Dinámica de golpeo y propiedades cinéticas de guantes de boxeo y de MMA

[ES] La creciente popularidad de las Artes Marciales Mixtas (MMA) como deporte competitivo ha suscitado preguntas sobre la respuesta dinámica y propiedades de los guantes de MMA. Los impactos de alta potencia de los puñetazos en MMA son muy similares a los del boxeo, pero en la competición de MMA se utilizan guantes de 4 onzas sin dedos, en contraste con los guantes de boxeo que son totalmente cerrados. Este estudio evaluó las propiedades cinéticas y la dinámica de golpeo del guante de MMA y comparó los resultados con los del guante de boxeo tradicional. Los guantes, montados en un puño moldeado, fueron golpeados repetidamente sobre un yunque instrumentado diseñado para los impactos durante un periodo de 5 horas en el que se realizaron 10.000 golpes continuos y consistentes. Los datos cinéticos de los impactos se muestrearon al principio de la toma de datos y seguidamente cada 30 minutos (cada 1.000 golpes). El guante de MMA produjo un pico de fuerza 4‐5 veces mayor, y un índice de carga 5 veces más rápido que los guantes de boxeo. También, el guante de MMA mostró síntomas de fatiga del material, con incrementos de la fuerza pico del 35% y del índice de carga del 60% a lo largo del test. Las características del guante de boxeo también se deterioraron pero en menor medida. En resumen, las propiedades cinéticas del guante de MMA se diferenciaron sustancialmente de las del guante de boxeo, resultando en impactos caracterizados por fuerzas pico más altas y un desarrollo de fuerza más rápido. Las propiedades del material, incluyendo la rigidez y el grosor, juegan un papel en las características cinéticas del impacto, y se puede deducir que alterarán los mecanismos de lesión producidos por traumatismos contundentes.[EN] With the growing popularity of Mixed Martial Arts (MMA) as a competitive sport, questions regarding the dynamic response and properties of MMA gloves arise. High‐energy impacts from punches are very similar to boxing yet MMA competition requires the use of 4 oz fingerless glove, compared to the larger full enclosure boxing glove. This work assessed the kinetic properties and strike dynamics of MMA gloves and compared findings with traditional boxing gloves. Gloves mounted on a molded fist were impacted repetitively on an instrumental anvil designed for impact, over a 5 hour period resulting in 10,000 continuous and consistent strikes. Kinetic data from impacts were sampled at the beginning of the data collection and subsequently every 30 minutes (every 1,000 strikes). MMA gloves produced 4‐5 times greater peak force and 5 times faster load rate compared to the boxing glove. However, MMA gloves also showed signs of material fatigue, with peak force increasing by 35% and rate of loading increasing by 60% over the duration of the test. Boxing glove characteristics did deteriorate but to a lesser extent. In summary, the kinetic properties of MMA glove differed substantially from the boxing glove resulting in impacts characterized by higher peak forces and more rapid development of force. Material properties including stiffness and thickness play a role in the kinetic characteristics upon impact, and can be inferred to alter injury mechanisms of blunt force trauma.[PT] A crescente popularidade das Artes Marciais Mistas (MMA), como desporto competitivo, tem suscitado questões sobre a dinâmica e as propriedades das luvas de MMA. Os impactos de alta potência dos socos em MMA são muito similares aos do boxe, mas na competição de MMA utilizam‐se luvas de 4 onças sem dedos, em contraste com as luvas do boxe que são totalmente fechadas. Este estudo analisou as propriedades cinéticas e a dinâmica dos socos das luvas de MMA e comparou os resultados com as luvas de boxe tradicional. As luvas, calçadas num punho moldado, foram golpeadas repetidamente sobre um aparelho instrumentalizado, desenhado para os impactos dos socos durante o período de 5 horas, em que se realizaram 10.000 socos contínuos e consistentes. Os dados cinéticos dos impactos foram recolhidos no início e seguidamente em cada 30 minutos (cada 1.000 golpes). As luvas de MMA produziram um pico de força 4‐5 vezes maior e um índice de carga 5 vezes mais rápido do que as luvas de boxe. As luvas de MMA mostraram também alguma fatiga do material, com incremento da força pico de 35% e no índice de carga de 60% no decurso do teste. As características das luvas de boxe também se deterioraram, mas em menor medida. Em resumo, as propriedades cinéticas das luvas de boxe de MMA diferenciaram‐se substancialmente das luvas de boxe, resultando impactos caracterizados por forças pico mais altas e o desenvolvimento de força mais rápida. As propriedades do material, incluindo a rigidez e a espessura, têm um papel fundamental nas características cinéticas do impacto. Pode‐se, assim, deduzir que se alteram os mecanismos de lesão produzidos pelos traumatismos contundentes

