This thesis draws from music technology to create novel sonifications of heart rate information that may be of clinical utility to physicians. Current visually-based methods of analysis involve filtering the data, so that by definition some aspects are illuminated at the expense of others, which are decimated. However, earlier research has demonstrated the suitability of the auditory system for following multiple streams of information. With this in mind, sonification may offer a means to display a potentially unlimited number of signal processing operations simultaneously, allowing correlations among various analytical techniques to be observed. This study proposes a flexible listening environment in which a cardiologist or researcher may adjust the rate of playback and relative levels of several parallel sonifications that represent different processing operations. Each sonification "track" is meant to remain perceptually segregated so that the listener may create an optimal audio mix. A distinction is made between parameters that are suited for illustrating information and parameters that carry less perceptual weight, which are employed as stream separators. The proposed sonification model is assessed with a perception test in which participants are asked to identify four different cardiological conditions by auditory and visual displays. The results show a higher degree of accuracy in the identification of obstructive sleep apnea by the auditory displays than by visual displays. The sonification model is then fine-tuned to reflect unambiguously the oscillatory characteristics of sleep apnea that may not be evident from a visual representation. Since the identification of sleep apnea through the heart rate is a current priority in cardiology, it is thus feasible that sonification could become a valuable component in apnea diagnosis.

Introduction: Concussions are a physiologically & psychologically stressful event. Stress markers may provide insight into concussion recovery, but have not been examined. Purpose & Method: To investigate the stress response of concussed athletes compared to controls from injury to post-RTP. Concussed athletes’ Mood states, Perceived Stress, HRV, and Morning & Afternoon Cortisol were assessed at 3 phases of recovery following concussion. Results: Repeated measures ANOVA revealed significant interactions for TMD, Depression, Anger, Confusion, Fatigue, HF norm (rest), LF norm (rest), HF norm (difference between sitting & standing), LF norm (difference between sitting & standing), and LF/HF ratio (difference between sitting & standing). Vigor & Tension demonstrated significant changes over time in the concussed group. Significant difference between the two groups for morning Cortisol levels at phase 3 was revealed. Conclusion: Concussed athletes display elevated levels of stress post-injury. Findings warrant further investigation of stress markers in concussed athletes during recovery.

Introduction: Concussions are a physiologically & psychologically stressful event. Stress markers may provide insight into concussion recovery, but have not been examined. Purpose & Method: To investigate the stress response of concussed athletes compared to controls from injury to post-RTP. Concussed athletes’ Mood states, Perceived Stress, HRV, and Morning & Afternoon Cortisol were assessed at 3 phases of recovery following concussion. Results: Repeated measures ANOVA revealed significant interactions for TMD, Depression, Anger, Confusion, Fatigue, HF norm (rest), LF norm (rest), HF norm (difference between sitting & standing), LF norm (difference between sitting & standing), and LF/HF ratio (difference between sitting & standing). Vigor & Tension demonstrated significant changes over time in the concussed group. Significant difference between the two groups for morning Cortisol levels at phase 3 was revealed. Conclusion: Concussed athletes display elevated levels of stress post-injury. Findings warrant further investigation of stress markers in concussed athletes during recovery.

Long-term adaptation of cardiovascular system in response to regular physical activity depends not only on its type, intensity and volume, but on arterial blood pressure (ABP) during exercise as well. Although it is proved haemodynamic load is not the only factor responsible for the shaping of athlete's myocardium, both the extent and the type of cardiac remodelling are influenced greatly by the degree of pressure overload during exercise training. The aim of our study was to compare myocardium loading conditions during veloergometric and treadmill interval tests. Methods. Distance runners (all males, n = 16) served as subjects. Their age was 23.6 ± 5.5 yrs, body mass – 70.7 ± 4.7 kg, body mass index – 21.7 ± 1.9 kg/m2, training experience – 8.7 ± 5.6 yrs. Interval tests were applied on separate days. Each of them consisted of increasing intensity exercise interspaced with passive resting period (in seated position) of 4 min in duration. Heart rate (HR) was recorded throughout both tests while ABP was measured during recovery period between treadmill stages. Tests were continued till HR reached 90 percent of age-predicted maximum. Results. Systolic ABP, HR and double product were higher (p<0.05) after the discontinuation of veloergometric workload as compared with treadmill load requiring similar oxygen consumption. Runners' systolic ABP response was bigger to veloergometry as compared with treadmill running eliciting the same HR (p<0.05). Significant correlation was found... [to full text]

