Cardiovascular response to different types of acute stress stimulations

Introduction: Stress is an ubiquitous phenomenon in the modern world and one of the major risk factors for cardiovascular disease. Th e aim of our study was to evaluate the eff ect of various acute stress stimuli on autonomic nervous system (ANS) activity, assessed on the basis of heart rate (HRV) and blood pressure (BPV) variability analysis. Materials and Methods: The study included 15 healthy volunteers: 9 women, 6 men aged 20- 30 years (23.3 ± 1.8). ANS activity was assessed by HRV and BPV measurement using Task Force Monitor 3040 (CNSystems, Austria). ECG registration and Blood Pressure (BP) measurement was done 10 minutes at rest, 10 minutes aft er the stress stimulus (sound signal, acoustic startle, frequency 1100 Hz, duration 0.5 sec, at the intensity 95 dB) and 10 minutes aft er the cold pressor test. The cold pressor test (CPT) was done by placing the person’s hand by wrist in ice water (0-4°C) for 120 s. Results: Every kind of stress stimulation (acoustic startle; the CPT) caused changes of HRV indicator values. The time domain HRV analysis parameters (pNN50, RMSSD) decreased aft er acoustic stress and the CPT, but were signifi cantly lower aft er the CPT. In frequency domain HRV analysis, signifi cant diff erences were observed only after the CPT: (LF-RRI 921.23 ms2 vs. 700.09 ms2; p = 0.009 and HF-RRI 820.75 ms2 vs. 659.52 ms2; p = 0.002). Th e decrease of LF-RRI and HF-RRI value aft er the CPT was signifi cantly higher than aft er the acoustic startle (LF-RRI 34% vs. 0.4%, p = 0.022; HF-RRI 19.7% vs. 7% ms2, p = 0.011). The decreased value of the LF and HF components of HRV analysis are indicative of sympathetic activation. Nonlinear analysis of HRV indicated a signifi cant decrease in the Poincare plot SD1 (p = 0.039) and an increase of DFAα2 (p = 0.001) in response to the CPT stress stimulation. The systolic BPV parameter LF/HF-sBP increased significantly after the CPT (2.84 vs. 3.31; p = 0.019) and was higher than aft er the acoustic startle (3.31 vs. 3.06; p = 0.035). Signifi cantly higher values of diastolic BP (67.17 ± 8.10 vs. 69.65 ± 9.94 mmHg, p = 0.038) and median BP (83.39 ± 8.65 vs. 85.30 ± 10.20 mmHg, p = 0.039) were observed in the CPT group than in the acoustic startle group. Conclusions: The Cold Pressor Test has a greater stimulatory effect on the sympathetic autonomic system in comparison to the unexpected acoustic startle stress. Regardless of whether the stimulation originates from the central nervous system (acoustic startle) or the peripheral nervous system (CPT), the final response is demonstrated by an increase in the low frequency components of blood pressure variability and a decrease in the low and high frequency components of heart rate variability

Wpływ pionizacji na aktywność autonomicznego układu nerwowego u wyczynowych pływaków

