Heart Rate Variability Profile Research Articles

Examining the feasibility and utility of heart rate variability on intervention outcomes targeting emotion regulation in autism: a brief report

Autistic youth experience several behavioral and emotional characteristics that can predispose them to emotion dysregulation (ED). Current literature examining ED in autism spectrum disorder (ASD) is limited to parent- and self-reported measures, indicating a need for biological or physiological methods to better assess emotion regulation in ASD. Utilizing the autonomic nervous system, specifically heart rate variability (HRV), may be a promising method to objectively measure ED in ASD, given it is one of the body’s primary means of regulating physiological arousal. Our pilot study is one of the first to examine the feasibility, utility, and construct validity of HRV along with clinical measures within an intervention targeting ED-specific symptoms in ASD. Participants included 30 autistic youth ages 8–17 years who participated in the pilot study of Regulating Together, a group-based intervention targeting emotion regulation. We demonstrate HRV is feasible, demonstrates adequate test–retest reliability, and is complimentary to clinician- and parent-reported measures. Our preliminary findings also point to certain HRV profiles being indicative of long-term outcomes after receiving treatment. HRV may be a useful, objective tool in determining differential needs of long-term follow-up care for treatment maintenance at screening or baseline stages.

Different heart rate variability profile during sleep in mid-later life adults with remitted early-onset versus late-onset depression

BackgroundIn mid-later life adults, early-onset and late-onset (i.e., onset ≥50 years) depression appear to be underpinned by different pathophysiology yet have not been examined in relation to autonomic function. Sleep provides an opportunity to examine the autonomic nervous system as the physiology changes across the night. Hence, we aimed to explore if autonomic profile is altered in mid-later life adults with remitted early-onset, late-onset and no history of lifetime depression. MethodsParticipants aged 50–90 years (n = 188) from a specialised clinic underwent a comprehensive clinical assessment and completed an overnight polysomnography study. General Linear Models were used to examine the heart rate variability differences among the three groups for four distinct sleep stages and the wake after sleep onset. All analyses controlled for potential confounders – age, sex, current depressive symptoms and antidepressant usage. ResultsFor the wake after sleep onset, mid-later life adults with remitted early-onset depression had reduced standard deviation of Normal to Normal intervals (SDNN; p = .014, d = −0.64) and Shannon Entropy (p = .004, d = −0.46,) than those with no history of lifetime depression. Further, the late-onset group showed a reduction in high-frequency heart rate variability (HFn.u.) during non-rapid eye movement sleep stage 2 (N2; p = .005, d = −0.53) and non-rapid eye movement sleep stage 3 (N3; p = .009, d = −0.55) when compared to those with no lifetime history. LimitationsCausality between heart rate variability and depression cannot be derived in this cross-sectional study. Longitudinal studies are needed to examine the effects remitted depressive episodes on autonomic function. ConclusionThe findings suggest differential autonomic profile for remitted early-onset and late-onset mid-later life adults during sleep stages and wake periods. The differences could potentially serve as peripheral biomarkers in conjunction with more disease-specific markers of depression to improve diagnosis and prognosis.

Heart rate variability profile changes associated with specialist police selection activities: A case study.

Police Tactical Groups (PTGs) are specialist police units tasked with rigorous physical and psychosocial duties. Consequently, selection courses (SCs) for service in these units must also be rigorous. Given the intensity of SCs, holistic monitoring for potential overstress may be beneficial. Heart Rate Variability (HRV) is one holistic stress measure that can be obtained in austere environments. The purpose of this study was to profile HRV during a PTG SC. Six (n = 6) qualified male police officers attempted a 36-hour PTG selection course held at an Australian state facility. HRV was obtained from Equivitaltrademark EQ02 + LifeMonitor bioharnesses. The selection course consisted of physically demanding events with minimal sleep (approx. 45 mins). Only one candidate completed the full selection course; whose results are reported here. A visual time-series of 384 consecutive 5 min HRV analyses was generated. Contextual analysis was applied to appreciate HRV changes between SC serials. HRV decline occurred during the planning of a navigation exercise and a pack march. Increases in HRV were observed throughout the pack march exercise and rest period. This case study demonstrates the potential utility for selection personnel to obtain additional insight into candidate responses to various occupational challenges throughout an SC. Information provided by HRV monitoring may support leadership decisions when evaluating personnel holistically. For example, the ability to continue occupational task execution even while experiencing potential overstress (as measured by HRV) and after food and sleep deprivation is desirable. HRV may potentially inform stakeholders regarding overstress in PTG candidates.