Activació dels músculs del tronc durant situacions que requereixen l’estabilització del raquis. Estudi de cas únic

L’objectiu d’aquest estudi va ser analitzar la intensitat de la contracció i la coordinació de 14 músculs del tronc i del muscle d’un subjecte durant la recepció i el llançament d’una pilota medicinal (acció pliomètrica), una acció d’embranzida en posició dempeus (pressió de pit horitzontal amb politja) i l’ús del Bodyblade® (barra flexible l'oscil·lació de la qual sotmet el cos a vibracions i desequilibris continus). Igualment, amb l'objecte de facilitar la discussió en relació amb l'estabilització activa del raquis, es va registrar la resposta dels músculs esmentats durant l'aplicació controlada sobre el tronc de càrregues i descàrregues desequilibrants. Els nostres resultats indiquen que l'activació dels músculs del tronc és important, tant per a estabilitzar el raquis davant pertorbacions i desequilibris sobtats, com per a l'execució d'accions on els membres superiors manegen objectes. En aquest sentit, la coactivació dels músculs del tronc va ser necessària per estabilitzar el raquis davant les oscil·lacions del Bodyblade® i davant les forces de reacció produïdes en empènyer una càrrega pesada en posició erecta. De la mateixa manera, la recepció i el llançament immediat de la pilota medicinal és una activitat relativament complexa que requereix l'acció coordinada dels músculs del tronc i de les extremitats

Employment and Disability Policy: the role of the psychologist

Persons with minor or major disabilities represent a significant portion of the U.S. working-age population. Based on the 1993 Survey of Income and Program Participation (SIPP), approximately 30 million (19%) men and women 18 to 64 years of age report some type of physical or mental limitation. For approximately 55% of these individuals (about 10% of those 18 to 64), the limitations are severe

Digital tracking algorithm reveals the influence of structural irregularities on joint movements in the human cervical spine

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.clinbiomech.2018.04.015 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Background Disc height loss and osteophytes change the local mechanical environment in the spine; while previous research has examined kinematic dysfunction under degenerative change, none has looked at the influence of disc height loss and osteophytes throughout movement. Methods Twenty patients with pain related to the head, neck or shoulders were imaged via videofluoroscopy as they underwent sagittal-plane flexion and extension. A clinician graded disc height loss and osteophytes as “severe/moderate”, “mild”, or “none”. A novel tracking algorithm quantified motions of each vertebra. This information was used to calculate intervertebral angular and shear displacements. The digital algorithm made it practical to track individual vertebrae in multiple patients through hundreds of images without bias. Findings Cases without height loss/osteophytes had a consistent increase in intervertebral angular displacement from C2/C3 to C5/C6, like that of healthy individuals, and mild height losses did not produce aberrations that were systematic or necessarily discernable. However, joints with moderate to severe disc height loss and osteophytes exhibited reduced range of motion compared to adjacent unaffected joints in that patient and corresponding joints in patients without structural irregularities. Interpretation Digitally-obtained motion histories of individual joints allowed anatomical joint changes to be linked with changes in joint movement patterns. Specifically, disc height loss and osteophytes were found to influence cervical spine movement in the sagittal plane, reducing angular motions at affected joints by approximately 10% between those with and without height loss and osteophytes. Further, these joint changes were associated with perturbed intervertebral angular and shear movements.Natural Sciences and Engineering Research Council (NSERC) Discovery Grant

Lower extremity joint kinetics and lumbar curvature during squat and stoop lifting

<p>Abstract</p> <p>Background</p> <p>In this study, kinematics and kinetics of the lower extremity joint and the lumbar lordosis during two different symmetrical lifting techniques(squat and stoop) were examined using the three-dimensional motion analysis.</p> <p>Methods</p> <p>Twenty-six young male volunteers were selected for the subjects in this study. While they lifted boxes weighing 5, 10 and 15 kg by both squat and stoop lifting techniques, their motions were captured and analyzed using the 3D motion analysis system which was synchronized with two forceplates and the electromyographic system. Joint kinematics was determined by the forty-three reflective markers which were attached on the anatomical locations based on the VICON Plug-in-Gait marker placement protocol. Joint kinetics was analyzed by using the inverse dynamics. Paired t-test and Kruskal-Wallis test was used to compare the differences of variables between two techniques, and among three different weights. Correlation coefficient was calculated to explain the role of lower limb joint motion in relation to the lumbar lordosis.</p> <p>Results</p> <p>There were not significant differences in maximum lumbar joint moments between two techniques. The hip and ankle contributed the most part of the support moment during squat lifting, and the knee flexion moment played an important role in stoop lifting. The hip, ankle and lumbar joints generated power and only the knee joint absorbed power in the squat lifting. The knee and ankle joints absorbed power, the hip and lumbar joints generated power in the stoop lifting. The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and the biceps femoris were found important for maintaining the straight leg during the stoop lifting. At the time of lordotic curvature appearance in the squat lifting, there were significant correlations in all three lower extremity joint moments with the lumbar joint. Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting.</p> <p>Conclusion</p> <p>In conclusion, the knee extension which is prominent kinematics during the squat lifting was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).</p