The transition from mechanical ventilation (MV) to spontaneous ventilation during weaning is associated with hemodynamic alterations and autonomic nervous system (ANS) alterations (reflected by heart rate variability [HRV]). Although cardiac dysrhythmias are an important manifestation of hemodynamic alterations, development of dysrhythmias during MV and weaning and subsequent impact on length of MV has received little attention. The purposes of this dissertation were to 1) evaluate the relationship of heart rate variability (HRV) during weaning to the development of cardiac dysrhythmias and 2) determine the relationship of cardiac dysrhythmias to length of MV. A convenience sample of 35 patients (66.7% men; mean age 53.3 years) who required MV was enrolled in this study. Continuous 3-lead electrocardiographic data were collected for 24 hours at baseline during MV and for the first 2 hours during the initial weaning trial. HRV was evaluated using spectral power analysis. Twenty- seven patients out of 30 were exposed to a combination of pressure support (8-15 cm H2O) and continuous positive airway pressure 5 cm H2O during weaning trial. Three patients self- extubated and received supplemental oxygen through either a partial rebreathing or non-rebreathing mask. Low frequency (LF) power HRV decreased, while high frequency (HF) and very low frequency (VLF) power HRV did not change during weaning. Multiple regression analyses showed that LF and HF HRV were significant predictors of occurrence of ventricular and supraventricular ectopic beats during weaning, while VLF power predicted occurrence of ventricular ectopic beats only. The mean of occurrence of supraventricular ectopic beats per hour during weaning was double the mean at baseline, while the mean of ventricular ectopic beats per hour did not change. Mean number of supraventricular ectopic beats per hour during weaning was a significant predictor of length of MV. This dissertation has fulfilled an important gap in the evidence base for cardiac dysrhythmias during weaning from MV. Cardiac dysrhythmias and HRV alterations should be systemically evaluated during MV and weaning trials in order to decrease length of MV.

This study examined the emotional and physiological differences between masticatory muscle pain patients and age, height, and weight matched pain-free controls. Physiological activation and emotional reactivity were assessed in the 22 muscle pain patients and 23 pain-free controls during a baseline rest period, while discussing a personally relevant stressor, and during a post-stressor recovery period. Physiological activity was assessed through the use of the frequency domain heart rate variability indices. Activity in the high frequency heart rate variability range is an index of parasympathetic activity while activity in the low frequency heart rate variability range is an index of both sympathetic and parasympathetic activity (Akselrod, 1981). The muscle pain patients showed significantly more physiological activation during both the baseline rest and the post-stressor recovery periods. These physiological differences were quantified by higher low frequency heart rate variability and lower high frequency heart rate variability during these study periods. This pattern of higher activation was also present in the report of emotional reactivity in the muscle pain patients. The emotional and physiological differences between the groups across study periods were more pronounced in muscle pain patients who reported a traumatic life experience. These results provide evidence of physiological activation and emotional responding in masticatory muscle pain patients that differentiates them from matched pain-free controls. The use of HRV indices to measure physiological functioning quantifies the degree of sympathetic and parasympathetic activation. Study results suggest the use of these HRV indices will improve understanding of the role that excitatory and inhibitory mechanisms play in the onset and maintenance of chronic masticatory muscle pain conditions.

Despite having fewer cognitive resources, older adults regulate their emotions as well as, if not better than, younger adults. This study aimed to (1) test the limits of older adults’ emotion regulation capacity and (2) gain a better understanding of how older adults use their more limited resources to regulate their emotions. Participants included 48 healthy older adults aged 65-85 from the community and 50 healthy younger adults aged 18-25 from the student population. They were randomly assigned to one of four experimental groups involving an initial activity that was high or low in self-regulatory demand followed by a test task of emotion regulation or attention regulation. As expected, older adults performed equally as well as younger adults on the emotion regulation test task, though worse on the attention regulation test task. Using resting heart rate variability (HRV) as a physiological measure of self-regulatory capacity, older adults appeared to allocate more resources toward the emotion regulation task compared to the attention regulation task, and relative to younger adults. The results suggest that older adults maintain their emotion regulation capacity in part by allocating more resources toward emotion regulation goals.

