Effects of isokinetic eccentric training on knee extensor and flexor torque and on gait of individuals with long term ACL reconstruction: A controlled clinical trial

Abstract-This study investigated the effects of the isokinetic eccentric training (IET) on the knee extensor and flexor torque and kinematic gait parameters in individuals with ACL reconstruction. Sixteen men with ACL reconstructed (ACLr) whose torque and the gait were evaluated, before and after 12 weeks of IET, was compared to a control group (14 individuals). Student t, MANOVA and ANOVA tests were performed with 5% of significance. The training increased the isometric, concentric at 30 and 120º/s (p < .05) and eccentric at 30º/s (p < .01) extensor torque on the affected limb (AL), and eccentric at 30 and 120º/s (p < .01), on the non-affected limb (NAL). In the flexors, there was an increase on the torque: isometric, concentric at 30º/s and eccentric at 30 and 120º/s (p < .01) in AL and in eccentric at 30 (p < .05) and 120º/s (p < .01) in NAL. With respect to the angular and spatio-temporal variables gait, there was no difference between pre-and post-training in LCAr group. Compared to control group, the cycle time, in two members, was lower in LCAr group, and stride length and cadence were higher in the AL of the LCAr (p < .05). Moreover, the knee flexion-extension angles (minimum and maximum) remained lower in LCAr, pre-and post-training (p < .01). The torque gain associated with eccentric isokinetic training did not affect the kinematic parameters of gait in patients undergoing ACL reconstruction. Keywords: gait, exercise, muscle strength, movement, anterior cruciate ligament reconstruction Resumo-"Efeitos do treinamento isocinético excêntrico de extensores de joelho e torque flexor na marcha de indivíduos com reconstrução do LCA: Um ensaio clínico controlado." Este estudo investigou os efeitos do treinamento isocinético excêntrico (TIE) sobre o torque extensor e flexor do joelho e parâmetros cinemáticos da marcha de indivíduos com reconstrução do LCA. Dezesseis homens com LCA reconstruído (LCAr), foram avaliados quanto ao torque e marcha, antes e após 12 semanas de TIE e comparados com um grupo controle (14 indivíduos). Testes t Student, MANOVA e ANOVA foram realizados com 5% de significância. O treinamento aumentou o torque extensor isométrico, concêntrico a 30 e 120º/s (p < 0,05) e excêntrico a 30º/s (p < 0,01) no membro afetado (MA), e excêntrico a 30 e 120º/s (p < 0,01), no membro não afetado (MNA). Nos flexores, houve um aumento no torque: isométrico, concêntrico a 30º/s e excêntrico a 30 e 120º/s (p < 0,01) no MA, e excêntrico a 30 (p < 0,05) e 120º/s (p < 0,01) no MNA. Com relação às variáveis espaço-temporais e angulares da marcha, não houve diferença entre as avaliações pré e pós-treino no grupo LCAr. Comparado ao controle, a duração do ciclo, nos dois membros, foi menor no LCAr, e comprimento da passada e cadência foram maiores no MA do grupo LCAr (p < 0,05). Além disso, os ângulos (mínimo e máximo) de flexão-extensão do joelho permaneceram menores no LCAr, pré e pós-treino (p < 0,01). O ganho de torque associado ao treinamento isocinético excêntrico não modificou os parâmetros cinemáticos da marcha nos indivíduos submetidos à reconstrução do LCA. Palavras-chave: marcha, exercício, força muscular, movimento, reconstrução do ligamento cruzado anterior H.H. Santos, C.O. Sousa, J.A. Barela, A.M.F. Barela & T.F. Salvini Motriz, Rio Claro, v.20 n.4, p. 431-441, Oct./Dec. 2014 432 Resumen-"Efectos del entrenamiento excéntrico isocinético en extensor de la rodilla y el par flexor y sobre la marcha de las personas con reconstrucción ACL: Un ensayo clínico controlado." Este estudio investigó los efectos del entrenamiento isocinético excéntrico (EIE) en el torque del extensor y del flexor de la rodilla y parámetros cinemáticos de la marcha de personas con la reconstrucción del LCA. Dieciséis hombres con LCA reconstruido (LCAr), fueron evaluados para el par y la marcha antes y después de 12 semanas de EIE y se compararon con un grupo control (14 personas). Prueba t Student, ANOVA y MANOVA se realizaron con 5 % de significación. La formación aumentó extensor torque isométrico, concéntrico 30 y 120°/s (p < 0,05) y la excéntrica 30°/s (p < 0,01) en el miembro afectado (MA), y la excéntrica 30 y 120°/s (p < 0,01) en el miembro no afectado (MNA). Flexor, hubo un aumento en el par motor: isométrica , concéntrica 30°/s excéntrica 30 y 120°/s (p < 0,01) en MA, excéntrico y 30 (p < 0,05 ) y 120°/ s (p < 0,01) en el MNA. Con respecto a las variables angulares y espacio-temporal de andar, no hubo diferencia entre pre y post-entrenamiento en grupo LCAr. En comparación con el grupo control, el tiempo de ciclo, em los dos miembros, fue menor en LCAr, y la longitud del paso y cadencia fueron mayores en el LCAr del MA (p < 0,05). Por otra parte, los ángulos de flexión-extensión de la rodilla (mínimo y máximo) se mantuvieron bajos en LCAr, pre y post-entrenamiento (p < 0,01). El aumento del torque asociado con el entrenamiento isocinético excéntrico no afectó los parámetros cinemáticos de la marcha en las personas sometidas a la reconstrucción del LCA

