G. Schwaberger

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

SummaryThe 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.

Method for the analysis of the entrainment between heart rate and ventilation rate

SummaryA digital computer program was developed which allows to continuously represent the relation between heart rate and ventilation rate. Using this program, experiments in anesthetized rabbits were performed. We found periods of synchronization, periods of transient entrainment and escape, and periods of complete desynchronization. By testing the respective roles for the entrainment mechanism of ventilation rate and heart rate it was found that spontaneous adjustments of the ventilation rate play a more pronounced role. Thus, as soon as spontaneous or induced variations of the heart rate and/or the ventilation rate shift both rhythms close to synchronization, variations of the ventilation pattern, which seem to be of reflex nature, tend to induce entrainment.

Heart rate deflection related to lactate performance curve and plasma catecholamine response during incremental cycle ergometer exercise

The correlation between the behaviour of the heart rate/work performance (fcW) curve and blood lactate ([la]b) and plasma adrenaline/noradrenaline concentrations ([A]/[NA]) during incremental cycle ergometer exercise was investigated. A group of 21 male sports students was divided into two groups: group I, with a clear deflection of thefcW curve; group II, without or with an inverse deflection of thefcW curve. The aerobic threshold (Thaer) and the lactate turn point (LTP) were defined. Between Thaer and maximal work performance (fcWmax) the behaviour of thefcW curve as well as the behaviour of [la−]b and [A]. [NA] were described mathematically. Thefc, systolic blood pressure (BPS),W, [la−]b, [A] and [NA] at rest, Thaer, LTP,fcWmax, after 3 and 6 min of recovery (Re3/Re6) were calculated. A significant difference between the two groups could only be detected forfc at LTP, Re3 and Re6 (P < 0.05). No significant, correlation could be found between individualfcW-behaviour and individual time course of [la−]b, [A] and [NA]. However, a significant correlation was visible between [la−/W-behaviour and individual catecholamine response. These results and the fact that the different flattening at the top of thefcW curve was related to diminished stress-dependent myocardial function led us to the conclusion that it is possible that sympathetic drive is not directly involved in mechanisms of regulation between load dependentfc and myocardial function. In addition, individualfcW behaviour was independent of BPS andWmax, or individual conditions of energy supply.

Validation of a field test for the non-invasive determination of badminton specific aerobic performance

Aim: To develop a badminton specific test to determine on court aerobic and anaerobic performance. Method: The test was evaluated by using a lactate steady state test. Seventeen male competitive badminton players (mean (SD) age 26 (8) years, weight 74 (10) kg, height 179 (7) cm) performed an incremental field test on the badminton court to assess the heart rate turn point (HRTP) and the individual physical working capacity (PWCi) at 90% of measured maximal heart rate (HRmax). All subjects performed a 20 minute steady state test at a workload just below the PWCi. Results: Significant correlations (p<0.05) for Pearson’s product moment coefficient were found between the two methods for HR (r = 0.78) and velocity (r = 0.93). The HR at the PWCi (176 (5.5) beats/min) was significantly lower than the HRTP (179 (5.5) beats/min), but no significant difference was found for velocity (1.44 (0.3) m/s, 1.38 (0.4) m/s). The constant exercise test showed steady state conditions for both HR (175 (9) beats/min) and blood lactate concentration (3.1 (1.2) mmol/l). Conclusion: The data indicate that a valid determination of specific aerobic and anaerobic exercise performance for the sport of badminton is possible without HRTP determination.

TSH, T3, rT3 and fT4 in maximal and submaximal physical exercise

SummaryThe response of various thyroid hormone parameters to maximal physical exercise (MPE) was investigated in 14 medium and long distance runners and 13 divers. The effect of submaximal long time physical exercise (SMPE) was examined in seven divers. The TSH-level decreases significantly during MPE and slightly rises again after the end of the exercise. In SMPE, however, TSH continuously rises until 15 min after the end of the exercise. The T3 level rises significantly in MPE and falls below the initial value 15 min after the exercise finishes, during SMPE it remains practically unchanged and slightly decreases after the finish. In MPE, the rT3 level does not change and slightly decreases after termination, while the fT4 level continuously decreases from the beginning till 15 min after the exercise period. The latter two parameters do not show any change in SMPE. As possible reasons for the changes of TSH levels a decrease (MPE) or an increase (SMPE) of pituitary secretion might play a role. Furthermore, in MPE the rise in T3 level might be related to hemoconcentration, and the decrease in fT4 level to an elevated cellular utilization.

