Root Mean Square Of The Successive Differences Research Articles

안마의자를 활용하는 마사지가 성인 남녀의 자율신경균형도에 미치는 즉각적 영향: 전향적 관찰연구

Objectives The aim of this study was to examine the immediate impact of a massage chair intervention on homeostasis and the balance of the autonomic nervous system in individuals aged 20 to 64. Methods This study was a single-center, prospective, single-arm, investigator-initiated observational study. Non-underweight adults without significant health concerns underwent a 40-minute massage chair intervention. Measurements of heart rate variability, functional near-infrared spectroscopy, and vital signs were conducted before and after the intervention. Additionally, participants completed the Mibyeong questionnaire and a satisfaction survey. Results A 40-minute massage chair session led to a notable decrease in average heart rate and low frequency to high frequency (LF/HF) ratio, coupled with an increase in root mean square of the successive differences (RMSSD) and standard deviation of NN interval (SDNN). No adverse reactions were noted. Subjects with elevated sympathetic nerve activity exhibited a reduction in LF/HF ratio, whereas those with heightened parasympathetic activity demonstrated an increase in LF/HF ratio post-intervention. Conclusions The findings indicate that the massage chair intervention has the potential to activate the parasympathetic nervous system, promote blood pressure homeostasis and autonomic nervous system balance. However, further research over a more extended period is crucial to validate these conclusions.

Effects of Auricular Vagus Nerve Stimulation on Cardio-Respiratory Functions After Aerobic Exercise

The aim of our study is to find out whether the return rate of parasympathetic activity (PA) can be accelerated with auricular transcutaneous vagus nerve stimulation (TVNS). Pulmonary function test, ANS activity, pulse and blood pressure measurements were made. Individuals ran for 15 minutes. Those in the TVNS group received 5 minutes of auricular VNS. In the control group, headphones were attached but no current was given. After the end of their procedures, they were compared with pre-exercise. In the TVNS group, the pulse parameter was higher than in the initial measurement (p=0.001). There was a significant (p=0.007) rise in the FEV1 value in the VNS group. The sympathetic nervous system (SNS) index (p<0.05) increased in both groups when compared to the initial measurement, although there was no significant difference in the index values between the groups. The TVNS group showed an increase from the first measurement (p<0.05), but there was no significant difference in the parasympathetic nervous system (PNS) Index between the groups (p>0.05). The groups' values for the first and second measures were equal (p>0.05), and the root mean square of the successive differences (RMSSD) values did not reveal a significant difference. TVNS can improve respiratory parameters in healthy individuals in the acute period after exercise, and it seems that it can also increase activation in both the sympathetic and parasympathetic system. It can be stated that TVNS may lead to variable results in different circumstances in sports

Heart rate variability and its association with symptoms of orthostatic hypotension in spinal cord injury

Context/objective To assess differences in autonomic function using heart rate variability (HRV) parameters between people with and without orthostatic hypotension (OH), and to determine symptoms of OH in people with spinal cord injury (SCI). Methods R-R interval and blood pressure (BP) data were recorded using Finometer PRO® in both the supine position and at a 60-degree tilt using a tilt table, each lasting for 6 minutes. R-R interval data were processed using the Kubios HRV analysis software to convert R-R interval into time and frequency domains for further analysis. Results Compared to the non-OH group, the SCI group with OH exhibited lower values for root mean square of the successive differences (RMSSD) and standard deviation of normal-to-normal interval (SDNN), along with an elevated heart rate during tilt-up. Participants with OH symptoms had a lower average heart rate in the supine and 60-degree positions compared to asymptomatic participants. Logistic regression analysis indicated that SDNN in the supine position correlated with the presence of OH, and that the mean heart rate in the 60-degree position was related to the presence of symptoms. Conclusions Differences in HRV parameters were observed in people with SCI and OH, suggesting a reduced parasympathetic activity in the supine position, likely as a response to maintain homeostasis in BP regulation. Despite the presence or absence of OH symptoms, there was no difference in HRV parameters. This finding suggests that autonomic function may not be the primary determinant of these symptoms, with other factors likely being more influential.

