Bakgrund: Dykreflexen är en reflex som aktiveras när däggdjur håller andan och när receptorer i ansiktet utsätts för kyla. Det är en evolutionär adaption som har utvecklats för att spara på syre i situationer då ny syretillförsel inte finns att tillgå. Den syresparande funktionen aktiveras även vid endast kylstimulering av ansiktet. Denna studie har undersökt vilken effekt dykreflexen har på återhämtningen efter aerob submaximal fysisk aktivitet. Syfte: Syftet med studien var att undersöka om dykreflexen påverkar återhämtningen efter aerob submaximal fysisk aktivitet med avseende på puls och självskattad ansträngning.  Metod: Studiedesignen var en randomiserad cross-over design. Studiedeltagarna var sina egna kontroller. Interventionen var applicering av kyla mot ansiktet (5–10 ºC) mot pannan och ögonen efter avslutad submaximal aerob fysisk aktivitet. Ett kontrolltest utfördes med hudtempererat vatten (27–33 ºC). Insamlade data var pulsåterhämtning och skattad ansträngning 60sek och 180sek efter avslutad submaximal aerob fysisk aktivitet. Resultat: Mediandifferensen mellan HRR60s med och utan kyla visade 0,5 pulsslag större återhämtning med interventionen. Mediandifferensen för HRR180s med och utan kyla visade 2 pulsslag större återhämtning med interventionen. Resultatet av självskattningen enligt Borgs RPE60s samt Borgs RPE180s visar 0,5 skalsteg större mediandifferens med interventionen. Signifikansnivå var satt till P = 0,05. Resultatet från de olika testerna visade P = 0,286 för HRR60s, P = 0,212 för HRR180s, P = 0,374 för Borgs RPE60s samt P = 1,000 för Borgs RPE180s. Konklusion: Resultaten visade inte någon statistiskt signifikant skillnad sett till pulsåterhämtning och självskattad ansträngning mellan interventionen med kyla i ansiktet och kontrolltestet med hudtempererat vatten i ansiktet. / Background: The diving reflex is a response triggered when mammals hold their breath and receptors in the face are exposed to cold. It's an evolutionary adaptation developed to conserve oxygen in situations where fresh oxygen isn't readily available. The oxygen-conserving function activates even with just facial cold stimulation. This study explored the impact of the diving reflex on recovery after aerobic submaximal physical activity. Objective: The purpose of the study was to investigate if the diving reflex affects recovery following aerobic submaximal physical activity in terms of heart rate and perceived exertion. Method: The study design was a randomized crossover design. Participants acted as their own controls. The intervention was cold stimulus (5–10°C) to the forehead and eyes after completing submaximal aerobic physical activity. The same procedure was conducted in the control test, but with skin-tempered water (27–33°C). Collected data included pulse recovery and perceived exertion at 60 seconds and 180 seconds after completing submaximal aerobic physical activity. Results: The median difference between HRR60s with and without cold showed a 0.5 bpm greater recovery with the intervention. The median difference for HRR180s with and without cold showed a 2 bpm greater recovery with the intervention. The self-assessed results using Borgs RPE60s and Borgs RPE180s displayed a 0.5 scale higher median difference with the intervention. The significance level was set at P = 0.05. The test results showed P = 0.286 for HRR60s, P = 0.212 for HRR180s, P = 0.374 for Borgs RPE60s, and P = 1.000 for Borgs RPE180s. Conclusion: The results do not show any statistically significant difference in terms of pulse recovery and self-perceived exertion between the intervention using facial cold application and the control test with application of skin-temperature water on the face.