Introduction. Evaluation of heart rate variability (HRV) constitutes a useful tool in the analysis of changes in the autonomic nervous system (ANS), occurring as an adaptation to physical exercise. Changing body position from supine to standing upright is reflected by higher activity of the sympathetic ANS component. The aim of this study was to analyze the effect of tilting up on the activity of ANS in professional swimmers.Material and methods. The study included 10 healthy swimmers in the transitory phase of their training cycle, and the control group comprising 31 healthy volunteers. The evaluation of ANS activity was based on the temporal and spectral indices of HRV, as well as on the analysis of changes in arterial blood pressure and heart rate at rest and during Tilt-UpTest (TUT), determined prior to and after the training.Results. Prior to the training, the tilting up of swimmers was reflected by a significant decrease in: rMSSD, pNN50, HF,NHF, as well as by an increase in VLF and LF/HF (p < 0.05). After the training, a significant decrease in: pNN50, HF and NHF was documented after position changes, along with an increase in NLF and LF/HF (p < 0.05).Conclusions. The change of position (tilt up) induced significant changes in all studied vegetative indices, suggesting an increase in sympathetic tone. The TUT protocol used in this study can be useful in the evaluation of the vegetative response of athletes to external stimulation; this application can be important in the context of overtraining prevention.Wstęp. Analiza zatokowego rytmu pracy serca (HRV) stanowi przydatne narzędzie służące do oceny procesów adaptacyjnych organizmu do wysiłku fizycznego, zachodzących w autonomicznym układzie nerwowym (ANS). Zmiana pozycji ciała z leżącej na stojącą powoduje większą aktywność składowej współczulnej ANS. Celem pracy była ocena wpływu pionizacji na czynność ANS u wyczynowych pływaków.Materiał i metody. Badaniami objęto 10 zdrowych pływaków (5 kobiet, 5 mężczyzn, śr. wieku 21 ± 2 lata) w okresie treningu przejściowego oraz 31 zdrowych ochotników, którzy stanowili grupę kontrolną. Oceny aktywności ANS oparto na wskaźnikach analizy czasowej i częstotliwościowej HRV, zmianach ciśnienia tętniczego i częstości rytmu serca w spoczynku, podczas testu zmiany pozycji ciała (TUT) w okresie przed treningiem i po nim.Wyniki. U pływaków przed treningiem podczas pionizacji zanotowano istotne statystycznie zmniejszenie wartościwskaźników: rMSSD, pNN50, HF, NHF oraz wzrost wartości VLF, LF/HF (p < 0,05). Po treningu podczas pionizacji, w porównaniuz pozycją leżącą, zanotowano istotne statystycznie zmniejszenie wartości wskaźników: pNN50, HF, NHF oraz wzrost NLF, LF/HF (p < 0,05).Wnioski. Bodziec pionizacyjny spowodował istotną zmianę wszystkich ocenianych parametrów układu wegetatywnego, wskazując na wzrost napięcia składowej współczulnej. Po treningu u pływaków odpowiedź na stymulację była mniejsza. Zastosowany TUT może być przydatny w ocenie zdolności reagowania układu wegetatywnego sportowców na bodźce zewnętrzne, co wydaje się istotne w kontekście zapobieganiu występowania zespołu przetrenowania

Past strong experiences determine acute cardiovascular autonomic responses to acoustic stress

Background: Stress is a major risk factor for cardiovascular (CV) disease. We hypothesized that past strong experiences might modulate acute CV autonomic responses to an unexpected acoustic stimulus. A i m: The study’s aim was to compare acute CV autonomic responses to acoustic stress between students with and without a past strong experience associated with the acoustic stimulus. Materials and Methods: Twenty five healthy young volunteers - medical and non-medical students - were included in the study. CV hemodynamic parameters, heart rate (HR), and blood pressure (BP) variability were assessed for 10 min at rest and for 10 min after two different acoustic stimuli: a standard sound signal and a specific sound signal used during a practical anatomy exam (so-called "pins"). Results: Both sounds stimulated the autonomic nervous system. The "pins" signal caused a stronger increase in HR in medical students (69 ± 10 vs. 73 ± 13 bpm, p = 0.004) when compared to non-medical students (69 ± 6 vs. 70 ± 10, p = 0.695). Rises in diastolic BP, observed 15 seconds after sound stressors, were more pronounced after the "pins" sound than after the standard sound signal only in medical students (3.1% and 1.4% vs. 3% and 4.4%), which was also reflected by low-frequency diastolic BP variability (medical students: 6.2 ± 1.6 vs. 4.1 ± 0.8 ms2, p = 0.04; non-medical students: 6.0 ± 4.3 vs. 4.1 ± 2.6 ms2, p = 0.06). Conclusions: The "pins" sound, which medical students remembered from their anatomy practical exam, provoked greater sympathetic activity in the medical student group than in their non-medical peers. Thus, past strong experiences modulate CV autonomic responses to acute acoustic stress