Effect of different anesthesia depths on perioperative heart rate variability and hemodynamics in middle-aged and elderly patients undergoing general anesthesia.

BACKGROUND: To analyze the effects of different anesthesia depths on perioperative heart rate variability and hemodynamics in middle-aged and elderly patients undergoing general anesthesia, and to provide a basis for clinical application. METHODS: A total of 111 patients with gastric cancer who were treated with epidural anesthesia combined with general anesthesia were selected as the study subjects, and the patients were randomly divided into group A, group B and group C. The bispectral index (BIS) was maintained by adjusting the infusion speed of anesthetics, the BIS of group A was maintained at 50 ~ 59, the BIS of group B was maintained at 40 ~ 49, and the BIS of group C was maintained at 30 ~ 39. The high-frequency power (HFP), low-frequency power (LFP), total power (TP), mean arterial pressure (MAP), heart rate (HR), diastolic blood pressure (DBP), and systolic blood pressure (SBP) were measured before anesthesia induction (T1), immediately after intubation (T2), 3 min after intubation (T3), and 6 min after extubation (T4). The cognitive function of the patients was evaluated before and 48 h after surgery. RESULTS: The HFP, LFP/HFP, TP, HR, DBP and SBP between the three groups at T1 ~ T3 are significantly difference from each other (P < 0.05). There were significant differences in spontaneous breathing recovery time, eye opening time and extubation time among group A, B and C groups, and group B had the lowest spontaneous breathing recovery time, eye opening time and extubation time (P < 0.05). There was no significant difference in the incidence of adverse reactions during anesthesia between the three groups. The cognitive function score of group B was significantly higher than that of group A and group C (P < 0.05). CONCLUSIONS: BIS maintenance of 40 ~ 49 has little effect on perioperative heart rate variability and hemodynamics in middle-aged and elderly patients undergoing general anesthesia, which is helpful for postoperative recovery.

Dysfunction of the autonomic nervous system in gastro-esophageal reflux disease: Consequences for the cardiovascular system.

OBJECTIVE: The pathophysiology of gastro esophageal reflux disease (GERD) implicates autonomic dysregulation of the lower esophageal sphincter tone. Our goal is to investigate whether this dysregulation of the autonomic nervous system (ANS) function observed in isolated GERD cases can affect other systems, such as cardiovascular regulation. METHODS: Twenty-five participants were included in the study, 11 patients with isolated GERD and 14 controls. All patients and 7 controls responded to a COMposite Autonomic Symptoms Score 31 (COMPASS 31) questionnaire and underwent functional explorations including EMLA test, sympathetic skin response (SSR), 24-hour heart rate recording and ambulatory blood pressure measurement (ABPM). Seven additional controls underwent a 24-hour heart rate recording only. RESULTS: GERD patients (Age: mean 36.81±7.82; SR= 0.22) showed high clinically dysautonomic scores (COMPASS 31) (p = 0.015), increased Heart rate variability (HRV) parameters (daytime, nighttime, 24-hour SDNN (standard deviation of the RR interval (NN)), respectively p = 0.003, p < 0.001, p = 0.001; daytime and nighttime very low frequencies (VLF) respectively p = 0.03 and p = 0.007), impaired nocturnal dipping of blood pressure (3/11 patients) and high positivity of EMLA test (7/11, p = 0.037). These outcomes were strongly correlated with clinical dysautonomic assessment. No difference was observed between patients and controls regarding SSR. CONCLUSION: Our data suggests a high parasympathetic tone amongst patients with GERD and a dysregulation of parasympathetic and sympathetic balance in the cardiovascular system with an impairment of the peripheral sympathetic fibers of cutaneous microcirculation, assessed by the EMLA test. GERD may be an inaugural symptom of autonomic neuropathy. Further functional exploration of peripheral small fibers seems to be necessary.

Human physiological responses to different types of human-dog interactions: A randomised crossover study.