Lower extremity joint kinetics and lumbar curvature during squat and stoop lifting

<p>Abstract</p> <p>Background</p> <p>In this study, kinematics and kinetics of the lower extremity joint and the lumbar lordosis during two different symmetrical lifting techniques(squat and stoop) were examined using the three-dimensional motion analysis.</p> <p>Methods</p> <p>Twenty-six young male volunteers were selected for the subjects in this study. While they lifted boxes weighing 5, 10 and 15 kg by both squat and stoop lifting techniques, their motions were captured and analyzed using the 3D motion analysis system which was synchronized with two forceplates and the electromyographic system. Joint kinematics was determined by the forty-three reflective markers which were attached on the anatomical locations based on the VICON Plug-in-Gait marker placement protocol. Joint kinetics was analyzed by using the inverse dynamics. Paired t-test and Kruskal-Wallis test was used to compare the differences of variables between two techniques, and among three different weights. Correlation coefficient was calculated to explain the role of lower limb joint motion in relation to the lumbar lordosis.</p> <p>Results</p> <p>There were not significant differences in maximum lumbar joint moments between two techniques. The hip and ankle contributed the most part of the support moment during squat lifting, and the knee flexion moment played an important role in stoop lifting. The hip, ankle and lumbar joints generated power and only the knee joint absorbed power in the squat lifting. The knee and ankle joints absorbed power, the hip and lumbar joints generated power in the stoop lifting. The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and the biceps femoris were found important for maintaining the straight leg during the stoop lifting. At the time of lordotic curvature appearance in the squat lifting, there were significant correlations in all three lower extremity joint moments with the lumbar joint. Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting.</p> <p>Conclusion</p> <p>In conclusion, the knee extension which is prominent kinematics during the squat lifting was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).</p

Macrophage-derived Wnt opposes Notch signaling to specify hepatic progenitor cell fate in chronic liver disease

During chronic injury a population of bipotent hepatic progenitor cells (HPCs) become activated to regenerate both cholangiocytes and hepatocytes. Here we show in human diseased liver and mouse models of the ductular reaction that Notch and Wnt signaling direct specification of HPCs via their interactions with activated myofibroblasts or macrophages. In particular, we found that during biliary regeneration, expression of Jagged 1 (a Notch ligand) by myofibroblasts promoted Notch signaling in HPCs and thus their biliary specification to cholangiocytes. Alternatively, during hepatocyte regeneration, macrophage engulfment of hepatocyte debris induced Wnt3a expression. This resulted in canonical Wnt signaling in nearby HPCs, thus maintaining expression of Numb (a cell fate determinant) within these cells and the promotion of their specification to hepatocytes. By these two pathways adult parenchymal regeneration during chronic liver injury is promoted

Communication Research

Contains reports on nine research projects.Bell Telephone Laboratories, Incorporate

High blood pressure in school children: prevalence and risk factors

BACKGROUND: The purpose of this study was to determine the prevalence of high blood pressure (HBP) and associated risk factors in school children 8 to 13 years of age. METHODS: Elementary school children (n = 1,066) were examined. Associations between HBP, body mass index (BMI), gender, ethnicity, and acanthosis nigricans (AN) were investigated using a school based cross-sectional study. Blood pressure was measured and the 95(th )percentile was used to determine HBP. Comparisons between children with and without HBP were utilized. The crude and multiple logistic regression adjusted odds ratios were used as measures of association. RESULTS: Females, Hispanics, overweight children, and children with AN had an increased likelihood of HBP. Overweight children (BMI ≥ 85(th )percentile) and those with AN were at least twice as likely to present with HBP after controlling for confounding factors. CONCLUSION: Twenty one percent of school children had HBP, especially the prevalence was higher among the overweight and Hispanic group. The association identified here can be used as independent markers for increased likelihood of HBP in children

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy