Pulse Wave Research Articles

Early and Late Effects of Medium Cutoff Dialyzer on Arterial Stiffness in Maintenance Hemodialysis Patients

ABSTRACTIntroductionRemoving uremic toxins from the body is one of the most critical points in the maintenance hemodialysis (MHD) population. This study aimed to evaluate the effects of medium cutoff (MCO) membranes on pulse wave velocity (PWV) and augmentation index (AIx), early markers of arterial stiffness, in MHD patients over both short‐ and long‐term periods.MethodsTwenty MHD patients were included in this study. Patients were switched from low‐flux to MCO membranes. Hemodynamic parameters and laboratory results were recorded in the low‐flux membrane as baseline and the second week and the sixth month after switching to the MCO membranes. PWV and AIx were measured using the IME Mobil‐O‐Graph.FindingsThe median was 69.5 years old, with 60% female predominance. 35% of the patients were diabetic, 70% had hypertension, and 21.1% were smokers. The median systolic, diastolic blood pressure, mean arterial pressure, and pulse were similar at all study time points. The pulse pressure tended to decrease with a significant reduction in the sixth month (p = 0.73 and p = 0.03). We did not observe any significant differences regarding the PWV measurements (p = 0.71 and p = 0.62) and total vascular resistance (p = 0.23 and p = 0.79). The median AIx decreased during the study time points, with a significant difference between the second‐week MCO and the sixth‐month MCO measurements (p = 0.04).DiscussionOur findings underscore the potential benefits of MCO membranes to provide a favorable cardiovascular profile in conventional HD setting.

Pulse wave parameters as a predictor of the development of post-transplant diabetes mellitus after kidney transplantation

Pulse wave parameters as a predictor of the development of post-transplant diabetes mellitus after kidney transplantation

Accuracy of pulse wave velocity for screening coronary artery disease: a systematic review and meta-analysis

Abstract Coronary artery disease (CAD) is the leading cause of cardiovascular events and showed high prevalence and healthcare costs in 2019. However, CAD screening for cardiovascular event prevention is invasive and expensive. This study aims to estimate the ability of a noninvasive method, pulse wave velocity (PWV), to detect the presence or absence of coronary artery disease in patients with suspected CAD. A systematic review and meta-analysis of the available evidence was conducted, comparing PWV with the gold standard diagnostic method, angiography. The literature search was systematically performed in the PubMed, Scopus and Web of Science databases from inception to August 2024. Study quality assessment was performed using the Diagnostic Accuracy Study Quality Assessment Tool (QUADAS-2). Publication bias was assessed using the method proposed by Deeks. Statistical analyses were performed with the STATA SE software, version 15. The eight included studies had a cross-sectional design, in which the presence of CAD was measured simultaneously by PWV and angiography. To assess the accuracy of the tests, the overall sensitivity and specificity were combined into a single value, the diagnostic odds ratio (dOR), which provided a value of 3.61, indicating a high probability of detecting CAD by PWV. The implementation of PWV as a screening technique in healthcare centers could bring great benefits to patients with suspected CAD and increase efficiency in the use of healthcare resources.

Position-definable coherent microwave pulse train generation in an actively mode-locked optoelectronic oscillator

An approach to generating position-definable coherent microwave pulse trains is proposed and demonstrated based on an actively mode-locked optoelectronic oscillator (OEO). In this scheme, a low-frequency signal with a customized waveform is employed as the mode-locking signal to periodically manipulate the intracavity gain of the OEO. Once the repetition frequency of the mode-locking signal satisfies the active mode-locking condition, microwave pulses are generated at the time positions corresponding to the gain peaks. The temporal distribution of the microwave pulses within one period is determined by the waveform of the mode-locking signal. Therefore, through designing the waveform of the mode-locking signal, coherent microwave pulse trains with user-defined pulse positions can be obtained. In the experiment, a non-uniformly spaced microwave pulse train, a series of microwave pulse clusters, and a binary-encoded microwave pulse sequence with a “Barker code” format are generated by the actively mode-locked OEO, all of which are with an identical carrier frequency of 10 GHz.