Previous studies of human-dog interventions vary in terms of type of interaction, which is rarely quantified, leading to contradictory findings and limited comparability. To uncover the influence of different types of interactions, the present study investigated if it was possible to detect differences in immediate physiological measurements of healthy humans during different standardised types of interaction with a dog. Thirty-three healthy participants (women = 25, men = 8, >18 years) were exposed to four different test situations with standardised types of interaction intensity with a dog in random order: no dog present (CONTROL), looking at a dog (VISUAL), petting a dog (TACTILE) or performing tricks with a dog (ACTIVE). Each test situation lasted 10 min with a 30-min break between each. Heart rate (HR), heart rate variability (HRV) and skin conductance (tonic level (SCL) and peak counts (SCR)) were continuously recorded. Blood pressure (BP) and salivary cortisol (s-cortisol) were measured before and after each test situation. Linear Mixed Models were applied. HR, HRV, BP, SCL and SCR increased with increased interaction with the dog (for all: p < 0.001). HRV increased with decreased HR (p = 0.002), increased SCL (p = 0.027), and SCR (p < 0.001) depending on the type of interaction. Generally, s-cortisol increased with increased HR (p = 0.042), SCL increased with increased SCR (p < 0.001), and SCR increased with increased HRV (p = 0.013), depending on type of interaction. The physiological measurements HR, HRV, BP, SCL and SCR are influenced by different types of dog interaction, and thus it is important to quantify and report the type of interaction in human-dog interaction studies. (ClinicalTrials.gov ID:NCT04696419).

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.

Improving Prefrontal Oxygenation and Cardiac Autonomic Activity Following Meditation: A Functional Near-Infrared Spectroscopy (fNIRS) Study.

OBJECTIVE: The empirical evidence explicitly demonstrates that meditation practice enhances both brain functions and mental well-being. A meditative relaxation approach called the mind sound resonance technique (MSRT) has shown promising effects on children, adolescents, and people with psychological illnesses. This study aimed to investigate the effects of MSRT practice on brain hemodynamics, heart rate variability (HRV), mindfulness, and anxiety levels in college students. METHODS: Fifty volunteers in all genders (females, n = 30; males, n = 20) aged between 19 and 30 years were chosen from an educational institute and allocated into two groups, i.e., MSRT (n = 25) and supine rest (SR; n = 25). Enrolled participants were measured cerebral hemodynamics and HRV before, during, and after the MSRT or SR practice. The self-reported assessments including state anxiety and mindfulness were assessed before and after the intervention. RESULTS: The results demonstrated that practicing MSRT significantly improved oxygenation (p < 0.05) in the right prefrontal cortex (PFC) and increased low-frequency (LF) (p < 0.05) and decreased high-frequency (HF) (p < 0.05) component of HRV when compared to the baseline. The between-group analysis showed a significant difference between MSRT and SR in the standard deviation of the normal-to-normal (SDNN) (p < 0.05) component of HRV. CONCLUSION: These crumbs of evidence imply that MSRT sessions may foster the development of anxiety-related coping skills by elevating mindfulness, promoting PFC oxygenation, and modulating HRV in MSRT practitioners.

The brain-heart-immune axis: a vago-centric framework for predicting and enhancing resilient recovery in older surgery patients.

Nearly all geriatric surgical complications are studied in the context of a single organ system, e.g., cardiac complications and the heart; delirium and the brain; infections and the immune system. Yet, we know that advanced age, physiological stress, and infection all increase sympathetic and decrease parasympathetic nervous system function. Parasympathetic function is mediated through the vagus nerve, which connects the heart, brain, and immune system to form, what we have termed, the brain-heart-immune axis. We hypothesize that this brain-heart-immune axis plays a critical role in surgical recovery among older adults. In particular, we hypothesize that the brain-heart-immune axis plays a critical role in the most common surgical complication among older adults: postoperative delirium. Further, we present heart rate variability as a measure that may eventually become a multi-system vital sign evaluating brain-heart-immune axis function. Finally, we suggest the brain-heart-immune axis as a potential interventional target for bio-electronic neuro-immune modulation to enhance resilient surgical recovery among older adults.

The Effect of Short-Term Exposure to Lower Body Positive Pressure on Motor Signal Processing, Reaction Times, and Cardiovascular Parameters in Healthy Volunteers Using Medical Anti-shock Trousers.

