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Biomedical subjects

R Rost

Publications and source records attributed to R Rost.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Sports medicine aspects in children and adolescents].

In opposite to adults, exercise and sports are natural elements in the life of children and adolescents. However, they gain new aspects in the modern achievement-oriented society. The competitive sports are moving more and more towards the children's and adolescents's age. Additionally, sport should be done early during live for prevention of civilization diseases later on. Finally, physical therapy gains growing importance in the therapy and rehabilitation of children and adolescents. As to strength, children are not just 'small adults'. In children, the physical capacity in the aerobic range is larger and in the anaerobic range is smaller than in adults. The question of trainability and talent, respectively, plays an important role in the competitive sport as well as in the consultation of children for their sport career. The danger of the child during sport is discussed from the view of internal and orthopedic medicine. Concepts of sports medical preventions are derived from this discussion. The question of sports with pre-existing diseases in children and adolescents is only marginally discussed.

Adolescent↗
PubMed1997

The athlete's heart. Historical perspectives--solved and unsolved problems.

Clinicians are coming back to Henschen's assessment of the athlete's heart as a physiologic and positive phenomenon. An athlete's heart may be affected by clinical conditions. Regarding the extreme performance of the athlete's heart in training and competition, conditions that may be harmless in sedentary people can be fatal for the athlete. The athlete's heart therefore deserves the particular interest and care of the sports cardiologist.

Adaptation, Physiological↗
PubMed1997

Blood glutathione status following distance running.

In 12 moderately trained subjects reduced glutathione (GSH) and oxidized glutathione (GSSG) as well as thiobarbituric acid reactive substances (TBARS) were measured in the blood before and during the first two hours and first two days after a 2.5-h run. The participants covered between 19 and 26 km (20.8 +/- 2.5 km, mean +/- SD). The running speed was between 53 and 82% of the speed at which blood lactate concentration reached 4 mmol/L lactate (67.9 +/- 8.2%, mean +/- SD) assessed during a previously performed treadmill test. Blood samples were collected 1 h before, immediately before, immediately after, 1 and 2 h after, as well as 1 and 2 days after the run. Immediately after exercise GSH was significantly decreased (p < 0.01) and GSSG significantly increased (p < 0.01). In all subjects the ratio of GSH to GSSG showed a marked decline to 18 +/- 4% (mean +/- SD) of the pre-exercise values (p < 0.01). One hour later the mean GSH and GSSG values returned to baseline. However, there were considerable inter-individual differences. In some subjects the GSH/ GSSG ratio overshot the pre-exercise levels, in others the ratio remained low even two hours after exercise. Compared with the pre-exercise values TBARS concentrations did not change significantly at any time point after exercise. The findings suggest that after prolonged exercise in moderately trained subjects a critical shift in the blood glutathione redox status may be reached. The changes observed were generally short-lived, the duration of which may have depended on the relative importance of reactive oxygen species generation by the capillary endothelial cells and neutrophil and eosinophil granulocytes after the end of exercise.

Adult↗
PubMed1997

Assessment of isometric contractions performed with maximal subjective effort: corresponding results for EEG changes and force measurements.

In order to find a parameter or parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were taken in connection with isometric muscle contractions performed with 80% of the subjective maximal force (IMC80) or with maximal subjective effort (IMC100). Criteria based on EEG recordings and force measurements have been considered as indicators for maximal subjective effort in a given movement. The following criteria were selected: A. If the mean spectral theta amplitude across the parieto-occipital area decreases from IMC80 to IMC100 then the isometric contraction is taken to be performed with maximal effort; B. If the obtained force values can be fitted to a switch function and if the achieved forces are only a predetermined percentage lower than the maximal force value obtained over all trials then this isometric contraction is accepted to be performed with maximal effort. 18 out of 24 cases fulfill the EEG criterion whereas the criterion for force measurements is fulfilled in 16 out of 24 trials. The comparison between the results obtained by means of the EEG criterion and by means of criterion for force measurement shows that the results are in agreement in 22 out of 24 cases (p < .001). The high correspondence of the assessments allows us to suspect that both criteria specify the same phenomenon, namely the performance of a motor task with maximal subjective effort.