The Effects of Endurance Training and High-Intensity Resistance Training on Pulse Wave Velocity and QT Dispersion

Objectives: This study aimed to examine the effects of endurance and high-intensity resistance training on arterial stiffness and ventricular repolarization in elite athletes. Methods: A total of 50 male athletes from different sports disciplines (volleyball, football, judo, and wrestling) and a sedentary group of 30 males participated in this study. Data collected from all participants included age, height, body weight, cardiovascular hemodynamic parameters, arterial stiffness parameters, and ECG measurements. Results: There was no significant age difference between the athlete group (20.42 ± 1.903 years) and the control group (20.97 ± 1.771 years) (p > 0.05). However, body mass index (BMI) values in the control group (24.83 ± 2.22 kg/m2) were significantly different from those in the athlete group (22.39 ± 2.663 kg/m2) (p < 0.05). Significant differences were found between the athlete and control groups in QT dispersion, systolic blood pressure, pulse pressure, and central pulse pressure values (p < 0.05), while similar results were obtained for arterial stiffness parameters (p > 0.05). Conclusions: The lack of a difference in pulse wave velocity and augmentation index (AIx) values between the athletes and the control group suggests that athletes do not bear additional risks regarding arterial stiffness. However, increased systolic blood pressure, pulse pressure, and central pulse pressure, among the hemodynamic parameters, indicate potential variations in vascular wall compliance and hemodynamic responses in the cardiovascular system. The increase in QT dispersion suggests that athletes may exhibit a heterogeneous repolarization process and an elevated risk of ventricular arrhythmias compared to the general population.

Mechanosensitive Ca2+ channel TRPV1 activated by low-intensity pulsed ultrasound ameliorates acute kidney injury through Notch1-Akt-eNOS signaling.

Acute Kidney Injury (AKI) is a significant medical condition characterized by the abrupt decline in kidney function.Low-intensity pulsed ultrasound (LIPUS), a non-invasive therapeutic technique employing low-intensity acoustic wave pulses, has shown promise in promoting tissue repair and regeneration. A novel LIPUS system was developed and evaluated in rat AKI models, focusing on its effects on glomerular filtration rate (GFR), blood urea nitrogen (BUN), serum creatinine (SCr), and the Notch1-Akt-eNOS signaling pathway. The results demonstrated that LIPUS treatment improved GFR, BUN, SCr levels, and renal pathology in AKI rats. Invitro experiments using HUVEC cells revealed that LIPUS stimulation promoted angiogenesis, cell migration mechanically-dependent calcium ion influx, which was partially attenuated by TRPV1 knockdown. RNA sequencing analysis indicated LIPUS-induced activation of the Notch pathway, phosphorylation of Akt and eNOS. Furthermore, inhibition or genetic silencing of Notch1 abolished the beneficial effects of LIPUS on angiogenesis, renal function, and Akt-eNOS phosphorylation in both cells and AKI rats. These findings suggest that LIPUS-induced calcium influx promotes Akt-eNOS phosphorylation, nitric oxide (NO) production, angiogenesis, and improved renal function in AKI via Notch1-Akt-eNOS signaling, positioning LIPUS as a promising therapeutic strategy for AKI by targeting vascular regeneration.

Comparing achievability and reproducibility of pulsed wave doppler and tissue doppler myocardial performance index and spatiotemporal image correlation annular plane systolic excursion in the cardiac function assessment of normal pregnancies.

Multiple techniques have been proposed for functional fetal cardiology, including pulsed-wave (PW) and tissue Doppler imaging (TDI), Myocardial Performance Index (MPI), annular plane systolic excursion (TAPSE/MAPSE) and spatiotemporal image correlation (STIC). We aimed to compare these techniques' achievability and reproducibility to determine their clinical utility for each cardiac side. Uncomplicated pregnancies from 22 to 39weeks were recruited and images and volumes stored for offline analysis. PWD-MPI values were calculated using previously demonstrated automation algorithms, and the remaining volumes were evaluated by two experienced operators. 79 women were scanned generating 222 volumes, with high achievability (>86 %) for all three modalities on both cardiac sides; highest for TAPSE/MAPSE (94 %). Repeatability (ICC) on the right side of the heart was highest for TAPSE (inter-observer 0.86; intraobserver 0.73), compared to PWD-MPI (0.69) and TDI-MPI (0.83). For the left side, repeatability was high for both PWD-MPI (0.80) and TDI-MPI (0.86) though low for MAPSE (inter-observer 0.7, intra-observer 0.69). There was poor correlation between PWD-MPI and TDI-MPI values. TAPSE appears most reliable for evaluation of right heart function, compared to PWD-MPI for the left. As TDI-MPI correlates poorly with PWD-MPI, the latter appears to be the functional tool of choice.