Heart rate variability analysis in obstructive sleep apnea patients with daytime sleepiness.

Recent studies suggest that sleepy patients with obstructive sleep apnea (OSA) are at higher risk for incident cardiovascular disease. This study assessed cardiac autonomic function in sleepy versus non-sleepy patients with OSA using heart rate variability (HRV) analysis. We hypothesized that HRV profiles of sleepy patients would indicate higher cardiovascular risk. Electrocardiograms (ECG) derived from polysomnograms (PSG) collected by the Sydney Sleep Biobank were used to study HRV in groups of sleepy (ESS ≥ 10) and non-sleepy OSA patients (ESS < 10). HRV parameters were averaged across available ECG signals during N2 sleep. A total of 421 patients were evaluated, with a mean age of 54 (14) years, body mass index of 33 (9) kg/m2, apnea-hypopnea index of 21 (28) events/h, and 66% male. The sleepy group consisted of 119 patients and the non-sleepy group 302 patients. Sleepy patients exhibited lower HRV values for: root mean square successive difference (RMSSD, p = 0.028), total power (TP, p = 0.031), absolute low frequency (LF, p = 0.045), and high-frequency (HF, p = 0.010) power compared to non-sleepy patients. Sleepy patients with moderate-to-severe OSA exhibited lower HRV values for: (RMSSD, p = 0.045; TP, p = 0.052), absolute LF (p = 0.051), and HF power (p = 0.025). There were no differences in other time and frequency domain HRV markers. This study shows a trend toward parasympathetic withdrawal in sleepy OSA patients, particularly in moderate-to-severe cases, lending mechanistic support to the link between the sleepy phenotype and CVD risk in OSA.

Differential Heart Rate Variability Profiles During Sleep in Older Adults with Remitted Early‐onset versus Late‐onset Depression

AbstractBackgroundSleep is a physiological state involving a dynamic autonomic profile that is ideal for detecting subtle changes in autonomic nervous system functioning. The current study sought to determine if heart rate variability (HRV) during different periods of sleep is impaired in older adults with early‐onset (EOD), late‐onset (LOD), and no history of lifetime depression (NOD).MethodA total of 188 older adults aged 50‐90 years were recruited from the Healthy Brain Ageing clinic at the Brain and Mind Centre, University of Sydney. This samples comprised 49 participants with EOD, 37 with LOD, and 102 with NOD. Each participant underwent medical, psychiatric and neuropsychological assessments, as well as overnight polysomnography.ResultFindings show that for HRV during wake‐after‐sleep‐onset (WASO), only older adults with remitted EOD have significantly lower SDNN and Shannon Entropy, two HRV indices of interest, in comparison to the NOD group, suggesting that those with EOD have diminished overall autonomic function and cardiac complexity respectively. By contrast, older adults with remitted LOD have significantly lower parasympathetic activities during deeper sleep stages (i.e. N2 and N3), as evidenced by a reduction in high‐frequency HRV relative to the EOD group. Overall, our findings suggest that the EOD and LOD phenotypes have differential heart rate profiles during sleep.ConclusionA history of depression, in particular whether this history is early‐ or late‐ onset, is associated with the integrity of autonomic functioning during both wakefulness and sleep in older adults. HRV may have potential as a biomarker of depression and could complement other biomarkers to enhance diagnostic accuracy and prognostic monitoring. As older adults with early‐life depression seem to experience more pronounced autonomic dysfunction, this further emphasizes the need for early and effective interventions, as well as proactive preventative strategies for those with remitted major depressive disorder.

Abnormal heart rate variability and its application in predicting treatment efficacy in patients with chronic migraine: An exploratory study.

