Wiktor Niewiadomski

Suppression of heart rate variability after supramaximal exertion.

Wingate test is short anaerobic exercise, performed with maximal power, whereas aerobic exercise at 85% maximal heart rate (HRmax) may be performed for long period. Sustained HR elevations and changes in autonomic activity indices have been observed after latter kind of exercise. Several studies reported reduction in mean interval between consecutive R peaks in ECG (RRI) 1 h after Wingate test; however, underlying changes in autonomic activity remain elusive. In eight young males, RRI and heart rate variability (HRV) were measured daily over two 5‐day trials. Subjects exercised on third day of each trial, measurements were taken 1 h after (i) two consecutive 30‐s bouts of Wingate tests or (ii) after a 30‐min exercise at 85% HRmax, with subjects in supine rest and breathing either spontaneously or at controlled rates of 6 and 15 breaths / min. RRI was significantly shorter after Wingate and submaximal exercise, reduction of high‐ and low‐frequency components of HRV attained reliability only after Wingate tests. This pattern remained preserved for three modes of breathing: spontaneous, 6 and 15 breaths /min. After 24 and 48 h, no exercise effects were traceable. We hypothesize that (i) anaerobic exertion is followed by sustained inhibition of vagal activity, (ii) parasympathetic system plays dominant role in mediating suppression of high‐ and low‐HRV frequency components during postexercise recovery, (iii) degree of alteration of autonomic activity caused by anaerobic and strenuous aerobic exercise may be similar and (iv) normalization of vagal activity precedes normalization of sympathetic cardiac nerves activity during final stage of postexercise recovery.

Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations

Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations Strength training is recommended for slowing age-dependent deterioration of muscular strength and for rehabilitating patients with muscle weakening illnesses. Reliable assessment of muscle strength is important for proper design of strength training regimes for prevention, rehabilitation, and sport. One repetition maximum (1RM) is an established measure of muscular strength and is defined as the value of resistance against which a given movement can be performed only once. Proper assessment of 1RM is time consuming, and may lead to muscle soreness as well as temporary deterioration of the function of the tested muscles. Attempts at indirect 1RM determination based on the maximum number of repetitions performed have predicted 1RM with a variable degree of accuracy. Cardiovascular safety has been neglected in 1RM determination, although arterial blood pressure increases considerably when exercising against maximal or near maximal resistance. From the perspective of cardiovascular safety, favorable 1RM measurement methods should avoid performance of repetitions until failure; movement against high resistance and muscle fatigue both increase blood pressure. Although such techniques are likely less accurate than the current methods, their prediction accuracy be sufficient for therapeutic strength training.

Ambulatory monitoring device for central hemodynamic and ECG signal recording on PCMCI flash memory cards

The new ambulatory monitoring, universal 4-channel recorder enabling simultaneous collection of ECG and central haemodynamics signals was constructed. The system is based on 80C552 family controller with built-in analogue to digital converters and 20 MB PCMCIA (type II) FLASH MEMORY CARD is used as a data storage. The communication with the system is performed via specialised keys and the small, built-in LCD. We design and constructed the miniaturised, tetrapolar, current impedance cardiography device with built-in one channel of ECG, which was applied as a detector of the central haemodynamics signals. The device enables the full disclosure of the collected data, which could be used in off-line, beat-to-beat evaluation of cardiac output, stroke volume, ejection time, pre-ejection period and heart rate.

Impedance cardiography: Recent advancements

The aim of this paper is the presentation of recent advancements in impedance cardiography regarding methodical approach, applied equipment and clinical or research implementations. The review is limited to the papers which were published over last 17 months (dated 2011 and 2012) in well recognised scientific journals.

