A Systematic Review of the Relationship Between Traumatic Brain Injury and Disruptions in Heart Rate Variability.

Autonomic nervous system dysfunction is increasingly recognized as a common sequela of traumatic brain injury (TBI). Heart rate variability (HRV) is a specific measure of autonomic nervous system functioning that can be used to measure beat-to-beat changes in heart rate following TBI. The objective of this systematic review was to determine the state of the literature on HRV dysfunction following TBI, assess the level of support for HRV dysfunction following TBI, and determine if HRV dysfunction predicts mortality and the severity and subsequent recovery of TBI symptoms. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two raters coded each article and provided quality ratings with discrepancies resolved by consensus. Eighty-nine papers met the inclusion criteria. Findings indicated that TBI of any severity is associated with decreased (i.e., worse) HRV; the severity of TBI appears to moderate the relationship between HRV and recovery; decreased HRV following TBI predicts mortality beyond age; HRV disturbances may persist beyond return-to-play and symptom resolution following mild TBI. Overall, current literature suggests HRV is decreased following TBI and may be a good indicator of physiological change and predictor of important outcomes including mortality and symptom improvement following TBI.

A systematic review of heart rate variability (HRV) biofeedback treatment following traumatic brain injury (TBI).

OBJECTIVE: Autonomic nervous system dysregulation is a common consequence of traumatic brain injury (TBI). Heart rate variability (HRV) is a cost-effective measure of autonomic nervous system functioning, with studies suggesting decreased HRV following moderate-to-severe TBI. HRV biofeedback treatment may improve post-TBI autonomic nervous system functioning and post-injury emotional and cognitive functioning. We provide a systematic evidence-based review of the state of the literature and effectiveness of HRV biofeedback following TBI. METHOD: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two coders coded each article and provided quality ratings. Seven papers met inclusion criteria. All studies included a measure of emotional functioning and 5 studies (63%) included neuropsychological outcomes. RESULTS: Participants completed 11 sessions of HRV biofeedback on average (range = 1 to 40). HRV biofeedback was associated with improved HRV following TBI. There was a positive relationship between increased HRV and TBI recovery following biofeedback, including improvements in cognitive and emotional functioning, and physical symptoms such as headaches, dizziness, and sleep problems. CONCLUSION: The literature on HRV biofeedback for TBI is promising, but in its infancy; effectiveness is unclear due to poor-to-fair study quality, and potential publication bias (all studies reported positive results).

The relationship between acute stress and neurophysiological and behavioral measures of food-related inhibitory control: An event-related potential (ERP) study.

Stress influences many health-related behaviors including diet and nutrition intake, often resulting in increased calorie intake, fewer healthy eating behaviors, and poorer nutrition. Food intake is modulated by inhibitory control and has important implications for our physical, mental, and emotional health. Yet, little is known about the relationship between stress and food-related inhibitory control. We tested the influence of a short-term experimental stressor on behavioral and event-related potential (ERP; N2 and P3 components) measures of food-related inhibitory control. Ninety-seven healthy participants were randomly assigned to complete the Trier Social Stress Test (TSST) (n = 48, 27 females [52.9%]) or a neutral control condition (n = 49, 35 females [70%]) immediately followed by food-specific go/no-go and neutral go/no-go tasks while electroencephalogram (EEG) data were recorded. Stress levels were successfully manipulated, with heightened self-report and physiological measures (heart rate and systolic blood pressure) of the stress response in individuals who completed the TSST compared to control. As expected, the high calorie food-specific go/no-go task elicited larger N2 amplitude than the neutral task. N2 component amplitude was also significantly larger following the TSST relative to the control task. There were no significant between-group or task differences for P3 amplitude or behavioral measures. Findings suggest heightened N2 amplitude following psychological stress that is not specific to food or inhibition processes and may reflect heightened arousal following stress. Future research in individuals with overweight/obesity or experiencing chronic stress will further clarify the role of stress in food-related inhibitory control.

Impact of a 12-Week Group-Based Compassion Focused Therapy Intervention on Heart Rate Variability.