Effects of exposition to glycol ethers on heart rate recovery, parasympathetic modulation and oxygen diffusion at rest and during exercise

Introduction Daily exposition to ether glycols is common. Caretakers using cleaning products are critically exposed by combining physical activity with exposition to highly concentrated products. Previous animal studies showed hemato-, respiratory and autonomic nervous system toxicity amongst others. Yet, no controlled study explored the combination of an exposition to glycol ethers with physical activity in humans. Methods 30 young healthy participants were exposed a control condition (ambient air) and to one of three vaporized glycol ethers: propylene glycol n-propyl ether (PGPE, 25 ppm, n = 10) or propylene glycol ethyl ether (PGEE, 35 ppm, n = 10) or propylene glycol monomethyl ether (PGME, 35 ppm, n = 10) in a single-blind cross-over design. They performed an orthostatic test (5-min supine, 5-min standing) and a 6-min steady-state exercise at 1.5 W/kg followed by 10-min recovery in PGPE/PGEE conditions. In addition, an incremental exercise to exhaustion followed in PGME condition. Heart rate variability (HRV) was measured throughout the protocol, Heart rate recovery (HRR) was assessed during the 10-min recovery post steady-state exercise. Root-mean-square of the successive differences (RMSSD), power spectrum of the low- (LF) and high-frequency (HF) bands, tau, amplitude and T30 were computed for HRR. Near Infrared spectroscopy (NIRS) and cardiac output (using thoracic impedance) were measured for PGME exposition. PO2, PCO2 and pH were measured regularly via arterialized and venous blood sampling. Results Resting values of supine LF (1,180 ± 851 vs. 2,993 ± 2,259 ms2) and standing RMSSD (32 ± 17 vs. 41 ± 17 ms) increased under PGEE. Supine and standing HR decreased under PGPE (65.5 ± 4.8 vs. 61.3 ± 6.9 and 83.8 ± 7.0 vs. 76.1 ± 10.0 bpm) whereas standing RMSSD (26.6 ± 10.0 vs. 37.0 ± 14.9 ms) and LF (825 ± 474 vs. 2,028 ± 1,471 ms2) increased. Parasympathetic reactivation (e.g., RMSSD, LF and HF) was increased post-exercise under exposition to all three glycol ethers. In addition, amplitude significantly increased when exposed to PGEE. However, unexpectedly, HRR was neither slowed nor speeded. Finally, no differences were observed in any NIRS variables or cardiac output. Accordingly, the modelled muscle oxygen diffusion coefficient was not modified between any solvent conditions. Arterialized blood pH (7.35 ± .06 vs. 7.39 ± .04) and PaCO2 (34.1 ± 5.0 vs. 35.7 ± 4.3 mmHg) increased whilst PaO2 (81.8 ± 9.7 vs. 77.9 ± 10.6 mmHg) decreased. Discussion/Conclusion: The decrease in supine/standing HR associated with a general increase in HRV during recovery likely indicate an increase in parasympathetic modulation, which is compatible with the sedative effects of glycol ethers previously described in animal models. However, HR recovery was not altered. Despite no change in the O2 diffusion coefficient, there was an increase in PaCO2, a decrease in PaO2 and an increase in blood pH, all indicative of potential impaired blood oxygenation during exercise, to be further investigated. To conclude, exposition to different glycol ethers induced an enhanced parasympathetic activation without any changes in HR recovery or O2 diffusion.

Daily cardiac autonomic responses during the Tour de France in a male professional cyclist.

Heart rate variability (HRV) is a common means of monitoring responses to training, yet in professional cycling, one may question its usefulness, particularly during multi-day competitions such as Grand Tours. This study aims to report and analyze HRV responses in a male professional cyclist over a season, including the Tour de France. A professional cyclist recorded resting and exercise inter-beat intervals during 5 months, comprising a training period with two altitude sojourns and two competition blocks, including the Tour de France. Resting recordings lasted 5 min in the supine position and were used for computation of mean heart rate (HR), root mean square of the successive differences (RMSSDs), and power in the low- and high-frequency bands (LF and HF, respectively). Training load quantification was based on recorded HR during exercise and expressed as training impulses (TRIMPSs). LF (3,319 ± 2,819 vs. 1,097 ± 1,657 ms2), HF (3,590 ± 1858 vs. 1,267 ± 1,683 ms2), and RMSSD (96 ± 26 vs. 46 ± 30 ms) were higher and HR (47 ± 4 vs. 54 ± 2 bpm) was lower during the training period when compared to the two competition blocks. The coefficient of variation (CV) was significantly lower during the training period than during the two competition blocks for RMSSD (26 vs. 72%), LF (85 vs. 160%), and HF (58 vs. 141%). The present study confirms that monitoring daily HRV responses during training periods is valuable in professional cycling, but questions its usefulness during the Tour de France. Moreover, the previous suggestion that CV in RMSSD would help to predict poor performance was not confirmed in a professional cyclist.

