293 research outputs found
Cardiac Parasympathetic Reactivation in Elite Soccer Players During Different Types of Traditional High-Intensity Training Exercise Modes and Specific Tests: Interests and Limits
Background: The cardiac parasympathetic reactivation is currently used in soccer with a daily or weekly monitoring. However, previous studies have not investigated how this cardiac parasympathetic reactivation is in elite soccer players along different types of traditional high-intensity training exercise and specific tests. In this context, the present study aim to analyse it and to determine the interests and limits of this type of physiological information.
Objectives: The present study aims to examine how different traditional training exercise modes affect the cardiac parasympathetic reactivation function in elite soccer players.
Materials and Methods: Twenty-two international soccer players participating in UEFA Championâs League took part in this study (age: 24.3 ± 4.2 years; height: 178.1 ± 6.2 cm; body mass: 80.3 ± 5.7 kg). Players performed different training methods including: short-duration intermittent exercises (INT) in-line and with changes of direction (COD) (10 - 10 seconds, 15 - 15 seconds, 30 - 30 seconds, e.g. an alternance of 10 - 10 seconds is 10 seconds of running according to the maximal aerobic speed (MAS) and 10-sec of recovery), INT including agility and technical skills (8 - 24-seconds), small-sided-games (SSGs) with and without goalkeepers (2 vs. 2, 3 vs. 3, 4 vs. 4), and repeated sprint ability (RSA) efforts (10 Ă 20 m, 10 Ă 30 m, 15 Ă 20 m). Heart rate (HR) decline was recorded 3 minutes after each exercise.
Results: HR declines were greater after the RSA compared to SSGs (P < 0.001) and INT (P < 0.01), especially at 1 min post-exercise. In addition, when the analysis focused on each type of exercise, greater HR declines were observed in on-field players at 1 minute when there was: inclusion of goalkeepers in SSGs (for 2 vs. 2 and 3 vs. 3, P < 0.01); increase of sprint distances or number of sprint repetitions in RSA (P < 0.01); increase of intensity (% of maximal aerobic speed), and the use of COD or inclusion of technical skills during INT, especially for the 30 - 30-seconds.
Conclusions: This study revealed that cardiac parasympathetic reactivation function varied after INT, RSA and SSG, but also according to the rules manipulation. Therefore, this study provides interesting information for the training monitoring and playersâ recovery profile, with the aim of facilitating a more efficient planning and manipulation of training recovery strategies according to their fitness markers
Six-wave mixing: secular resonances in a higher-order mechanism for second-harmonic generation
Specific heat and magnetization study on single crystals of a frustrated, quasi one-dimensional oxide: Ca3Co2O6
Specific heat and magnetization measurements have been carried out under a
range of magnetic fields on single crystals of Ca3Co2O6. This compound is
composed of Ising magnetic chains that are arranged on a triangular lattice.
The intrachain and interchain couplings are ferromagnetic and
antiferromagnetic, respectively. This situation gives rise to geometrical
frustration, that bears some similarity to the classical problem of a
two-dimensional Ising triangular antiferromagnet. This paper reports on the
ordering process at low-T and the possibility of one-dimensional features at
high-T.Comment: 7 pages, 6 figures, accepted for publication in PR
Modulation control and spectral shaping of optical fiber supercontinuum generation in the picosecond regime
Numerical simulations are used to study how fiber supercontinuum generation
seeded by picosecond pulses can be actively controlled through the use of input
pulse modulation. By carrying out multiple simulations in the presence of
noise, we show how tailored supercontinuum Spectra with increased bandwidth and
improved stability can be generated using an input envelope modulation of
appropriate frequency and depth. The results are discussed in terms of the
non-linear propagation dynamics and pump depletion.Comment: Aspects of this work were presented in Paper ThJ2 at OECC/ACOFT 2008,
Sydney Australia 7-10 July (2008). Journal paper submitted for publication 30
July 200
Isokinetic evaluation of knee muscles in soccer players: discriminant analysis [Avaliação isocinĂ©tica dos mĂșsculos do joelho em jogadores de futebol: anĂĄlise discriminante]; [EvaluaciĂłn isocinĂ©tica de los mĂșsculos de la rodilla en jugadores de fĂștbol: anĂĄlisis discriminante]
Introduction:
Muscle activity in soccer players can be measured by isokinetic dynamometer, which is a reliable tool for assessing human performance.