Heart rate variability (HRV) is considered an index of self-regulatory capacity, and trait compassion predicts healthy HRV and self-regulation. Compassion focused psychotherapy interventions have been shown to increase levels of compassion in the general population but no studies to date have examined if these interventions also increase HRV in a distressed clinical sample. The present study examined whether a 12-week compassion focused therapy intervention administered in group format would improve resting HRV and impact HRV reactivity during self-critical writing and self-compassion writing tasks administered before and after the intervention. A total of 31 participants in a university counseling center completed the intervention and HRV assessments. Resting HRV did not significantly change over the course of the intervention in the overall sample. Only those who showed a reliable increase in self-compassion also had a significant increase in resting HRV post-intervention. Additionally, the self-critical writing task was associated with a significant decrease in HRV, with HRV staying low during self-compassionate writing and then significantly increasing during recovery. Reliable change in self-compassion predicted increased HRV reactivity to self-critical and self-compassion writing tasks following the intervention, indicating greater engagement with the task. Findings support the idea that increased self-compassion increases HRV reactivity and potentially strengthens ability to engage with difficult emotions in psychotherapy.

What Mediates the Relationship Between Religious Service Attendance and Aspects of Well-Being?

Religious service attendance predicts increased well-being across a number of studies. It is not clear, however, whether this relationship is due to religious factors such as intrinsic religiosity or due to nonreligious factors such as social support or socially desirable responding. The purpose of the present study was to examine the relationship between religious service attendance and well-being while simultaneously examining intrinsic religiosity, social support, and socially desirable responding as potential mediators of the relationship. A sample of 855 participants (71 % female, average age 19.5) completed questionnaires assessing religiosity, social support, socially desirable responding, and well-being. Path models were estimated using maximum likelihood estimation to analyze the data. Intrinsic religiosity was the strongest mediator of the relationship between religious service attendance and depressive and anxiety symptoms. This suggests that the mental health benefits of religious service attendance are not simply the result of increased social support or a certain response style on questionnaires; rather, it appears that the relationship is at least partly the result of people trying to live their religion in their daily lives.

The Effects of Job Instability and Financial Strain on C-Reactive Protein in a Sample of Mexican Immigrants.

OBJECTIVE: Mexican immigrants have lower cardiovascular disease risk than US citizens, but risk increases with level of acculturation. Our study investigated whether job stress and financial strain would be related to inflammation (C-reactive protein), lipids, and blood pressure, and if they would play a role in the acculturation process in Mexican immigrants. METHODS: A sample of 310 Mexican immigrants living in the United States were studied on measures of job stress, financial strain, acculturation, and cardiovascular disease risk factors (C-reactive protein, lipids, and blood pressure). RESULTS: Job instability, financial strain, and acculturation, were related to inflammation, but psychological demands and decision latitude were not related. Lipids and blood pressure were not related to the variables of interest. Body mass index (BMI) was related to both increased acculturation and inflammation, and when controlling for BMI, acculturation was no longer a significant predictor of inflammation. Job instability and financial strain remained significant predictors of inflammation after controlling for BMI, sex, and age. Job instability and financial strain were not related to acculturation, suggesting that these factors are significant stressors for both newly arrived and more established immigrants. CONCLUSIONS: Job instability and financial strain predict increased inflammation in Mexican immigrants but they do not play a role in the relationship between acculturation and C-reactive protein. The effects of acculturation on inflammation in this study were mediated by BMI.

Religious orientation and life aspirations.

The effects of religiosity on well-being appear to depend on religious orientation, with intrinsic orientation being related to positive outcomes and extrinsic orientation being related to neutral or negative outcomes. It is not clear, however, why intrinsic and extrinsic religiosity has the relationships they do. Self-determination theory may provide a useful framework of intrinsic and extrinsic aspirations that may help to answer this question. The purpose of the present study was to examine whether intrinsic and extrinsic religiosity would be related to intrinsic and extrinsic life aspirations. We hypothesized that intrinsic religiosity would be positively related to intrinsic life aspirations and negatively related with extrinsic life aspirations, and that extrinsic religiosity would be positively related to extrinsic life aspirations and negatively related to intrinsic aspirations, and that life aspirations would partially mediate the relationships between religious orientation and outcome. To study these hypotheses, a random national sample (total number of 425, average age of 52, 59 % female) completed the measures of religious orientation, life aspirations, affect, and life satisfaction. It was found that intrinsic religiosity was positively related to positive affect, life satisfaction, and intrinsic life aspirations and was negatively related to negative affect and extrinsic life aspirations. Extrinsic religiosity was positively related to extrinsic life aspirations and was not related to the intrinsic life aspirations. When both religious orientation and life aspiration variables were included together in the model predicting outcome, both remained significant indicating that religious orientation and life aspirations are independent predictors of outcome. In conclusion, although religious orientation and life aspirations are significantly related to each other and to outcome, life aspirations did not mediate the effects of religious orientation. Therefore, self-determination theory does not appear to completely account for the effects of religious orientation.

Perfectionism and life aspirations in intrinsically and extrinsically religious individuals.

Religiosity is related to positive health and life satisfaction but the pathways through which this occurs have not been clearly delineated. The purpose of this study was to examine potential mediators of the relationships between intrinsic and extrinsic religiosity and negative affect and life satisfaction. Perfectionism and life aspirations are two possible pathways through which religious orientation is related to outcome. It was hypothesized that adaptive perfectionism and intrinsic life aspirations would act as mediators between intrinsic religiosity and negative affect and life satisfaction, and that maladaptive perfectionism and extrinsic life aspirations would act as mediators between the extrinsic religiosity and negative affect and life satisfaction. Two consecutive samples of religious college students (N = 540 and N = 485) completed measures of the Age Universal Religious Orientation Index, the Frost Multi-Dimensional Perfectionism Scale, the Aspiration Index, the Beck Depression Inventory-II, the Spielberger State-Trait Anxiety Inventory, and the Satisfaction with Life Scale. Intrinsic religiosity had a direct negative relationship with negative affect and positive relationship with life satisfaction. Contrary to the hypotheses, intrinsic religiosity had its strongest indirect effect via maladaptive perfectionism such that increased intrinsic religiosity was related to decreased maladaptive perfectionism which in turn lead to better negative affect and life satisfaction. Extrinsic religiosity was related to increased maladaptive perfectionism and thereby indirectly contributed to worse negative affect and life satisfaction. Interestingly, when the effects of maladaptive perfectionism were controlled, the direct effects of extrinsic religiosity were related to reduced negative affect and increased life satisfaction. Overall, the strongest mediator in this study of both intrinsic and extrinsic religiosity was maladaptive perfectionism, with intrinsic religiosity related to decreased maladaptive perfectionism and extrinsic religiosity related to increased maladaptive perfectionism.

Ethnic differences in relationship orientation, marital quality and ambulatory blood pressure.

Mexican Americans typically have better cardiovascular health than Caucasians, despite being relatively economically disadvantaged. Given research indicating the importance of relationship quality on one's health, our study examined whether certain relationship orientations (eg, communal or exchange) differed between Caucasians and Mexican Americans and if these orientations could help explain the Hispanic Paradox. We recruited 582 adults from a community being primarily Caucasian (40%) and foreign-born Mexican Americans (55%). Participants wore 24-hour ambulatory blood pressure (ABP) monitors and completed self-report measures of relationship satisfaction and relationship orientation. Results indicated that Caucasians tended to have more of a communal relationship orientation compared to foreign-born Mexican Americans. Communal orientation was predictive of higher relationship satisfaction and while higher relationship satisfaction predicted lower systolic blood pressure when ethnicity was added into the model this relationship was eliminated and foreign-born Mexican Americans had higher ABP compared to Caucasians. Even though communal and exchange relationship orientation don't seem to give us any more information to unravel the Hispanic Paradox, there are important ethnic differences in how we engage in marriage relationships and future research will need to examine the health effects of these differences.

Using the Research Domain Criteria as a framework to integrate psychophysiological findings into stress management and psychotherapy interventions.

Research on the psychophysiology of stress is expanding rapidly, but the field lacks a clear integrative framework to help translate research findings into empirically supported stress interventions. The Research Domain Criteria (RDoC) is an excellent candidate to explore as a framework to integrate stress research. The RDoC framework is a dimensional, multi-modal approach to psychopathology proposed as an alternative to categorical approaches used by the International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual (DSM). The goal of this paper is to explore the RDoC as a framework to integrate psychophysiology research into therapeutic interventions for stress. The RDoC consists of six domains: negative valence systems, positive valence systems, cognitive systems, social processes systems, arousal/regulatory systems, and sensorimotor systems, and provides an excellent structure for integrating information from multiple levels of functioning including physiology, behavior, and self-report, as well as genes, molecules, cells, and brain circuits. Integrating psychophysiological research on stress using the RDoC framework can direct and amplify stress management and psychotherapeutic interventions. First, the RDoC provides a clear foundation for conceptualizing the stress response in terms of important concepts such as allostasis and adaptation. In this perspective, the terms "allostatic response" or "adaptation response" are more descriptive terms than "stress response" in understanding bodily responses to life threats and challenges. Second, psychophysiological approaches can be used in the context of modalities such as biofeedback and mindfulness to both collect psychophysiological data and then integrate that data into a broader therapeutic framework. Heart rate variability (HRV) biofeedback is being used more frequently as part of a therapeutic intervention package with stress management and psychotherapy, and HRV data is also used to provide outcome evidence on the efficacy of treatment. Mindfulness practices are commonly used in combination with stress management and psychotherapy, and psychophysiological data (HRV, EEG, blood pressure, etc.) is often collected to explore and understand mind/body relationships. In conclusion, the lack of a clear framework to assess and understand mind/body functioning limits current stress research and interventions. The RDoC provides a strong framework to assess and integrate physiological and psychological data and improve stress interventions.

The Brain Is Adaptive Not Triune: How the Brain Responds to Threat, Challenge, and Change.

Theory impacts how research is conducted. A popular theory used to conceptualize brain functioning is the triune brain theory. The triune brain theory is an evolutionary theory of brain development that emphasizes three key brain regions consisting of the brainstem, the limbic system, and the cortex that function relatively independently in coping with stress via fight or flight, emotion, and cognition, respectively. However, modern neuroscience research demonstrates that the triune brain theory does not accurately explain how the brain functions in everyday life or during the stress response. Specifically, emotion and cognition are interdependent and work together, the limbic system is not a purely emotional center nor are there purely emotional circuits in the brain, and the cortex is not a purely cognitive center nor are there purely cognitive circuits in the brain. We propose a new evolutionarily based model, the adaptive brain, that is founded on adaptive prediction resulting from interdependent brain networks using interoception and exteroception to balance current needs, and the interconnections among homeostasis, allostasis, emotion, cognition, and strong social bonds in accomplishing adaptive goals.

Understanding the connection between spiritual well-being and physical health: an examination of ambulatory blood pressure, inflammation, blood lipids and fasting glucose.

Growing research has demonstrated a link between spiritual well-being and better health; however, little is known about possible physiological mechanisms. In a sample of highly religious healthy male and female adults (n = 100) ages 19-59 (m = 28.28) we examined the influence of spiritual well-being, as measured by the Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being (FACIT-Sp-Ex), on physiological risk factors for heart disease. Specifically we examined 24-h ambulatory blood pressure (BP), inflammation (hs-C-reactive protein), fasting glucose, and blood lipids. Regression analyses reveal that higher levels of spiritual-wellness (total FACIT-Sp-Ex score) was significantly related to lower systolic ambulatory BP (ß = -.345; P < .001), diastolic ambulatory BP (ß = -.24; P = .02), hs-C-reactive protein (ß = -.23; P = .04), fasting glucose (ß = -.28; P = .006), and marginally lower triglycerides (ß = -.21; P = .09) and VLDL (ß = -.21; P = .10) controlling for age, gender, and church attendance. Results remained generally consistent across the Meaning, Peace, Faith and Additional Spiritual Concerns subscales of the FACIT-Sp-Ex. Spiritual well-being may be cardio protective.

Spirituality and severity of menopausal symptoms in a sample of religious women.

Menopause represents an important life change, particularly for religious women whose identity is significantly related to family. Two competing hypotheses are examined: one, because religious women have their identity focused on family and child rearing, spirituality will be related to increased menopausal symptoms because menopause represents a loss of identity and purpose; and two, because spirituality can provide strength and comfort during difficult times, it will, therefore, be related to decreased menopausal symptoms. To test these competing hypotheses, questionnaires were administered to 218 women (average age 55, 35% premenopausal, 26% peri-menopausal, 39% postmenopausal) who were members of the Church of Jesus Christ of Latter Day Saints. Regression analyses indicated that higher levels of spiritual strength were related to decreased levels of reported menopausal symptoms. Spiritual strength was also related to increased benefit finding during menopause, decreased concern with body appearance, and increased use of adaptive coping strategies. We conclude that finding strength in spirituality may help religious women cope better with the life changes associated with menopause.

Integrating Breathing Techniques Into Psychotherapy to Improve HRV: Which Approach Is Best?

INTRODUCTION: Approaches to improve heart rate variability and reduce stress such as breathing retraining are more frequently being integrated into psychotherapy but little research on their effectiveness has been done to date. Specifically, no studies to date have directly compared using a breathing pacer at 6 breaths per minute with compassion focused soothing rhythm breathing. CURRENT STUDY: In this randomized controlled experiment, 6 breaths per minute breathing using a pacer was compared with compassion focused soothing rhythm breathing, with a nature video being used as a control group condition. METHODS: Heart rate variability (HRV) measures were assessed via electrocardiogram (ECG) and respiration belt, and an automated blood pressure machine was used to measure systolic diastolic blood pressure, and heart rate (HR). A total of 96 participants were randomized into the three conditions. Following a 5-min baseline, participants engaged in either 6 breath per minute breathing, soothing rhythm breathing, or watched a nature video for 10 min. To induce a stressful state, participants then wrote for 5 min about a time they felt intensely self-critical. Participants then wrote for 5 min about a time they felt self-compassionate, and the experiment ended with a 10-min recovery period. RESULTS: Conditions did not significantly differ at baseline. Overall, HRV, as measured by standard deviation of NN intervals (SDNN), low frequency HRV (LF HRV), and LF/HF ratio, increased during the intervention period, decreased during self-critical writing, and then returned to baseline levels during the recovery period. High frequency HRV (HF HRV) was not impacted by any of the interventions. The participants in the 6 breath per minute pacer condition were unable to consistently breathe at that rate and averaged about 12 breaths per minute. Time by Condition analyses revealed that both the 6 breaths per minute pacer and soothing breathing rhythm conditions lead to significantly higher SDNN than the nature video condition during breathing practice but there were no significant differences between conditions in response to the self-critical and self-compassionate writing or recovery periods. The 6 breath per minute pacer condition demonstrated a higher LF HRV and LF/HF ratio than the soothing rhythm breathing condition, and both intervention conditions had a higher LF HRV and LF/HF ratio than the nature video. CONCLUSIONS: Although the 6 breath per minute pacer condition participants were not able to breath consistently at the low pace, both the participants attempting to breathe at 6 breaths per minute as well as those in the soothing rhythm breathing condition effectively increased HR variability as measured by SDNN, and attempting to breathe at 6 breaths per minute led to the highest LF HRV and LF/HF ratio. Both breathing approaches impacted HRV more than watching a relaxing nature video and can potentially be used as key adjuncts in psychotherapy to aid in regulating physiological functioning, although it appears that consistent breathing practice would be needed.

The Association Between Experimentally Induced Stress, Performance Monitoring, and Response Inhibition: An Event-Related Potential (ERP) Analysis.

Psychological stress is increasingly associated with alterations in performance and affect. Yet, the relationship between experimentally induced psychological stress and neural indices of performance monitoring and error processing, as well as response inhibition, are unclear. Using scalp-recorded event-related potentials (ERPs), we tested the relationship between experimental stress, using the Trier Social Stress Test (TSST), and the error-related negativity (ERN), error positivity (Pe), and N2 ERP components. A final sample of 71 undergraduate students were randomly assigned to go through the TSST (n = 36; 18 female) or a brief mindfulness relaxation exercise (n = 35; 16 female) immediately followed by a go/no-go task while electroencephalogram (EEG) data were collected. Salivary cortisol, heart rate, and blood pressure confirmed increased physiological stress in the TSST group relative to control. Reaction times, accuracy, and post-error slowing did not differ by stress group. Two-group (TSST, control) by 2-trial type (correct, incorrect for ERN/Pe; go correct, no-go correct for N2) repeated measures ANOVAs for the ERN, Pe, and N2 showed the expected main effects of trial type; neither the ERN nor the N2 ERP components showed interactions with the stress manipulation. In contrast, the Pe component showed a significant Group by Trial interaction, with reduced Pe amplitude following the stress condition relative to control. Pe amplitude did not, however, correlate with cortisol reactivity. Findings suggest a reduction in Pe amplitude following experimental stress that may be associated with reduced error awareness or attention to errors following the TSST. Given the variability in the extant literature on the relationship between experimentally induced stress and neurophysiological reflections of performance monitoring, we provide another point of data and conclude that better understanding of moderating variables is needed followed by high-powered replication studies to get at the nuance that is not yet understood in the relationship between induced stress and performance monitoring/response inhibition processes.

Adding HRV biofeedback to psychotherapy increases heart rate variability and improves the treatment of major depressive disorder.

Heart rate variability (HRV) is a significant marker of health outcomes with decreased HRV predicting increased disease risk. HRV is decreased in major depressive disorder (MDD) but existing treatments for depression do not return heart rate variability to normal levels even with successful treatment of depression. Heart rate variability biofeedback (HRVB) increases heart rate variability but no studies to date have examined whether combining HRVB with psychotherapy improves outcome in MDD treatment. The present study used a randomized controlled design to compare the effects of HRVB combined with psychotherapy on MDD relative to a psychotherapy treatment as usual group and to a non-depressed control group. The HRVB+psychotherapy group showed a larger increase in HRV and a larger decrease in depressive symptoms relative to the other groups over a six-week period, whereas the psychotherapy group only did not improve HRV. Results support the supplementation of psychotherapy with HRVB in the treatment of MDD.

Hispanic ethnicity, stress psychophysiology and paradoxical health outcomes: A review with conceptual considerations and a call for research.

It is not wise to generalize psychophysiological findings from WEIRD (Western, Educated, Industrialized, Rich, Democratic) samples to all people and yet this occurs frequently in research. Case-in-point is our understanding of psychophysiological responses to stress which suggest universality despite our knowledge that these pathways are moderated by factors such as ethnicity and culture. Here we discuss the epidemiological phenomenon commonly referred to as the Hispanic health paradox to illustrate the importance of culture in understanding stress. We posit that despite high stress exposure, Hispanics may experience relatively low levels of stress contributing to their paradoxical health advantages. Building on our prior work, we present a new, culturally-tailored stress theory model to illustrate how sociocultural factors may moderate the experience of stress (through appraisals) with downstream effects on psychophysiological mechanisms. We support the model with available data and end this paper with a call for research that more carefully considers cultural and ethnic factors in psychophysiological research.

Diurnal cortisol variation is associated with nocturnal blood pressure dipping.

OBJECTIVE: To investigate if diurnal cortisol variation is associated with nocturnal blood pressure (BP) dipping. METHODS: In this study, 302 healthy adults (51% female; average age 31 years) underwent 24-hour ambulatory BP assessment with BP measured randomly approximately every 20 minutes during waking hours and every hour during sleep. Salivary cortisol was obtained at five time points. Cortisol and BP have natural diurnal variations and disruptions in these diurnal variations are related to pathological conditions, such as greater risk for cardiovascular disease. A lack of a drop in cortisol from day to night and a lack of a drop in BP from waking to sleeping have both been associated with negative outcomes. It is not known, however, if diurnal variations in cortisol and BP are related, or if changes in cortisol from day to night influence BP dipping. RESULTS: Diurnal cortisol variation was a significant predictor of BP dipping. Controlling for gender, body mass index, age, phase of menstrual cycle, sleep quality, morning cortisol, and daytime measures of the relevant cardiovascular assessments did not significantly affect the results. Cortisol variation was found to have a stronger relationship with BP dipping than any of the covariates measured. CONCLUSION: Decreased diurnal variation in cortisol is associated with decreased diurnal variation in BP. Future studies could benefit from examining how these two variables interact in predicting disease outcomes.

The Impact of Resonance Frequency Breathing on Measures of Heart Rate Variability, Blood Pressure, and Mood.

Heart rate variability biofeedback (HRVB) significantly improves heart rate variability (HRV). Breathing at resonance frequency (RF, approximately 6 breaths/min) constitutes a key part of HRVB training and is hypothesized to be a pathway through which biofeedback improves HRV. No studies to date, however, have experimentally examined whether RF breathing impacts measures of HRV. The present study addressed this question by comparing three groups: the RF group breathed at their determined RF for 15 min; the RF + 1 group breathed at 1 breath/min higher than their determined RF for 15 min; and the third group sat quietly for 15 min. After this 15-min period, all groups participated in the Paced Auditory Serial Addition Task (PASAT) for 8 min, and then sat quietly during a 10-min recovery period. HRV, blood pressure, and mood were measured throughout the experiment. Groups were not significantly different on any of the measures at baseline. After the breathing exercise, the RF group reported higher positive mood than the other two groups and a significantly higher LF/HF HRV ratio relative to the control group, a key goal in HRVB training (p < 0.05). Additionally, the RF group showed lower systolic blood pressure during the PASAT and during the recovery period relative to the control group, with the RF + 1 group not being significantly different from either group (p < 0.05). Overall, RF breathing appears to play an important role in the positive effect HRVB has on measures of HRV.