Microgravity, as experienced during spaceflight has notable effects on the cognition and cardiovascular systems. However, its effect on motor signal processing is not known. In this study, we planned to study the effect of microgravity simulation with a lower body positive pressure of 50 mmHg on motor signal processing, reaction times, and cardiovascular parameters. Thirty healthy human volunteers participated in this investigation, and continuous ECG and non-invasive blood pressure were measured at baseline, during, and after a lower body positive pressure of 50 mmHg. Bereitschafts potential was recorded at 0 mmHg and 50 mmHg pressure values in a lower body positive pressure (LBPP) suit. Parameters recorded during the pressure change of 0 mmHg to 50 mmHg were RR interval, heart rate, systolic blood pressure, diastolic blood pressure, stroke volume, cardiac output, and peripheral vascular resistance. Heart rate variability (HRV) was calculated from RR intervals during resting and pressure of 50 mm of Hg. We also compared simple and choice reaction times for visual and auditory stimuli during 50 mmHg LBPP exposure with baseline recording. We found a significant increase in systolic blood pressure, stroke volume, and cardiac output from baseline at 50 mmHg of LBPP. We found a significant change in amplitude and area of Bereitschaft potential at the C4 site at 50 mmHg of LBPP. We found a significant change in low-frequency power (LF) as compared to the baseline in HRV. Simple reaction time (visual & auditory) and auditory choice reaction time were improved at 50 mmHg of LBPP. Motor signal processing and reaction time were improved during 50 mmHg of lower body positive pressure exposure.

Cardiac autonomic regulation during submaximal exercise in women with fibromyalgia.

Fibromyalgia (FM) patients present impaired cardiac autonomic regulation during maximal exercise; however, it is unknown whether these alterations also manifest during submaximal exercise. The aim of this study was to compare the on-transient heart rate (HR) response and HR variability during a constant-load submaximal cycling exercise between FM and control (CON) women. Ten women with FM (age: 45.2±9.3 years) and 10 age-matched CON women (age: 48.4±6.1 years) performed a 15-min cycling exercise, with the work rate fixed at 50% of the individual peak power output attained in a maximal graded exercise test. The time intervals between consecutive heartbeats were recorded regularly during the exercise for subsequent analysis of on-transient HR response and HR variability indices. The on-transient HR time constant was similar (P=0.83) between the FM (41.0±14.1 sec) and CON (42.2±10.4 sec). During the 5-10 and 10-15 min of exercise, HR variability indices indicating sympathetic and parasympathetic activities were similar (P>0.05) between FM and CON groups. In conclusion, women with FM presented a normal cardiac autonomic response to submaximal cycling exercise. These findings have clinical relevance, as submaximal exercises are commonly prescribed for FM patients.

Impact of surgical aortic valve replacement and transcatheter aortic valve implantation on cardiovascular and cerebrovascular controls: A pilot study.

Surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI) are options in severe aortic valve stenosis (AVS). Cardiovascular (CV) and cerebrovascular (CBV) control markers, derived from variability of heart period, systolic arterial pressure, mean cerebral blood velocity and mean arterial pressure, were acquired in 19 AVS patients (age: 76.8 ± 3.1 yrs, eight males) scheduled for SAVR and in 19 AVS patients (age: 79.9 + 6.5 yrs, 11 males) scheduled for TAVI before (PRE) and after intervention (POST, <7 days). Left ventricular function was preserved in both groups. Patients were studied at supine resting (REST) and during active standing (STAND). We found that: (i) both SAVR and TAVI groups featured a weak pre-procedure CV control; (ii) TAVI ensured better CV control; (iii) cerebral autoregulation was working in PRE in both SAVR and TAVI groups; (iv) SAVR and TAVI had no impact on the CBV control; (v) regardless of group, CV and CBV control markers were not influenced by STAND in POST. Even though the post-procedure preservation of both CV and CBV controls in TAVI group might lead to privilege this procedure in patients at higher risk, the missing response to STAND suggests that this advantage could be insignificant.

Quantifying exercise intensity with fractal correlation properties of heart rate variability: a study on incremental and constant-speed running.

The short-term scaling exponent of detrended fluctuation analysis (DFAα1) applied to interbeat intervals may provide a method to identify ventilatory thresholds and indicate systemic perturbation during prolonged exercise. The purposes of this study were to (i) identify the gas exchange threshold (GET) and respiratory compensation point (RCP) using DFAα1 values of 0.75 and 0.5 from incremental exercise, (ii) compare DFAα1 thresholds with DFAα1 measures during constant-speed running near the maximal lactate steady state (MLSS), and (iii) assess the repeatability of DFAα1 between MLSS trials. Twelve runners performed an incremental running test and constant-speed running 5% below, at, and 5% above the MLSS, plus a repeat trial at MLSS. During 30-min running trials near MLSS, DFAα1 responses were variable (i.e., 0.27-1.24) and affected by intensity (p = 0.031) and duration (p = 0.003). No difference in DFAα1 was detected between MLSS trials (p = 0.597). In the early phase (~ 8 min), DFAα1 measures at MLSS (0.71 [0.13]) remained higher than the DFAα1 identified at RCP from the incremental test (0.57 [0.13]; p = 0.024). In addition, following ~ 18 min of constant speed running at MLSS, DFAα1 measures (0.64 [0.14]) remained higher than 0.5 (p = 0.011)-the value thought to demarcate the boundaries between heavy and severe exercise intensities. Accordingly, using fixed DFAα1 values associated with the RCP from incremental exercise to guide constant-speed exercise training may produce a greater than expected exercise intensity, however; the dependency of DFAα1 on intensity and duration suggest its potential utility to quantify systemic perturbations imposed by continuous exercise.