This study aimed to investigate the extent of autonomic nervous system dysfunction in patients with chronic migraine using heart rate variability analysis. In addition, we explored the potential association between heart rate variability and treatment outcomes in patients receiving preventive treatment. In this cross-sectional and prospective study, we compared heart rate variability profiles in 81 preventive-naïve chronic migraine patients and 58 healthy controls. In addition, treatment responses of patients, who received a 12-week treatment with flunarizine, were assessed in relation to baseline heart rate variability. We observed that chronic migraine patients had a reduced heart rate variability, signifying autonomic dysfunction in comparison to healthy controls. Furthermore, patients presenting normal heart rate variability, characterized by a standard deviation exceeding 30 milliseconds in normal-to-normal RR intervals, experienced a superior response to flunarizine treatment. This improvement was exemplified by a significantly larger reduction in monthly headache days for patients with higher heart rate variability compared to those with lower heart rate variability: -9.7 (5.9) vs. -6.2 (6.0) days (p = .026). Autonomic dysfunction occurs in chronic migraine as evaluated by heart rate variability. A preserved function is associated with a better treatment outcome to flunarizine.Trial registration: Neurologic Signatures of Chronic Pain Disorders, NCT02747940. Registered 22 April 2016, https://clinicaltrials.gov/ct2/show/NCT02747940.

Major Depressive Disorder and Chronic Fatigue Syndrome Show Characteristic Heart Rate Variability Profiles Reflecting Autonomic Dysregulations: Differentiation by Linear Discriminant Analysis.

Major depressive disorder (MDD) and chronic fatigue syndrome (CFS) have overlapping symptoms, and differentiation is important to administer the proper treatment. The present study aimed to assess the usefulness of heart rate variability (HRV) indices. Frequency-domain HRV indices, including high-frequency (HF) and low-frequency (LF) components, their sum (LF+HF), and their ratio (LF/HF), were measured in a three-behavioral-state paradigm composed of initial rest (Rest), task load (Task), and post-task rest (After) periods to examine autonomic regulation. It was found that HF was low at Rest in both disorders, but was lower in MDD than in CFS. LF and LF+HF at Rest were low only in MDD. Attenuated responses of LF, HF, LF+HF, and LF/HF to task load and an excessive increase in HF at After were found in both disorders. The results indicate that an overall HRV reduction at Rest may support a diagnosis of MDD. HF reduction was found in CFS, but with a lesser severity. Response disturbances of HRV to Task were observed in both disorders, and would suggest the presence of CFS when the baseline HRV has not been reduced. Linear discriminant analysis using HRV indices was able to differentiate MDD from CFS, with a sensitivity and specificity of 91.8% and 100%, respectively. HRV indices in MDD and CFS show both common and different profiles, and can be useful for the differential diagnosis.

Self-recorded heart rate variability profiles are associated with health and lifestyle markers in young adults.

To quantify associations between self-recorded heart rate variability (HRV) profiles and various health and lifestyle markers in young adults. Otherwise healthy volunteers (n = 40, 50% male) recorded 60-s, post-waking HRV with a cost-free mobile application in supine and standing positions for 7days. The 7-day average and coefficient of variation (CV, reflects daily fluctuation) for the mean RR interval and root mean square of successive differences (LnRMSSD) were assessed. 7-day sleep duration and physical activity profiles were characterized via wrist-worn accelerometer. Subsequent laboratory assessments included aerobic fitness ([Formula: see text]O2peak) and markers of cardiovascular, metabolic, and psychoemotional health. Associations were evaluated before and after [Formula: see text]O2peak adjustment. Bivariate correlations (P < 0.05) demonstrated that higher 7-day averages and/or lower CV values were associated with higher activity levels and superior cardiovascular (lower systolic and diastolic blood pressure [BP] and aortic stiffness [cf-PWV]), metabolic (lower body fat percentage, fasting glucose, and low-density lipoprotein cholesterol [LDL-C]), and psychoemotional health (lower perceived stress) markers, with some variation between sexes and recording position. In males, associations between HRV parameters and cf-PWV remained significant following [Formula: see text]O2peak adjustment (P < 0.05). In females, HRV parameters were associated (P < 0.05) with numerous cardiovascular (systolic and diastolic BP, cf-PWV) and metabolic (fasting glucose and LDL-C) parameters following [Formula: see text]O2peak adjustment. Higher or more stable supine and standing HRV were generally associated with superior health and lifestyle markers in males and females. These findings lay groundwork for future investigation into the usefulness of self-recorded ultra-short HRV as a health-promoting behavior-modification tool in young adults.

