Heart Rate Variability, Deceleration Capacity of Heart Rate, and Death: A Veteran Twins Study.

BACKGROUND: Autonomic function can be measured noninvasively using heart rate variability (HRV), which indexes overall sympathovagal balance. Deceleration capacity (DC) of heart rate is a more specific metric of vagal modulation. Higher values of these measures have been associated with reduced mortality risk primarily in patients with cardiovascular disease, but their significance in community samples is less clear. METHODS AND RESULTS: This prospective twin study followed 501 members from the VET (Vietnam Era Twin) registry. At baseline, frequency domain HRV and DC were measured from 24-hour Holter ECGs. During an average 12-year follow-up, all-cause death was assessed via the National Death Index. Multivariable Cox frailty models with random effect for twin pair were used to examine the hazard ratios of death per 1-SD increase in log-transformed autonomic metrics. Both in the overall sample and comparing twins within pairs, higher values of low-frequency HRV and DC were significantly associated with lower hazards of all-cause death. In within-pair analysis, after adjusting for baseline factors, there was a 22% and 27% lower hazard of death per 1-SD increment in low-frequency HRV and DC, respectively. Higher low-frequency HRV and DC, measured during both daytime and nighttime, were associated with decreased hazard of death, but daytime measures showed numerically stronger associations. Results did not substantially vary by zygosity. CONCLUSIONS: Autonomic inflexibility, and especially vagal withdrawal, are important mechanistic pathways of general mortality risk, independent of familial and genetic factors.

Prognostic value of cardiac deceleration capacity in patients with atrial fibrillation after catheter ablation: A systematic review and meta-analysis.

INTRODUCTION: Cather ablation (CA) is a well-recognized treatment alternative for atrial fibrillation (AF) patients despite more than 20% ablation-treated patients suffering from AF recurrence. The underlying mechanism of AF recurrence postablation is probably associated with high cardiac parasympathetic activity, which can be assessed with deceleration capacity (DC) of heart rate. Given that the relationship between DC and AF recurrence is still controversial, this systematic review and meta-analysis was performed to investigate the characteristics of DC in patients with and without AF recurrence, evaluating the prognostic value of DC in AF patients after CA. METHODS: A literature search was systematically performed in the Embase, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases until October 01, 2023. The observational studies reporting either the pre- and postablation DC in both recurrence and non-recurrence groups or the ratios based on DC for predicting AF recurrence were mainly included. Weighted mean differences (WMD) or odds ratios (OR) based on DC would be calculated with a random-effect model, if heterogeneity estimated with the I2 index and Q statistic was significant (I2 > 50% or p < .05); otherwise, a fixed-effect model would be utilized. RESULTS: A total of eight observational studies involving 914 AF patients treated with radiofrequency or cryoballoon ablation were included in this study. Ablation-treated patients with AF recurrence had the higher DC postablation in relation to those without recurrence (WMD, 1.00; 95% confidence interval [CI], 0.33-1.67; p < .01), which was present up to 3 months of follow-up (WMD, 1.54; 95% CI, 1.11-1.96; p < .01), whereas there was no statistical significance in DC before ablation between recurrence and non-recurrence groups (WMD, 0.34; 95% CI, -0.12 to 0.79; p = .15). The high DC postablation was a risk factor for AF recurrence in ablation-treated patients (OR, 2.17; 95% CI, 1.44-3.25; p < .01). CONCLUSION: The high DC postablation was associated with the risk of AF recurrence, suggesting that DC may act as a prognostic indicator in AF patients treated with CA.

Assessing the reliability of biomechanical variables during a horizontal deceleration task in healthy adults.

Horizontal deceleration technique is an underpinning factor to musculoskeletal injury risk and performance in multidirectional sport. This study primarily assessed within- and between-session reliability of biomechanical and performance-based aspects of a horizontal deceleration technique and secondarily investigated the effects of limb dominance on reliability. Fifteen participants completed four horizontal decelerations on each leg during test and retest sessions. A three-dimensional motion analysis system was used to collect kinetic and kinematic data. Completion time, ground contact time, rate of horizontal deceleration, minimum centre of mass height, peak eccentric force, impulse ratio, touchdown distance, sagittal plane foot and knee angles at initial contact, maximum sagittal plane thorax angle, and maximum knee flexion moment were assessed. Coefficients of variation (COV) and intraclass correlation coefficients (ICC) were used to assess within- and between-session reliability, respectively. Seven variables showed "great" within-session reliability bilaterally (COV ≤9.13%). ICC scores were 'excellent' (≥0.91; n = 4), or 'good' (0.76-0.89; n = 7), bilaterally. Limb dominance affected five variables; three were more reliable for the dominant leg. This horizontal deceleration task was reliable for most variables, with little effect of limb dominance on reliability. This deceleration task may be reliably used to assess and track changes in deceleration technique in healthy adults.