Effects of posture on heart rate variability in non-frail and prefrail individuals: a cross-sectional study

BackgroundFrailty is an aging-related syndrome leading to high mortality in older adults. Without effective assessment and prevention of frailty, the incidence of frailty and relevant adverse outcomes will increase by 2050 as worldwide populations age. Although evidence suggested heart rate variability (HRV) is a potential measure of frailty, the role of HRV in frailty assessment remains unclear because of controversial findings. This study examined the effects of posture on HRV parameters in non-frail and prefrail individuals to understand the role of HRV in assessing frailty.MethodsForty-six participants aged ≥ 50 years were recruited between April and August 2022. Frailty was defined using Fried’s criteria. HRV was measured in standing, sitting, and lying postures, respectively, using a Polar Watch, and analyzed using Kubios HRV Standard 3.5.0 (Kubios). The five most commonly used parameters were examined, including standard deviations of all normal-to-normal intervals (SDNN), root mean square of the successive differences (RMSSD), low frequency (LF), high frequency (HF), and LF/HF. Independent t-tests and Mann–Whitney tests were used for inter-group comparisons. Friedman tests were used for intra-group comparisons across postures.ResultsThe non-frail group showed significant differences in HRV parameters across postures (all p < 0.05), whereas the prefrail group did not demonstrate any difference (all p > 0.05). The differences in the non-frail group included higher RMSSD and HF in the lying posture compared to those in the standing posture (29.54 vs 21.99 p = 0.003, 210.34 vs 96.34 p = 0.001, respectively), and higher LF and LF/HF in the sitting posture compared to those in the lying posture (248.40 vs 136.29 P = 0.024, 1.26 vs 0.77 p = 0.011, respectively).ConclusionsThe effects of posture on HRV were blunted in the prefrail group, which suggests an impaired cardiac autonomic functioning. Measuring the effects of posture on HRV parameters may contribute to frailty assessment. However, further evidence from larger cohorts and including additional HRV parameters is needed.

Physiological and psychological stress response of blood donors during the blood donation process.

Blood donation can be a potentially stressful event, leading to the activation of an acute stress response. Knowing and identifying potential stressors could help in optimizing the donation experience. The present study aimed to measure the physiological and psychological stress changes before, during and after blood donation. Physiological and psychological stress response was assessed in 70 blood donors. To evaluate physiological stress response, pulse rate, respiratory rate, blood pressure (BP), beat-to-beat BP and lead II electrocardiogram were recorded. Baroreflex sensitivity was calculated using the available software. Psychological stress response was assessed using the State-Trait Anxiety Inventory scale. A significant increase in systolic blood pressure, diastolic blood pressure and mean arterial pressure was observed in the pre-donation period (p < 0.001). Among the time-domain parameters, SDSD (standard deviation of differences between adjacent respiratory rate intervals) and RMSSD (root mean square of the successive differences) were significantly lower during the post-donation period (p < 0.005, p < 0.007, respectively). Among the frequency-domain parameters, LF nu (relative power of the low-frequency band in normalized units), HF nu (relative power of the high-frequency band in normalized units) and LF% (relative power of the low-frequency band in percentage) were significantly lower before donation compared to during donation (p < 0.001, p < 0.001 and p < 0.012, respectively). LF nu, LF% and LF/HF ratio were also significantly lower during donation compared to after donation (p < 0.05, p < 0.016 and p < 0.042, respectively). Baroreflex sensitivity was also statistically higher during the pre-donation period. State score was significantly higher among the blood donors during the pre-donation period. Physiological and psychological stress is experienced by blood donors during the pre-donation period. A pre-donation informative conversation should be carried out with each blood donor and potential stressors should be identified in each.

Reliability of carotid-femoral arterial waveforms for the derivation of ultra-short term heart rate variability in injured British servicemen: An inter-rater reliability study.

In this study, the comparative precision of carotid versus femoral arterial waveforms to measure ultra-short term heart rate variability (HRVUST) following traumatic injury was investigated for the first time. This was an inter-rater reliability study of 50 British servicemen (aged 23-44 years) with non-acute combat-related traumatic injury (CRTI). Paired continuous arterial waveform data for HRVUST analysis, were simultaneously sampled at the carotid and femoral arterial sites (14-16 seconds) during pulse wave velocity (PWV) measurement. HRVUST was reported as the root mean square of the successive differences (RMSSD). Following the determination of the superior sampling site (carotid versus femoral), the blinded inter-rater agreement in RMSSD for the preferred site was quantified using the Intra-class Correlation Coefficient (ICC) and the Bland-Altman plot. The mean age of participants was 34.06±4.88 years. The femoral site was superior to the carotid site with a significantly higher number of reliable signals obtained (Fisher's Exact test; p<0.001). The inter-rater agreement in femoral-derived RMSSD was excellent [ICC 0.99 (95%CI: 0.994-0.997)] with a moderate level of agreement (mean difference [bias]: 0.55; 95% CI: -0.13-1.24 ms). In this study, we demonstrated that the femoral artery is a more reliable site than the carotid artery for HRVUST measurement and post-trauma risk stratification following CRTI.