<p>Emerging evidence indicates that the commensal microbiota communicates with the brain and influences behavior. In animal models, perturbation of the microbiota is accompanied by changes in brain-derived neurotrophic factor (BDNF) levels in the brain. However, underlying mechanisms are unknown. We investigated whether vagal-parasympathetic and sympathetic branches of the autonomic nervous system are involved in the microbiota-gut-brain signalling and attempt to identify specific brain regions that are responsive to alterations in the intestinal microbiota. Specific pathogen-free Balb/c mice, with or without surgical vagotomy or chemical sympathectomy, received oral non-absorbable antimicrobials (ATM) <em>ad libitum</em> for 7 days. Behavior was tested on day 7 in the light/dark preference and step-down latency tests. Specific brain regions were sectioned and stained for the neuronal activation marker, <em>c-fos</em>. Perturbation of the microbiota significantly enhanced the exploratory behavior of mice in both tests and increased the expression of <em>c-fos</em> and phosphorylated <em>c-fos</em> in the hippocampus and dentate gyrus. <em>c-fos</em> expression in the nucleus of the solitary tract was unaffected and neither vagal-parasympathetic nor sympathetic neurotransmission were required for induction of the behavioral change following perturbation of the microbiota. Instability of the commensal microbiota enhances the activation of the hippocampal formation and influences host behavior in a manner that is independent of vagal-parasympathetic and sympathetic autonomic neurotransmission.</p> / Master of Health Sciences (MSc)

No description available.

Research has indicated that the frontal and temporal lobes are involved in the mediation of heart rate and blood pressure. However, whereas these regions of the brain have been identified in the mediation of heart rate and blood pressure, the specific cerebral processes involved in determining the direction and magnitude of change in heart rate and blood pressure has not been adequately addressed. The present paper proposes that changes in the magnitude of cerebral activation between the left and right frontal and temporal lobes is partly that which determines the direction and magnitude of changes in heart rate and blood pressure. The present investigation sought to test part of this proposition, namely, that increasing magnitude of cerebral activity within the right anterior temporal region generates increasing levels of sympathetic control of heart rate and blood pressure and that the right lateral frontal region acts to inhibit sympathetic activity. A total of 45 right handed men, with no history of significant head injury, were exposed to 55 dB, 75 dB, and 90 dB white noise presentations. Right frontal lobe functioning was assessed by performance on the Ruff Figural Fluency Test (RFFT), with the participants scoring in the lower one-third classified as Low Fluency. Those scoring in the upper one-third were classified as High Fluency. Quantitative electroencephalography, measured at 19 electrodes sites arranged according to the International 10/20 System, as well as heart rate and blood pressure responses to white noise presentation were measured. Although the results failed to support any of the hypotheses concerning the effects of varying intensity of white noise on cardiovascular activity, partial support was found for the hypotheses that varying intensity of white noise would generate differential changes in high beta magnitude between the Low and High Fluency groups. The results are discussed in terms of support for the model being tested. Alternative explanations of the findings are also provided that demonstrate correspondence between the QEEG and cardiovascular data. Finally, limitations of the model and the methods of the present investigation are discussed and suggestions for improvement are provided. / Ph. D.