Measurements of the reaction pˉp→ϕη\bar{p}p \to \phi \eta of antiproton annihilation at rest at three hydrogen target densities

The proton-antiproton annihilation at rest into the $\phi\eta$ final state was measured for three different target densities: liquid hydrogen, gaseous hydrogen at NTP and at a low pressure of 5 mbar. The yield of this reaction in the liquid hydrogen target is smaller than in the low-pressure gas target. The branching ratios of the $\phi\eta$ channel were calculated on the basis of simultaneous analysis of the three data samples. The branching ratio for annihilation into $\phi\eta$ from the $^3S_1$ protonium state turns out to be about ten times smaller as compared to the one from the $^1P_1$ state.Comment: 10 pages, 3 Postscript figures. Accepted by Physics Letters

Study of the diffuse gamma-ray emission from the Galactic plane with ARGO-YBJ

The events recorded by ARGO-YBJ in more than five years of data collection have been analyzed to determine the diffuse gamma-ray emission in the Galactic plane at Galactic longitudes 25{\deg} < l < 100{\deg} and Galactic latitudes . The energy range covered by this analysis, from ~350 GeV to ~2 TeV, allows the connection of the region explored by Fermi with the multi-TeV measurements carried out by Milagro. Our analysis has been focused on two selected regions of the Galactic plane, i.e., 40{\deg} < l < 100{\deg} and 65{\deg} < l < 85{\deg} (the Cygnus region), where Milagro observed an excess with respect to the predictions of current models. Great care has been taken in order to mask the most intense gamma-ray sources, including the TeV counterpart of the Cygnus cocoon recently identified by ARGO-YBJ, and to remove residual contributions. The ARGO-YBJ results do not show any excess at sub-TeV energies corresponding to the excess found by Milagro, and are consistent with the predictions of the Fermi model for the diffuse Galactic emission. From the measured energy distribution we derive spectral indices and the differential flux at 1 TeV of the diffuse gamma-ray emission in the sky regions investigated.Comment: 11 pages, 6 figures, published in AP

4.5 years multi-wavelength observations of Mrk 421 during the ARGO-YBJ and Fermi common operation time

We report on the extensive multi-wavelength observations of the blazar Markarian 421 (Mrk 421) covering radio to gamma-rays, during the 4.5 year period of ARGO-YBJ and Fermi common operation time, from August 2008 to February 2013. In particular, thanks to the ARGO-YBJ and Fermi data, the whole energy range from 100 MeV to 10 TeV is covered without any gap. In the observation period, Mrk 421 showed both low and high activity states at all wavebands. The correlations among flux variations in different wavebands were analyzed. Seven large flares, including five X-ray flares and two GeV gamma-ray flares with variable durations (3-58 days), and one X-ray outburst phase were identified and used to investigate the variation of the spectral energy distribution with respect to a relative quiescent phase. During the outburst phase and the seven flaring episodes, the peak energy in X-rays is observed to increase from sub-keV to few keV. The TeV gamma-ray flux increases up to 0.9-7.2 times the flux of the Crab Nebula. The behavior of GeV gamma-rays is found to vary depending on the flare, a feature that leads us to classify flares into three groups according to the GeV flux variation. Finally, the one-zone synchrotron self-Compton model was adopted to describe the emission spectra. Two out of three groups can be satisfactorily described using injected electrons with a power-law spectral index around 2.2, as expected from relativistic diffuse shock acceleration, whereas the remaining group requires a harder injected spectrum. The underlying physical mechanisms responsible for different groups may be related to the acceleration process or to the environment properties.Comment: 17 pages, 9 figures, 5 tables, Accepted for publication in ApJ

The cosmic ray proton plus helium energy spectrum measured by the ARGO-YBJ experiment in the energy range 3-300 TeV

The ARGO-YBJ experiment is a full-coverage air shower detector located at the Yangbajing Cosmic Ray Observatory (Tibet, People's Republic of China, 4300 m a.s.l.). The high altitude, combined with the full-coverage technique, allows the detection of extensive air showers in a wide energy range and offer the possibility of measuring the cosmic ray proton plus helium spectrum down to the TeV region, where direct balloon/space-borne measurements are available. The detector has been in stable data taking in its full configuration from November 2007 to February 2013. In this paper the measurement of the cosmic ray proton plus helium energy spectrum is presented in the region 3-300 TeV by analyzing the full collected data sample. The resulting spectral index is $\gamma = -2.64 \pm 0.01$. These results demonstrate the possibility of performing an accurate measurement of the spectrum of light elements with a ground based air shower detector.Comment: 18 pages, 8 figures, preprint submitted to Phys. Rev.