Cardio-Hypothalamic-Pituitary Coupling during Rest and in Response to Exercise.

The objective of this study was to examine cardio hypothalamic-pituitary coupling and to better understand how the temporal relations between these systems are altered during rest and exercise conditions. An intensive within subjects study design was used. Seven adult males completed two visits, each consisting of either a 24 h period of complete rest or a 24 h period containing a high-intensity exercise bout. An intravenous catheter was used to collect serum samples every 10 min throughout the 24 h period (i.e., 145 samples/person/condition) to assess growth hormone (GH) dynamics throughout the 24 h period. Cardiac dynamics were also collected throughout the 24 h period and epoched into 3 min windows every 10 min, providing serial short-time measurements of heart rate variability (HRV) concurrent to the GH sampling. The standard deviation of the normal RR interval (SDNN), the root mean square of successive differences (rMSSD), and sample entropy (SampEn) was calculated for each epoch and used to create new profiles. The dynamics of these profiles were individually quantified using SampEn and recurrence quantification analysis (RQA). To address our central question, the coupling between these profiles with GH was assessed using cross-SampEn and cross-RQA (cRQA). A comparison between the epoched HRV profiles indicated a main effect between profiles for sample entropy (p < 0.001) and several measures from RQA. An interaction between profile and condition was observed for cross-SampEn (p = 0.04) and several measures from cRQA. These findings highlight the potential application of epoched HRV to assess changes in cardiac dynamics, with specific applications to assessing cardio hypothalamic-pituitary coupling.

Heart rate variability predicts outcome of short-term psychotherapy at the workplace.

The bio-psycho-social model highlights intra-individual and inter-individual interactions, including psychotherapy. The processing of these interactions within a person takes place, among others, in the central autonomic network (CAN). The CAN's autonomic output to the periphery can be indexed by heart rate variability (HRV), representing individual adaptive capacity. Further, the CAN influences the hypothalamus-pituitary-adrenal axis with its product cortisol. The aim consisted in investigating HRV and cortisol as well as their relation to symptom course in response to short-term psychotherapy. A single-arm, uncontrolled, explorative study was conducted at an outpatient psychotherapeutic consultation in the workplace offered to employees with mental or psychosomatic complaints. Questionnaires included symptoms of depression, irritation and functional impairment. Circadian profile of HRV and salivary cortisol concentrations collected pre and post short-term psychotherapeutic intervention (4-12 sessions) were assessed. Multilevel-linear mixed regressions were calculated. Out of 29 participants (mean age 42; 72% female), 24% were on sick leave from work. Cortisol concentrations were neither affected by intervention nor by symptom course. The proportion of individuals showing a vagally mediated HRV in the range of the lowest quartile assessed for age- and sex-matched healthy controls was reduced at follow-up (pre 34%, post 22%; p=.017). Higher vagally mediated HRV at baseline predicted lower symptom burden at follow-up. Thus, the results support the assumption that HRV reflects the capability of an organism to adapt and recover. Patients with reduced HRV might need additional psychotherapeutic sessions to achieve the same symptom improvements than patients with retained HRV.