Monitoring Blood Pressure Variability via Chaotic Global Metrics using Local Field Potential Oscillations

The intention was to associate blood pressure (BP) variability (BPV) measurements to Local field potentials (LFPs). Thus, assessing how LFPs can co-vary with BPV to permit implantable brain devices (via LFPs) to control output. Elevated BPV is a considerable cardiovascular disease risk factor. Often patients are resistant to pharmacotherapies. An alternative treatment is Deep Brain Stimulation (DBS). Mathematical techniques based on nonlinear dynamics assessed their correlation of BPV chaotic global metrics to LFPs. Chaos Forward Parameter (CFP6) was computed for LFPs, at three electrode depths in the mid-brain and sensory thalamus. Mean, root mean square of the successive differences (RMSSD) and the chaotic global metrics (CFP1 to CFP7) were computed for the BP signal. The right ventroposterolateral (RVPL) nucleus provided a substantial correlation via CFP6 for BP with R-squared up to approximately 79% by means of LFP gamma oscillations. Investigation of BPV via LFPs as a proxy marker might allow therapies to be attuned in a closed-loop system. Whilst all patients were chronic pain patients the chaotic global relationship should be unperturbed. LFPs correlation does not unconditionally predict its causation. There is no certainty DBS in these locations would be therapeutic but can be used as an assessment tool.

Observational and genetic evidence support a relationship between cardiac autonomic function and blood pressure.

It is unclear how cardiac autonomic function, as indicated by heart rate (HR), heart rate variability (HRV), HR increase during exercise, and HR recovery after exercise, is related to blood pressure (BP). We aimed to examine the observational and genetic evidence for a potential causal effect of these HR(V) traits on BP. We performed multivariable adjusted linear regression using Lifelines and UK Biobank cohorts to investigate the relationship between HR(V) traits and BP. Linkage disequilibrium score regression was conducted to examine genetic correlations. We used two-sample Mendelian randomization (2SMR) to examine potential causal relations between HR(V) traits and BP. Observational analyses showed negative associations of all HR(V) traits with BP, except for HR, which was positively associated. Genetic correlations were directionally consistent with the observational associations, but most significant genetic correlations between HR(V) traits and BP were limited to diastolic blood pressure (DBP). 2SMR analyses suggested a potentially causal relationship between HR(V) traits and DBP but not systolic blood pressure (SBP). No reverse effect of BP on HR(V) traits was found. One standard deviation (SD) unit increase in HR was associated with a 1.82 mmHg elevation of DBP. In contrast, one ln(ms) unit increase of the root mean square of the successive differences (RMSSD) and corrected RMSSD (RMSSDc), decreased DBP by 1.79 and 1.83 mmHg, respectively. For HR increase and HR recovery at 50 s, every additional SD increase was associated with a lower DBP by 2.05 and 1.47 mmHg, respectively. Results of secondary analyses with pulse pressure as outcome were inconsistent between observational and 2SMR analyses, as well as between HR(V) traits, and therefore inconclusive. Both observational and genetic evidence show strong associations between indices of cardiac autonomic function and DBP, suggesting that a larger relative contribution of the sympathetic versus the parasympathetic nervous system to cardiac function may cause elevated DBP.

Transcutaneous Auricular Vagus Nerve Stimulation Normalizes Induced Gastric Myoelectrical Dysrhythmias in Controls Assessed by Body-Surface Gastric Mapping

ObjectivesTranscutaneous auricular vagus nerve stimulation (TaVNS) is a supplementary treatment for gastric symptoms resulting from dysrhythmias. The main objective of this study was to quantify the effects of 10, 40, and 80 Hz TaVNS and sham in healthy individuals in response to a 5-minute water-load (WL5) test. Materials and MethodsEighteen healthy volunteers aged between 21 and 55 years (body mass index: 27.1 ± 3.2) were recruited. Each subject fasted for up to eight hours and participated in four 95-minute sessions, which consisted of 30 fasted baseline, 30 minutes TaVNS, WL5, and 30 minutes post-WL5. Heart rate variability was assessed using sternal electrocardiogram. Body-surface gastric mapping and bloating (/10) were recorded. One-way ANOVA with post hoc Tukey test was performed to test the difference between TaVNS protocols in terms of frequency, amplitude, bloating scores, root mean square of the successive differences (RMSSD), and stress index (SI). ResultsOn average, the subjects consumed 526 ± 160 mL of water, with volume ingested correlated to bloating (mean score 4.1 ± 1.8; r = 0.36, p = 0.029). In general, the reduction in frequency and rhythm stability during the post-WL5 period in sham was normalized by all three TaVNS protocols. Both 40- and 80-Hz protocols also caused increases in amplitude during the stim-only and/or post-WL5 periods. RMSSD increased during the 40-Hz protocol. SI increased during the 10-Hz protocol but decreased during the 40- and 80-Hz protocols. ConclusionTaVNS proved effective in normalizing gastric dysrhythmias by WL5 in healthy subjects by altering both parasympathetic and sympathetic pathways.