Conditions of acceleration and deceleration of the cancer cell growth under osmotic pressure.

In this paper, we study a pattern formation in the epidermal layer of skin during tumor development and appearance of a binary surface consisting of healthy and cancer cells forming Turing patterns under external osmotic pressure. The basic methodology of introducing the external influences, for example, time-targeted drug therapy or radiation exposure, influence of electromagnetic fields, laser radiation or other tumor-targeting physical influences act differently in different phases of the cell cycle. In some cases, this can lead to a slowdown in the growth of cancer cells, and sometimes vice versa. Therefore, it is of particular interest to choose the right parameters such as starting time of external pressure, its magnitude and duration depending on the cell cycle of developing cancer cells. We propose a biologically inspired model that allows us to simulate the growth of cancer cells under conditions of osmotic pressure. We divide this growth into two phases. The first is characterized by active cell division, and the second by their growth. In this article, we introduce two types of pressure: short-term and long-term, and looked at what this leads to in different phases. We have found an interesting result, that there are some resonant points in time both in the first and second phases, when the introduction of additional pressure leads to the most significant slowdown in the growth of cancer cells.

Protein Deceleration and Sequencing Using Si3N4-CNT Hybrid Nanopores.

Protein sequencing is crucial for understanding the complex mechanisms driving biological functions and is of utmost importance in molecular diagnostics and medication development. Nanopores have become an effective tool for single molecule sensing, however, the weak charge and non-uniform charge distribution of protein make capturing and sensing very challenging, which poses a significant obstacle to the development of nanopore-based protein sequencing. In this study, to facilitate capturing of the unfolded protein, highly charged peptide was employed in our simulations, we found that the velocity of unfolded peptide translocating through a hybrid nanopore composed of silicon nitride membrane and carbon nanotube is much slower compared to bare silicon nitride nanopore, it is due to the significant interaction between amino acids and the surface of carbon nanotube. Moreover, by introducing variations in the charge states at the boundaries of carbon nanotube nanopores, the competition and combination of the electrophoretic and electroosmotic flows through the nanopores could be controlled, we then successfully regulated the translocation velocity of unfolded proteins through the hybrid nanopores. The proposed hybrid nanopore effectively retards the translocation velocity of protein through it, facilitates the acquisition of ample information for accurate amino acid identification.

Ideal 24-h physical activity trajectory reduces all-cause, cause-specific mortality and cardiovascular outcomes through aging deceleration and inflammation regulation: A UK biobank study.

BACKGROUND: Physical activity (PA) is associated with mortality and cardiovascular disease (CVD). However, the effect of circadian PA trajectories remains ambiguous. This study aimed to explore ideal circadian PA patterns to reduce mortality and CVD, and potential mediators. METHODS: 502,400 participants from UK Biobank were recruited between 2006 and 2010. Among them, 102,323 participants got valid continuously capturing acceleration data over 7 days by wrist-worn accelerometer. K-means cluster analysis was used to identify PA trajectories. The associations of PA with all-cause, cause-specific mortality and CVD were assessed by cox regression. A sensitivity test was also conducted, starting from the time of acceleration collection and excluding participants with corresponding disease prior to it. Furthermore, the mediation of aging and inflammation were explored. RESULTS: During a median follow-up of 12.9 years, 3482 deaths were recorded (704 were due to CVD). Five distinct PA trajectories were identified: Persistently Low, Moderate and Stable, Single Increase, Double Increase, and Vigorous patterns. Ideal PA trajectory patterns offered progressively protective benefits against all-cause, CVD caused mortality and CVD, especially in Double Increase and Vigorous patterns. Other cause-specific mortality and renal failure incidence showed similar trend. The sensitivity result was consistent. The mediating effects of phenotypic age and inflammation markers were statistically significant. CONCLUSION: Ideal PA trajectories offered protective benefits against all-cause, cause-specific mortality and CVD. The protection was associated with both intensity and circadian distribution. Double Increase and Vigorous activity patterns decreased these risks more significantly. Crucially, this protection was mediated by aging deceleration and inflammation regulation.