Short-term Heart Rate Variability to Evaluate Cardiovascular Autonomic Neuropathy in Newly Diagnosed Type 2 Diabetes Mellitus Patients: A Cross-sectional Study

Introduction: Cardiovascular Autonomic Neuropathy (CAN) may be seen in patients of Type 2 Diabetes Mellitus (T2DM). In many previous studies it was seen that there is reduced heart rate variability in DM patients. Reduced heart rate variability is earliest indicator for the CAN. In different earlier studies, it was found that results of Short-term Heart Rate Variability (HRV) analysis of five minutes is comparable to standard 24 hours HRV analysis. In DM patients CAN is mostly found to be associated with a longer duration of disease, but according to some studies CAN may be present in newly diagnosed diabetes patients also, but the percentage is lower. Aim: To assess the short-term HRV profile as cardiovascular risks among newly diagnosed T2DM patients and to find the correlation of HRV parameters with duration of disease and biochemical parameters; Fasting Plasma Glucose (FPG) and Postprandial Plasma Glucose (PPPG) for early detection and management of CAN. Materials and Methods: The present study was a cross-sectional study conducted in the Department of Physiology in collaboration with the Department of Endocrinology at R.G. Kar Medical College and Hospital, Kolkata, West Bengal, India, from September 2020 to August 2021 on 56 newly diagnosed T2DM (age group 30 to 64 years). Study subjects were grouped according to the Standard deviation of NN intervals (SDNN) (millisecond) value as cardiovascular risk factor. Group 1 was the low risk group, group 2 was the moderate risk group, group 3 was the high-risk group. HRV testing was done with Physiograph Polyrite-D instrument with bio-amplifiers, 4 channels and accessories (RMS latest software-Version 3.0.16) in Autonomic Function Research Laboratory to measure HRV parameters. After collecting data, analysis was done using Statistical Package for Social Sciences (IBM, SPSS) version 23.0 Unpaired student’s t-test, Chi-square test, Analysis of Variance (ANOVA) test, Pearson correlation test were performed and statistical significance of different parameters were evaluated. It was considered statistically significant when p-value &lt;0.05. Results: By assessing HRV parameters as cardiovascular risk factors among newly diagnosed T2DM patients the present study showed there was significantly (p-value=0.0065) high LF/HF ratio in males (1.70±1.19) than in females (0.99±0.69). The SDNN value was significantly highest in low cardiovascular risk group (137.29±25.49 ms) and lowest in high cardiovascular risk group (26.07±12.03 ms) (p-value=0.00001). Low Frequency and High Frequency Ratio (LF:HF ratio) was significantly more in age group of 51-60 years. Among all the patients, 34 (61%) patients had increased parasympathetic activity and 22 (39%) subjects had increased sympathetic activity. Female patients showed significantly more increased parasympathetic 24 (75%) activity than males 10 (41.7%). There was a significant association between SDNN values with the duration of disease (p-value=0.004). Conclusion: The present study showed that cardiac autonomic neuropathy is present even at the time of diagnosis of newly diagnosed T2DM as there was sympathovagal imbalance. Female patients have more parasympathetic drive than males which indicates that females are more cardioprotective.

Heart Rate Variability in Schizophrenia and Autism.

Suppressed heart rate variability (HRV) has been found in a number of psychiatric conditions, including schizophrenia and autism. HRV is a potential biomarker of altered autonomic functioning that can predict future physiological and cognitive health. Understanding the HRV profiles that are unique to each condition will assist in generating predictive models of health. In the current study, we directly compared 12 adults with schizophrenia, 25 adults with autism, and 27 neurotypical controls on their HRV profiles. HRV was measured using an electrocardiogram (ECG) channel as part of a larger electroencephalography (EEG) study. All participants also completed the UCLA Loneliness Questionnaire as a measure of social stress. We found that the adults with schizophrenia exhibited reduced variability in R-R peaks and lower low frequency power in the ECG trace compared to controls. The HRV in adults with autism was slightly suppressed compared to controls but not significantly so. Interestingly, the autism group reported feeling lonelier than the schizophrenia group, and HRV did not correlate with feelings of loneliness for any of the three groups. However, suppressed HRV was related to worse performance on neuropsychological tests of cognition in the schizophrenia group. Together, this suggests that autonomic functioning is more abnormal in schizophrenia than in autism and could be reflecting health factors that are unique to schizophrenia.

Maternal Mental Health and Parenting Stress and Their Relationships to Characteristics of the Child With Fragile X Syndrome.