Objectives:
To perform isokinetic analyses and to determine which variables differentiate the under-17 (U17) soccer category from the professional (PRO).
Methods:
Thirty four players were assessed (n=17 for each category). The isokinetic variables used for the knee extension-flexion analysis were: peak torque (Nm), total work (J), average power (W), angle of peak torque (deg.), agonist/ antagonist ratio (%), measured for three velocities (60°/s, 120°/s and 300°/s), with each series containing five repetitions. Three Wilks' Lambda discriminant analyses were performed, to identify which variables were more significant for the definition of each of the categories.
Results:
The discriminative variables at 60°/s in the PRO category were: extension peak torque, flexion total work, extension average power and agonist/antagonist ratio; and for the U17s were: extension total work, flexion peak torque and flexion average power. At 120°/s for the PRO category the discriminant variables were: flexion peak torque and extension average power; for the U17s they were: extension total work and flexion average power. Finally at 300°/s, the variables found in the PRO and U17 categories respectively were: extension average power and extension total work.
Conclusion:
Isokinetic variables for flexion and extension knee muscles were able to significantly discriminate between PRO and U17 soccer players.
RESUMO
Introdução:
A atividade muscular em jogadores de futebol pode ser medida por meio do dinamÎmetro isocinético, que é um instrumento confiåvel para avaliação do desempenho humano.
Objetivos:
Conduzir anålises isocinéticas e discriminar quais variåveis diferenciam a categoria sub-17 (S17) da profissional (PRO).
MĂ©todos:
Trinta e quatro jogadores de futebol (n=17 para cada categoria) foram avaliados. As variĂĄveis isocinĂ©ticas utilizadas para a anĂĄlise de extensĂŁo-flexĂŁo do joelho foram: pico de torque (Nm), trabalho total (J), potĂȘncia mĂ©dia (W), Ăąngulo de pico de torque (graus), razĂŁo agonista/antagonista (%), testadas em trĂȘs velocidades (60°/s, 120°/s e 300°/s), com cada sĂ©rie contendo cinco repetiçÔes. TrĂȘs anĂĄlises discriminantes foram feitas usando o mĂ©todo Wilk's Lambda para identificar quais variĂĄveis fariam uma discriminação significativa entre as duas categorias.
Resultados:
As variĂĄveis discriminantes a 60°/s na categoria PRO foram: pico de torque extensores, trabalho total flexores, potĂȘncia mĂ©dia de extensores e razĂŁo agonista/antagonista; e para os S17 foram: trabalho total de extensores, pico de torque de flexores e potĂȘncia mĂ©dia de flexores. A 120°/s para a categoria PRO as variĂĄveis discriminantes foram: pico de torque de flexores e potĂȘncia mĂ©dia de extensores; para os S17 foram: trabalho total de extensores e potĂȘncia mĂ©dia de flexores. A 300°/s, as variĂĄveis encontradas para as categorias PRO e S17 foram, respectivamente: potĂȘncia mĂ©dia de extensores e trabalho total de extensores.
ConclusĂŁo:
As variĂĄveis isocinĂ©ticas para os mĂșsculos do joelho flexores e extensores foram capazes de fazer uma discriminação significativa entre jogadores de futebol PRO e S17.
RESUMEN
IntroducciĂłn:
La actividad muscular en jugadores de fĂștbol puede ser medida por medio del dinamĂłmetro isocinĂ©tico, que es un instrumento confiable para evaluaciĂłn del desempeño humano.
Objetivos:
Conducir anĂĄlisis isocinĂ©ticos y discriminar quĂ© variables diferencian la categorĂa sub-17 (S17) de la profesional (PRO).