The potential to track changes in training status and fitness levels of especially team sport participants by making use of more time efficient and accessible methods such as heart rate variability (HRV) and heart rate recovery (HRR) cannot be overlooked and needs to be considered. However, studies that have investigated this aspect in team sport participants are scarce. It is against this background that the main objectives of this study were firstly, to determine the relationships between HRV and HRR as well as the fitness levels of a cohort of university-level rugby players. The second objective was to determine the validity of the BioForce Heart Rate Variability System to determine the HRV of a cohort of university-level rugby players. Twenty-four university-level rugby players (age: 20.1 ± 0.41 years; body stature: 182.7 ± 6.2 cm; body mass: 89.7 ± 12.7 kg) of a South African university’s Rugby Institute participated in the first part of the study. During the test day players’ fasting baseline HRV (baseline HRV) values were taken. This was followed by the measurement of the post-breakfast HRV (Pre-Yo-Yo IR1 HRV). Players were then required to perform the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) while they were fitted with a portable Cosmed K4b2 gas analyser apparatus and a Fix Polar Heart Rate Transmitter Belt. After completion of the test, HRR was taken on 1 and 3 minutes and followed by the measurement of HRV (Post-Yo-Yo IR1 HRV). For the second part of the study a group of twenty u/21 university-level rugby players (age: 20.06 ± 0.40 years; body stature: 181.8 ± 5.5 cm; body mass: 91.1 ± 10.7 kg) of a South African university’s Rugby Institute were recruited to participate in this study. HRV was measured simultaneously by the Actiheart monitor system as well as the BioForce Heart Rate Variability System over three times periods: during the morning in a fasting state just after players had woken up (baseline); in the morning just after the players ate breakfast (pre-anaerobic); after completion of a high-intensity anaerobic training session (post-anaerobic) and after completion of a 20 min recovery session (post-recovery). Significant correlations (p ≤ 0.05) were found between Pre-Yo-Yo IR1 HRV and heart rate (HR) at the respiratory compensation point (RCP-HR (bpm)) (r = -0.468) as well as oxygen uptake at the RCP (RCP- 2max VO (% of 2max VO )) (r = 0.476), respectively. A forward stepwise regression analysis showed that HR at ventilatory threshold 1 (VT1-HR (bpm)) contributed significantly (p ≤ 0.05) to the post-Yo-Yo IR1 HRV with a variance of 39.8%. Final Yo-Yo IR1 level also contributed significantly (p ≤ 0.05) to 3 minute post-Yo-Yo IR1 HRR with a variance of 16.5%. For the second part of the study the majority of significant relationships (p < 0.05) between the Actiheart and Bioforce obtained HRV results were observed for the post-recovery period (Mean RR, SDNN, RMSSD and Peak LF power), followed by the pre-anaerobic period (Mean R-R and SDNN) and the baseline period (LF:HF ratio). No significant relationships were observed between the HRV results of the two apparatuses during the post-anaerobic period. In conclusion, HRV and HRR may have the potential to act as affordable and easy measurement tools of team sport participants’ fitness levels. However, the study results suggested that the BioForce Heart Rate Variability System that is used to obtain team sport participants’ HRV is especially valid to determine HRV after recovery periods that follow hard training sessions. The results do however cast a shadow of doubt over the accuracy of this apparatus when used directly after hard training sessions. / MSc (Sport Science), North-West University, Potchefstroom Campus, 2014

The electro-optic technique of measuring the cardiovascular pulse wave known as photoplethysmography (PPG) is clinically utilised for noninvasive characterisation of physiological components by dynamic monitoring of tissue optical absorption. There has been a resurgence of interest in this technique in recent years, driven by the demand for a low cost, compact, simple and portable technology for primary care and community-based clinical settings, and the advancement of computer-based pulse wave analysis techniques. PPG signal provides a means of determining cardiovascular properties during the cardiac cycle and changes with ageing and disease. This thesis focuses on the photoplethysmographic signal for cardiovascular assessment. The contour of the PPG pulse wave is influenced by vascular ageing. Contour analysis of the PPG pulse wave provides a rapid means of assessing vascular tone and arterial stiffness. In this thesis, the parameters extracted from the PPG pulse wave are examined in young adults. The results indicate that the contour parameters of the PPG pulse wave could provide a simple and noninvasive means to study the characteristic change relating to arterial stiffness. The pulsatile component of the PPG signal is due to the pumping action of the heart, and thus could reveal the circulation changes of a specific vascular bed. Heart rate variability (HRV) represents one of the most promising quantitative markers of cardiovascular control. Calculation of HRV from the peripheral pulse wave using PPG, called pulse rate variability (PRV), is investigated. The current work has confirmed that the PPG signal could provide basic information about heart rate (HR) and its variability, and highly suggests a good alternative to understanding dynamics pertaining to the autonomic nervous system (ANS) without the use of an electrocardiogram (ECG) device. Hence, PPG measurement has the potential to be readily accepted in ambulatory cardiac monitoring due to its simplicity and comfort. Noncontact PPG (NPPG) is introduced to overcome the current limitations of contact PPG. As a contactless device, NPPG is especially attractive for physiological monitoring in ambulatory units, NICUs, or trauma centres, where attaching electrodes is either inconvenient or unfeasible. In this research, a prototype for noncontact reflection PPG (NRPPG) with a vertical cavity surface emitting laser (VCSEL) as a light source and a high-speed PiN photodiode as a photodetector is developed. The results from physiological experiments suggest that NRPPG is reliable to extract clinically useful information about cardiac condition and function. In summary, recent evidence demonstrates that PPG as a simple noninvasive measurement offers a fruitful avenue for noninvasive cardiovascular monitoring. Key words: Photoplethysmography (PPG), Cardiovascular assessment, Pulse wave contour analysis, Arterial stiffness, Heart rate (HR), Heart rate variability (HRV), Pulse rate variability (PRV), Autonomic nervous system (ANS), Electrocardiogram (ECG).

