equation QT = QTc square root of 60/HR, so that the relationship between heart rate and QT interval is not adequately described under the given conditions. After examination of approaches reported in the literature and our own approaches, the expression QT = a e-b (HR-60) is used as a possibility differentially to describe the data by nonlinear regression. The parameters a and b may be interpreted as QT reference value and shortening parameter. The QT reference value a, a parameter in reference to heart rate of 60 beats/min, has a comparable significance to the expression QTc in the Bazett equation. A reduction in the shortening parameter b indicates whether substances influencing the QT interval additionally produce overproportional shortening of the QT interval with increasing heart rate. After administration of sotalol, an increase can be observed in both the QT reference value and also in the shortening parameter. The suggested approach is an attempt to provide a more precise assessment of the QT interval under different conditions.

Adult↗
PubMed1990

[Effect of beta blockade on hemodynamics in physical exertion].

Beta-receptor blocking agents are known for more than 20 years. They are of definite use in the therapy of arterial hypertension and coronary heart disease. Beta-blockers lower the sympathoadrenergic discharge to the heart and circulation, particularly if the former is increased. Beta-blockers induce a negative chronotropic and inotropic effect and inhibit beta 2-mediated vasodilation. Thus beta-sympathicolysis during physical activity results in damping of heart rate increase and of elevation of cardiac contractility. Systolic blood pressure does not increase much, and usually there is no decline in diastolic blood pressure, due to elevated peripheral resistance. With adequate dosage, there may even be a slight increase in diastolic pressure, an effect eventually vaning in chronic therapy. Pulmonary capillary wedge pressure is elevated to above normal via inhibition of contractility and relaxation of the heart. Stroke volume, cardiac output and the double-product decrease, the arteriovenous oxygen difference under exercise increases clearly and the maximum aerobic performance capacity decrease in healthy individuals. In coronary patients, this may protect against cardiac overload and increase symptom-free physical work capacity, due to a relative decrease in the myocardial O2 requirement and improved coronary perfusion resulting from prolonged diastole. With verified indication (hypertensive-hyperkinetic impairments of cardiovascular function, coronary heart disease), the goal is an overlapping, endurance-oriented training to reduce the overall sympathetic activation, in order to minimize medication in the long run.

Adrenergic beta-Antagonists↗
PubMed1989

[Doping--also a problem in general practice?].

In 1986, the Medical Commission of the IOC defined doping as the use of pharmacological substances belonging to disallowed groups of active substances (stimulants, narcotics, anabolic steroids, beta-blockers, diuretics). With certain restrictions, this applies also to alcohol, local anesthetics and corticosteroids. The use of disallowed methods (blood doping, manipulation of a urine sample) is also forbidden. These days the greatest importance is attached to anabolic steroids (including testosterone), since these substances--discontinued in good time--cannot be detected on the day of competition but still have a promoting effect on performance. Competitive sports prepared the way here for the use of anabolic steroids in general athletics and in particular usually non-olympic sports (such as bodybuilding). Against this background, effects, adverse effects and the risks of anabolic steroid use are discussed. The aim must be to prevent the use of doping, especially in uncontrollable general sports, by promoting proper awareness.

Anabolic Agents↗
PubMed1989

The long-term involution of physiological cardiomegaly and cardiac hypertrophy.

The long-term involution of physiological cardiomegaly and cardiac hypertrophy. Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 244-249, 1989. Forty-five former athletes in endurance disciplines, primarily Olympic medalists and World Cup, European Cup, and German champions, for whom results of an exercise ECG and radiological heart volume measurement were available from their active competitive phase, were examined. The study protocol included clinical examination, laboratory controls, resting and exercise ECG, determination of cardiac volume, and one- and two-dimensional echocardiographic examination. Of the 45 former athletes contacted, 38 appeared for examination. Of these, four presented with heart disease (two with infarction, one with aortic stenosis, and one with arrhythmia). The remaining 34 were divided into groups of still active (more than 300 kcal.wk-1) and inactive (less than 300 kcal.wk-1) athletes. The interval between the first and second examination averaged 23 yr. The active former athletes showed a weight increase of 5.2% (P less than 0.01) and a reduction of 14% in ergometric performance (P less than 0.02). The inactive group had a marked weight increase of 17.4% (P less than 0.001); the ergometric performance was lowered by 20% (P less than 0.001). The absolute heart size had decreased in the active group by 6.1% (NS) and the relative heart size by 10.7% (P less than 0.005); the corresponding values in the inactive group were 4.5% (NS) and 18% (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