MĂ©todos:
Fueron evaluados treinta y cuatro jugadores de fĂștbol (n=17 para cada categorĂa). Las variables isocinĂ©ticas utilizadas para el anĂĄlisis de extensiĂłn-flexiĂłn de la rodilla fueron: pico de torque (Nm), trabajo total (J), potencia media (W), ĂĄngulo de pico de torque (grados), razĂłn agonista/antagonista (%), probadas en tres velocidades (60°/s, 120°/s y 300°/s), con cada serie conteniendo cinco repeticiones. Fueron realizados tres anĂĄlisis discriminantes usando el mĂ©todo Wilk's Lambda para identificar quĂ© variables harĂan una discriminaciĂłn significativa entre las dos categorĂas.
Resultados:
Las variables discriminantes a 60°/s en la categorĂa PRO fueron: pico de torque extensores, trabajo total flexores, potencia media de extensores y razĂłn agonista/antagonista; y para los S17 fueron: trabajo total de extensores, pico de torque de flexores y potencia media de flexores. A 120°/s para la categorĂa PRO las variables discriminantes fueron: pico de torque de flexores y potencia media de extensores; para los S17 fueron: trabajo total de extensores y potencia media de flexores. A 300°/s, las variables encontradas para las categorĂas PRO y S17 fueron, respectivamente: potencia media de extensores y trabajo total de extensores.
ConclusiĂłn:
Las variables isocinĂ©ticas para los mĂșsculos de la rodilla flexores y extensores fueron capaces de hacer una discriminaciĂłn significativa entre jugadores de fĂștbol PRO y S17
Analgesic and Anti-Inflammatory Effects of the Novel Semicarbazide-Sensitive Amine-Oxidase Inhibitor SzV-1287 in Chronic Arthritis Models of the Mouse.
Semicarbazide-sensitive amine oxidase (SSAO) catalyses oxidative deamination of primary amines. Since there is no data about its function in pain and arthritis mechanisms, we investigated the effects of our novel SSAO inhibitor SzV-1287 in chronic mouse models of joint inflammation. Effects of SzV-1287 (20 mg/kg i.p./day) were investigated in the K/BxN serum-transfer and complete Freund's adjuvant (CFA)-evoked active immunization models compared to the reference SSAO inhibitor LJP-1207. Mechanonociception was assessed by aesthesiometry, oedema by plethysmometry, clinical severity by scoring, joint function by grid test, myeloperoxidase activity by luminescence, vascular leakage by fluorescence in vivo imaging, histopathological changes by semiquantitative evaluation, and cytokines by Luminex assay. SzV-1287 significantly inhibited hyperalgesia and oedema in both models. Plasma leakage and keratinocyte chemoattractant production in the tibiotarsal joint, but not myeloperoxidase activity was significantly reduced by SzV-1287 in K/BxN-arthritis. SzV-1287 did not influence vascular and cellular mechanisms in CFA-arthritis, but significantly decreased histopathological alterations. There was no difference in the anti-hyperalgesic and anti-inflammatory actions of SzV-1287 and LJP-1207, but only SzV-1287 decreased CFA-induced tissue damage. Unlike SzV-1287, LJP-1207 induced cartilage destruction, which was confirmed in vitro. SzV-1287 exerts potent analgesic and anti-inflammatory actions in chronic arthritis models of distinct mechanisms, without inducing cartilage damage
Practitioners' Perceptions of the Soccer Extra-Time Period: Implications for Future Research
Qualitative research investigating soccer practitionersâ perceptions can allow researchers to create practical research investigations. The extra-time period of soccer is understudied compared to other areas of soccer research. Using an open-ended online survey containing eleven main and nine sub questions, we gathered the perceptions of extra-time from 46 soccer practitioners, all working for different professional soccer clubs. Questions related to current practices, views on extra-time regulations, and ideas for future research. Using inductive content analysis, the following general dimensions were identified: âimportance of extra-timeâ, ârule changesâ, âefficacy of extra-time hydro-nutritional provisionâ, ânutritional timingâ,
âfuture research directionsâ, âpreparatory modulationsâ and ârecoveryâ. The majority of practitioners (63%) either agreed or strongly agreed that extra-time is an important period
for determining success in knockout football match-play. When asked if a fourth substitution
should be permitted in extra-time, 67% agreed. The use of hydro-nutritional strategies prior