Les somnambules présentent des caractéristiques qui suggèrent un dysfonctionnement dans la régulation du sommeil lent profond (SLP). La fonction autonome est étroitement liée à la régulation des stades de sommeil et reflète l’intensité du SLP. Notre objectif est d’étudier la fonction autonome pendant le SLP des somnambules et des sujets témoins avant et après une privation de sommeil. Quatorze somnambules adultes (9 femmes et 5 hommes ; 28,1 ± 5,8 ans) et 14 sujets témoins appariés pour l’âge et le sexe (27,8 ± 6,0 ans) ont été évalués par vidéo - polysomnographie pour une nuit de base et pendant le sommeil de récupération après 25 heures de privation de sommeil. La fréquence cardiaque (FC) et les composantes spectrales de la variabilité de la FC ont été évaluées. Les composantes de basses (LF) et de hautes fréquences (HF) en valeur absolue et en unités normalisées (LFn et HFn) ainsi que le ratio LF/HF ont été analysés à partir de segments de 5 minutes d’électrocardiogramme sélectionnés lors du SLP des deux premiers cycles de sommeil. Au cours du premier cycle de sommeil, les somnambules, mais pas les sujets témoins, ont montré une diminution des LFn et du ratio LF/HF ainsi qu’une augmentation des HFn lors du sommeil de récupération par rapport au sommeil normal. Au cours du deuxième cycle, les somnambules ont montré une FC plus élevée en sommeil de récupération par rapport au sommeil de base et l’inverse a été trouvé chez les sujets témoins. Les somnambules ont montré une augmentation de l’activité parasympathique ainsi qu’une diminution de l’activité sympathique au cours du premier cycle du sommeil de récupération par rapport à la valeur initiale. Puisque cette fenêtre de temps est fortement associée à la survenue d'épisodes de somnambulisme chez les sujets prédisposés, cette hyperactivité parasympathique pourrait être impliquée dans la physiopathologie de somnambulisme. / Sleepwalkers show a dysfunction in the regulation of slow-wave sleep (SWS). Autonomic function is closely related to sleep stage regulation and reflects SWS intensity. We thus investigated cardiac autonomic function during SWS in sleepwalkers and controls during normal sleep and recovery sleep following sleep deprivation. Fourteen adult sleepwalkers (9 women, 5 men; 28.1±5.8 years) and 14 sex- and age-matched normal controls (27.8± 6.0 years) were evaluated prospectively by video-polysomnography for one baseline night and during recovery sleep following 25 hours of sleep deprivation. Heart rate (HR) and the spectral components of HR variability during subjects' SWS were investigated during the first and second sleep cycles of both sleep conditions. Five-minute segments of electrocardiographic recordings from SWS were used to investigate HR, low-frequency (LF) and high-frequency (HF) components of the HR spectral decomposition in absolute and normalized units (LFn and HFn), and LF/HF ratio during subjects’ first two sleep cycles. During the first sleep cycle, sleepwalkers, but not controls, showed a decrease in LF/HF ratio and LFn as well as increased HFn from baseline to recovery sleep. During the second sleep cycle, sleepwalkers showed increased HR from baseline to recovery sleep whereas a decrease in HR was observed in controls. Compared to control subjects, sleepwalkers show a greater increase of parasympathetic tone and greater decrease of sympathetic tone during the first sleep cycle of their recovery sleep as compared to baseline. Since the first sleep cycle during recovery sleep constitutes a time window preferentially associated with the occurrence of somnambulistic episodes in predisposed participants, this parasympathetic hyperactivity may be implicated in the pathophysiology of sleepwalking.

