Biomedical subjects

R Pokan

Publications and source records attributed to R Pokan.

43 records · Page 3Linked to original sources

PubMed1994

[Physical activity at intermediate altitude by healthy probands and patients with coronary sclerosis].

For the majority of the population, exposure to altitudes higher than 2000 m above sea level constitutes a situation of pronounced stimulation of the organism. The question comes in of the health relevance of physical activity at intermediate altitudes for the healthy subjects, but above all for people with heart problems. At first, there is an acute adaption on the cardiovascular and the respiration system as well as the system of oxygen carriage, until the chronic adaption processes of the same systems are completed. Doubtlessly, these adaption processes at intermediate altitudes and in particular training in such regions considerably improve the endurance capacity under conditions of the kind mentioned. However there is little evidence, for an absolute improvement of the maximal aerobic capacity. As a rule, the effects of adaption to higher altitudes can also be expected in patients with coronary sclerosis. But a lowered level of capacity must be taken into account in these cases. Accordingly, the medication as well as the intensity of stress should be adapted to altered conditions of this kind. Training intensity must be reduced according to altitude, and any treatment for angina, must be intensified. It may be necessary to re-determine the appropriate training intensity as well as the dosage in pharmacotherapy by ergometric methods to match the new requirements. However, when a comparison is tried to kinetotherapy under normal conditions, an immediate therapeutical effect of exposition to higher altitudes appears to be at least doubtful.

Acclimatization↗

PubMed1993

Correlation between inflection of heart rate/work performance curve and myocardial function in exhausting cycle ergometer exercise.

The heart rate/work performance (fc/W) curve is usually S-shaped but a flattening at the top is not always seen. By means of radionuclide ventricular scintigraphy, the left ventricular ejection fraction (LVEF) of 15 sports students was investigated. The behaviour of the fc/W curve during cycle ergometry with increasing exercise intensities was examined. During exercise, the LVEF showed a distinct initial increase reaching roughly constant values at stress levels below-maximum, and sometimes even falling again. The inflections of the fc/W curve and left ventricular ejection fraction/performance curve (LVEFPC) were calculated from a second degree polynomial fit. From this function, the slopes of the tangents at the points of aerobic threshold and maximum performance were calculated together with the differences of the angles as a measure of the fc/W curve and LVEFPC inflections. It follows that the fc/W curve inflection became less pronounced or was even absent altogether when the decrease in LVEF towards the end of the ergometer exercise became more distinct. A significant negative correlation was found between the existence and extent of the fc/W curve inflection and the stress-dependent myocardial function, expressed as the inflection of the LVEFPC (P < 0.01, r = 0.673). Thus, it would seem that the absence of a fc/W curve inflection was related to a diminished stress-dependent myocardial function.

Adult↗

PubMed1992

[Nisoldipine in comparison with long-term nitrates].

Nisoldipine represents a new attractive second generation calcium channel blocker of the dihydropyridine-class for the treatment of all types of coronary artery disease. The effect on chronic ischemia is comparable to long-acting nitrates, side-effects have been rarely observed. The advantages will be the high vascular selectivity with only slight negative inotropic effect as well as a long-lasting positive influence on the myocardial metabolism. Up to now, no studies have been reported which compare nisoldipine and long-acting nitrates directly, but this calcium antagonist appears to influence duration and intensity of symptomatic and silent episodes of ischemia similar to the nitrates.

Angina Pectoris↗

PubMed1992

[Females in performance sports from the sports medicine viewpoint].

Especially in the endurance disciplines, the performance of women went up considerably in the course of the past few decades. This seems to be peculiar to the female sex and can be taken as a hint to a higher adaptability of the female organism with respect to the various motor capacities required for strength and endurance. During the past 10 years, however, the rate, with which the performance gap in the endurance disciplines narrowed, has slowed down distinctly. Thus, it seems, that the era during which the women vigorously caught up on the men, is coming to an end in the endurance sports. The different capacity of the sexes with respect to strength is rooted in the differently dimensioned cross sections of the muscle fibres and in the higher activation capability of the skeletal muscles of men. No differences exist with respect to the relative proportions of the ST-, FTa- and FTb-fibres and with respect to the biochemistry of the muscles. Just as in case of men, the adaptation of the cardiovascular system to endurance training manifests in a uniform enlargement of all of the heart's cavities. It is true, that women have a smaller heart volume and lower values for the maximum oxygen uptake, but these differences or by no means related to sex alone. Very often, they are produced by the fact that the endurance training of the women did not go that far. As regards the energy substrates, there is the hypothesis that women have better utilization of free fatty acids under conditions of prolonged and intensive physical work.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Density↗

PubMed1991

[Metabolic and cardiovascular adaptation and the performance of professional tennis players].