Adult↗
PubMed1996

[Effect of low dose omega-3 fatty acid supplementation on plasma lipids and lipoproteins in coronary patients with dyslipoproteinemia].

In a prospective study, 20 patients (aged 48-67 years) with primary hyperlipoproteinaemia of phenotypes IIa, IIb, IV and with proven coronary sclerosis received four different doses of long-chain polyunsaturated omega-3 fatty acids. 0.18 to 1.1 g per day were administered in the form of fish oil capsules over four 2-week periods. The aim was to study the effect of different low dose supplementations of n-3 fatty acids on the plasmalipid- and lipoprotein composition and to determine a threshold of effectiveness. Significant reduction of the triglyceride level was registered in all subjects with the greatest decrease in those patients who presented with the highest base levels. The cholesterol and LDL-cholesterol values on average remained almost unchanged, apart from a significant increase of LDL-cholesterol in patients with type IV hyperlipoproteinaemia. The HDL-cholesterol fraction also showed a significant increase in type IIb patients which was related to alterations of the HDL-3 subfraction. The minimal effective dose of a daily administration of omega-3 fatty acids can be expected between 0.18 g and 0.35 g. The observed changes of plasmalipids and lipoproteins reflect the beneficial effect of long-chain polyunsaturated omega-3 fatty acids in respect to plasma-triglyceride reduction and HDL-cholesterol increase as seen in other studies, despite the use of supplementations far below 1 g per day.

Aged↗
PubMed1995

Theta power decreases in preparation for voluntary isometric contractions performed with maximal subjective effort.

In order to find EEG parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were realized in connection with isometric contractions (IMC). IMC were performed with submaximal and maximal subjective effort. Mean spectral power density within the theta band was found as an indicator for maximal subjective effort. The theta power across the parieto-occipital area decreases from rest through movements performed with submaximal force to movements performed with maximal effort. It is argued that this theta decrease possibly reflects a down-regulation of the posterior attention system in order to minimize the influences of external stimuli during the preparation for voluntary IMC performed with maximal subjective effort.

Adult↗
PubMed1994

Activation processes during mental practice in stroke patients.

In healthy subjects, mental practice is known to improve motor performance. It is also known to be accompanied by a higher central nervous activity. Since such effects seem to be desirable for rehabilitation, we investigated the possibility of detecting changes in central nervous activity by means of EEG in stroke patients, and whether these changes were similar to those observed in healthy subjects. 12 left-sided hemiplegic patients who underwent a specific post-stroke rehabilitation treatment were requested to perform a simple arm movement sequence. In the following mental practice period the patients were requested to image the same sequence without any real movement. EEG background activity was recorded during rest and imagination periods. After the calculation of z-transformed power values within the theta, alpha, and beta-1 band, differences between rest and imagination periods were evaluated for their significance. Stroke patients show significant decreases of theta, alpha, as well as beta-1 power during mental practice in comparison to the rest period. These changes are similar to those obtained in healthy subjects. Theta power decreases in central and parietal leads. Central alpha power diminishes only during imagination of the contralateral arm. This phenomenon as well as the decrease of beta-1 power in central derivation were also obtained during real motor performance and might indicate an activation of the sensorimotor cortex. In accordance with the hypothesis of internal feedback mechanisms, this activation is a necessary prerequisite for motor learning during mental practice.

Aged↗
PubMed1994

Clinical characteristics of illness caused by Bordetella parapertussis compared with illness caused by Bordetella pertussis.