Obesity and metabolic syndrome in a diverse pediatric kidney transplant population: which anthropometric measure best predicts arterial stiffness?

Obesity and metabolic syndrome (MS) accelerate arterial stiffening, increasing cardiovascular (CV) risk after transplant. BMI is limited by inability to differentiate muscle, fat mass, and fat distribution patterns. The aim of this study was to identify the best anthropometric measure to detect arterial stiffness as assessed by pulse wave velocity (PWV) in a racially diverse pediatric transplant population. Kidney transplant recipients 6-20years old and ≥ 6months post-transplant were prospectively enrolled. PWV was measured oscillometrically by Mobil-O-Graph. Skeletal muscle-to-fat mass ratio (SM:FM) and percent body fat (PBF) were evaluated by dual-frequency bioelectrical impedance. BMI and waist-to-height ratio (WHR) were calculated. Associations of arterial stiffness (high PWV) with obesity and MS as defined by WHR, SM:FM, PBF, and BMI were evaluated. Participants (n = 67) were 15 (IQR 11, 18) years old and 39 (IQR 10, 68) months post-transplant. Participants with SM:FM-obesity (OR 3.2) and WHR-obesity (OR 3.0) had increased odds of high PWV (p = 0.04) while PBF-obesity (OR 2.6, p = 0.09) and BMI-obesity (OR 2.2, p = 0.17) were not significant. Participants with WHR-MS (OR 12.5, p = 0.02), SM:FM-MS (OR 5.2, p = 0.03), and PBF-MS (OR 5.0, p = 0.02) had increased odds of arterial stiffness, while BMI-MS was not significant (OR 3.7, p = 0.08). Obesity is associated with arterial stiffness in a racially diverse cohort of pediatric transplant recipients. Anthropometric measures that assess body fat distribution (WHR) and body composition (SM:FM) are more strongly associated with arterial stiffness than BMI. MS has a stronger association with arterial stiffness than obesity alone, particularly when WHR is used.

Parameter-Tuned Pulsed Wave Photobiomodulation Enhances Stem Cells From Apical Papilla Differentiation: Evidence From Gene and Protein Analyses.

This study examines the effects of pulsed wave photobiomodulation (pwPBM) on the osteogenic differentiation of stem cells from the apical papilla (SCAP). Using 810 nm near-infrared (NIR) light with 300 Hz pulses and a 30% duty cycle, pwPBM was applied at a total energy density of 750 mJ/cm2. Osteogenesis was evaluated through both invitro and invivo analyses. Invitro experiments demonstrated significant enhancement of alkaline phosphatase (ALP) activity, along with upregulation of key osteogenesis-related genes and proteins, as confirmed by real-time polymerase chain reaction (PCR) and Western blot analyses. Invivo, histological assessments following SCAP transplantation revealed increased bone tissue formation, further corroborated by osteocalcin staining. These findings underscore the potential of pwPBM as an innovative and effective tool for dental tissue regeneration and engineering.

Phase-dependent Hanbury-Brown and Twiss effect for the complete measurement of the complex coherence function

Hanbury-Brown and Twiss (HBT) effect is the foundation for stellar intensity interferometry. However, it is a phase insensitive two-photon interference effect. Here we extend the HBT interferometer by mixing intensity-matched reference fields with the input fields before intensity correlation measurement. With the freely available coherent state serving as the reference field, we experimentally demonstrate the phase sensitive two-photon interference effect when the input fields are thermal fields in either continuous wave or non-stationary pulsed wave and measure the complete complex second-order coherence function of the input fields without bringing them together from separate locations. Moreover, we discuss how to improve the signal level by using the more realistic continuous wave broadband anti-bunched light fields as the reference field. Our investigations pave the way for developing new technology of remote sensing and interferometric imaging with applications in long baseline high-resolution astronomy.

