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Biomedical subjects

K Röcker

Publications and source records attributed to K Röcker.

15 recordsLinked to original sources
PubMed2004

Hypertrophic cardiomyopathy--sports-related aspects of diagnosis, therapy, and sports eligibility.

Hypertrophic cardiomyopathy (HCM) is one of the primary causes of sudden cardiac death in athletes < 35 years of age. The highest risk of sudden cardiac death is associated with syncope, early age, extreme ventricular hypertrophy, ventricular tachycardia, and a family history of sudden death. The relative risk in competitive sports is unknown. Usually, sports eligibility is rejected. However, some athletes with HCM tolerate extreme athletic lifestyles without complications. Sports-related aspects of diagnosis, therapy, and sports eligibility are presented, and discussed. Two case reports are presented: a 20-year-old professional soccer player and a 66-year-old long-distance runner. Athletes with HCM should not participate in most competitive sports with the possible exception of those of low dynamic and low static intensity. Participation in low to moderate athletic activities may be allowed in selected patients without risk factors and > 35 years of age.

Cardiomyopathy, Hypertrophic↗
PubMed2002

Exercise-induced, persistent and generalized muscle cramps. A case report.

We are reporting on a 46-year-old man who has suffered of muscle cramps for 4 years, occurring immediately after jogging and playing tennis and lasting for 7-8 hours. Repeated neurological, orthopedic, internal medical and endocrinological examinations showed no pathological findings. Physiotherapy, supplementation of fluids and electrolytes had no effect, nor did medication therapy with muscle relaxants. During spiroergometry without medication, there was an overproportional increase of heart rate and respiratory rate with delayed pCO2 increase after exercise with otherwise normal blood gas levels. This reaction was considerably reduced during spiroergometry under beta-blockade (metoprolol 100 mg); at the same time, the muscle cramps could no longer be induced. Both excessive respiratory regulation and direct hyperadrenergic stimulation should be discussed as the primary cause of the muscle cramps. According to recent findings, b-blockers with intrinsic sympathocomimetic activity should be avoided in therapy.

Adrenergic beta-Antagonists↗
PubMed1999

[The significance of physical activity on the physiological stress reaction].

The extent of physical activity and the dynamic performance capacity show an inverse relationship to cardiovascular mortality, independent of the influence of other risk factors, but the underlying mechanism remains uncertain. Most concepts assume that the aerobic capacity of the peripheral musculature is increased by training, and thus improved cardiocirculatory regulation and especially a more favorable stress reaction pattern are attained. This adaptation is essentially an inverse adaptation mechanism as in established cardiocirculatory insufficiency. Based on an extended stress concept, it can be seen that training effects, especially in autonomic circulatory regulation, occur under physiological conditions to a lower degree in the renin-angiotensin-aldosterone system and in inflammatory reaction. The training effects depend on the form of exercise, the baseline condition, the extent of training, and genetic predisposition. It can be particularly demonstrated when the aerobic capacity has been sufficiently enlarged in an adequate proportion of the peripheral musculature. To what extent and under what conditions these training effects can be used under the pathophysiological conditions of established cardiocirculatory insufficiency is presently under investigation.

Adaptation, Physiological↗
PubMed1999

Muscular fatigue, maximum strength an stress reactions of the shoulder musculature in paraplegics.

In paraplegic patients, shoulder complaints attributable to muscle dysbalances arising from the particular daily form of exercise are often observed. The goal of therapy is to correct these imbalances through muscular training, whereby eccentric exercise might offer advantages due to lower fatigue with concurrent higher maximum strength. This study therefore examines muscle fatigue, maximum strength, and suitability for paraplegics of eccentric exercise of the shoulder. Muscle fatigue, isokinetic peak torque, and EMG activity were determined eccentric (Ecc) and concentric (Con) in 41 paraplegic subjects (13 early rehabilitants; 16 trained in wheelchair sports; 12 untrained). Serum CK, myoglobin, and subjective pain were collected for one week after exercise. In eccentric exercise, there was less muscle fatigue in all groups. Highest Ecc/Con peak torque ratio was found in trained subjects in all movements, followed by the untrained and the early rehabilitants. EMG-activity was lower in eccentric compared to concentric exercise (Ecc/Con ratio <1). CK and myoglobin concentrations, like pain symptoms, showed a marked increase after exercise. It is concluded that the Ecc/Con strength patterns among paraplegics are altered. Eccentric exercise offers advantages on the basis of lower muscular fatigue independent of training status and lesion time and higher maximum strength with increasing duration of paraplegia and additional athletic training. However, due to structural damage and subjective pain eccentric exercise can only be recommended with reservations in therapy and training.