Impact of Nadi Shuddhi Pranayama on Apnea Hypopnea Index, Respiratory Distress Index, and Oxygen Desaturation Index Among Adolescents With Sleep Apnea Syndrome.

Background Sleep apnea syndrome has gained significant recognition over the last decade as a potential cause of substantial childhood morbidity. This study aimed to evaluate the impact of the Apnea Hypopnea Index (AHI), Respiratory Distress Index (RDI), and Oxygen Desaturation Index (ODI) among adolescents with sleep apnea syndrome. Objectives The objective of this study is to compare the impact of Nadi Shuddhi Pranayama with routine treatment modalities on the AHI, RDI, and ODI among adolescents with sleep apnea syndrome. Specifically, the study aims to evaluate the effectiveness of Nadi Shuddhi Pranayama in improving AHI, RDI, and ODI in this population. Methods This study was an interventional case-control study and enrolled 34 adolescents aged 10 to 18 years who were diagnosed with sleep apnea syndrome. The participants were divided into two groups: the Nadi Shuddhi Pranayama group (n=17) and the control group (n=17). Baseline assessments included the collection of demographic information, medical history, and polysomnography results to determine the AHI, RDI, and ODI. Follow-up assessments were conducted post-intervention to measure changes in the AHI, RDI, and ODI. Results There were no significant differences between groups in terms of age (p = 0.176) or gender distribution (p = 0.300). After the intervention period, participants in the Nadi Shuddhi Pranayama group showed significant improvements in the Apnea Hypopnea Index compared to the standard care group (p = 0.007). However, there were no significant differences in the Respiratory Distress Index (p = 0.547) or Oxygen Desaturation Index (p = 0.304) between the groups post-intervention. Subgroup analysis based on severity categories (Mild, Normal) for the Apnea Hypopnea Index showed a significant difference between the Nadi Shuddhi Pranayama and standard care groups (p = 0.037). However, there were no significant differences in the Respiratory Distress Index (p = 0.300) and Oxygen Desaturation Index (p = 0.169) between the groups in this subgroup. Conclusion These findings suggest that Nadi Shuddhi Pranayama may improve the Apnea Hypopnea Index in adolescents with sleep apnea, particularly in those with mild symptoms, but did not significantly affect the Respiratory Distress Index or Oxygen Desaturation Index.

The impact of controlled breathing on autonomic nervous system modulation: analysis using phase-rectified signal averaging, entropy and heart rate variability.

Objective The present study investigated how breathing stimuli affect both non-linear and linear metrics of the autonomic nervous system (ANS). Approach The analyzed dataset consisted of 70 young, healthy volunteers, in whom arterial blood pressure (ABP) was measured noninvasively during 5-minute sessions of controlled breathing at three different frequencies: 6, 10, and 15 breaths/min. CO2 concentration and respiratory rate were continuously monitored throughout the controlled breathing sessions. The ANS was characterized using non-linear methods, including Phase-Rectified Signal Averaging (PRSA) for estimating heart acceleration and deceleration capacity (AC, DC), multiscale entropy (MSEn), approximate entropy (ApEn), sample entropy (SampEn), and fuzzy entropy (FuzzyEn), as well as time and frequency domains (low frequency, LF; high-frequency, HF; total power, TP) of heart rate variability (HRV). Main Results Higher breathing rates resulted in a significant decrease in end-tidal CO2 concentration (p < 0.001), accompanied by increases in both ABP (p<0.001) and heart rate (p<0.001). A strong, linear decline in AC and DC (p<0.001 for both) was observed with increasing respiratory rate. All entropy metrics increased with breathing frequency (p<0.001). In the time-domain, HRV metrics significantly decreased with breathing frequency (p<0.01 for all). In the frequency-domain, HRV LF and HRV HF decreased (p = 0.038 and p = 0.040, respectively), although these changes were modest. There was no significant change in HRV TP with breathing frequencies. Significance Alterations in CO2 levels, a potent chemoreceptor trigger, and changes in HR most likely modulate ANS metrics. Non-linear PRSA and entropy appear to be more sensitive to breathing stimuli compared to frequency-dependent HRV metrics. Further research involving a larger cohort of healthy subjects is needed to validate our observations. .