Abstract P392: Association Between Blood Pressure Variability and Subclinical Measures of Cardiovascular Disease in Desk Workers

Introduction: Previous research has demonstrated that variability in resting blood pressure (BP) across arms, measurements, or days may be associated with an increased risk for cardiovascular disease (CVD) and mortality. Yet, the extent to which BP variability increases cardiovascular risk and the mechanisms explaining this association are unclear. This study evaluated associations between BP variability with subclinical pathways of CVD development (arterial stiffness (pulse wave velocity [PWV]) and cardiac autonomic function (heart rate variability [HRV]) in desk workers. Hypothesis: Higher BP variability will be associated with higher PWV and lower (worse) HRV Methods: This secondary analysis of baseline data from the Effect of Reducing Sedentary on Blood Pressure randomized controlled trial included 265 sedentary and inactive desk workers (mean age 44.9±11.6 years; 82.0% white; 57.9% female) with elevated-to-stage 2 hypertension and who were not using antihypertensive medication. Sequential BP measurements determined the arm with the higher systolic BP by using an oscillometric device (Omron HEM-907XL). BP was then measured at least twice from the arm with the higher systolic BP at the first (visit-1) and second (visit-2) visits, occurring ≤30 days apart. Systolic BP variability metrics included inter-arm (first measurements between arms at visit-1), intra-arm (first two measurements on the arm with higher systolic BP at visit-1), and inter-visit (average BP from repeated measurements on the same arm across visits-1 and -2). Subclinical measures of CVD included resting carotid- femoral(cfPWV) and carotid-radial(crPWV) PWV (Complier Analyse) and the log transformed standard deviation of normal R-R intervals (SDNN) and the root mean square of the successive differences (RMSSD) HRV measures (Polar Electro). Adjusted linear regression estimated the associations between subclinical measures of CVD and BP variability metrics; Metrics were operationalized into three categories: differences of 0-5 mmHg, 6-10 mmHg, and 11 or more mmHg. Results: The prevalence of having 6 mmHg or more difference for the inter-arm, intra-arm, and inter-visit systolic BP was 43%, 38%, and 53%, respectively. PWV and HRV were not different across categories of inter-arm systolic BP variability or inter-visit systolic BP variability (all p&gt;0.05). However, a same-day intra-arm difference in systolic BP of 6-10 mmHg within visit-1 was associated with higher cfPWV (β=0.42 m/s, (95% CI: 0.07, 0.77) as compared to those with an intra-arm difference of 0-5 mmHg. Conclusion: These data suggest that higher systolic BP variability in the same arm within visit, but not variability across arms or between visits, may be associated with higher aortic stiffness in desk workers with untreated elevated-to-stage 2 hypertension.

A Systematic Review of Heart Rate Variability as a Measure of Stress in Medical Professionals.

Understanding the physiological effects of responding to crises is a critical component in understanding how to manage and prepare medical professionals to be crisis responders. Heart rate variability (HRV) is the variation in rate between a succession of R-R intervals. This variation is not only affected by physiological processes such as respiration or metabolic rate but is also directly controlledby the autonomic nervous system. As such, heart rate variability has been proposed as a noninvasive tool to measure the physiological stress response. The aim of this systematic review is to consolidate heart rate variability literature in the context of medical emergencies to determine if heart rate variability changes predictably from baseline when responding to medical crises. This may demonstrate utility as an objective, noninvasive measure of stress response. A systematic literature review of six databases yielded 413 articles, 17 of which met our inclusion criteria of being written in English, measuring HRV in healthcare providers, and measuring HRV in real or simulated medical resuscitations or procedures. Articles were then analyzed using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) scoring system. Out of the 17 articles reviewed, 11 demonstrated statistically significant results showing heart rate variability responding in a predictable manner to stress. Three articles utilized a medical simulation as the stressor, six used medical procedures, and eight used medical emergencies encountered during clinical work. Overall, a predictable trend in heart rate variability metrics of standard deviation from the mean value of normal-to-normal(N-N) intervals (SDNN), root mean square of the successive differences (RMSSD),mean number of times per time interval in which the change in successive normal sinus (N-N) intervals exceeds 50 ms (PNN50), low frequency % (LF%), and low-frequency-to-high-frequency ratio (LF/HF) was observed when responding to stress. This systematic literature review showed that heart rate variability among healthcare providers responding to stressful scenarios follows a predictable pattern of change and expands our understanding of the physiology of stress in healthcare providers. This review supports the use of HRV to monitor stress during high-fidelity simulation to ensure that appropriate physiological arousal is achieved during the training of medical personnel.