Impact Deceleration Differences on Natural Grass Versus Synthetic Turf High School Football Fields.

American football has the highest rate of concussions in United States high school sports. Within American football, impact against the playing surface is the second-most common mechanism of injury. The objective of this study was to determine if there is a difference in impact deceleration between natural grass and synthetic turf high school football fields. A Century Body Opponent Bag (BOB) manikin was equipped with a Riddell football helmet and 3 accelerometers were placed on the forehead, apex of the head, and right ear. The manikin was dropped from a stationary position onto its front, back, and left side onto natural grass (n = 10) and synthetic turf (n = 9) outdoor football fields owned and maintained by public and private institutions on O'ahu, Hawai'i. Data was collected on 1,710 total drops. All accelerometers in forward and backward falls, and 1 accelerometer in side falls showed significantly greater impact deceleration on synthetic turf compared to the natural grass surfaces (P < .05). The results of this study provide evidence-based rationale to inform youth sports policies, particularly those aimed at injury prevention through safer playing environments and equipment.

Error-related cardiac deceleration: Functional interplay between error-related brain activity and autonomic nervous system in performance monitoring.

Coordinated interactions between the central and autonomic nervous systems are crucial for survival due to the inherent propensity for human behavior to make errors. In our ever-changing environment, when individuals make mistakes, these errors can have life-threatening consequences. In response to errors, specific reactions occur in both brain activity and heart rate to detect and correct errors. Specifically, there are two brain-related indicators of error detection and awareness known as error-related negativity and error positivity. Conversely, error-related cardiac deceleration denotes a momentary slowing of heart rate following an error, signaling an autonomic response. However, what is the connection between the brain and the heart during error processing? In this review, we discuss the functional and neuroanatomical connections between the brain and heart markers of error processing, exploring the experimental conditions in which they covary. Given the current limitations of available data, future research will continue to investigate the neurobiological factors governing the brain-heart interaction, aiming to utilize them as combined markers for assessing cognitive control in healthy and pathological conditions.

Acute vertical deceleration injury: A case of cranial impalement.

In forensic science and in modern times, impalement is a rare event. When this occurrence involves the head, it is even more unusual since this region is very small compared to the rest of the body. Although impalements are rare, they represent scenarios that must be treated with great care by forensic pathologists. They may involve a mixture of blunt and penetrating wounds, and the injuries observed at autopsy must be interpreted correctly. For this reason, if possible, the interconnection between the body and the impaling object should be maintained until the autopsy table. In this report, it is presented a case of cranial penetrating trauma that occurred after a suicidal fall from a great height with impact on the railing below, by reporting both the on-site scene inspection and autopsy data. The critical forensic issues that may arise in the practical management of such cases are discussed, starting from the fact that there is still no clear and unambiguous definition of impalement.

Cardiac deceleration capacity is associated with severity of inflammation in COVID-19.

PURPOSE: In this pilot study, we investigated the cardiac autonomic activity of coronavirus disease 2019 (COVID-19)-infected hospitalized patients. COVID-19 is characterized by cough, fever, and dyspnea, which in some severe cases can lead to hypoxia, respiratory failure, and shock. Since breathing disorders and pulmonary diseases are tightly linked to autonomic dysfunction, we analyzed the cardiac autonomic activity by measuring the deceleration capacity (DC) in COVID-19 patients. METHODS: In 14 adults (4 men and 10 women) with a median age of 63.5 years and positive for SARS-CoV-2 by polymerase chain reaction (PCR) with severe symptoms requiring hospital treatment, a high-resolution digital 30 min electrocardiogram (ECG) in Frank leads configuration was performed in a resting supine position within the first 48 h after hospital admission. DC was assessed using validated software and associated with several markers of inflammation and clinical course. RESULTS: The study revealed a significant association between reduced DC (≤ 2.5 ms) and older age (74 years) in COVID-19 patients, compared to those with a higher DC > 2.5 ms (56.5 years). However, the duration of hospitalization was similar for both groups. There was a nonsignificant trend towards a higher maximum viral load in patients with reduced DC. Further, patients with a DC ≤ 2.5 ms showed higher levels of inflammatory markers such as C-reactive protein (CRP) and procalcitonin (PCT), as well as leukocytosis, compared to patients with a DC > 2.5 ms. Also, the COVID-19-severity marker ferritin was significantly elevated in patients with lower DC. Other markers associated with COVID-19, such as lactate dehydrogenase (LDH) and creatine kinase (CK), exhibited comparable levels in both groups. CONCLUSIONS: Reduced DC (≤ 2.5 ms) was significantly associated with older age, increased inflammatory markers, and elevated ferritin in patients with COVID-19. These findings suggest that DC might serve as a valuable indicator for predicting the risk of severe inflammation in COVID-19 and possibly complications associated with this disease, such as heart failure. Further studies are needed to confirm these observations and clarify the clinical significance of DC in COVID-19 and other infectious diseases.