In conjunction with a pertussis vaccine efficacy trial in Germany, nasopharyngeal specimens were collected from May, 1992, to March, 1993, from patients with cough illnesses. Clinical data were obtained by initial and follow-up questionnaires. Bordetella parapertussis was isolated from 38 patients (mean age, 3.5 years; 68% girls). Clinical characteristics in these cases were compared with those of 76 patients (matched by age and sex) with illness caused by Bordetella pertussis during the same period. Findings were: (B. pertussis/B. parapertussis): cough > 4 weeks 57%/37% (P = 0.06); whoop 80%/59% (P = 0.07); whoop > 2 weeks 26%/18% (P = 0.05); paroxysms 90%/83% (P = 0.5); body temperature > or = 38 degrees C 9%/0% (P = 0.17); vomiting 47%/42% (P = 0.69); and mean leukocyte and lymphocyte counts 12,500/mm3 and 7600/mm3 (P < 0.0001) and 7800/mm3 and 3500/mm3 (P < 0.0001), respectively. Illness caused by B. parapertussis was typical of pertussis but less severe than that caused by B. pertussis. In contrast with B. pertussis infection, lymphocytosis is not a characteristic of B. parapertussis infection. This is most likely a result of the lack of production of lymphocytosis-promoting factor toxin by B. parapertussis.

Bordetella↗
PubMed1994

Mental practice of motor skills used in poststroke rehabilitation has own effects on central nervous activation.

In the last years it has been shown that the use of the EMG triggered electrical myostimulation (ETEM) brings good results in poststroke rehabilitation. It has been hypothesized that the relearning effects obtained by means of ETEM are due to the reinstatement of proprioceptive feedback. However, the technique is most powerful if imagination of motor acts (the so called mental practice) is used as an initial part of ETEM. Since mental practice in healthy people leads to central nervous activation processes as well as to an improvement of motor skills, we investigated the effects of mental practice alone on central nervous activity by means of EEG in stroke patients. Twelve left-sided hemiplegic patients who underwent a specific poststroke rehabilitation treatment were requested to perform a simple arm movement sequence. In the following mental practice period the patients were requested to imagine the same sequence without any real movement. EEG background activity was recorded during baseline and imagination periods. After the calculation of z-transformed power values within the alpha and beta-1 band, differences between rest and imagination periods were evaluated for significance. Stroke patients showed significant decreases of alpha as well as beta-1 power during mental practice in comparison to the rest period. These changes are similar to those obtained in healthy subjects. Central alpha power diminished only during imagination of the contralateral arm. This phenomenon as well as the decrease of beta-1 power in central derivation were also obtained during real motor performance and might indicate an activation of the sensorimotor cortex. In accordance with the hypothesis of internal feedback mechanisms, this activation is a necessary prerequisite for motor learning during mental practice. We conclude that mental practice of motor skills might have own effects in poststroke rehabilitation.

Aged↗
PubMed1993

Effect of a short maximal physical exercise on the eosinophil cationic protein.

Eosinophil cationic protein (ECP) has been shown to be a marker of eosinophil granulocyte activation. In 10 healthy young subjects the plasma concentrations of ECP were measured before and after a graded maximal bicycle exercise test. The analyses were carried out 30 min before and immediately before exercise, immediately after exercise and 20 and 45 min later. The post-exercise values were corrected for plasma volume changes which were calculated from hematocrit and hemoglobin values. Immediately post-exercise the ECP increased significantly (p < 0.01) from 1.25 +/- 0.28 at rest to 2.40 +/- 0.59 micrograms/l. Twenty and 45 min later the values normalized and significant differences from the pre-exercise values could no longer be measured. The results provide strong evidence for an activation of eosinophil granulocytes after a short maximal exercise.

Adult↗
PubMed1992

Effects of simulated microgravity (HDT) on blood fluidity.

Exposures to microgravity and head-down tilt (HDT) produce similar changes in body fluid. This causes an increase in hematocrit that significantly affects hemorheological values. Lack of physical stimulation under bed rest conditions and the relative immobility of the crew during spaceflight also affects the blood fluidity. A group of six healthy male subjects participated as volunteers, and blood samples were collected 10 days before, on day 2 and day 9, and 2 days after the HDT phase. Blood rheology was quantified by plasma viscometry, red cell aggregability, and red cell deformability. A reduced red cell deformability, an indication of the diminished quality of the red blood cells, was measured under HDT conditions that finally led to the so-called "space flight anemia." Enhanced red cell membrane fragility induced by diminished physical activity and an increase in hemoglobin concentration are responsible for this effect. Plasma viscosity is reduced as a result of diminished plasma proteins. However, despite the reduction in plasma proteins, including fibrinogen, alpha 2-macroglobulin, and immunoglobulin M, red cell aggregation was enhanced, principally because of the increase in hematocrit. Our results of hemorheological alterations under HDT conditions may help to elucidate the formerly documented hematologic changes during spaceflight.

