Comparación de los niveles de activación de los músculos estabilizadores del core y agonistas durante la realización del ejercicio push up sobre equipamientos con diferentes grados de estabilidad

En los últimos años, provenientes del área de la rehabilitación, han aparecido en el sector del fitness multitud de implementos/equipamientos que basan su funcionamiento en la generación de inestabilidad para el practicante que los utiliza, estos se publicitan con la premisa de que mientras se realizan ejercicios en ellos, la activación de la musculatura del CORE es mucho mayor que sin ellos. De esta forma han surgido los comúnmente llamados materiales generadores de inestabilidad o desestabilizadores, pudiendo ser de muchos tipos. Los dispositivos de suspensión son concretamente un tipo de materiales inestables que han aparecido de manera aún más reciente y que se fundamentan en la desestabilización para la postura que provoca la realización de ejercicios mientras se está sujeto a unas cintas colgadas. Sin embargo son escasos los estudios que han medido objetivamente el nivel de intensidad que su uso aporta tanto en el CORE como en las extremidades en comparación con otros dispositivos tradicionales de inestabilidad que provocan la desestabilización por la deformación de su material al colocar total o parcialmente el peso corporal sobre él. El propósito del presente estudio descriptivo ha sido analizar mediante electromiografía superficial la activación muscular máxima y media del pectoral mayor en su porción central(P), porción anterior del deltoides (PAD), porción lateral del tríceps braquial (PLTB), serrato anterior (SA), oblicuo externo (OE), multífidus lumbar (MF), recto femoral (RF), y erector espinal dorsal (EED) en el lado dominante en 30 sujetos varones, jóvenes y físicamente activos mientras realizaban una serie de 5 repeticiones de flexiones de brazos (push up) en diferentes materiales desestabilizadores o generadores de inestabilidad ubicados en los miembros superiores WobbleBoard® (WBR); TRX Suspension Trainer® (TRX); Stability Disc® (SD); Fitness Dome® (FD) y en una condición estable tradicional (CE). Los valores de activación obtenidos para cada grupo muscular fueron normalizados respecto la máxima contracción voluntaria isométrica de cada sujeto. Los resultados obtenidos, tanto en la activación media como en la máxima, han mostrado que el entrenamiento con el TRX presenta mayores niveles de activación muscular(p ≤ 0.05) en comparación con las otras condiciones, en casi todos los grupos musculares de la cintura lumbopélvica (OE, MF, RF) y también en el serrato anterior (SA). Para el resto de grupos musculares estudiados no fue así, no apareciendo diferencias para la PLTB y PAD, aunque sí aparecieron mayores niveles de activación muscular en el P a favor del TRX en comparación con el Stability Disc®. En cuanto a la comparación entre el resto de condiciones debe resaltarse que se ha encontrado una mayor activación muscular máxima (p ≤ 0.05) en el oblicuo externo al realizar el ejercicio sobre el Stability Disc respecto de hacerlo en el WobbleBoard, no sucediendo así en la activación media obtenida. En cuanto a la comparación entre el resto de condiciones debe resaltarse que se ha encontrado una mayor activación muscular máxima (p ≤ 0.05) en el oblicuo externo al realizar el ejercicio sobre el Stability Disc respecto de hacerlo en el WobbleBoard no sucediendo así en la activación media obtenida. En función de las evidencias obtenidas, se puede concluir que en general el entrenamiento en suspensión con el TRX presenta unos niveles de activación muscular, tanto máxima como media, en el CORE más elevados que el resto de dispositivos de desestabilización, entre los que no se encuentran destacables diferencias que hagan recomendar uno por encima de otro en términos de porcentaje de activación muscular. En los músculos de las extremidades, se encontró mayor activación muscular (p≤0.05) en el pectoral (P) cuando se realizaba el ejercicio sobre el TRX en comparación con el Stability Disc (SD), pero no se encontraron mayores activaciones ni en la porción lateral del tríceps braquial (PLTB), ni en la porción anterior del deltoides (PAD) Además se puede indicar que el tradicional push up, excepto si se compara con el TRX, es un ejercicio que aporta demandas en activación muscular del CORE similares a la mayoría de aparatos desestabilizadores estudiados. En consecuencia, se puede reseñar que muchos de los nuevos dispositivos sólo podrían aportar un elemento diversificador en términos de variedad en los programas de acondicionamiento neuromuscular del tronco y las extremidades superiores, pero no así en aspectos de eficacia en la activación muscular

Post-activation performance enhancement (PAPE) after a single-bout of high-intensity flywheel resistance training