A novel automated peak frequency annotation algorithm for identifying deceleration zones and ventricular tachycardia ablation sites.

BACKGROUND: Current annotation of local fractionated signals during ventricular electroanatomic mapping (EAM) requires manual input subject to variability and error. OBJECTIVES: The purpose of this study was to evaluate a novel peak frequency (PF) annotation software for its ability to automatically detect late potentials (LPs) and local abnormal ventricular activity (LAVA), determine an optimal range for display, and assess its impact on isochronal late activation mapping (ILAM). METHODS: EAM data from 25 patients who underwent ventricular tachycardia (VT) ablation were retrospectively analyzed. Samplings of electrogram PFs from areas of normal bipolar voltage, areas of low voltage, and areas of low voltage with fractioned signals were performed. An optimal range of frequency display was identified from these patients and applied to a validation cohort of 10 prospective patients to assess high PF within scar as a predictor of VT ablation target sites, in particular deceleration zones (DZs) identified by ILAM, LP, and LAVA. RESULTS: Voltage and PF ranges of normal endocardial tissue varied widely. Using 220 Hz as a frequency cutoff value in areas of low bipolar voltage, areas of high fractionation were identified with sensitivity of 91% and specificity of 85% There was no significant reduction in targeted DZ surface areas, and colocalization with DZs was observed in all cases. Applied to the prospective cohort, PF predicted fractionated areas and DZ in 9 of 10 patients. CONCLUSION: A PF annotation algorithm with a cutoff of 220 Hz accurately identifies areas of fractioned signals and accurately predicts DZs during ILAM.

Deceleration Profiles Between the Penultimate and Final Steps of Planned and Reactive Side-Step Cutting.

CONTEXT: Noncontact anterior cruciate ligament injury often occurs during rapid deceleration and change-of-direction maneuvers. These activities require an athlete to generate braking forces to slow down the center of mass and change direction in a dynamic environment. During preplanned cutting, athletes can use the penultimate step for braking before changing direction, resulting in less braking demand during the final step. During reactive cutting, athletes use different preparatory movement strategies during the penultimate step when planning time is limited. However, possible differences in the deceleration profile between the penultimate and final steps of preplanned and reactive side-step cuts remain unknown. OBJECTIVE: To comprehensively evaluate deceleration during the penultimate and final steps of preplanned and reactive cutting. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirty-six women (age = 20.9 ± 1.7 years, height = 1.66 ± 0.07 m, mass = 62.4 ± 8.7 kg). INTERVENTION: Participants completed 90° side-step cutting maneuvers under preplanned and reactive conditions. MAIN OUTCOME MEASURE(S): Approach velocity, velocity at initial contact, and cutting angle were compared between conditions. Stance time, deceleration time, and biomechanical indicators of deceleration were assessed during the penultimate and final steps of preplanned and reactive 90° cuts. Separate repeated-measures analysis-of-variance models were used to assess the influence of step, condition, and their interaction on the biomechanical indicators of deceleration. RESULTS: Approach velocity (P = .69) and velocity at initial contact of the penultimate step (P = .33) did not differ between conditions. During reactive cutting, participants achieved a smaller cutting angle (P < .001). We identified a significant step-by-condition interaction for all biomechanical indicators of deceleration (P values < .05). CONCLUSIONS: A lack of planning time resulted in less penultimate step braking and greater final step braking during reactive cutting. As a result, participants exhibited a decreased cutting angle and longer stance time during the final step of reactive cutting. Improving an athlete's ability to respond to an external stimulus may facilitate a more effective penultimate step braking strategy that decreases the braking demand during the final step of reactive cutting.