The Era of Risk Factors Should End; the Era of Biologic Age Should Begin

Introduction: Risk factors, a 75-year-old concept, are instrumental in the management of the general population. Newer biomarkers can explain residual risk and protection from risk. The population needs a new platform to make more comprehensible the importance of managing risk. Biologic age, the number of years left to live, is the platform that will receive the attention of patients. Method: Risk factor odds ratios are used to approximate the years lost to the modifiable risk, calculating a biologic age. Newer biomarkers confirm the predication and can be used to explain the pleomorphic properties of medications and unrealized risk. The biomarkers represent the following biologic processes: repair, inflammation, immune function, hematologic, clotting factors, metabolic-nutritional, organ maintenance, anthropomorphic, environmental, endothelial function, sleep, co-morbidities, frailty, and electromagnetic. Risk factors and biomarkers are ranked in the order of significance in reducing biologic age. Results: A six-step method of patient management using biologic age and biomarkers is presented. Conclusions: Knowledge of risk factors and therapies to improve risk has increased over the last 75 years. Biologic age is more appropriate in explaining the significance of this knowledge and may improve patient compliance to lifestyle changes and medication compliance. Appropriate counseling with utilization of biomarkers of biologic processes, such as high sensitivity-CRP, circulating stem cells, number of co-morbidities, frailty, electrocardiogram, and pulse wave velocity will improve compliance and personalize care. The 6-minute walk should be incorporated into the vital signs due to prognostic significance.

Adaptable Blueprint for Non-metal Near-Infrared Organic Photocatalysts by Aromatic Sulfones.

We present a versatile approach to designing and utilizing high-performance nonmetal near-infrared (NIR) organic photocatalysts based on aromatic sulfones. Current NIR photocatalysts are mainly metal complexes and inorganic materials, while the few reported nonmetal organic NIR photocatalysts primarily use photosensitization to produce active species such as singlet oxygen. Our sulfone-rosamine-based redox photocatalyst 3 demonstrates exceptional capabilities, including high ability for metal-free photo-oxidative bromination, intrinsically oxygen-independent redox reactions, and remarkable photostability with a turnover number (TON) exceeding 2800. We showcase the photocatalyst's efficacy in photo-oxidative bromination of aromatic compounds under 738 nm illumination. The reaction mechanism is elucidated through electrochemical studies, time-resolved spectral measurements, and DFT calculations. Transient absorption measurements using the randomly interleaved pulse train (RIPT) method reveal the photoexcited state of 3 in the reaction. The photocatalyst 3 demonstrated its versatility for several aromatic substances, including those exhibiting strong light absorption in the visible region. This aromatic sulfone-based approach offers a robust blueprint for developing nonmetal NIR organic photocatalysts with superior photo-oxidation ability and stability, addressing key limitations of conventional organic NIR photocatalysts.

Advanced Triboelectric Nanogenerator Sensing Technologies for High‐Efficiency Cardiovascular Monitoring

Triboelectric nanogenerators (TENGs) have emerged as transformative technologies in biosensing, offering unprecedented energy efficiency and precision in monitoring vital physiological signals. This review delves into the cutting‐edge advancements in TENG sensors, highlighting their exceptional potential in bioengineering applications. Key operating mechanisms and advanced materials are explored, with a focus on their impact on sensor sensitivity, durability, and biocompatibility. Cardiovascular monitoring is presented as a pivotal application, where TENG sensors demonstrate exceptional capability in detecting subtle mechanical signals such as pulse waves and heartbeats in real time. Their self‐powered nature eliminates the need for external energy sources, and their inherent scalability and adaptability make them ideal for integration into wearable or implantable devices. Benefits such as miniaturization, energy efficiency, and biocompatibility are discussed, alongside challenges like material fatigue and long‐term stability in biomedical environments. Future directions include optimizing TENG materials for enhanced mechanical robustness and expanding their integration into advanced medical diagnostics. This review provides a comprehensive roadmap for leveraging TENG technologies to revolutionize continuous cardiovascular monitoring and broader medical applications.