Comparison of ANN and ANFIS Models for AF Diagnosis Using RR Irregularities

Classification of normal sinus rhythm (NSR), paroxysmal atrial fibrillation (PAF), and persistent atrial fibrillation (AF) is crucial in order to diagnose and effectively plan treatment for patients. Current classification models were primarily developed by electrocardiogram (ECG) signal databases, which may be unsuitable for local patients. Therefore, this research collected ECG signals from 60 local Thai patients (age 52.53 ± 23.92) to create a classification model. The coefficient of variance (CV), the median absolute deviation (MAD), and the root mean square of the successive differences (RMSSD) are ordinary feature variables of RR irregularities used by existing models. The square of average variation (SAV) is a newly proposed feature that extracts from the irregularity of RR intervals. All variables were found to be statistically different using ANOVA tests and Tukey’s method with a p-value less than 0.05. The methods of artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were also tested and compared to find the best classification model. Finally, SAV showed the best performance using the ANFIS model with trapezoidal membership function, having the highest system accuracy (ACC) at 89.33%, sensitivity (SE), specificity (SP), and positive predictivity (PPR) for NSR at 100.00%, 94.00%, and 89.29%, PAF at 88.00%, 90.57%, and 81.48%, and AF at 80.00%, 96.00%, and 90.91%, respectively.

Slow, deep breathing intervention improved symptoms and altered rectal sensitivity in patients with constipation-predominant irritable bowel syndrome.

Limited treatment options have been shown to alter the natural course of irritable bowel syndrome (IBS). Slow, deep breathing (SDB) is a common pain self-management intervention. This pilot study aimed to explore the impact of SDB on measures of autonomic and anorectal functions as well as patient-reported symptoms in constipation-predominant IBS (IBS-C). Eighty-five IBS-C patients were enrolled in this study and randomly assigned to the experimental group (Group A, n = 42) and the control group (Group B, n = 43). SDB was conducted at six breathing cycles per minute with an inhalation for 4 s and exhalation for 6 s at a ratio of 2:3 and repeated for 30 min during the intervention. All subjects underwent high-resolution anorectal manometry (HRAM) and completed the standardized IBS symptom severity system (IBS-SSS) questionnaire. Meanwhile, changes in stool consistency, weekly frequency of complete spontaneous bowel movements (CSBMs), and weekly frequency of spontaneous bowel movements (SBMs) were recorded. All IBS-C patients received electrocardiogram (ECG) recordings for heart rate variability (HRV) analysis at baseline, weeks 3, 6. At baseline, no differences were found between Groups A and B. The IBS-SSS score and its five sub-scores of Group B patients were significantly higher at week 6 than those of Group A patients (all p < 0.001). Furthermore, compared with Group B patients, Group A patients had a significantly higher threshold volume for the first sensation (p < 0.001), desire to defecate (p = 0.017), and maximum tolerable volume (p = 0.018) at week 6 of the SDB treatment. We also noted significant improvements in stool consistency (p = 0.002), weekly SBM frequencies (p < 0.001), and weekly CSBM frequencies (p = 0.018) of Group A patients at week 6 when compared with Group B patients. Finally, the corrected high frequency (HF) of Group A patients was significantly higher than the HF of Group B patients at week 3 (p < 0.001) and at week 6 (p < 0.001). Likewise, patients in Group A had a significantly higher root mean square of the successive differences (RMSSD) than that of patients in Group B at week 3 (p < 0.001) and at week 6 (p < 0.001). We found that a 6-week SDB intervention improved symptoms and altered rectal sensation in IBS-C patients. Moreover, SDB enhanced vagal activity. These findings suggest that the effect of SDB on IBS-C may be due to mechanisms involving autonomic responses.