Fracturas vertebrales causadas por reductores de velocidad o "lomos de burro" / Spinal fractures caused by speed bumps

Objetivo: Presentar una serie de casos de fracturas vertebrales en pasajeros de autobús asociadas al pasaje por reductores de velocidad. Materiales y métodos: Se realizó un estudio descriptivo y retrospectivo de una serie de casos de lesiones vertebrales torácicas y lumbosacras sufridas por pasajeros a causa del impacto del vehículo con reductores de velocidad. Se incluyó a pacientes tratados en dos instituciones, entre el 1 de enero de 2012 y el 1 de enero de 2023. Resultados: Se registraron 23 pacientes con lesiones vertebrales de la columna toraco-lumbosacra, 14 mujeres (60,9%) y 9 hombres (39,1%), promedio de la edad 43 años (DE ± 12; rango 25-62). Casi todos eran pasajeros (n = 22; 95,7%) que viajaban sentados en la última fila del autobús (n = 20; 86,5%). Un solo caso correspondía a un conductor del vehículo. Se documentaron 29 lesiones vertebrales, 28 fracturas toracolumbares (de T10 a L2; 96,6%) y una fractura de coxis (3,4%). La vértebra más comprometida fue L1 (n = 16; 55%). Las fracturas más graves (A3/A4) se asociaron con tratamiento quirúrgico (p = 0,007) y una mayor mediana de días de internación (p = 0,005). Conclusiones: Las lesiones vertebrales asociadas al impacto vehicular con reductores de velocidad son fracturas causadas por un mecanismo de compresión axial, más frecuentes en pasajeros ubicados en la última fila de asientos del autobús. Comprometen predominantemente la charnela toracolumbar y la vértebra fracturada con más frecuencia es L1 y exclusivamente uno de los platillos vertebrales. Nivel de Evidencia: IV

Objective: To present a case series of spinal fractures in bus passengers caused by passing over speed bumps. materials and methods: A descriptive and retrospective study of a case series of thoracic and lumbosacral spinal injuries suffered by passengers as a result of vehicle impacts with speed bumps was conducted. Patients treated at two institutions from January 1, 2012 to January 1, 2023 were included. Results: 23 patients with vertebral injuries of the thoracolumbosacral spine were recorded: 14 women (60.9%) and 9 men (39.1%), average age 43 years (SD±12; range=25-62). Almost all of the patients were passengers (n=22, 95.7%) sitting in the last row of seats on the bus (n=20, 86.5%). A single case was documented involving the vehicle's driver. 29 spinal injuries were recorded, 28 thoracolumbar fractures (from T10 to L2; 96.6%) and 1 coccyx fracture (3.4%). The most frequently involved vertebra was L1 (n=16; 55%). The most severe fractures (A3/A4) were associated with surgical treatment (p=0.007) and a longer median hospital stay (p=0.005). Conclusions: Spinal injuries during vehicular impact with speed bumps are caused by an axial compression mechanism, with greater involvement of passengers who are located in the last row of seats. They primarily affect the thoracolumbar joint, with the L1 vertebra and exclusively one of the vertebral endplates being fractured most frequently. Level of Evidence: IV

Using a penalized likelihood to detect mortality deceleration.

We suggest a novel method for detecting mortality deceleration by adding a penalty to the log-likelihood function in a gamma-Gompertz setting. This is an alternative to traditional likelihood inference and hypothesis testing. The main advantage of the proposed method is that it does not involve using a p-value, hypothesis testing, and asymptotic distributions. We evaluate the performance of our approach by comparing it with traditional likelihood inference on both simulated and real mortality data. Results have shown that our method is more accurate in detecting mortality deceleration and provides more reliable estimates of the underlying parameters. The proposed method is a significant contribution to the literature as it offers a powerful tool for analyzing mortality patterns.