This study investigated the post-activation performance enhancements (PAPE) induced by a highintensity single set of accentuated eccentric isoinertial resistance exercise on vertical jump performance. Twenty physically active male university students performed, in randomized counterbalanced order, two different conditioning activities (CA) after a general preestablished warm-up: a conditioning set of 6 maximum repetitions at high intensity (i.e., individualized optimal moment of inertia [0.083 ± 0.03 kg·m-2]) of the flywheel halfsquat exercise in the experimental condition, or a set of 6 maximal countermovement jumps (CMJ) instead of the flywheel exercise in the control condition. CMJ height, CMJ concentric peak power and CMJ concentric peak velocity were assessed at baseline (i.e., 3 minutes after the warm-up) and 4, 8, 12, 16 and 20 minutes after the CA in both experimental and control protocols. Only after the experimental protocol were significant gains in vertical jump performance (p < 0.05, ES range 0.10–1.34) at 4, 8, 12, 16 and 20 minutes after the CA observed. In fact, the experimental protocol showed greater (p < 0.05) CMJ height, concentric peak power and concentric peak velocity enhancements compared to the control condition. In conclusion, a single set of high-intensity flywheel training led to PAPE in CMJ performance after 4, 8, 12, 16 and 20 minutes in physically active young men.Ciencias de la Actividad Física y del Deport

Validity and reliability of inertial measurement system for linear movement velocity in flywheel squat exercise

The aim of this study was to examine the validity and reliability of an Inertial Measurement System integrated into a secondary pulley (IMS) for determining linear velocity during flywheel squat exercises. Thirty-one male participants who were highly experienced in a flywheel resistance exercise training performed flywheel squat exercises with three incremental loads, and mean velocity (MV), mean propulsive velocity (MPV) and max velocity (Vmax) of the exercises were simultaneously recorded with a validated linear encoder and the IMS, in two different sessions. Validity was analyzed using ordinary least products regression (OLP), Lin’s concordance correlation coefficient (CCC), and Hedge’s g for the values from the linear encoder and the IMS. Test-retest reliability was determined by coefficient of variation (CV), Intraclass correlation coefficient (ICC), and standard error of measurement (SEM). Results showed a high degree of validity (OLP intercept = − 0.09 – 0.00, OLP slope = 0.95 – 1.04, CCC = 0.96 – 0.99, Hedge’s g \u3c 0.192, SEM = 0.04 – 0.08) and reliability (CV \u3c 0.21 %, ICC \u3e 0.88, SEM \u3c 0.08). These results confirm that the IMS provides valid and reliable measures of movement velocity during flywheel squat exercises

The use of the ESS Bilbao installations for laser fusion studies

In this work the use of ESS-Bilbao fast neutron lines for irradiation of materials for nuclear fusion is studied. For the comparison of ESS-Bilbao with an inertial fusion facility a simplified model of HiPER chamber has been used. Several positions for irradiation at ESS-Bilbao have been also compared. The material chosen for the damage analysis is silica due to its importance on IFC optics. In this work a detailed comparison between the two facilities for silica irradiation is given. The comparison covers the neutron fluxes, doses, defect production and PKA spectra. This study is also intended as a methodological approach or guideline for future works on other materials

Hand exo-muscular system for assisting astronauts during extravehicular activities

Human exploration of the Solar System is one of the most challenging objectives included in the space programs of the most important space agencies in the world. Since the Apollo program, and especially with the construction and operation of the International Space Station, extravehicular activities (EVA) have become an important part of space exploration. This article presents a soft hand exoskeleton designed to address one of the problems that astronauts face during spacewalks: hand fatigue caused by the pressurized EVA gloves. This device will reduce the stiffness of the spacesuit glove by counteracting the force exerted by the pressurized glove. To this end, the system makes use of a set of six flexible actuators, which use a shape memory alloy (SMA) wire as the actuating element. SMAs have been chosen because some of their features, such as low volume and high force-to-weight ratio, make them a suitable choice taking into account the constraints imposed by the use of the device in a spacesuit. Besides describing the different mechanical and electronic subsystems that compose the exoskeleton, this article presents a preliminary assessment of the device; several tests to characterize its nominal operation have been carried out, as well as position and force control tests to study its controllability and evaluate its suitability as a force assistive device.The research leading to these results has received funding from the STAMAS (Smart Technology for Artificial Muscle Applications in Space) project,** funded by the European Union's Seventh Framework Program for Research (FP7) (Grant No. 312815)

The validity and reliability of a new instrumented device for measuring ankle dorsiflexion range of motion