COMPARISON OF HEART RATE VARIABILITY OF CHRONIC SPINAL CORD INJURY PATIENTS IN SUPINE AND SITTING POSITIONS

Background: Sympathetic and parasympathetic activity shift in response to body position changing. Spinal cord injury (SCI) patients have problems controlling autonomic functions occurs as a result of an imbalance between the sympathetic and parasympathetic nervous systems. Despite the fact that changing body position is often used in SCI rehabilitation, few studies have compared the autonomic activity of SCI patients at different body positions. Heart rate variability (HRV) can be used to invasively assess cardiac autonomic modulation. This study aims to obtain information about the autonomic modulation features of SCI patients in supine and sitting positions using HRV measurements. Methods: This study was a cross-sectional study approach. Participants of this study were 14 chronic SCI patients with injury durations more than a year. Measurement of HRV is using Polar H10 (1B56EB2E). HRV measurements in the subjects of this study were Root Mean Square of the Successive Differences (RMSSD) and Low Frequency/High Frequency (LF/HF) ratio in supine and sitting positions. Results: There was a significant difference in the value of RMSSD in chronic SCI patients from supine to sitting position (p 0.019). There was no significant difference in the value of LF/HF ratio in chronic SCI patients from supine to sitting position (p 0.408). Conclusions: Parasympathetic activity (RMSSD) decreased significantly in chronic SCI patients due to postural changing from supine to sitting position. Despite the fact that sympathetic activity is disrupted in SCI patients, the sympathovagal balance can still be maintained with changes in body position.

Autonomic Nervous System Function After Dynamic Exertion Among Athletes At Medical Clearance Following Concussion

The autonomic nervous system (ANS) is commonly disrupted following sport-related concussion (SRC), and safe return to play/activity (RTP/A) is predicated on physiological recovery of ANS and other inter-related subsystems. Ultrashort (<5 min) heart rate variability (HRV) following exercise may be a proxy measure of ANS function but has predominately been measured following aerobic exertion without sport-specific movements. Dynamic exertion involves rapid change-of-direction tasks at varying intensities to perturb the vestibular and ocular subsystems in addition to the ANS. To date, researchers have yet to examine ultrashort HRV following dynamic exertion among athletes at medical clearance to RTP/A. PURPOSE: Compare age-estimated percentage of heart rate (HR %max) throughout a dynamic exertion assessment, in addition to post-exertion blood pressure and ultrashort HRV outcomes between athletes upon RTP/A from SRC with healthy athletes. METHODS: A sample of 23 (Female = 10, 43.5%) athletes at medical clearance to RTP/A (CONCUSS) and 23 sex-, age-, and sport-matched healthy athletes (CONTROL) completed a 5-min seated rest period prior to and following the dynamic exertion test. The dynamic exertion test is comprised of a12-min treadmill run and a series of functional movements and change-of-direction tasks. The root-mean-square of the successive differences (RMSSD) and standard deviation of successive heart beats (SDNN) were obtained from the final 3-min of pre- and post-EXiT rest periods. Between-group comparisons were conducted with a series of independent sample t-tests for HR %max and blood pressure, and 2X2 (GROUP X TIME) ANOVAs for RMSSD and SDNN. RESULTS: Main effects were observed for GROUP whereby CONCUSS had lower (less variable) RMSSD (p = .049, Ƞp2 = .209) and SDNN (p = .047, Ƞp2 = .212) than CONTROL, and for TIME as a reduction in RMSSD (p < .001, Ƞp2= .740) and SDNN (p < .001, Ƞp2= .760). HR %max and blood pressure were similar between groups (p > .05). CONCLUSION: ANS dysfunction may persist beyond clinical recovery in some athletes returning to sport after SRC. This is the first study to report differences in HRV between recently concussed and healthy athletes after dynamic exertion. Future work should consider the role of ANS function post-exertion to improve medical clearance decision making.

Training-related Changes In Cardiac Autonomic Function Assessed Before And After Graded Exercise Testing

