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Biomedical subjects

W Hollmann

Publications and source records attributed to W Hollmann.

At least 19 recordsLinked to original sources
PubMed1992

The excretion of 17-ketosteroids and 17-hydroxycorticosteroids in night urine of elite rowers during altitude training.

During an altitude training camp (23 days, 1850 m above sea level) we collected night urine from 36 German elite rowers in order to measure the excretion of urea, creatinine, 17-ketosteroids (17-KS), and 17-hydroxycorticosteroids (17-OHCS). 17-KS and 17-OHCS represent the major metabolites from endogenous anabolic and catabolic steroid hormone systems. There was no significant change in the excretion of 17-OHCS during the training camp (mean value: females 0.0025 +/- 0.0011, males 0.0033 +/- 0.0012 mg/kgbw.h). Significant increases in the excretion of 17-KS (mean value: females 0.007 +/- 0.003, males 0.0092 +/- 0.0039 mg/kgbw.h) and in the ratio 17-KS/17-OHCS (mean value: females 3.13 +/- 1.65, males 3.11 +/- 1.71) were found during the first week and towards the end of the training camp. To investigate training effects on the excretion of these hormone metabolites, we used a recently described classification for rowing training (categories I to IV of rowing-specific training according to lactate levels and non-rowing specific categories) and a corresponding rowing data base. More than 80% of training was performed at a lactate level lower than 2 mmol/l. Using multiple regression analysis, the general finding was that in males the ratio of 17-KS/17-OHCS increased with rowing specific and non specific training regimes where a lactate level below 2 mmol/l was observed. Training at higher lactate levels caused a decrease in the ratio that may be interpreted as a shift in the production from endogenous androgenic steroid hormones to cortisol. No significant effects of single training variables were found in female rowers, which indicates major training influences on testosterone metabolism. The influence of further factors such as a relationship between urine urea and 17-KS in males are described and need further explanation.

17-Hydroxycorticosteroids↗
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↗
PubMed1991

Low vertebral bone density values in young non-elite female runners.

Thirty-five female runners (26.6 +/- 0.9 years, range 17-35) were scheduled for bone mineral density evaluation, using quantitative computed tomography of the lumbar spine. In 17 women with oligo-amenorrhea, vertebral bone mineral density was under the normal range (defined from a control group of 46 sedentary healthy females in the same age range), while it was within the normal range in all runners with regular menses (n = 18). When age classes were considered, all runners aged 17-21 (11/11) were found to have oligo-amenorrhea and low bone mineral density values, the difference in mineral density with the controls of the same age quartile being highly significant (p less than 0.001). Runners from the two youngest age classes (17-21 and 22-26) had started training early after menarche (0.9 +/- 0.6 and 2.5 +/- 1.6 years, respectively). These results show that very young female runners with oligo-amenorrhea may have impressively low bone mineral density values. The possibility that early onset of training, close to menarcheal age, might be a risk factor for low mineral density, deserves further investigation.

Adolescent↗
PubMed1991

Exercise changes in plasma tryptophan fractions and relationship with prolactin.

In the past the hypothesis was advanced that plasma tryptophan fractions mediate behavioural and neuroendocrine effects of exercise. To assess changes in free and total plasma tryptophan levels during and after exercise over a time period, and possible functional implications, 6 male volunteers were subjected to an endurance test of 1 hour duration on a bicycle ergometer at a work load below the 4 mmol/l lactate threshold. Total and free plasma tryptophan were determined by high-performance liquid chromatography with electrochemical detection, prolactin by radioimmunoassay, glycerol and nonesterified fatty acids (NEFA) by enzymatic methods. No significant changes in total tryptophan were found. Free plasma tryptophan increased significantly (23%, p less than 0.01) from 40 to 60 minutes of exercise. Highest levels were observed after 10 minutes of recovery (50% against preexercise). Prolactin levels correlated with free plasma tryptophan throughout the test (r = 0.77, p less than 0.001, all measured values) and during recovery (10 minutes: r = 0.88, p less than 0.05; 20 minutes: r = 0.86, p less than 0.05). These findings may further support the hypothesis that changes in peripheral amino acid concentrations may influence physiological reaction of exercise mediated by brain systems.

Adult↗
PubMed1991

An examination of the hemodynamic and metabolic effects of carteolol during different workloads on a bicycle ergometer.

The influence of 10 mg carteolol/day on the serum concentrations of insulin, C-peptide, glucagon, free fatty acids, adrenaline, noradrenaline, blood glucose, blood lactate levels, on heart rate and systolic blood pressure was investigated during different workloads on a bicycle ergometer in a placebo-controlled randomised double-blind study involving twelve male volunteers. The subjects performed standardized increasing exercises until subjective exhaustion as well as three 40-minute endurance exercises of varying intensity, corresponding to a lactate concentration of 1.0 to 2.0 mmol/l, 2.5 to 3.5 mmol/l and more than 3.5 mmol/l in the region of the anaerobic threshold, each exercise being followed by one rest day. The most important findings are: --the ISA of carteolol is of significance for the influence on the heart rate at rest but plays a minor role with respect to the degree of reduction in the heart rate and blood pressure under exercise; --carteolol exerts a minor influence on the metabolic parameters investigated in this study. This can be partly ascribed to the pronounced ISA of carteolol. In the case of endurance exercises, which lead to blood lactate concentrations of more than 3 mmol/l, the blood glucose levels showed a tendency to decrease. However, this was not statistically significant.