Disección de aorta secundario a trauma, manejo clínico en Hospital General / Aortic dissection secondary to trauma, clinical management in General Hospital

INTRODUCCIÓN. La disección de aorta es una patología poco frecuente, cuando se presenta, lo hace de una manera catastrófica manifestada por dolor torácico o lumbar intenso acompañado de compromiso hemodinámico agudo, un diagnóstico y tratamiento temprano suelen ser cruciales para evitar la muerte del paciente, así mismo, una disección de aorta puede ser secundario a un trauma torácico por desaceleración y se presenta en 1,5% a 2%, lo que induce sobre todo a un desgarro localizado en la región del istmo aórtico. CASO CLÍNICO. Paciente masculino de 35 años, con antecedente de accidente en vehículo motorizado que provocó un traumatismo cráneo encefálico moderado, hematoma epidural parietal derecho, con resolución quirúrgica hace 18 meses, se descartó lesiones a nivel de tórax con radiografía de tórax normal, además se realizó ecografía FAST en ventana perihepática, suprapúbica, periesplénica y subxi-foidea sin encontrar alteración. Acudió al servicio de emergencia por un cuadro de hemiparesia derecha más disartria de 4 horas de evolución, se realiza tomografía de cráneo sin encontrarse lesión, catalogándose como evento cerebrovascular isquémico con recuperación neurológica. Durante su estancia hospitalaria presenta un cuadro de disnea de grandes esfuerzos y tras realizar exámenes complementarios de control se llega a una conclusión de una cardiomegalia, por lo que es referido a consulta de cardiología donde se realiza ecocardiograma, en la cual se observa disección de aorta ascendente más aneurisma por lo que se decide su ingreso y se instaura tratamiento mediante medidas de soporte, con derivación a hospital de especialidades para cirugía cardiotorácica. CONCLUSIONES. La disección de aorta secundario a un traumatis-mo es poco frecuente, sin embargo, el diagnostico siempre debe estar presente en caso de trauma por desaceleración, ya que es vital para la supervivencia del paciente y su manejo oportuno.

INTRODUCTION. Aortic dissection is an infrequent pathology; when it occurs, it does so in a catastrophic manner manifested by intense thoracic or lumbar pain accompanied by acute he-modynamic compromise. Early diagnosis and treatment are usually crucial to avoid the patient's death; likewise, aortic dissection can be secondary to thoracic trauma due to deceleration and occurs in 1.5% to 2%, which mainly induces a localized tear in the region of the aortic isthmus. CLINICAL CASE. 35-year-old male patient, with a history of motor vehicle accident that caused a moderate head injury, right parietal epidural hematoma, with surgical resolution 18 months ago, chest injuries were ruled out with normal chest X-ray, and FAST ultrasound was performed in perihepatic, suprapubic, perisplenic and subxiphoid window without finding any alteration. She went to the emergency department for a picture of right hemiparesis and dysarthria of 4 hours of evolution, a cranial tomography was performed without finding any lesion, being clas-sified as an ischemic cerebrovascular event with neurological recovery. During his hospital stay he presented with dyspnea of great effort and after performing complementary control tests, a cardiomegaly was found, so he is referred to a cardiology clinic where an echocardiogram is per-formed, which showed dissection of the ascending aorta plus aneurysm, admission is decided and treatment is instituted through supportive measures, with referral to a specialty hospital for cardiothoracic surgery. CONCLUSIONS. Aortic dissection secondary to trauma is rare, however, the diagnosis should always be present in case of trauma due to deceleration, as it is vital for the survival of the patient and its timely treatment.

Plasma myoglobin indicates muscle damage associated with acceleration/deceleration during football.

BACKGROUND: Monitoring muscle damage in athletes assists not only coaches to adjust the training workload but also medical staff to prevent injury. Measuring blood myoglobin concentration can help evaluate muscle damage. The novel portable device utilized in this study allows for easy on-site measurement of myoglobin, providing real-time data on the player's muscle damage. This study investigated the relationship between external load (global positioning system parameters) and internal loads (myoglobin concentration and creatine kinase activity) in 15 male professional football players before and after a match. METHODS: Whole blood samples from participants' fingertips were collected before the match (baseline) and at 2, 16, and 40 h after the match. Myoglobin concentrations were measured using the IA-100 compact immunoassay system. Creatine kinase concentrations were measured in a clinical laboratory, and match loads were monitored using a global positioning system device. RESULTS: The mean myoglobin concentration was significantly higher at 2 h than at the other time points (P<0.05), and decreased to baseline levels within 16 h post-match. The mean creatine kinase concentration increased after the match but did not reach a significant level. Muscle damage monitored by myoglobin after football match-play was strongly associated with acceleration/deceleration metrics rather than the sprint/high-speed running distance. CONCLUSIONS: Our findings indicate that myoglobin is a more sensitive marker of muscle damage than creatine kinase after football match-play. Monitoring myoglobin in athletes can aid in determining their recovery status from the previous training load and help practitioners manage the training load.