EAS age determination from the study of the lateral distribution of charged particles near the shower axis with the ARGO-YBJ experiment

The ARGO-YBJ experiment, a full coverage extensive air shower (EAS) detector located at high altitude (4300 m a.s.l.) in Tibet, China, has smoothly taken data, with very high stability, since November 2007 to the beginning of 2013. The array consisted of a carpet of about 7000 m$^2$ Resistive Plate Chambers (RPCs) operated in streamer mode and equipped with both digital and analog readout, providing the measurement of particle densities up to few particles per cm$^2$. The unique detector features (full coverage, readout granularity, wide dynamic range, etc) and location (very high altitude) allowed a detailed study of the lateral density profile of charged particles at ground very close to the shower axis and its description by a proper lateral distribution function (LDF). In particular, the information collected in the first 10 m from the shower axis have been shown to provide a very effective tool for the determination of the shower development stage ("age") in the energy range 50 TeV - 10 PeV. The sensitivity of the age parameter to the mass composition of primary Cosmic Rays is also discussed

New data on OZI rule violation in bar{p}p annihilation at rest

The results of a measurement of the ratio R = Y(phi pi+ pi-) / Y(omega pi+ pi-) for antiproton annihilation at rest in a gaseous and in a liquid hydrogen target are presented. It was found that the value of this ratio increases with the decreasing of the dipion mass, which demonstrates the difference in the phi and omega production mechanisms. An indication on the momentum transfer dependence of the apparent OZI rule violation for phi production from the 3S1 initial state was found.Comment: 11 pages, 3 PostScript figures, submitted to Physics Letter

Observation of TeV gamma rays from the Cygnus region with the ARGO-YBJ experiment

We report the observation of TeV gamma-rays from the Cygnus region using the ARGO-YBJ data collected from 2007 November to 2011 August. Several TeV sources are located in this region including the two bright extended MGRO J2019+37 and MGRO J2031+41. According to the Milagro data set, at 20 TeV MGRO J2019+37 is the most significant source apart from the Crab Nebula. No signal from MGRO J2019+37 is detected by the ARGO-YBJ experiment, and the derived flux upper limits at 90% confidence level for all the events above 600 GeV with medium energy of 3 TeV are lower than the Milagro flux, implying that the source might be variable and hard to be identified as a pulsar wind nebula. The only statistically significant (6.4 standard deviations) gamma-ray signal is found from MGRO J2031+41, with a flux consistent with the measurement by Milagro.Comment: 14 pages, 4 figure

Observation of TeV gamma-rays from the unidentified source HESS J1841-055 with the ARGO-YBJ experiment

We report the observation of a very high energy \gamma-ray source, whose position is coincident with HESS J1841-055. This source has been observed for 4.5 years by the ARGO-YBJ experiment from November 2007 to July 2012. Its emission is detected with a statistical significance of 5.3 standard deviations. Parameterizing the source shape with a two-dimensional Gaussian function we estimate an extension \sigma=(0.40(+0.32,-0.22}) degree, consistent with the HESS measurement. The observed energy spectrum is dN/dE =(9.0-+1.6) x 10^{-13}(E/5 TeV)^{-2.32-+0.23} photons cm^{-2} s^{-1} TeV^{-1}, in the energy range 0.9-50 TeV. The integral \gamma-ray flux above 1 TeV is 1.3-+0.4 Crab units, which is 3.2-+1.0 times the flux derived by HESS. The differences in the flux determination between HESS and ARGO-YBJ, and possible counterparts at other wavelengths are discussed.Comment: 17 pages, 4 figures, have been accepted for publication in Ap

Search for Gamma Ray Bursts with the Argo-YBJ Detector in Scaler Mode

We report on the search for Gamma Ray Bursts (GRBs) in the energy range 1-100 GeV in coincidence with the prompt emission detected by satellites using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) air shower detector. Thanks to its mountain location (Yangbajing, Tibet, P.R. China, 4300 m a.s.l.), active surface (about 6700 m**2 of Resistive Plate Chambers), and large field of view (about 2 sr, limited only by the atmospheric absorption), the ARGO-YBJ air shower detector is particularly suitable for the detection of unpredictable and short duration events such as GRBs. The search is carried out using the "single particle technique", i.e. counting all the particles hitting the detector without measurement of the energy and arrival direction of the primary gamma rays. Between 2004 December 17 and 2009 April 7, 81 GRBs detected by satellites occurred within the field of view of ARGO-YBJ (zenith angle < 45 deg). It was possible to examine 62 of these for >1 GeV counterpart in the ARGO-YBJ data finding no statistically significant emission. With a lack of detected spectra in this energy range fluence upper limits are profitable, especially when the redshift is known and the correction for the extragalactic absorption can be considered. The obtained fluence upper limits reach values as low as 10**{-5} erg cm**{-2} in the 1-100 GeV energy region. Besides this individual search for a higher energy counterpart, a statistical study of the stack of all the GRBs both in time and in phase was made, looking for a common feature in the GRB high energy emission. No significant signal has been detected.Comment: accepted for publication in Ap