Quantification of respiratory sinus arrhythmia in control dogs and in dogs with various severity classes of myxomatous mitral valve disease.

INTRODUCTION: Loss of respiratory sinus arrhythmia (RSA) is a negative prognostic factor in dogs with myxomatous mitral valve disease (MMVD). The aim of this study was to calculate the percentage (%) of RSA in healthy dogs and dogs in various MMVD classes. ANIMALS: Control and MMVD dogs were prospectively included in the study. MATERIALS AND METHODS: Respiratory sinus arrhythmia was calculated from a dual channel electrocardiography and breathing curve recording using the peak-to-trough method, in percent of the average heart rate. RESULTS: One hundred and forty-nine dogs were studied, including 24 control and 125 MMVD dogs of different severity classes. An overall %RSA decrease was documented with increasing disease severity up to the Ca class along with a relative %RSA increase in the Cc class. The %RSA magnitude differed between B2 and Ca (P<0.001), and between Ca and Cc (P = 0.001) groups, respectively. The %RSA showed a medium negative correlation with the La:Ao ratio (r2 = -0.568, P<0.001) and with the E-wave velocity (r2 = -0.561, P<0.001). DISCUSSIONS: A decrease in %RSA was shown with increased disease severity up to acute congestive heart failure (CHF). Dogs receiving cardiac therapy leading to stabilized CHF might restore their ability to exhibit RSA, often revealing a higher %RSA compared to those in acute CHF. STUDY LIMITATIONS: Low number of respiratory cycles for analysis. Therapy effect not evaluated. CONCLUSIONS: The findings of this study can serve as the basis for future risk stratification and carry the potential of proving an additional clinical marker for diagnostic and therapeutic decisions making when managing MMVD dogs.

Influence of an inspiratory muscle fatigue protocol on healthy youths on respiratory muscle strength and heart rate variability. A randomized controlled trial.

Introduction: Inspiratory muscle fatigue has been shown to have effects on the autonomic nervous system and physical condition. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength and heart rate variability in healthy youths. Materials and Methods: A randomized controlled clinical trial, employing double-blinding, was conducted with twenty-seven participants aged 18-45 years, non-smokers and engaged in sports activity at least three times a week for a minimum of 1 year. Participants were randomly assigned to three groups: Inspiratory Muscle Fatigue group, Activation group, and Control group. Measurements of heart rate variability, diaphragmatic ultrasound, and maximum inspiratory pressure were taken at two stages: before the intervention and immediately after treatment. Results: In our results with respect to baseline to post-treatment, the inspiratory muscle fatigue group showed lower values in the Sniff contraction velocity variable (10.96 cm/s ± 1.99-8.34 cm/s ± 1.23; p < 0.01) and higher values in the activation group (10.59 cm/s ± 0.89-12.66 cm/s ± 1.15; p < 0.01) with respect to the control group (10.27 cm/s ± 1.48-9.97 cm/s ± 1.42). On the other hand, the inspiratory muscle fatigue group showed higher values in the Low frequency variable (49.37 n.u. ± 13.91 to 69.48 n.u. ± 8.22; p < 0.01) and lower values in the activation group (57.92 n.u. ± 8.37 to 41.59 n.u. ± 11.21; p < 0.01) with respect to the control group (50.83 n.u. ± 17.30 to 52.10 n.u. ± 20.64). Additionally, significant correlations were found between respiratory variables and heart rate variability variables. Conclusion: Acute fatigue of the inspiratory musculature appears to negatively impact heart rate variability and inspiratory muscle strength in healthy youths. Clinical Trial Registration: https://clinicaltrials.gov/study/NCT06278714; Identifier: NCT06278714.

Short-term heart rate variability: A potential approach to frailty assessment in older adults.