Effects of continuous positive airway pressure treatment on arterial stiffness and inflammatory factors in patients with coronary heart disease complicated with obstructive sleep apnea

BackgroundContinuous Positive Airway Pressure (CPAP) treatment brings more benefits than risks to most coronary heart disease (CHD) patients with obstructive sleep apnea (OSA). However, the pathophysiological mechanism by which CPAP treatment improves the prognosis of patients with CHD and OSA remains unclear. The purpose of this study was to clarify whether CPAP can improve arterial stiffness and inflammatory factor levels in CHD patients with OSA, and to further improve prognosis.Method59 patients with coronary heart disease complicated by moderate to severe sleep apnea were divided into a CPAP treatment group (CPAP + coronary heart disease standard treatment) and a control group (only coronary heart disease standard treatment). Peripheral blood test reports were collected and pulse wave velocity (PWV) measurements were performed for each patient at the beginning, 3 months, and 6 months of treatment.ResultsAfter 6 months of treatment, the CPAP group showed more significant improvement in the levels of inflammatory factors such as white blood cell (WBC), neutrophil (N), C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin (PCT), and PWV than the control group.ConclusionAfter active treatment with CPAP, arterial stiffness and inflammatory cytokine levels in patients with coronary heart disease and OSA improved. This association should be given more attention in clinical practice, and sleep apnea should be actively treated.

Evolution of arterial stiffness and association with cardiovascular risk factors in the Spanish population. Follow-up EVA.

To analyse the increase of arterial stiffness over a five-year period and its relationship with cardiovascular risk factors and sex-based differences in a Spanish population without cardiovascular disease. Longitudinal study. Analysis of the increase in arterial stiffness measures evaluated with SphygmoCor and Vasera of 480 subjects followed for 5 years of the 501 subjects included in the baseline evaluation, selected through random sampling stratified by age and sex, mean age of 55.9 years, 50.3% women. Increases per year: carotid-femoral pulse wave velocity (cf-PWV), 0.22 (SD 0.36) m/sec, brachial-ankle pulse wave velocity (ba-PWV), 0.18 (SD 0.30) m/sec, Cardio-Ankle Vascular Index (CAVI), 0.04 (SD 0.18) and Central Augmentation Index (CAI), 0.38 (SD 2.66). Multiple regression, increases in cf-PWV and ba-PWV showed an association with mean arterial pressure in global (β=0.02; β=-0.02) and in men (β=0.02; β=-0.03). In women, increases in ba-PWV and CAVI showed a negative association with BMI (β=-0.06; β=--0.03). The four measures of arterial stiffness increase over five years globally and by sex. These increases differ according to the measure used, age, sex and associated cardiovascular risk factors. Hypertensive people has greater increases in ba-PWV in global and by sex. The average blood pressure is associated with increases in cf-PWV and ba-PWV in global and in men. BMI is negatively associated with increases in ba-PWV and CAVI in women. Study registered at ClinicalTrials.gov. (NCT02623894).

Metal Powder Production by Atomization of Free-Falling Melt Streams Using Pulsed Gaseous Shock and Detonation Waves

A new method of producing metal powders for additive manufacturing by the atomization of free-falling melt streams using pulsed cross-flow gaseous shock or detonation waves is proposed. The method allows the control of shock/detonation wave intensity (from Mach number 4 to about 7), as well as the composition and temperature of the detonation products by choosing proper fuels and oxidizers. The method is implemented in laboratory and industrial setups and preliminarily tested for melts of three materials, namely zinc, aluminum alloy AlMg5, and stainless steel AISI 304, possessing significantly different properties in terms of density, surface tension, and viscosity. Pulsed shock and detonation waves used for the atomization of free-falling melt streams are generated by the pulsed detonation gun (PDG) operating on the stoichiometric mixture of liquid hydrocarbon fuel and gaseous oxygen. The analysis of solidified particles and particle size distribution in the powder is studied by sifting on sieves, optical microscopy, laser diffraction wet dispersion method (WDM), and atomic force microscopy (AFM). The operation process is visualized by a video camera. The minimal size of the powders obtained by the method is shown to be as low as 0.1 to 1 μm, while the maximum size of particles exceeds 400–800 μm. The latter is explained by the deficit of energy in the shock-induced cross-flow for the complete atomization of the melt stream, in particular dense and thick (8 mm) streams of the stainless-steel melt. The mass share of particles with a fraction of 0–10 μm can be at least 20%. The shape of the particles of the finest fractions (0–30 and 30–70 μm) is close to spherical (zinc, aluminum) or perfectly spherical (stainless steel). The shape of particles of coarser fractions (70–140 μm and larger) is more irregular. Zinc and aluminum powders contain agglomerates in the form of particles with fine satellites. The content of agglomerates in stainless-steel powders is very low. In general, the preliminary experiments show that the proposed method for the production of finely dispersed metal powders demonstrates potential in terms of powder characteristics.