Aerobic training improves cardiac autonomic function, leading to increased heart rate variability (HRV) and decreased heart rate (HR) at rest. Intense exercise such as graded exercise testing (GXT) acutely increases HR and decreases HRV, which eventually return to resting levels post-exercise. Autonomic recovery after exercise may improve with training. PURPOSE: To examine the relationship between HRV and HR before and after GXT, and to assess changes resulting from 18 weeks of aerobic training. METHODS: Healthy young adults (n = 12, 7f; age 20.9 ± 0.6) completed physiological testing prior to enrollment in a marathon training course, and again after training. Testing included a 10-minute seated monitoring of HR/HRV (REST) with a Polar RS800cx watch and chest-strap, followed by GXT, and a 20-minute seated recovery period with HR/HRV monitoring. Recovery data were divided into two 10-minute segments (REC1 and REC2) for analysis. Mean HR and the following HRV measures were assessed using Kubios HRV Version 3.3: Standard deviation (SDNN), root mean square of the successive differences (RMSSD), high frequency power (HF), low frequency power (LF), low frequency to high frequency ratio (LF/HF), sample entropy (SE), and detrended fluctuation analysis α1 (DFAα1) and α2 (DFAα2). Repeated measures ANOVA was used to compare 10-minute segments (REST, REC1, and REC2) and to assess changes with training. RESULTS: All HRV measures and HR were different between segments (p ≤ 0.05), with HR lowest during REST and highest during REC1. Similarly, HRV measures reflected greatest variability during REST and lowest during REC1. Several measures of HRV, as well as HR changed with training. Heart rate decreased (p = 0.023) at REST (75.0 ± 17.3, 70.1 ± 14.2 bpm), during REC1 (106.3 ± 13.7, 100.1 ± 10.7) and REC2 (102.8 ± 11.9, 95.6 ± 10.3). With training, RMSSD increased (REST: 56.5 ± 29.3, 64.7 ± 32.4 ms; REC1: 6.8 ± 3.4, 8.5 ± 4.5; REC2: 9.4 ± 4.5, 11.1 ± 4.1; p = 0.048). Similarly, HF (p = 0.031) and DFAα1 (p = 0.017) exhibited greater variability across the three segments after training. CONCLUSIONS: Differences in cardiac autonomic function between timepoints before and after GXT were observed. Aerobic training reduced HR and increased selected HRV variables.

Effects of overnight military training and acute battle stress on the cognitive performance of soldiers in simulated urban combat.

Understanding the effect of stress, fatigue, and sleep deprivation on the ability to maintain an alert and attentive state in an ecologically valid setting is of importance as lapsing attention can, in many safety-critical professions, have devastating consequences. Here we studied the effect of close-quarters battle (CQ battle) exercise combined with overnight military training with sleep deprivation on cognitive performance, namely sustained attention and response inhibition. In addition, the effect of the CQ battle and overnight training on cardiac activity [heart rate and root mean square of the successive differences (RMSSD)] during the cognitive testing and the relationship between cardiac activity and cognitive performance were examined. Cognitive performance was measured with the psychomotor vigilance task (PVT) and the sustained attention to response task (SART). Altogether 45 conscripts participated in the study. The conscripts were divided into control (CON) and experimental (EXP) groups. The CON completed the training day after a night of sleep and the EXP after the overnight military training with no sleep. Results showed that the effect of the overnight training on cognitive performance and the between-group difference in heart rate (HR) and heart rate variability (HRV) depended on the cognitive test. Surprisingly, the cognitive performance was not largely affected by the CQ battle. However, as expected, the CQ battle resulted in a significant decrease in RMSSD and an increase in HR measured during the cognitive testing. Similarly, the HR parameters were related to cognitive performance, but the relationship was found only with the PVT. In conclusion, fatigue due to the overnight training impaired the ability to maintain sufficient alertness level. However, this impairment in arousal upregulation was counteracted by the arousing nature of the SART. Hence, the conscripts' cognitive performance was mainly preserved when performing a stimulating task, despite the fatigue from the sleep loss of the preceding night and physical activity.

Effect of Transcranial Pulsed Current Stimulation on Fatigue Delay after Medium-Intensity Training.

The purpose of this study was to investigate the effect of transcranial pulsed current stimulation (tPCS) on fatigue delay after medium-intensity training. Materials and Methods: Ninety healthy college athletes were randomly divided into an experimental group (n = 45) and control group (n = 45). The experimental group received medium-intensity training for a week. After each training, the experimental group received true stimulation of tPCS (continuous 15 min 1.5 mA current intensity stimulation). The control group received sham stimulation. The physiological and biochemical indicators of participants were tested before and after the experiment, and finally 30 participants in each group were included for data analysis. Results: In the experimental group, creatine kinase (CK), cortisol (C), time-domain heart rate variability indices root mean square of the successive differences (RMSSD), standard deviation of normal R-R intervals (SDNN), and frequency domain indicator low frequency (LF) all increased slowly after the intervention. Among these, CK, C, and SDNN values were significantly lower than those in the control group (p < 0.05). Testosterone (T), T/C, and heart rate variability frequency domain indicator high frequency (HF) in the experimental group decreased slowly after the intervention, and the HF value was significantly lower than that in the control group (p < 0.05). The changes in all of the indicators in the experimental group were smaller than those in the control group. Conclusion: The application of tPCS after medium-intensity training enhanced the adaptability to training and had a significant effect on the maintenance of physiological state. The application of tPCS can significantly promote the recovery of autonomic nervous system function, enhance the regulation of parasympathetic nerves, and delay the occurrence of fatigue.