Adult↗
PubMed1991

[Development of physical performance and endurance in childhood and adolescence].

The information available in sports medicine regarding the development of performance and maximum stress is presented for children and adolsecents, and the importance of age-appropriate sports for general health is also discussed. A description of the five main forms of stress on the motor system follows, i.e., coordination, flexibility, strength, speed, and endurance, and their effectos on the performance parameters boys and girls from childhood to adolescence. Data on cardiopulmonary-metabolic performance parameters are discussed for children and adolescents. These include functional and morphological data on the heart, circulation, respiration, metabolism, and skeletal musculature. Precocious young people are physically capable of a higher performance level and can tolerate more stress than their normal counterparts or those with delayed development. With regard to the five forms of stress mentioned above, health questions related to the ability to tolerate stress and age-related levels of training are dealt with. The negative effects on health are considered with regard to the development of amenorrhea and a decrease in the mineral content of the skeletal system as a result of extensive endurance training.

Adolescent↗
PubMed1989

[The behavior of arterial blood pressure in dynamic and static muscle exercise with respect to atrial natriuretic peptide and neurotransmitters].

The development of the first semi-automatic blood pressure measuring instrument including optic and acoustic registration of systolic and diastolic blood pressure has led to a reliable assessment of arterial blood pressure during increasing ergometer exercise. There is a linear connection between workload intensity and systolic pressure. Intraarterially and noninvasively obtained values are identical with regard to systolic behavior. In principle, the intraarterially measured diastolic blood pressure, too, increases in healthy subjects, which, nevertheless, may often not be demonstrated in such a clear way due to artefacts occurring during blood pressure measuring. There are no significant differences between untrained and endurance-trained subjects at a given work load. Persons exhibiting a better performance capacity only reach higher maximal systolic values. The male and female subjects' regression lines significantly differ--the reason possibly being the woman's smaller muscle mass. Age-induced differences, too, are significant. Bodybuilders with extremely developed muscle mass do not show any significant differences with regard to blood pressure behavior during exercise. When establishing a relation to the relative muscle force the bodybuilders show blood pressure values even lower than normal values.

Animals↗
PubMed1988

Satellite cell activation in human skeletal muscle after training: evidence for muscle fiber neoformation.

In subjects who had undergone monopedal bicycle ergometer work for 30 min 4 days a week for 6 weeks under aerobic conditions, biopsies from the M. vastus lateralis were studied in the light and electron microscope. In some cases very small myofibers with central nuclei were found. At the ultrastructural level, these fibers turned out to be myotubes. The satellite cells occasionally appeared to be activated and to fuse with muscle fibers. It was concluded that these observations represented evidence for the development of new muscle fibers.

Adaptation, Physiological↗
PubMed1988

[International sports medicine--current responsibilities and goals].

A brief historical outline of the development of sports medicine is followed by an explanation of the structure of the World Federation of Sports Medicine (FIMS), and by a description of international tasks of sports medicine. Finally, topical aspects in research and practice are outlined.

Athletic Injuries↗
PubMed1988

Physical activity in the prevention of ischaemic heart disease.

Among the 5 main motor functions of coordination, flexibility, strength, velocity, and endurance, mainly the last one is of essential preventive cardiological significance. There are peripheral and central metabolic and haemodynamic adaptations which can reduce the oxygen demand of the heart muscle. The flow properties of the blood are improved combined with an antithrombotic effect. Endurance training induces alterations in the lipoprotein metabolism which could be useful for protection against arteriosclerosis. Effects of training on some hormones are described in connection with silent heart ischaemia. The listed protective results of endurance training are the sum of all possibilities of training related to different sports events, exercise intensities and duration. A recommendation is given for a minimum training program based on practical experience.

Adaptation, Physiological↗
PubMed1987

Regional cerebral blood flow in man at rest and during exercise.

Regional cerebral blood flow (rCBF) of the left hemisphere was measured in 12 healthy young men at rest and during physical work on a bicycle ergometer in the supine position at work-load levels of 25 W or 100 W using the intravenous 133Xe method. Regional mean cerebral blood flow, regional gray-matter flow, and relative gray-matter weight was determined for six regions of interest. Arterial blood pressure, pulse frequency and expiratory CO2 concentration were recorded. Cerebral blood flow in all regions was significantly (P less than 0.001) higher during exercise than at rest. The increase in the 100 W group (24.7%) was significantly (P less than 0.05) greater than in the 25 W group (13.5%), but resting blood flow levels and alveolar CO2 concentrations were also different in both groups. Mean arterial blood pressure, pulse frequency and alveolar CO2 concentrations, but not arterial pCO2, were significantly higher during exercise and there was a faster washout of whole-body xenon. The CBF increase was interpreted as a combined effect of elevated systemic blood pressure and functionally activated brain metabolism. There was no evidence of impaired cerebral autoregulation.

