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Biomedical subjects

A Niess

Publications and source records attributed to A Niess.

10 recordsLinked to original sources
PubMed2006

[Obesity--an interdisciplinary task].

In industrial nations, over the last five decades conditions concerning nutrition and physical exercise as well as socio-economic circumstances have changed radically. One of the consequences following from this development has been a rapid increase in the prevalence of obesity. Studies have shown that currently 20 percent of the German adult population suffer from obesity. Investigations into the etiology of obesity have to address complex interactions between genetic, socio-economic and psychosocial factors. A year ago, at the University Hospital Tübingen different departments joined to set up the "Plattform Adipositas". Endocrinologists, obesity surgeons, professionals in sports medicine and psychosomatic medicine as well as dieticians are collaborating to develop scientifically based therapy programs and treatment pathways for obese patients. The following article gives an account of this exemplary interdisciplinary cooperation.

Germany↗
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↗
PubMed2001

Metabolic reaction after concentric and eccentric endurance-exercise of the knee and ankle.

PURPOSE: Power training plays an essential part in many sport disciplines. The importance of eccentric power training remains a matter of controversial discussion. The objective of this study was therefore to investigate the difference in metabolic reaction between eccentric and concentric stress in comparable work. METHODS: Sixty-four men between 22 and 60 yr of age performed maximum isokinetic 1-min endurance tests of the knee and ankle each in concentric (180 degrees.s-1) and eccentric (60 degrees.s-1) modes with comparable total area of contraction-time curve (NS). Higher strength values (mean peak torque, P < 0.01), lower fatigue (fatigue index, P < 0.001), lower increase in lactate (P < 0.01), and lower ammonia production (P < 0.01) were found in eccentric than in concentric exercise, independent of the joint. The eccentric form of stress showed lower decrease and thus age-dependence in maximum strength and in fatigue than the concentric form. RESULTS: The results permit the conclusion that eccentric exercise leads to less fatigue and lower lactate and ammonia reaction than concentric exercise in comparable work levels. Variable visco-elastic properties of the muscle fibers themselves with additive passive strength in eccentric mode is considered as the cause. CONCLUSIONS: It remains uncertain whether the lower metabolic stress might be useful during the training process. A greater scope of training and increased number of training stimuli might be applied in primarily eccentric forms of exercise.

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

Metabolic and cardiocirculatory reactions after concentric and eccentric exercise of the shoulder.

Lower metabolic and cardiocirculatory reactions to eccentric compared to concentric exercise are known for large muscle groups. The extent of exercise reaction depends on the muscle mass involved and moreover differs between the various muscle groups, while it is unclear to which extent cardiovascular and metabolic reactions and differences between the types of work exist in the shoulder, also it is not known whether these reactions differ according to training status. Lactate production (LA), heart rate (HR), and blood pressure (BP) were examined following eccentric and concentric shoulder movements in 16 male gymnasts (GN) and 15 male untrained subjects (US). Differentiation was made according to the types of work for peak torque (PT) and local muscle endurance (LME). Following eccentric exercise, the increase of LA and HR was clearly lower than following concentric exercise (p<0.05). No difference was observed between the groups. Diastolic BP showed no changes, whereas systolic BP was higher following concentric exercise. Eccentric PT was higher than concentric PT in GN within a test-retest variability of 15%. LME showed a lower degree of fatigue under eccentric conditions, independent of the group. It is concluded that eccentric exercise of the shoulder leads to lower metabolic and cardiocirculatory reactions than concentric exercise, in spite of higher peak torque and less fatigue. Exercises consisting of a high proportion of eccentric movement may thus be beneficial in the therapy of shoulder complaints, especially in patients with cardiovascular disease.

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↗
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↗