Adult↗
PubMed1992

The athlete's heart. Historical perspectives.

Even an athlete's heart may be affected by clinical conditions. Regarding the extreme performances of the athlete's heart in training and competition, even conditions that might be harmless in sedentary people can be fatal for the athlete. Looking back on the history of the athlete's heart, some common mistakes in its assessment can be avoided that might harm the athlete on the misinterpretation of adaptational phenomena or the trivialization of clinical conditions.

Adaptation, Physiological↗
PubMed1991

[The value of physical activity for prevention of coronary heart disease].

The usefulness of exercise as a preventive measure is discussed on the basis of a review of epidemiological studies. While no preventive effect has been reliably shown for physical activity at the workplace, physical exercise during leisure time does have such an effect. The incidence of myocardial infarction can be reduced by some 50 to 60%, although the contributions of protection and selection cannot be differentiated. The present data, however, militate against the possibility that, among those actively practicing sport, a primarily positive health selection effect is operative. The optimum of physical exercise would appear to be defined by a daily calorie consumption of 300 to 400 kcal (1250-1800 kJ) per day. Within the framework of secondary prevention, physical exercise can result in a reduction in mortality rate of 20%. The possibility of exercise related incidence prompts the requirement for a thorough physical check-up of those in the relevant risk groups.

Coronary Disease↗
PubMed1991

[The importance of sports for the prevention of coronary heart disease--physiological and pathophysiological aspects].

For the application of physical conditioning in the prevention of coronary heart disease to be meaningful, account must be taken of physiological and pathophysiological baselines. Physical activity is associated with an increase in metabolic rate, and the prophylactic effect of exercise is due mainly to metabolic effects and not, as commonly thought, to hemodynamic factors. Raising the metabolic rate has a positive effect on risk factors which--with the exception of smoking--are largely metabolic. For this reason, the physiological aspects of the release of energy and its increase under physical exercise are described. Of decisive importance for prophylaxis is not so much the nature of the exercise--for example endurance training in particular--as the overall extent of physical exercise, and the resulting energy consumption. The hemodynamic effect of physical activity, in particular the optimization of cardiovascular function, is of importance not so much for primary preventive reasons as for reducing the oxygen requirement of the myocardium--a secondary preventive measure. For producing a cardiovascular training effect, forms of exercise performed close to the aerobic-anaerobic threshold (AAT) are optimal. A common mistake is to assume that the training effect achieved under physiological conditions can simply be extrapolated to the pathophysiological situation. Exercise workloads that are below the aerobic-anaerobic threshold fail to produce a training effect. Here, the major aim must be to achieve metabolic, coordinative and motivational effects. If the physiological responses to exercise, in particular heart rate, are modified by pathophysiological or pharmacological mechanisms, other, in particular respiratory and metabolic parameters should be used as regulators of training. Such parameters are considered in detail.

Adrenergic beta-Antagonists↗
PubMed1990

[Silent myocardial ischemia--risk for sports in coronary groups?].

The present discussion of SMI is of major impact on physical active coronary patients, since SMI during physical training could represent a potential risk factor. We carried out an investigation in 107 coronary patients of ambulant coronary groups (ACG) on the incidence of SMI during exercise testing and Holter monitoring (HM) including a training unit. With both techniques in approximately 1/3 of the patients SMI could be observed, when coronary medication was omitted. However the concordance of these two positive groups was found to be remarkably low. During HM SMI was found within the training units nearly as frequent as during normal daily life. By beta blockade (100 mg metoprolol) exercise SMI during HM was suppressed in 2/3. Our conclusion was that SMI is not of major significance in pharmacologically well controlled participants in ACG.

Adult↗