Hypothalamic-pituitary-adrenal and -gonadal axis function after exercise in sedentary and endurance trained elderly males

The aim of this study was to investigate hypothalamic-pituitary-adrenal (HPAA) and -gonadal (HPGA) axis responses to post-exercise (30 min at 65% VO2max) combined corticotrophin, luteinizing hormone and thyrotrophin releasing hormone challenge (0.7 microg/ kg body mass) in elderly distance runners (DR; age: 68.9+/-4.2 year) and sedentary individuals (SI; age: 69.1+/-2.6 year). Plasma cortisol, growth hormone, prolactin, luteinizing hormone, follicle stimulating hormone and total testosterone (T) concentrations pre- and post-exercise as well as in response to stimulation did not differ between DR and SI. Plasma adrenocorticotropic hormone returned to pre-exercise level in DR 60 min and in SI 90 min post-stimulation. Free T was lower in DR at all time points. Our results do not support the notion of altered releasing hormone-stimulable HPAA and HPGA synthesis-secretion capacity in elderly males after endurance training.

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.

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.

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.

[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.

[The microagglutination test--a simple and sensitive procedure for serodiagnosis of pertussis infections]

The microagglutination assay is a useful method for the diagnosis of B. pertussis infections. In a group of 30 patients with culture proven pertussis 27 (90%) had > or = fourfold increases in titers between acute and convalescent phase serum specimens. The microagglutination test offers several advantages over other more sophisticated B. pertussis antibody tests: only 50 microliters of serum is required, it is a standardized test, which doesn't require specialized technical expertise or equipment, it is easy to perform and good results are noted in a broad age range of patients. Disadvantages of the microagglutination test are: two separate serum specimens are necessary (acute and convalescent phase), the test does not differentiate IgA and IgG antibodies and the temporal association with recent immunization can lead to false positive results. In our opinion the microagglutination test is a useful method for the diagnosis of B. pertussis infections. This is especially true in cases where more sophisticated serologic tests such as ELISA can not be performed immediately but physicians and patients expect to get a result quickly.

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.

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.

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.

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.

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.

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.

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.

[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.