PURPOSE/BACKGROUND: A restriction in ankle dorsiflexion range of motion (ROM) has been linked to several clinical manifestations such as metatarsalgia, heel pain, nerve entrapment, ankle joint equinus, patellar and ankle injuries. The purpose of the present study was to examine the validity and reliability of the Leg Motion system for measuring ankle dorsiflexion ROM. STUDY DESIGN: Descriptive repeated-measures study. METHODS: Twenty-six healthy male university students were recruited to test the reliability of the Leg Motion system, which is a portable tool used for assessment of ankle dorsiflexion during the weight-bearing lunge test. The participants were tested two times separated by two weeks and measurements were performed at the same time of the day by the same single rater. To test the validity of the Leg Motion system, other maximal ankle dorsiflexion ROM assessments (goniometer, inclinometer and measuring tape) were measured in a single session (i.e., the first test session) during the weight-bearing lunge position using a standard goniometer, a digital inclinometer and a measuring tape measure with the ability to measure to the nearest 0.1 cm. RESULTS: Paired t-tests showed the absence of significant differences between right and left limb measurements of dorsiflexion in all tests. Mean values ± standard deviations were as follows: Leg Motion test (left 11.6cm±3.9; right 11.9cm ±4.0), tape measure (left 11.6cm±4.0; right 11.8cm±4.2), goniometer (left 40.6º±5.2; right 40.6º±5.2), and digital inclinometer (left 40.0º±5.8; right 39.9º±5.6). The Leg Motion composite values (i.e., average of the two legs) showed a significant (p<0.05) positive correlation with the tape measure (r=0.99), with the goniometer (r=0.66), and with the digital inclinometer (r=0.72). CONCLUSIONS: The results of the present study provide evidence to support the use of the Leg Motion system as a valid, portable, and easy to use alternative to the weight-bearing lunge test to assess ankle dorsiflexion ROM in healthy participants

Ionoluminescence induced by swift heavy ions in silica and quartz: A comparative analysis

Ionoluminescence (IL) of the two SiO 2 phases, amorphous silica and crystalline quartz, has been comparatively investigated in this work, in order to learn about the structural defects generated by means of ion irradiation and the role of crystalline order on the damage processes. Irradiations have been performed with Cl at 10 MeV and Br at 15 MeV, corresponding to the electronic stopping regime (i.e., where the electronic stopping power S e is dominant) and well above the amorphization threshold. The light-emission kinetics for the two main emission bands, located at 1.9 eV (652 nm) and 2.7 eV (459 nm), has been measured under the same ion irradiation conditions as a function of fluence for both, silica and quartz. The role of electronic stopping power has been also investigated and discussed within current views for electronic damage. Our experiments provide a rich phenomenological background that should help to elucidate the mechanisms responsible for light emission and defect creationThis work has been supported by Spanish Ministry MICINN through the project MAT-2008-06794-C03-03, JCI-2009-05681, and by Madrid Community through the project TECHNOFUSION (S2009/ENE-1679). OPR is grateful to CONACyT, Mexico, for extending a postdoctoral fellowshi

Ionoluminescence induced by swift heavy ions in silica and quartz: a comparative analysis

Ionoluminescence (IL) of the two SiO2 phases, amorphous silica and crystalline quartz, has been comparatively investigated in this work, in order to learn about the structural defects generated by means of ion irradiation and the role of crystalline order on the damage processes. Irradiations have been performed with Cl at 10 MeV and Br at 15 MeV, corresponding to the electronic stopping regime (i.e., where the electronic stopping power Se is dominant) and well above the amorphization threshold. The light-emission kinetics for the two main emission bands, located at 1.9 eV (652 nm) and 2.7 eV (459 nm), has been measured under the same ion irradiation conditions as a function of fluence for both, silica and quartz. The role of electronic stopping power has been also investigated and discussed within current views for electronic damage. Our experiments provide a rich phenomenological background that should help to elucidate the mechanisms responsible for light emission and defect creation

Cbfa-1 mediates nitric oxide regulation of MMP-13 in osteoblasts.

During bone development, osteoblast differentiation requires remodeling of the extracellular matrix. Although underlying mechanisms have not been elucidated, evidence points to the participation of the nitric oxide (NO) and cyclic guanosine 3',5'-monophosphate (cGMP) system. Here, we detected increased matrix metalloproteinase (MMP)-13 mRNA, protein and activity, as well as increased inducible NO synthase (iNOS) and NO production during the differentiation of MC3T3-E1 osteoblasts. Transcriptional activity of the MMP-13 promoter was augmented by NO, 8-bromo-cGMP (8-Br-cGMP), and by a dominant-positive form of protein kinase G (PKG1-alpha). The stimulatory effect on the MMP-13 promoter was partially inhibited by mutation of the osteoblast-specific element 2 (OSE-2) binding site. Core binding factor-1 (Cbfa-1) expression peaked at 7 days of differentiation, and was phosphorylated by PKG in vitro. Cbfa-1 was localized to cell nuclei, and its translocation was inhibited by the iNOS inhibitor 1400W. Immunohistological examination revealed that MMP-13 and Cbfa-1 expression levels are both reduced in 17-day-old embryos of iNOS-deficient mice. Silencing of Cbfa-1 mRNA blocked MMP-13 expression without interfering with endogenous NO production, confirming its role in NO-induced MMP-13 expression by MC3T3-E1 cells. The results described here suggest a mechanism by which NO regulates osteogenesis.S