Although previous research supports the notion that characteristics of both the child and the mother impact maternal well-being and parenting stress in mothers of children with FXS, more work is needed in which self-report measures are supplemented by physiological measures of stress and well-being. The inclusion of physiological measures, such as heart rate variability (HRV), may provide a window into the biological origins and consequences of maternal perceptions of their experiences, including the challenges of raising a child with developmental challenges. The proposed project, therefore, involved the collection of multimodal assessment data from mothers and their school-aged children with FXS. Further, given the importance of understanding how mothers of youth with FXS are faring in their everyday environment, the present study collected all data using telehealth procedures and wearable technology. Participants were 20 biological mothers and their children with FXS between the ages of 6 and 11 years. We measured maternal mental health and parenting stress through self-report as well as through HRV as a more objective measure of psychological well-being. We also examined the associations between these variables and child characteristics such as externalizing and internalizing behaviors as well as autism symptomatology. We found significant support for an elevated rate of depressive symptoms in the sample of mothers (35%) and some potential indicators for heightened rates of anxiety (15%) when compared to normed samples and rates in the general population. We also found that the mothers presented with an atypical HRV profile akin to those experiencing depression or chronic stress, although limitations of the present measure suggest the need for additional confirmatory research. Further, we found that child externalizing behaviors were the primary correlates of maternal well-being. These findings contribute to the growing body of literature regarding the unique challenges faced by these mother-child dyads and supports the importance of increasing the availability of services available to these mothers, not only for meeting the needs of their children's development and behavior, but in supporting their own well-being as well.

Association Between Self-Recorded Heart Rate Variability Profiles And Actigraphy-Derived Physical Activity In Young Healthy Adults

Mobile devices facilitate daily heart rate variability (HRV) tracking and serve as a potential behavior modification tool for cardiovascular health. It is currently unclear whether serial self-recorded HRV measures are influenced by physical activity (PA) levels. PURPOSE: To evaluate the association between self-recorded HRV profiles and actigraphy-derived PA levels in young, apparently healthy adults. METHODS: Men (n = 21, 24.4 ± 4.9 years) and women (n = 20, 21.4 ± 2.7 years) self-recorded post-waking HRV for 60 s in supine and standing positions using a heart rate chest strap and mobile application over one week. The week average of the natural logarithm of the root-mean square of successive R-R interval differences (LnRMSSDavg, a vagal HRV index) and the coefficient of variation (LnRMSSDcv, a marker of day-to-day fluctuation) were assessed. Throughout the observation period, subjects wore a validated wrist-based activity monitor to determine average sedentary time; light, moderate, moderate-vigorous (MV), and vigorous (V) PA; and total steps. Aerobic capacity (VO2max) was obtained via a maximal cycle ergometer test post-observation. RESULTS: In men, no associations were observed between any HRV and PA variables (P > 0.05). In women, sedentary time (606 ± 108 min) was associated (r = 0.59) with supine LnRMSSDcv (9.8 ± 5.2%), MVPA (259 ± 74 min) was associated with standing (13.0 ± 4.4%) and supine LnRMSSDcv (r = -0.45 and -0.51, respectively), VPA (152 ± 54 min) was associated with supine LnRMSSDcv (r = -0.53), and total step count (13,209 ± 2,560) was associated (r = 0.45) with supine LnRMSSDavg (4.1 ± 0.5) (all P < 0.05). VO2max was associated with the same PA variables in women (P < 0.05), but none of the PA variables in men (P > 0.05). After adjusting for VO2max (28.1 ± 5.9 mL·kg·min-1), all associations between HRV and PA variables in women became non-significant (P > 0.05). CONCLUSIONS: Significant associations between self-recorded HRV profiles and actigraphy-derived PA levels that were only observed in women appear to be explained by fitness. Thus, PA tailored to the enhancement of aerobic capacity will likely yield the greatest HRV improvements, reflected in higher average values with less day-to-day fluctuation. Supported by Georgia Southern University Faculty Research Committee Seed Funding Award.

Association Between Self-recorded Heart Rate Variability Profiles And Aerobic Fitness In Young Healthy Adults

Association Between Self-recorded Heart Rate Variability Profiles And Aerobic Fitness In Young Healthy Adults

A35 ASSOCIATIONS BETWEEN AUTONOMIC DYSFUNCTION, COLONIC DYSMOTILITY AND ABSENT DEFECATION REFLEXES IN PATIENTS WITH CHRONIC REFRACTORY CONSTIPATION

Abstract Background A defecation reflex involves sensory information from the colon sent to the central nervous system which results in propulsive motor patterns in the colon through programmed neural activity from the autonomic nervous system. Neurological causes of constipation are recognized but specific neurological pathways that contribute to pathophysiology of the disease is underexplored. Diagnosis and treatment usually do not involve the autonomic nervous system. Aims Our objective was to assess autonomic dysfunction and abnormal defecation reflexes as a possible cause of chronic constipation. Methods Defecation reflexes were assessed by high-resolution colonic manometry through balloon distention, meal intake, and rectal bisacodyl. Specific heart rate variability (HRV) parameters were used to assess general orthostatic autonomic reactivity, and autonomic functioning during high resolution colonic manometry, in 14 patients with chronic refractory constipation considered for surgery. Results All patients had a unique combination of motility, reflex ability and HRV profiles. Patients overall did not generate HAPWs or had lower HAPW amplitude and lower propulsive activity compared to healthy individuals. Half of the 14 patients were tested to have high sympathetic tone based on Baevsky’s stress index prior to HRCM, and 11 of the patients had sympathetic hyper-reactivity and/or low parasympathetic reactivity to at least one type of colonic stimulation during HRCM. Abnormal autonomic tone or autonomic reactivity to colonic stimulation was present in all four patients with absence of the vagosacral defecation reflex. Five of the seven patients with absence of the sacral defecation reflex showed high sympathetic tone or high sympathetic reactivity to stimulation. Only two patients had abnormality in coloanal coordination and this was associated with low parasympathetic reactivity to stimulation in both patients. Conclusions The assumption that colonic resection was needed to remove an inert colon was wrong in most patients, but most patients had some form of reflex abnormality. Sympathetic dominance far outweighed parasympathetic dysfunction. Incorporation of assessments of defecation reflexes and autonomic nervous system activity into diagnosis of chronic refractory constipation provides a comprehensive pathophysiological understanding of specific defective neurological pathways contributing to dysmotility. This forms the basis for our individualized treatment efforts through sacral neuromodulation. Funding Agencies CIHR

Enhanced cardiac vagal tone in mental fatigue: Analysis of heart rate variability in Time-on-Task, recovery, and reactivity.

Heart Rate Variability (HRV) has been suggested as a useful tool to assess fatigue-sensitive psychological operations. The present study uses a between and within-subject design with a cognitively demanding task and a documentary viewing condition, to examine the temporal profile of HRV during reactivity, Time-on-Task (ToT), and recovery. In the cognitive task group, participants worked on a bimodal 2-back task with a game-like character (the Gatekeeper task) for about 1.5 hours, followed by a 12-minute break, and a post-break block of performance (about 18 min). In the other group, participants watched documentaries. We hypothesized an increasing vagal-mediated HRV as a function of Time spent on the Gatekeeper task and no HRV change in the documentary viewing group. We also analyzed the trial-based post-response cardiac activity as a physiological associate of task-related motivation. Relative to the documentary-viewing, ToT was associated with an elevated level of subjective fatigue, decreased heart rate, and increased HRV, particularly in the vagal-mediated components. Based on fatigued participants’ post-error cardiac slowing, and post-error reaction time analyses, we found no evidence for motivation deficits. The present findings suggest that the parasympathetic branch of the autonomous nervous system functioning as a relaxation system tends to be activated under increasing mental fatigue. In addition, the study shows that many HRV indices also seem to change when individuals are engaged in a prolonged, less fatiguing activity (e.g. documentary viewing). This finding emphasizes the relevance of comparisons/control conditions in ToT experiments.

Effect of Competitive Status and Experience on Heart Rate Variability Profiles in Collegiate Sprint-Swimmers.

Flatt, AA, Hornikel, B, Nakamura, FY, and Esco, MR. Effect of competitive status and experience on heart rate variability profiles in collegiate sprint-swimmers. J Strength Cond Res 36(10): 2898-2904, 2022-Interindividual differences in training history may be a determinant of heart rate variability (HRV) profiles in collegiate sprint-swimmers and may account for differences observed between elite and subelite athletes. We therefore compared HRV profiles among national-level and conference-level sprint-swimmers while accounting for individual swim-training history. Twenty-eight short-distance swimmers (18 men and 10 women) recorded postwaking HRV throughout a 4-week standardized training period. The 4-week mean (M) and coefficient of variation (CV, a marker of daily fluctuation) were calculated for resting heart rate (RHR) and the natural logarithm of the root mean square of successive differences (LnRMSSD). Swimmers were categorized as national-level (n = 12) or conference-level (n = 16) competitors. Years of competitive experience was documented for each individual to index training history. p < 0.05 was considered statistically significant. No sex-related differences were observed for any variables (p > 0.05). LnRMSSDM (effect size [ES] = 0.95), LnRMSSDCV (ES = -1.18), RHRCV (ES = -1.05), and competitive experience (ES = 1.23) differed between status groups (p < 0.05). Accounting for multicollinearity between competitive experience and LnRMSSD variables (p < 0.05), competitive experience remained associated with LnRMSSDM (r = 0.44, p = 0.02). With competitive experience included as a covariate, differences in LnRMSSDM between status groups disappeared (p > 0.05, ES = 0.31). National-level swimmers exhibit higher and more stable LnRMSSD than that of their conference-level teammates throughout standardized training. Differences in trend characteristics were attributed to training age. This information may assist practitioners with interpreting interindividual differences in HRV profiles throughout training periods among a mixed roster of athletes.

Is Active Lifestyle Related to Autonomic Nervous System Function and Lipid Profile in People with Overweight? A Study Pilot

Autonomic nervous system function is an important predictor of physical fitness. The objective of this study was to find out the associations of autonomic activity parameters, lipid profile, insulin concentrations, and insulin resistance in overweight men with the level of physical activity. A descriptive and correlational study was carried out in 28 overweight men: 14 physically active (PA) and 14 physically inactive (PI). The following variables were assessed: Level of physical activity, HRV (heart rate variability), basal insulin, HOMA-IR index (Homeostasis Model Assessment Insulin-Resistance), and lipid profile. The main results show a positive correlation between the spectral parameters of the HRV and total cholesterol (r = 0.24), LDL (r = 0.59), VLDL (r = 0.86), and insulin (r = 0.88) of sedentary people, evidencing a directly proportional correlation with BMI. We conclude that weight gain and a sedentary lifestyle are associated with an increase in sympathetic discharge, which, in turn, is associated with an increase in lipid profile and insulin levels.

Profiles of Heart Rate Variability and Bar Velocity after Resistance Exercise.

The aim of this investigation was to observe the association in the time course in recovery between multiple heart rate variability (HRV) metrics and neuromuscular performance, as assessed by mean bar velocity (BVM) in the back squat, over a 72-h period after an exhaustive back squat protocol. Eight resistance-trained males completed five laboratory visits within a 7-d period. The first visit involved short-term HRV recordings followed by a familiarization of BVM procedures and a one-repetition maximum test of the back squat. Forty-eight hours later, participants returned to the laboratory for prestimulus measurements, immediately followed by a back squat protocol (8 sets of 10 repetitions at 70% of one-repetition maximum with a 2-min rest). The HRV and the BVM measurements were replicated at 0.5, 24, 48, and 72 h after squat protocol. A multivariate profile analysis and repeated-measures correlation between recovery scores [(new/prestimulus) × 100] for each HRV metric and BVM was computed. All log-transformed (ln) HRV metrics, except low frequency (lnLF) (P = 0.051), had a significant interaction with BVM over time (P < 0.05), indicating that recovery scores in BVM and HRV were not parallel. In addition, recovery scores in all HRV metrics significantly differed from BVM (P < 0.05) in at least one time point across the 72-h period. Furthermore, repeated-measures correlation analysis indicated a lack of intraindividual association (P > 0.05) between the change in BVM and all HRV measurements over time. The time course in recovery in HRV measurements after an exhaustive bout of lower-body resistance exercise was not associated with neuromuscular performance recovery.