Change-of-Direction and Deceleration Deficits in National-Team Female Rugby Sevens Players: Interrelationships and Associations With Speed-Related Performance.

PURPOSE: To investigate the relationships between a series of direct and indirect measures of linear and multidirectional speed performance in elite female rugby sevens players. METHODS: Nineteen players from the Brazilian national team performed 40-m linear sprint and 505 change-of-direction (COD) tests on the same day. Based on the linear sprint and COD test performances, the COD deficit (CODD) and deceleration deficit (DD) were also obtained. A Pearson product-moment correlation analysis was used to determine the relationships between linear sprint and COD-derived variables. RESULTS: Linear sprint and 505 COD velocities were not significantly associated (P > .05). Large to very large significant associations (r values ranging from .54 to .78; P < .05) were detected between linear sprint velocity for the different distances tested (10, 15, 30, and 40 m) and CODD. The COD velocity presented a very large inverse significant correlation with CODD and DD (r = -.77 and -.79 respectively; P < .05). A large and significant correlation was identified between CODD and DD (r = .79; P < .05). CONCLUSIONS: Significant associations were observed between linear sprint and CODD, suggesting that faster players are less efficient at changing direction. No relationship was found between sprint velocity and DD, highlighting the independent nature of linear sprints and deceleration capabilities. A comprehensive and detailed analysis of multidirectional speed performance should consider not only linear sprint and COD performances but also complementary COD-derived variables such as the CODD and DD.

Driver Injury from Vehicle Side Impacts When Automatic Emergency Braking and Active Seat Belts Are Used.

As an advanced driver assistance system, automatic emergency braking (AEB) can effectively reduce accidents by using high-precision and high-coverage sensors. In particular, it has a significant advantage in reducing front-end collisions and rear-end accidents. Unfortunately, avoiding side collisions is a challenging problem for AEB. To tackle these challenges, we propose active seat belt pretensioning on driver injury in vehicles equipped with AEB in unavoidable side crashes. Firstly, records of impact cases from China's National Automobile Accident In-Depth Investigation System were used to investigate a scenario in which a vehicle is impacted by an oncoming car after the vehicle's AEB system is triggered. The scenario was created using PreScan software. Then, the simulated vehicles in the side impact were devised using a finite element model of the Toyota Yaris and a moving barrier. These were constructed in HyperMesh software along with models of the driver's side seatbelt, side airbag, and side curtain airbag. Moreover, the models were verified, and driver out-of-position instances and injuries were evaluated in simulations with different AEB intensities up to 0.7 g for three typical side impact angles. Last but not least, the optimal combination of seatbelt pretensioning and the timing thereof for minimizing driver injury at each side impact angle was identified using orthogonal tests; immediate (at 0 ms) pretensioning at 80 N was applied. Our experiments show that our active seatbelt with the above parameters reduced the weighted injury criterion by 5.94%, 22.05%, and 20.37% at impact angles of 90°, 105°, and 120°, respectively, compared to that of a conventional seatbelt. The results of the experiment can be used as a reference to appropriately set the collision parameters of active seat belts for vehicles with AEB.

Accuracy Improvement of Braking Force via Deceleration Feedback Functions Applied to Braking Systems.

Currently, braking control systems used in regional railways are open-loop systems, such as metro and tramways. Given that the performance of braking can be influenced by issues such as wheel sliding or the properties of the friction components present in brake systems, our study puts forward a novel closed-loop mechanism to autonomously stabilize braking performance. It is able to keep train deceleration close to the target values required by the braking control unit (BCU), especially in terms of the electrical-pneumatic braking transform process. This method fully considers the friction efficiency characteristics of brake pads and encompasses running tests using rolling stock. The test results show that the technique is able to stabilize the actual deceleration at a closer rate to the target deceleration than before and avoid wheel sliding protection (WSP) action, especially during low-speed periods.