Adult↗
PubMed1999

Ventilatory, lactate-derived and catecholamine thresholds during incremental treadmill running: relationship and reproducibility.

Anaerobic threshold as a basic criterion of training recommendation can be estimated by various parameters. The purpose of this study was to investigate the relationship and the reproducibility of ventilatory, lactate-derived and catecholamine thresholds of an incremental treadmill exercise. Therefore, 11 male subjects underwent two incremental treadmill tests within 7 days. The lactate threshold (LT) was determined at the lowest value of the lactate-equivalent (ratio lactate/performance). The individual anaerobic threshold (IAT) was calculated at LT+1.5 mmol/L lactate. The ventilatory thresholds, using mass-spectrometry, were defined by the V-slope method (AT) and at the deflection point of end-tidal CO2 (ET-CO2) concentration (RCP). The thresholds of epinephrine (TE) and norepinephrine (TNE) were calculated in the manner of LT. The running velocities were highly reproducible at LT (test-retest correlation coefficient r=0.90), IAT (r=0.97), AT (r=0.88) and RCP (r=0.95). By contrast TE (r=0.49) and TNE (r=0.46) showed a poor reproducibility. TE and TNE occurred 5-11% below LT and AT with a low correlation to LT and AT. LT was found 4% below AT, both were correlated with r=0.70 (p<0.01, test 1) and r=0.95 (p<0.01, test 2). IAT occurred 7-8% above RCP, in both tests a close correlation was found between IAT and RCP of r=0.97 (p<0.01). In summary, the ventilatory and lactate-derived thresholds show a high and similar reproducibility, but the catecholamine threshold does not. In the present exercise protocol, there are systematic differences between the lactate-derived and ventilatory thresholds, in spite of a close relationship, and these must be taken into account in recommendations derived for training.

Adult↗
PubMed1998

Endurance training in females: changes in beta-endorphin and ACTH.

Previous results from endurance training in women have been discrepant in regard to influences on basal and maximum adrenocorticotropin (ACTH) and beta-endorphin (beta-EP) concentrations before and after exhaustive exercise. A group of 23 untrained young women ran 3 times a week for 30 min at an individual specific intensity corresponding to their respective anaerobic threshold, derived from the lactate performance curve obtained from prior treadmill testing. ACTH and beta-EP were measured at rest, as well as 5 and 30 min after exhaustive progressive spiroergometric treadmill running, both before and after the 8 week endurance training program. Basal beta-EP did not change after training, but less elevated concentrations were measured both 5 (p < 0.05) and 30 min (p < 0.05) after exercise, after the training program. In contrast, the resting concentration of ACTH increased significantly; the respective maximum concentration was less elevated after 5 min and much less elevated 30 min after the exercise (p < 0.05). Positive correlations were found after the exhaustive exercise between beta-EP and ACTH, as well as between maximum lactate and ACTH. Training was associated with significant changes in maximum running speed (p < 0.01), maximum oxygen uptake (p < 0.01) and the running speed at the anaerobic threshold (p < 0.05). Maximum lactate and the level of perceived exertion remained unchanged, showing a similar level of exhaustion. Our results indicate that endurance training modulates the hormonal responses of beta-EP and ACTH to comparable workloads of high intensity. After the training program the maximum concentrations are significantly lower during the recovery period. The tendency to elevated basal ACTH, and thus elevated cortisol, might be a new factor to consider in evaluation of endurance training induced hormonal disturbances in women.

Adrenocorticotropic Hormone↗
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↗
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↗
PubMed1987

Transcutaneous monitoring of PO2 and PCO2 during running--a noninvasive determination of gas transport.

Transcutaneous pO2 and pCO2 (tcpO2 and tcpCO2) were measured during running with stepwise increased velocities and with constant speed, under both aerobic and anaerobic conditions, for the determination of blood gas transport during exercise. Arterial and transcutaneous blood gas values correlated significantly (pO2 r = 0.87, p less than 0.001, pCO2 r = 0.91, p less than 0.001 respectively). Transcutaneous pCO2 is a noninvasive method of monitoring arterial pCO2 and lactate formation during exercise. When athletes run, arterial pO2 falls to a specific limit depending on the intensity of work. This seems to be characteristic for maximum oxygen transport capacity. The aerobic endurance measured by the aerobic-anaerobic threshold may be dependent on the possibility of sustaining low arterial pO2 during high working levels at high oxygen consumption.

Blood Gas Monitoring, Transcutaneous↗