Cardiovascular and sympatho-adrenal responses to static handgrip performed with one and two hands

Summary12 healthy men aged 21–25 years performed, in the sitting position, a sustained handgrip at 25% of their maximum voluntary contraction, first with each hand separately and then with both hands simultanesouly. Heart are (HR), systolic blood pressure (SBP), stroke volume (determined reographically) and plasma catecholamine concentration were measured during each handgrip test. The HR and SBP increased consistently during each handgrip test while stroke volume decreased by approximately 20% of the initial value. Cardiac output did not change significantly. There were no significant differences in the magnitude and dynamics of the cardiovascular responses between the tests with one and with both hands. Plasma noradrenaline and adrenaline levels showed similar elevations in response to handgrip performed with the right hand and with both hands, while during the exercise performed with the left hand the increase in the plasma catecholamine concentration was less pronounced. It was concluded that: (1) during sustained handgrip, performed in the sitting position by young healthy subjects, the stroke volume markedly decreases and cardiac output does not change significantly in spite of the increased HR; (2) the cardiovascular and sympatho-adrenal responses to static handgrip do not depend on the mass of contracting muscle when the same relative tension is developed.

Effects of a brief Valsalva manoeuvre on hemodynamic response to strength exercises

Strength training is a recommended measure against loss of strength and muscle mass because of age‐ or illness‐induced inactivity. Strength exercises may impose heavy cardiovascular load by increasing heart rate and blood pressure. To increase strength efficiently, a heavy load has to be applied; this, however, leads to a spontaneous Valsalva manoeuvre, which additionally raises blood pressure. Avoidance of this manoeuvre is recommended. If the additional rise in arterial blood pressure caused by Valsalva manoeuvre is smaller than intrathoracic or intracranial pressures during this manoeuvre, Valsalva manoeuvre may actually protect arteries located in the thorax and in the brain by diminishing transmural pressure acting across these vessels. Effect of controlled breathing or brief Valsalva manoeuvre on arterial pressure at rest and during knee extension against 15‐repetition maximum resistance was evaluated. In 12 healthy young men blood pressure was measured continuously and non‐invasively, knee angle, speed of respiratory air or mouth pressure (MP) were continuously registered. Each combination of respiratory and exercise manoeuvres was repeated six times, for every of last three repetitions peak and trough systolic and diastolic pressure were determined. Strength exercises elevated peak pressures more than trough pressures, systolic more than diastolic. Valsalva manoeuvre increased only peak systolic and peak diastolic pressure. This increase was in average lesser than MP, thus rendering an argument in favour of protective role of brief Valsalva manoeuvre because of decline in transmural pressure acting on thoracic and possibly cerebral arteries. However, there was strong individual variability, and in few instances, arterial pressure increased because of brief Valsalva manoeuvre more than MP; thus in some subjects, the manoeuvre might enhance transmural pressure acting on thorax arteries.

Application of impedance cardiography ambulatory monitoring system for analysis of central hemodynamics in healthy man and arrhythmia patients

The authors constructed the ambulatory monitoring, 4-channel recorder enabling simultaneous collection of ECG and ICG signals from a built-in miniaturised ICG device on 20 MB PCMCIA Flash Memory Card. The system allows for off-line, beat-to-beat automatic evaluation of cardiac output, stroke volume, ejection time, pre-ejection period and heart rate. The system was checked in more than 40 healthy subjects in ambulatory conditions and in 10 patients showing the hemodynamic effects of arrhythmia. The patients of ICG signal during atrial fibrillation, supraventricular and ventricular ectopy were recorded. The device could record signals with acceptable quality during sleep time, static and moderate dynamic exercise on cycloergometer, tilt test and Valsalva manoeuvre. The system has been continuously testing and improving.

Dynamics of changes in the cardiovascular response to submaximal exercise during low-intensity endurance training with particular reference to the systolic time intervals

SummaryEighteen male volunteers (aged 20–23 years), not involved in any sporting activities, were submitted to 13 weeks of training consisting of 30 min exercise [at 50%–75% maximal oxygen intake % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Jf9qqqrpepC0xf9qiW7rqqrFfpeea0xe9LqFf0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-xir-f0-yqaqVeLsFr0-vr% 0-vr0xc8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaGGOaGabm% OvayaacaWaaSbaaSqaaGqaaiac0X1FpbWaaSbaaWqaaiaa-jdaaeqa% aSGaciyBaiaacggacaGG4baabeaakiaacMcacaGGDbaaaa!42A5!

Early hemodynamic response to the tilt test in patients with syncope.

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