to extra-time was predominately considered important or very important. However; only
41% of practitioners felt that it was the most important time point for the use of nutritional
products. A similar number of practitioners account (50%) and do not (50%) account for the
potential of extra-time when training and preparing players and 89% of practitioners stated that extra-time influences recovery practices following matches. In the five minute break prior to extra-time, the following practices (in order of priority) were advocated to players: hydration, energy provision, massage, and tactical preparations. Additionally, 87% of practitioners advocate a particular nutritional supplementation strategy prior to extra-time. In order of importance, practitioners see the following as future research areas: nutritional interventions, fatigue responses, acute injury risk, recovery modalities, training paradigms, injury epidemiology, and environmental considerations. This study presents novel insight into the practitioner perceptions of extra-time and provides information to readers about current
applied practices and potential future research opportunities
Avaliação da intensidade do treinamento técnico-tåtico e da fadiga causada em jogadores de futebol da categoria sub-20
Preparation, structural, dielectric and magnetic properties of LaFeO3-PbTiO3 solid solutions
Solid solutions of (1-x)LaFeO3-(x)PbTiO3 (0<x<1) have been prepared by
conventional solid-state reaction. These complex perovskites have been studied
by means of X-ray (XRPD) and neutron powder (NPD) diffraction, complemented
with dielectric, magnetic, heat capacity and M\"ossbauer measurements. Complete
solubility in the perovskite series was demonstrated. The NPD and XRPD patterns
were successfully refined as orthorhombic (x \leq 0.7) and tetragonal (x \geq
0.8). A composition-driven phase transformation occurs within the interval
0.7<x<0.8. The samples with x<0.5 showed evidence of long-range magnetic
ordering with an G-type antiferromagnetic arrangement of the magnetic moments
of the Fe3+ cations in the B-site with propagation vector k = (0,0,0). Based on
the obtained experimental data, a combined structural and magnetic phase
diagram has been constructed. The factors governing the structural, dielectric
and magnetic properties of (1-x) LaFeO3 - (x)PbTiO3 solid solutions are
discussed, as well as their possible multiferroicity.Comment: 33 pages, 15 figure
Chronic CaMKII inhibition blunts the cardiac contractile response to exercise training
Activation of the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) plays a critical role modulating cardiac function in both health and disease. Here, we determined the effect of chronic CaMKII inhibition during an exercise training program in healthy mice. CaMKII was inhibited by KN-93 injections. Mice were randomized to the following groups: sham sedentary, sham exercise, KN-93 sedentary, and KN-93 exercise. Cardiorespiratory function was evaluated by ergospirometry during treadmill running, echocardiography, and cardiomyocyte fractional shortening and calcium handling. The results revealed that KN-93 alone had no effect on exercise capacity or fractional shortening. In sham animals, exercise training increased maximal oxygen uptake by 8% (p < 0.05) compared to a 22% (p < 0.05) increase after exercise in KN-93 treated mice (group difference p < 0.01). In contrast, in vivo fractional shortening evaluated by echocardiography improved after exercise in sham animals only: from 25 to 32% (p < 0.02). In inactive mice, KN-93 reduced rates of diastolic cardiomyocyte re-lengthening (by 25%, p < 0.05) as well as Ca2+ transient decay (by 16%, p < 0.05), whereas no such effect was observed after exercise training. KN-93 blunted exercise training response on cardiomyocyte fractional shortening (63% sham vs. 18% KN-93; p < 0.01 and p < 0.05, respectively). These effects could not be solely explained by the Ca2+ transient amplitude, as KN-93 reduced it by 20% (p < 0.05) and response to exercise training was equal (64% sham and 47% KN-93; both p < 0.01). We concluded that chronic CaMKII inhibition increased time to 50% re-lengthening which were recovered by exercise training, but paradoxically led to a greater increase in maximal oxygen uptake compared to sham mice. Thus, the effect of chronic CaMKII inhibition is multifaceted and of a complex nature
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