Associations of Central Arterial Stiffness With Brain White Matter Integrity and Gray Matter Volume in MRI Across the Adult Lifespan.

Central arterial stiffening is associated with brain white matter (WM) damage and gray matter (GM) volume loss in older adults, but little is known about this association from an adult lifespan perspective. To investigate the associations of central arterial stiffness with WM microstructural organization, WM lesion load, cortical thickness, and GM volume in healthy adults across the lifespan. This is a cross-sectional study. A total of 173 healthy adults (22-81 years) were included in this study. 3-T, T1-weighted magnetization prepared rapid gradient echo (MPRAGE), single-shot echo-planar imaging diffusion-weighted, and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences. The participants underwent measurements of central arterial stiffness using carotid-femoral pulse wave velocity (cfPWV), diffusion tensor imaging (DTI) to measure whole-brain WM microstructural organization with free water (FW) and FW-corrected fractional anisotropy (FACOR), FLAIR to measure whole-brain WM hyperintensities (WMH), and MPRAGE to measure whole-brain cortical thickness and GM volume. The associations of age and cfPWV with MRI measures were assessed. Linear regression models to examine the associations of brain WM and GM measures with age, cfPWV, and age × cfPWV interaction after adjusting for sex, education, and intracranial volume (ICV) (voxel-wise and cluster threshold P < 0.05). To understand the direction of the interaction result, the sample was stratified into lower and higher cfPWV groups using a median split of cfPWV. Age × cfPWV interactions were observed in WM FW, WMH volume, cortical thickness, and GM volume (P < 0.01) such that the positive regression slopes between age, FW, and WMH volume were higher, while the negative regression slopes between age, cortical thickness, and GM volume were lower in those who had higher cfPWV relative to those who had lower cfPWV. Central arterial stiffening may accelerate the age-related deteriorations in GM and WM structure across the adult lifespan. Central arterial stiffening is associated with brain white matter (WM) damage and gray matter (GM) volume loss in older adults. We extended this investigation into an adult lifespan perspective by examining the associations of central arterial stiffening with brain structure in adults across age. A total of 172 healthy adults (22-81 years) underwent central arterial stiffening measure using applanation tonometry and brain measurement using MRI. We observed that higher central arterial stiffening may accelerate the age-related deterioration in brain WM and GM structure. These results suggest the importance of maintaining vascular health to slow age-related brain structural changes from an adult lifespan perspective. 4 TECHNICAL EFFICACY: Stage 5.

Prediction of Aneurysm Sac Shrinkage After Endovascular Aortic Repair Using Machine Learning-Based Decision Tree Analysis.

A simple risk stratification model to predict aneurysm sac shrinkagein patients undergoing endovascular aortic repair (EVAR) for abdominal aortic aneurysms (AAA) was developed using machine learning-based decision tree analysis. One hundred nineteen patients with AAA who underwent elective EVAR at Tokyo Medical University Hospital between November 2013 and July 2019 were included in the study. Predictors of aneurysm sac shrinkage identified in univariable analysis (P<0.05) were entered into the decision tree analysis. Univariable analysis revealed significant differences between patients with and without aneurysm sac shrinkage in the variables of age (<75 y or ≥75y), current smoking, operative type II endoleak, and preoperative pulse wave velocity (PWV) (<1800cm/s or ≥1800cm/s). The decision tree showed that preoperative PWV was the most relevant predictor, followed by operative type II endoleak and current smoking, and identified 6 terminal nodes with likelihoods of aneurysm sac shrinkage ranging from 5.6% to 63.6%. We established a decision tree model with 3 variables (preoperative PWV, operative type II endoleak, and current smoking) to predict aneurysm sac shrinkage in patients undergoing EVAR for AAA. This classification model may help identify patients with a high or low likelihood of aneurysm sac shrinkage.