Regulation of red cell 2,3-DPG and Hb-O2-affinity during acute exercise

SummaryReports from the literature and our own data on red cell 2,3-DPG and its importance for unloading O2 from Hb to the tissues during exhaustive exercise are contradictory. We investigated red cell metabolism during incremental bicycle ergometry of various durations. Furthermore changes in blood composition occurring during exercise were simulated under in vitro conditions. The effect of a moderate (11.2 mmol · l−1 lactate, pH=7.127) and severe (18 mmol · l−1 lactate, pH=6.943) lactacidosis on red cell 2,3-DPG concentration was compared with the effect of similar acidosis induced by HCl. Our data indicate that the concentration of 2,3-DPG in red cells depends on the degree of lactacidosis, but not on the duration of exercise. During moderate lactacidosis red cell 2,3-DPG remains unchanged. This can be explained by an interruption of red cell glycolysis on the PK and GAP-DH step caused by a lactate and pyruvate influx into the erythrocyte, as well as an intraerythrocytic acidosis and a drop in the NAD/NADH ratio. During severe lactacidosis and HCL-induced acidosis a decrease in 2,3-DPG due to an inhibition of 2,3-DPGmutase and other glycolytic enzymes can be found. Mathematical correction of the observed P-50 value for the decrease in 2,3-DPG occurring during severe lactacidosis showed that a decrease in Hb-O2-affinity during strenuous exercise depends on the degree of lactacidosis and temperature elevation.

Effect of β1-selective adrenergic blockade on maximal blood lactate steady state in healthy men

Abstract. The aim of this study was to compare the effect of taking bisoprolol (B), a highly β1-selective adrenoceptor antagonist to that of a placebo (P) on maximal lactate steady state (MLSS), which reflects the transition from oxidative to partially anaerobic metabolism. Ten healthy male subjects [mean (SD) age 23xa0(3)xa0years, height 181xa0(6)xa0cm, body mass 76xa0(6)xa0kg] randomly received oral P or B (5xa0mg·day–1) for 2xa0weeks using a double-blind crossover design. In the 2ndxa0week, the subjects performed an incremental cycle ergometer test until exhaustion to determine the second blood lactate turn point (LTP2). At regular intervals of 24–48xa0h, the subjects performed 2–3xa0steady-state tests to determine the MLSS. During the incremental exercise, heart rate (HR) was significantly lower at rest (15xa0beats·min–1), at LTP2 (23xa0beats·min–1) and at maximal power output (19xa0beats·min–1) when taking B compared to P. Oxygen pulse was significantly higher taking B and no significant differences were observed for any of the respiratory gas exchange measurements (RGEM) (oxygen consumption, carbon dioxide production, minute ventilation, respiratory exchange ratio), exercise intensity or blood lactate concentration (LA) at baseline, at LTP2 and at maximal power output. During exercise at constant intensity, significant differences between B and P were found for HR [148xa0(12) compared to 176xa0(11)xa0beats·min–1] and oxygen pulse [21.8xa0(1.9) compared to 19.2xa0(1.6)xa0ml] at MLSS. No difference was found for exercise intensity [216xa0(18) compared to 218xa0(18)xa0W], for RGEM, LA [5.3xa0(1.1) compared to 4.8xa0(1.5)xa0mmol·l–1] and ratings of perceived exertion [18.1xa0(1.6) compared to 17.4xa0(1.7)] for B and P at MLSS. In both, the power output at LTP2 was slightly higher than power output at MLSS (within an intensity step). Commonly measured cardiorespiratory and subjective variables determined during treatment with 5xa0mg bisoprolol can be used for testing cardiorespiratory fitness and for prescription of training intensity.

Arterial hypertension due to altitude

SummaryThe behavior of blood pressure under hypoxic conditions depends on individual factors, altitude and duration of stay at altitude. While most humans are normotensive at higher altitudes, a few will react with moderate hypertension or hypotension. Excessive elevation of arterial blood pressure is not even to be expected below 4,000 m. Rather, several weeks stay at higher altitude will decrease systolic and diastolic blood pressure at rest as well as during physical exertion. A high-altitude treatment for rehabilitation purposes at moderate altitude may be recommended for patients with cardio-circulatory disorders. Improvements can last several months even after returning to accustomed altitudes. Furthermore, endurance-trained hypertensive patients with pharmacologically controlled arterial blood pressure might be able to participate in mountain treks without additional health risk.ZusammenfassungDas Blutdruckverhalten unter hypoxischen Bedingungen hängt von individuellen Faktoren, Höhe und Dauer des Höhenaufenthaltes ab. Während die meisten Menschen in der Höhe normotensiv reagieren, können einige wenige auch mit mäßiggradigem Blutdruckanstieg oder sogar -abfall reagieren. Unter 4.000 m Höhe ist jedoch mit einer überschießenden Blutdrucksteigerung nicht zu rechnen. Ein Höhenaufenthalt in mittlerer Höhe zur Rehabilitation kardiozirkulatorischer Erkrankungsbilder ist zu empfehlen. Der Effekt der Medikamenteneinsparung kann mehrere Monate lang nach Rückkehr auf gewohnte Normalhöhe anhalten. Darüber hinaus sind ausdauertrainierte Hypertoniker mit medikamentös kontrolliertem Blutdruck ohne zusätzliches Gesundheitsrisiko fähig auch an Trekkingtouren teilzunehmen.