14 professional tennis players of world rank were examined (7 men, mean age 23 +/- 3 years; 7 women, mean age 18 +/- 2 years). Heart volume (HV) was 11.9 +/- 0.9 ml/kg in women, 12.7 +/- 1.3 ml/kg in men, 20-30% higher than in untrained persons. Correspondingly, end-diastolic (EDV) and end-systolic volume, left-ventricular muscle mass (LVM) and stroke volume (SV) were elevated, while contractility parameters as well as the ratios of SV and of LVM to EDV and HV were within normal limits. The changes are to be taken as adaptations in the sense of athlete's heart. Maximal treadmill speed was 18 km/h in women and 19.3 km/h in men, with maximal lactate levels of 9.3 mmol/l (women) and 11.4 mmol/l (men). Anaerobic threshold was reached at a treadmill speed of 13.3 km/h (women) and 14.8 km/h (men). These data indicate a good performance range and were clearly better than in earlier groups of tennis players. This adaptation requires additional interval and endurance training. In 11 tennis players the serum concentration of magnesium and in 5 that of iron was below the recommended lower limit (magnesium: 0.8 mmol/l; iron: 14 mumols/l). Serum concentrations of creatine kinase and of lactate dehydrogenase were always two to three times higher than normal, if tennis training had taken place the day before, but all other biochemical values were within normal limits.

Adaptation, Physiological↗

PubMed1990

[Prevention and therapy of obesity with diet and sports, an ambulatory therapy program for overweight children].

Dietary restriction together with ongoing power-orientated training provide best results in the therapy and prevention of obesity. Diet can reduce the resting metabolic rate by up to 20% within 14 days. Physical activity stimulates the resting metabolic rate and counteracts this energy saving effect, but is especially important for maintaining a steady state after weight reduction. Exercise reduces the risk factors accompanying obesity by favorable adaptation of the sympathoadrenergic system to physical activity. This can be seen in the effects on heart rate, stroke volume, blood pressure, as well as glycogenolytic and lipolytic activities. Body fat especially in the abdominal area, which is particularly connected with atherogenic risk, is diminished. Weight reduction is accompanied by a decrease of the cardioprotective cholesterol fraction. Diets high in unsaturated fatty acids combined with a staying power training have a synergistic effect: they reduce a decrease of HDL. It is difficult to demonstrate risk factors connected with overweight children. However, from the preventive medicine point of view it is advisable to start with therapeutic measures during childhood. In an out-patient pilot project we surveyed 18 obese children aged 9 to 13 years. The therapy plan consisted of dietary restriction (1200 kcal/d), an exercise program performed 3 times a week, and psychological assistance. All children of 12 to 13 years arrived at an overweight level less than 20%, the younger ones displayed a lower weight reduction effect. All 18 improved their aerobic capacity. In the 1st months of treatment, HDL-cholesterol decreased slightly, but increased above pre-treatment level, later on. We did not see any vitamin deficiencies during the therapeutic regimen.

Cardiovascular System↗

PubMed1990

[Effect of beta blockade on hemodynamics in physical exertion].

Beta-receptor blocking agents are known for more than 20 years. They are of definite use in the therapy of arterial hypertension and coronary heart disease. Beta-blockers lower the sympathoadrenergic discharge to the heart and circulation, particularly if the former is increased. Beta-blockers induce a negative chronotropic and inotropic effect and inhibit beta 2-mediated vasodilation. Thus beta-sympathicolysis during physical activity results in damping of heart rate increase and of elevation of cardiac contractility. Systolic blood pressure does not increase much, and usually there is no decline in diastolic blood pressure, due to elevated peripheral resistance. With adequate dosage, there may even be a slight increase in diastolic pressure, an effect eventually vaning in chronic therapy. Pulmonary capillary wedge pressure is elevated to above normal via inhibition of contractility and relaxation of the heart. Stroke volume, cardiac output and the double-product decrease, the arteriovenous oxygen difference under exercise increases clearly and the maximum aerobic performance capacity decrease in healthy individuals. In coronary patients, this may protect against cardiac overload and increase symptom-free physical work capacity, due to a relative decrease in the myocardial O2 requirement and improved coronary perfusion resulting from prolonged diastole. With verified indication (hypertensive-hyperkinetic impairments of cardiovascular function, coronary heart disease), the goal is an overlapping, endurance-oriented training to reduce the overall sympathetic activation, in order to minimize medication in the long run.

Adrenergic beta-Antagonists↗