Les personnes avec un trouble du spectre autistique (TSA) présentent une hyperactivité de la voie sympathique du système nerveux autonome (SNA) lors de l’éveil. Il est connu que le tonus sympathique est plus élevé le matin que le soir. Or, le sommeil a une influence sur l’activité du SNA. Ainsi, l’objectif de ce mémoire est de comparer l’activité du SNA d’un groupe d’adultes TSA à un groupe d’adultes neurotypiques (NT) le soir et le matin et de mettre en relation ces variables avec leurs paramètres subjectifs de sommeil.L’électrocardiogramme des participants a été réalisé avant et après une nuit de sommeil. Des comparaisons des paramètres de sommeil et des paramètres de variabilité de la fréquence cardiaque (VFC) le soir et le matin ont été réalisées entre les deux groupes, ainsi que des corrélations entre les paramètres de sommeil et les paramètres de VFC le matin.L’analyse de la VFC a montré une activité sympathique plus élevée le matin chez les adultes TSA comparativement aux adultes NT. De plus, de longs éveils nocturnes et une moins bonne efficacité de sommeil étaient corrélés avec une haute activité sympathique le matin. Ainsi, le sommeil perturbé du groupe d’adultes avec un TSA a possiblement affecté l’activité de leur SNA de manière à avoir une balance sympathovagale plus élevée le matin que le groupe NT. À notre connaissance, cette étude est la première à étudier l’activité cardiaque d’adultes TSA en lien avec leur sommeil et ainsi elle pourra améliorer notre compréhension de la physiopathologie de cette maladie. / Individuals with autistic spectrum disorder (ASD) show higher sympathetic activity of the autonomic nervous system (ANS) during wake. It is known that typically developing (TD) individuals show higher sympathetic activity in the morning compared to the evening. Studies suggest that sleep has an influence on ANS functioning. The goal of this study is to explore evening and morning ANS activity of a group of adults with ASD and a group of TD adults and to explore its relationships with subjective sleep parameters of participants. Electrocardiographic data of both groups were recorded before and after a night of sleep. Group comparisons were done on participant’s subjective sleep data and heart rate variability (HRV) in the evening and the morning. Correlations were then performed between subjective sleep measures and morning HRV parameters. Spectral analysis of the HRV showed higher sympathetic activity in the morning for the ASD group compared to the TD group. When all participants were grouped, longer nocturnal awakening and lower sleep efficiency were correlated with higher sympathetic activity in the morning. This suggest that sleep disturbances in ASD influences ANS functioning and results in higher sympathovagal balance in the morning. To our knowledge, this is the first study to investigate ANS activity of ASD adults in relation to sleep, and it may improve our understanding of the pathophysiology of this disease.

This work is trying to identify possible non-stimulatory effects and distant effects of muscle electrostimulation musculus quadriceps femoris based on a literature search. Furthermore evaluates the influence of High Tone Electrical Stimulation (HTEMS) muscles of lower limbs on the activity of the autonomic nervous system, expressed by heart rate variability, a spectral power in the individual frequency bands. Randomized crossover study involved 20 healthy subjects (12 men and 8 women), average age 24.6 ± 5.6 years. Heart rate variability was evaluated before application of HTEMS and immediately after. Measurements were performed with electrostimulator HiToP 191. The results did not show statistically significant increase in spectral power in the individual frequency bands. The study also deals with the reproducibility of measurements of sensitive and motor threshold for electrostimulation HTEMS method, which was confirmed. Powered by TCPDF (www.tcpdf.org)

This work is trying to identify possible non-stimulatory effects and distant effects of muscle electrostimulation musculus quadriceps femoris based on a literature search. Furthermore evaluates the influence of High Tone Electrical Stimulation (HTEMS) muscles of lower limbs on the activity of the autonomic nervous system, expressed by heart rate variability, a spectral power in the individual frequency bands. Randomized crossover study involved 15 healthy subjects (7 men and 8 women), average age 24.4 ± 2,5 years. Heart rate variability was evaluated in two situations: the situation without the application HTEMS and the situation with the aplication of HTEMS. Electrostimulation was done with HITOP 191. The results did not show statistically significant differences in all monitored components. The study also dealt with the reproducibility of measurements of perception and motor threshold for HTEMS.