Chronic pain patients have poorer pain inhibition, self-regulatory ability, executive functioning and autonomic inhibition than those without pain, supporting the view that suppressing pain is mentally taxing. In the current study, an alternate explanation was proposed; namely, that pain inhibition, self-regulation, executive functions, and heart rate variability (HRV) are all controlled by the same general inhibitory system. To test this hypothesis, participants came into the laboratory for three sessions. At the first session, individual differences in pain thresholds, self-regulatory strength, executive functioning, and HRV were measured. At the second and third sessions, self-regulatory persistence and within-session changes in pain thresholds were measured under conditions of high and low self-regulatory fatigue. Results revealed that those low in inhibitory strength, operationalized as the aggregate of pain inhibition, self-regulation, executive functioning, and HRV, became more sensitive to pain under conditions of self-regulatory fatigue, whereas no significant changes in pain threshold were found for those high in inhibitory strength. Additional analyses revealed that high baseline pain threshold marginally protected against the effects of self-regulatory fatigue. The findings provide some support for a general inhibitory system and suggest that physiological inhibition of pain and autonomic activity may be influenced by phasic self-regulatory fatigue.

This study investigated the heart rates of children in the first, third, and fifth grades of two schools during physical education class and recess time. One hundred and nine children (56 females, 53 males) participated in the eight-week study. Each participant wore a Polar Vantage XL receptor strap and watch receiver during physical education class and recess time on the same day. The average heart rates and percentage of time in and above the target heart zone of 150 to 200 beats per minute were recorded. A MANOVA analysis revealed no significant difference between heart rates during physical education and recess over the eight-week period. Gender differences, however, were significant as boys average heart rates were higher than girls and boys were in or above the target heart zone a higher percentage of the time than girls. This difference was especially evident at recess. / Fisher Institute for Wellness

Healthcare practitioners, whom perform accurate sub-maximal exercise tests in healthy individuals, need to understand the physiological demands and normal cardiovascular (CV) responses with exercise. Exercise testing delivers valid information about the physiological systems of individuals that may identify healthy individuals at risk of developing future cardiovascular disease (CVD). Exercise is a common way to assess physiological stress experienced by an individual, because CV abnormalities that are not present at rest, can be elicited during exercise testing and be used to determine the adequacy of cardiac function. Cardiovascular markers like, resting heart rate (HR) and systolic blood pressure (SBP) have been used as simple non-invasive and useful biomarkers of the fundamental status of blood circulation and the CV system in healthy individuals. Studies have contributed to exercise under sub-maximal and maximal stress testing. Modern- day literature lacks information on the safe HR and SBP responses to an increase in workload during a sub-maximal exercise protocol in healthy individuals. Consequently, the first purpose of this study was to identify the current evidence in the literature on CV response during a sub-maximal incremental exercise protocol. Different protocols and modalities contribute to various CV responses over a wide age group and gender. Heart rate and SBP increases in a linear fashion with an increase in workload, irrespective of protocol and modality. The amount of this increase, or the response of these markers, is still a grey area in the literature, especially in healthy individuals. The second purpose of this study was to analyse the HR and SBP response in healthy adults during a sub-maximal incremental exercise test, with an increase in workload (watt). The systematic review found mean changes from baseline for HR and SBP to be 75.7% and 63.5% respectively, on bicycle protocols (N = 3). The treadmill protocols (N = 2) found similar mean changes from baseline of 113.3% for HR and 36.1% for SBP. Descriptive measures as well as Linear regression analyses were performed, using Generalised estimated equations (GEE). An independent t-test was used to compare the males with the female participants: HR and SBP response to an increase in workload (watt). GEE adjustments were made for age, body mass index (BMI) and workload (watt). Significant difference levels were set at p ≤ 0.05. The present once-off subject availability results revealed that male subjects were heavier and taller than their female counterparts (p ≤ 0.05). They also had a noteworthy higher SBPrest, as well as BMI (p ≤ 0.05). The results from the GEE analyses we presented prediction equation, with all variables significant, except for the BMI (p = 0.972 females; p = 0.169 males). In conclusion, the literature review indicated a lack of information on the HR and SBP response with workload in healthy adults. It is advised that further research is needed to test the prediction equations in healthy individuals to determine the validity and reliability. They need to be tested in a controlled clinical environment, where the participants are monitored more thoroughly. By putting these predicted equations to the test, healthcare practitioners will be able to identify an exaggerated HR and SBP response with an increase in workload. If the individual’s response is exaggerated, the healthcare practitioner can intervene to prevent future cardiovascular events. / Thesis (MSc (Biokinetics))--North-West University, Potchefstroom Campus, 2013