Objectives: This study aimed to evaluate cardiac autonomic modulation using short-term heart rate variability (HRV) and compare it among frailty statuses in older Indian adults. Methods: A total of 210 subjects aged 60 years and above were recruited into three groups: frail (n = 70), pre-frail (n = 70), and non-frail (n = 70) from the outpatient department of Geriatric Medicine at a tertiary care hospital in India. Frailty status was assessed using the Rockwood frailty index (FI) criteria. HRV was derived from a 5-min ECG recording of standard limb leads and assessed using time domain, frequency domain, and nonlinear analysis of cardiac interval variability. Results: The HRV parameters indicative of parasympathetic modulation such as SDNN, SDSD, rMSSD, NN50, pNN50, absolute HF power, and SD1 were significantly lower in frail subjects compared with both pre-frail and non-frail subjects (P < 0.05). Absolute LF power and SD2 were also lower in frail subjects compared with pre-frail and non-frail subjects (P < 0.05). Measures of sympatho-vagal balance (LF/HF and SD1/SD2 ratios) did not show statistical significance. The FI demonstrated negative correlations with all HRV parameters. Conclusions: Frail individuals exhibit decreased sympathetic and parasympathetic modulation compared with pre-frail and non-frail individuals, although maintaining a balanced sympatho-vagal state. Furthermore, autonomic modulation declines progressively with increasing frailty.

Effect of protein supplements on cardiovascular health and exercise performance of young adult males.

Introduction: The modern fitness culture, propelled by celebrity influence and media exposure, has led to widespread acceptance and consumption of protein supplements, particularly among young adult males aspiring for an ideal physique. Despite the surge in usage, limited research has explored the impact of these supplements on cardiovascular health and exercise performance. This study aims to bridge this gap by clinically examining the cardiovascular system using heart rate variability (HRV) and comparing outcomes between those using protein supplements and a control group. Methodology: This study was conducted at the Department of Physiology, AIIMS Raipur. The cross-sectional study involved 60 young adult males aged 18-25 years. Participants were divided into two groups: group I (n = 30), comprising individuals using commercially available protein supplements for a minimum of three months, and group II (n = 30) as age-matched controls. Cardiovascular assessments, including HRV analysis, were performed at rest and after the Harvard step test. Pre-exercise and post-exercise parameters were statistically analyzed, and participants in the test group provided information on supplement labels. Results: Participants in both groups exhibited comparable pre-exercise cardiovascular parameters. However, post-exercise results did not reveal significant variations in systolic blood pressure, diastolic blood pressure, mean blood pressure, low frequency/high frequency (LF/HF) ratio, Standard deviation of the successive differences between adjacent NNs (SDNN), and standard deviation of successive differences (SDSD) between the test and control groups. The average exercise duration for the control group was longer than that of the test group. Amino acid profiles and nutritional content varied among 13 different protein supplement brands. Conclusion: The study found no statistically significant positive influence of protein supplements on cardiovascular health or exercise performance in young adult males.

Blunted cardiac autonomic dynamics to active standing test in postmenopausal women.

Introduction: Although both aging and menopause influence cardiovascular autonomic control, the effect of menopause per se remains unclear. The current study was undertaken to test the hypothesis that post-menopausal women (PMW) have a blunted cardiovascular autonomic adjustment to active standing compared to pre-menopausal women. Thus, we compared the heart rate variability (HRV) indexes from supine (SUP) to orthostatic (ORT) positions among young women (YW), young men (YM), older men (OM), and PMW. Methods: The participants rested for 10 min in SUP and then stood up and remained for 5 min in ORT. ECG was continuously recorded, and R-R time series of about 300 beats were analyzed using linear (spectral analysis) and non-linear (symbolic analysis) methods. The variation from SUP to ORT was calculated (Δ = ORT-SUP) for each HRV index. Results: In SUP, no difference was found for any HRV index among groups. However, Δ0V% and ΔLFn (cardiac sympathetic modulation) were reduced in PWM compared to all groups (OM, YW, and YM), while Δ2UV% and ΔHFn (cardiac vagal modulation) were reduced in PMW than the younger group (YW and YM). No differences were found among the male groups (OM and YM). Discussion: In light of our results, the cardiac autonomic dynamic response to orthostatic stress is blunted in post-menopausal women compared to younger women and older men, a finding that might be influenced not only by aging.

Cardiac function and autonomic cardiac function during a multi-stage cycling event: a brief report.