Arterielle Hypertonie unter Höheneinfluss

SummaryThe behavior of blood pressure under hypoxic conditions depends on individual factors, altitude and duration of stay at altitude. While most humans are normotensive at higher altitudes, a few will react with moderate hypertension or hypotension. Excessive elevation of arterial blood pressure is not even to be expected below 4,000 m. Rather, several weeks stay at higher altitude will decrease systolic and diastolic blood pressure at rest as well as during physical exertion. A high-altitude treatment for rehabilitation purposes at moderate altitude may be recommended for patients with cardio-circulatory disorders. Improvements can last several months even after returning to accustomed altitudes. Furthermore, endurance-trained hypertensive patients with pharmacologically controlled arterial blood pressure might be able to participate in mountain treks without additional health risk.ZusammenfassungDas Blutdruckverhalten unter hypoxischen Bedingungen hängt von individuellen Faktoren, Höhe und Dauer des Höhenaufenthaltes ab. Während die meisten Menschen in der Höhe normotensiv reagieren, können einige wenige auch mit mäßiggradigem Blutdruckanstieg oder sogar -abfall reagieren. Unter 4.000 m Höhe ist jedoch mit einer überschießenden Blutdrucksteigerung nicht zu rechnen. Ein Höhenaufenthalt in mittlerer Höhe zur Rehabilitation kardiozirkulatorischer Erkrankungsbilder ist zu empfehlen. Der Effekt der Medikamenteneinsparung kann mehrere Monate lang nach Rückkehr auf gewohnte Normalhöhe anhalten. Darüber hinaus sind ausdauertrainierte Hypertoniker mit medikamentös kontrolliertem Blutdruck ohne zusätzliches Gesundheitsrisiko fähig auch an Trekkingtouren teilzunehmen.

Alpinmedizinische Forschung in mittlerer Höhe : Aspekte und Notwendigkeit

SummaryAlpinism in all its variations is a leading factor in tourism. Within a few decades, alpine sports, even at high altitudes, have become available to a wide range of people. Now, more people than ever before are hiking, trekking, climbing and skiing at moderate and high altitudes. Annually, 40 million people spend time in the Alps and 100 million visit high altitudes worldwide. However, alpine excursions may entail health problems and many aspects of impaired adaptation to altitude remain unstudied. High-altitude research has mainly been associated with expeditions, with moderate altitudes receiving far less attention, though most tourism takes place at that level. The overwhelming numbers of alpine tourists mean that there is urgent need for high- and moderate-altitude medical research, which would also be within the realm of political responsibility in mountainous countries. Research in mountain medicine and dissemination of relevant findings can show how to improve and conserve performance in healthy individuals and could point the way toward new, safe approaches in the rehabilitation of patients with chronic diseases. It is imperative that mountain medicine continues to develop on a scientific basis.ZusammenfassungAlpinismus in all seinen Aspekten stellt heute einen bedeutsamen Faktor innerhalb der Freizeitwirtschaft alpiner Länder sowie der gesamten Reisebranche dar. Innerhalb weniger Jahrzehnte sind Alpinsportarten auch in großen Höhen einer breiten Masse zugänglich gemacht worden, so dass heute mehr Menschen auf Bergen unterwegs sind als jemals zuvor. Jährlich besuchen 40 Millionen Menschen die Alpen und weltweit 100 Millionen Touristen große Höhen. Tatsache ist dabei auch, dass alpine Exkursionen nicht immer ohne gesundheitliche Komplikationen ablaufen. Vieles im Zusammenhang mit Höhenunverträglichkeitsreaktionen und akuter Bergkrankheit liegt heute noch im Dunkeln. Große Höhen waren im Rahmen des Expeditionswesens immer wieder Anlass intensiver medizinischer Untersuchungen. Mittlere Höhen hingegen spielten in der Vergangenheit vergleichsweise eine deutlich geringere Rolle, obwohl hier der überwiegende Teil des Höhentourismus stattfindet. Die Notwendigkeit alpinmedizinischer Forschung ergibt sich in Anbetracht steigender Zahlen im Alpintourismus und sollte auch im Interesse politischer Verantwortungsträger gelegen sein. Alpinmedizinische Forschung und Wissensvermittlung dienen der Prävention, Leistungsverbesserung und der Erhaltung der Leistungsfähigkeit Gesunder sowie der Rehabilitation und risikolosen Roborierung chronisch Kranker und müssen daher auf wissenschaftlicher Basis ständig weiterentwickelt werden.