Comparative Effects of Different Exercise Types on Cardiovascular Health and Executive Function in Sedentary Young Individuals.

The present study aimed to compare the impacts of different exercise types on cardiovascular health and executive function in sedentary young individuals, and to determine the associations between cardiovascular function and executive function (EF) after exercise. Sixty-three sedentary participants were randomly divided into high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), resistance exercise (RE), and control groups. Macro- and microvascular endothelial function were assessed using brachial artery flow-mediated dilation and fingertip reactive hyperemia index, respectively. Arterial stiffness was evaluated through carotid-femoral pulse wave velocity, ankle-brachial index, and augmentation index. EF performance was evaluated using the Stroop and N-back tasks. Functional near-infrared spectroscopy was employed to measure cortical activation and real-time oxyhemoglobin concentration (Oxy-Hb) changes in different cerebral regions. Key circulating biomarkers for vascular and cognitive function, including BDNF, irisin, VEGF, IGF-1, and TNF-α, were measured using enzyme-linked immunosorbent assays. Eight weeks of HIIT, MICT, and RE effectively improved macro- and microvascular endothelial function while reducing arterial stiffness in sedentary young individuals. Furthermore, exercise-induced increase in BDNF level was correlated with enhanced macrovascular endothelial function, while increase in IGF-1 level was associated with enhanced microvascular endothelial function and reduced arterial stiffness. Notably, both HIIT and MICT, but not RE, efficiently enhanced Oxy-Hb level in certain brain regions, such as the FPA and DLPFC, leading to the improvement in EF performance. Exercise-induced increase in Oxy-Hb level and EF performance were correlated with enhanced BDNF level and endothelial function and reduced arterial stiffness. Our study demonstrated that 8 weeks of HIIT, MICT, and RE effectively improved endothelial function in both macro- and microvessels, and arterial stiffness among sedentary young individuals. However, HIIT and MICT, but not RE, notably increased blood oxygen level in the FPA and DLPFC brain regions and improved EF performance. Due to the efficiency and time-saving features of HIIT, the present study highlights HIIT as an effective exercise prescription for promoting vascular and EF in sedentary young individuals. Importantly, the observed improvements in cardiovascular function following exercise training is pivotal in improving EF, and elevated circulating levels of biomarkers like BDNF and IGF-1, induced by exercise, are involved in the regulatory mechanisms.

Transspinal stimulation downregulates flexion reflex pathways during walking in healthy humans.

The phase-dependent modulation pattern of the tibialis anterior (TA) flexion reflex was characterized during treadmill walking while transspinal stimulation was delivered at 15, 30, and 50 Hz above and below paresthesia in healthy participants. The flexion reflex was elicited following medial arch foot stimulation with a 30 ms (300 Hz) pulse train. During treadmill walking, the flexion reflex was evoked in the right leg every 3 to 5 steps, and stimuli were randomly dispersed across the step cycle that was divided into 16 equal bins. For each participant, condition and bin of the step cycle, the flexion reflex was measured as the area of the linear EMG envelope starting 20 ms after the end of the pulse train up to 200 ms and was normalized to the maximum locomotor TA EMG activity. The unconditioned flexion reflex was modulated in a phase-dependent manner. Transspinal stimulation, regardless frequency, or intensity produced pronounced flexion reflex depression during walking that coincided with an unchanged slope and intercept, computed from the linear relationship between the flexion reflex and background EMG activity. These findings suggest that transspinal stimulation above and below paresthesia intensities at 15, 30, and 50 Hz downregulates the flexion reflex. Based on our recently reported absent effects on the soleus H-reflex under similar conditions and our current findings we propose that transspinal stimulation downregulates flexion and not extension reflex pathways. More research is needed to delineate whether similar neuromodulation effects are present in flexion and extension reflexes after spinal cord injury in humans.