Introduction: Prolonged and repeated exercise performed during an ultra-endurance event can induce general and cardiac fatigue known as exercise-induced cardiac fatigue. Our objective was to find a possible correlation between the cardiac function and the autonomic cardiac function. Methods: During a multistage ultra-endurance event, a female well-trained cyclist underwent daily rest echocardiography and heart rate variability measurements to assess the cardiac function and the cardiac autonomic function. Results: The athlete completed 3,345 km at 65% of her maximum heart rate and 39% of her maximum aerobic power. A progressive improvement of the systolic function for both the left ventricle and the right ventricle was observed during the event. Discussion: Alterations were observed on the cardiac autonomic function with an imbalance between sympathetic and parasympathetic, but there was no sign of a significant correlation between the cardiac function and the autonomic cardiac function and no signs of cardiac fatigue either. Further analysis should be performed on a larger sample to confirm the obtained results.

Heart rate variability during sleep onset in patients with insomnia with or without comorbid sleep apnea.

OBJECTIVES: Pre-sleep stress or hyperarousal is a known key etiological component in insomnia disorder. Despite this, physiological alterations during the sleep onset are not well-understood. In particular, insomnia and obstructive sleep apnea (OSA) are highly prevalent co-morbid conditions, where autonomic regulation may be altered. We aimed to characterize heart rate variability (HRV) during sleep onset as a potential measure of pre-sleep hyperarousal. METHODS: We described the profile of pre-sleep HRV measures and explore autonomic differences in participants with self-reported insomnia disorder (with no OSA, n = 69; with mild OSA, n = 70; with moderate or severe OSA, n = 66), compared to normal sleep controls (n = 123). Heart rate data during the sleep onset process were extracted for HRV analyses. RESULTS: During the sleep onset process, compared to normal sleep controls, participants with insomnia had altered HRV, indicated by higher heart rate (p = 0.004), lower SDNN (p = 0.003), reduced pNN20 (p < 0.001) and pNN50 (p = 0.010) and lower powers (p < 0.001). Participants with insomnia and moderate/severe OSA may have further deteriorated HRV outcomes compared to no/mild OSA patients with insomnia but differences were not significant. Insomnia itself was associated with significantly higher heart rate, lower pNN20, and lower high frequency power even after adjustment for age, gender, BMI and OSA severity. CONCLUSIONS: Participants with insomnia had lower vagal activity during the sleep onset period, which may be compounded by OSA, reflected in higher heart rates and lower HRV. These altered heart rate dynamics may serve as a physiological biomarker for insomnia during bedtime wakefulness, or as a potential tool to evaluate the efficacy of behavioral interventions which target bedtime stress.

Effects of Singing on Vascular Health in Older Adults with Coronary Artery Disease: A Randomized Trial.

Background: The impact of singing on cardiovascular health has not been extensively studied. The aim of this study is to investigate the effect of singing on cardiovascular biomarkers in an aging population with coronary artery disease. Methods: Participants had three study visits separated by 2-7 days, according to a randomized, single-blind, cross-over, controlled design: (1) a 30-minute period of coached singing from an in-person music therapist, (2) a 30-minute period of singing along to an instructional video and (3) a 30-minute rest (control). Primary outcomes included macrovascular endothelial function assessed by brachial artery flow-mediated dilation and microvascular function assessed by peripheral arterial tonometry (Framingham reactive hyperemia index; fRHI). Heart rate variability was a secondary outcome. Results: Sixty-five subjects (mean age 67.7± 0.8, 40% women) completed the study. Compared to control, there was an increase in fRHI for the singing video intervention (estimate 0.54, SE 0.25, p=0.005) but not for the coaching intervention (estimate 0.11, SE 0.18, p=0.570). There was no change in macrovascular function with either intervention. The low frequency/high frequency (LF/HF) ratio increased by 2.80 (SE 1.03, p=0.008), and the LnHF power decreased by -0.90 ms2 (SE 0.29, p=0.003) with the video (during to pre-change). When assessing post- to pre- change, the coaching intervention showed a significant change of -0.62 ms2 (SE 0.29, p=0.036) in LnHF power. Conclusions: Singing along to an instructional video for 30 minutes improved microvascular, but not macrovascular, endothelial function, in older patients with CAD. HRV changes with singing are similar to that of exercise. Clinical trial registration: ClinicalTrials.gov, identifier: NCT04121741.