Adult↗
PubMed1987

Determination of endurance capacity and prediction of exercise intensities for training and competition in marathon runners.

Male and female marathon runners (n = 34) were studied in incremental and continuous running tests under both laboratory and field conditions. Aerobic capacity was determined based on the relationship between the lactate concentration and running velocity. We also analyzed the acid-base balance after the laboratory test of continuous running for 45 min. The individual running velocities in the incremental field test at given lactate concentrations were correlated with the marathon running velocities. Training workouts for six female runners were analyzed, and running speed during endurance training was compared with the lactate-velocity relationship in an incremental laboratory test. The main findings are summarized below. There is a very close relationship between the velocities determined at 2.5, 3, and 4 mmol/l in the incremental field test and the marathon running velocity (r = 0.88-0.99, P less than 0.001). The highest correlation between test and marathon velocities was found at a lactate concentration of 2.5 and 3.0 mmol/l. In field and laboratory running tests lasting 44 and 45 min at a speed chosen in accordance with the runner's current marathon time, lactate levels reached a steady state at approximately 3 mmol/l. A slight increase in blood lactate levels was compensated via respiratory mechanisms. In the continuous treadmill test (n = 8), we recorded the following changes after the first blood sample collection (i.e., 10 min) and post-exercise: blood lactate concentrations rose from 2.2 +/- 0.93 to 3.5 +/- 1.45 mmol/l; the negative base excess increased from -1.2 +/- 3.2 to -3.4 +/- 1.7 mval/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1987

[Exercise hypertension: historical, physiologic and clinical aspects of ergometry].

More than a decade before Riva Rocci in 1896 described the principles of blood pressure measurement as still employed today, in 1881 Zadek reported that there is an increase in blood pressure during physical work. The blood pressure increase during physical exercise as well as its extent as a relatively constant physiological response to a given workload were delineated accurately for the first time, however, in the 1950s. There is no significant difference between the blood pressure increase seen in conditioned athletes and untrained individuals at comparable workloads. In healthy male subjects, a comparison was carried out of the reactions of cardiopulmonary and metabolic parameters during five different modes of exercise. The highest values for oxygen uptake as well as the highest heart rates can be observed during treadmill ergometry; with this method, the largest muscle mass is activated. During both treadmill ergometry as well as during step climbing, the blood pressure can be measured only invasively. As compared with bicycle ergometry in the seated position, the stroke volume increase is only relatively small during supine pedaling. Accordingly, to reproduce situations similar to that of everyday activity exercise testing should be carried out in an upright position. Vascular and cardiac catheterization, however, can be performed more easily in the supine than in the seated position. With these facts in mind, the appropriate methods should be chosen according to the needs of the study and the condition of the patient. During continuously increasing workloads, the systolic pressure increases proportionately. Immediately after termination of exercise, this pressure decreases rapidly over two to three minutes. The diastolic pressure measured noninvasively during seated bicycle ergometry is not particularly accurate and should be interpreted with caution. In general, exercise blood pressure should be determined during a standardized test beginning with a workload of 30 watts for three minutes and subsequent workloads incremented 40 watts for three minutes each. The normal ranges for younger and older patients differ substantially. Additionally, body weight exerts an influence on exercise blood pressure. During exercise, patients with hypertension may show one of three different reactions: the increased pressure can be maintained relative to the normal values during the specified workloads, the blood pressure can show normalization and the systolic blood pressure can remain constant or even decrease at higher workloads.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Pressure Determination↗
PubMed1986

Delayed effects of prolonged exercise on serum lipoproteins.

The delayed lipoprotein changes after a 3-hour running test were examined in 14 moderately trained young male subjects. Fasting blood samples were obtained one day before, immediately before, and one, two, and four days after the race. Nonfasting samples were collected immediately after, one, and three hours after exercise. Three hours after the race, the ratio of unesterified cholesterol to cholesteryl esters was significantly increased, and one and two days after the race it was significantly decreased compared to the preexercise value. The HDL2/HDL3 ratio, measured by density-gradient ultracentrifugation was one and three hours after the running significantly elevated. However, no redistribution of the HDL2/HDL3 cholesterol ratio determined by a precipitation method with polyanions was found at this time. One day postexercise HDL cholesterol rose significantly above the preexercise value, and this was associated with an elevation of the HDL3 subfraction. On the following day a significant increase of HDL2 cholesterol and the HDL2/HDL3 cholesterol ratio was found. The apolipoproteins A-I, A-II, and B, measured by radial immunodiffusion, did not change during the first hours and the first two days after the race. On the second postexercise day the Lp(a) lipoprotein rose significantly above the preexercise value. Compared with the preexercise level the LCAT activity was significantly elevated three hours after the race and significantly decreased two days later. The present study suggests that during the first few days after prolonged exercise a number of plasma lipoprotein changes take place that are similar to those observed after a period of physical training.

Adult↗