Alternative assessment of knee joint muscle balance of soccer players through total work-based hamstring: quadriceps ratios     

Felipe Minozzo  Carlos Leonardo Figueiredo Machado  Eurico Nestor Wilhelm  Rafael Grazioli  Ronei Silveira Pinto 《European Journal of Sport Science》2018,18(10):1398-1404

Isokinetic hamstring-to-quadriceps (H:Q) ratios are frequently used to assess knee muscle strength imbalances and risk of injuries/re-injuries. The use of peak torque (PT) or total work (TW) to estimate joint stability may lead to different results because of the differences between these two neuromuscular variables. Thus, the current study aimed to compare the conventional and functional H:Q ratios calculated by PT and TW. Ninety-three male professional soccer players from Brazilian first division teams performed isokinetic concentric and eccentric contractions of the quadriceps and the hamstrings at 60°/s. Muscle strength balance was calculated using the conventional torque ratio (CTR) and conventional work ratio (CWR), functional torque ratio (FTR) and functional work ratio (FWR) were highly and moderately correlated between them (r?=?0.83 and r?=?0.73, respectively). The Wilcoxon statistical test revealed significant differences between CTR and CWR, as well as FTR and FWR (p?T-test demonstrated significant differences in mean CTR–CWR and FTR–FWR, whereas Bland–Altman plots showed non-consistent bias. In addition, the chi-square test demonstrated significant differences between players below the conventional reference values and functional reference values (p?相似文献   

Subtle distinctions in the construction of ‘reference societies’: the conflict-laden introduction of compulsory schooling and universal conscription in Chile (1885–1920)     

Cristina Alarcón 《比较教育学》2018,54(3):411-430

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Old Wine in old Bottles: the Neglected Role of Vocational Training Centres in Innovation     

Igone Porto Gómez  Jon Mikel Zabala-Iturriagagoitia  Urko Aguirre Larrakoetxea 《Vocations and Learning》2018,11(2):205-221

Vocational training centres are conceptually regarded as key players in the knowledge generation and dissemination processes that take place within innovation systems. However, the literature does not provide conclusive evidence of their influence on the generation, development and dissemination of innovations. The goal of this paper is to analyse whether vocational training centres are indeed relevant agents in the articulation, knowledge exchange and dissemination of a local innovation system. The paper explores the most influential agents driving cooperation and articulating the local innovation system in Durango, one of the twenty counties of the Basque Country, Spain. Social network analysis is applied to regional collaboration networks in order to address this purpose. Our results show evidence of the pivotal role played by vocational training centres within local innovation processes implemented by firms. For many local firms vocational training centres represent the main sources of knowledge in their innovation processes. In the Basque context, vocational training centres have a longer history than other knowledge infrastructures, such as universities and research centres. These long-standing centres thus constitute ‘old bottles’ that despite their history are still able to produce a ‘good old wine’ in terms of innovation, which is translated into competitive advantage for the territory. Science, technology and innovation policies should therefore not only aim to create more knowledge infrastructures, but also to reinforce the role that traditional and territorially established organizations like vocational training centres can play as intermediary agents.  相似文献   

A noise-filtering event generator for PIDPlus controllers     

Luca Merigo  Manuel Beschi  Fabrizio Padula  Antonio Visioli 《Journal of The Franklin Institute》2018,355(2):774-802

In this paper we propose a new event generator, which has strong noise-filtering capabilities, to be used in event-based control systems with a PIDPlus controller. An approximate frequency analysis is performed in order to characterize the event generator system and tuning guidelines are provided for its design parameter. Simulation and experimental results obtained with a laboratory setup demonstrate the effectiveness of the methodology in providing a satisfactory performance related to set-point and load disturbance step responses with a total variation that is significantly reduced with respect to the standard cases.  相似文献   

Sailing in all winds: Technological search over the business cycle     

Daniela Silvestri  Massimo Riccaboni  Antonio Della Malva 《Research Policy》2018,47(10):1933-1944

Business cycles modify firms’ incentives to innovate and the direction of innovation. By introducing a new measure of patent unconventionality this paper explores the impact of the business cycle on firms’ technological search strategies. We find that during upturns firms generate inventions characterized by a higher level of technological unconventionality. We also find that financially resilient and diversified firms produce more unconventional patents. While patent unconventionality is associated with technological impact and market value, firms extract more value by investing in unconventional inventions in downturns.  相似文献   

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats     

Helenita Antonia de Oliveira  Ednei Luiz Antonio  Flávio André Silva  Paulo de Tarso Camillo de Carvalho  Regiane Feliciano  Amanda Yoshizaki 《Journal of sports sciences》2018,36(20):2349-2357

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.  相似文献   

Effects of an unsupervised pedometer-based physical activity program on daily steps of adults with moderate to severe asthma: a randomized controlled trial     

Cristina Martins Coelho  Maycon Moura Reboredo  Felipe Martins Valle  Carla Malaguti  Larissa Almeida Campos  Lucas Mendes Nascimento 《Journal of sports sciences》2018,36(10):1186-1193

Supervised exercise has shown benefits for subjects with asthma, but little is known about the effectiveness of unsupervised physical activity on this population. We investigated the effects of a 12-week unsupervised pedometer-based physical activity program on daily steps and on clinical and psychological parameters of adults with asthma. Clinically stable adults with moderate to severe asthma were encouraged to take daily 30-minute walks and were randomized to pedometer and control groups. The pedometer group received pedometers and individualized daily step targets. Changes in daily steps (average of steps taken during six consecutive days), six-minute walk test (6MWT), health-related quality of life, asthma control and anxiety and depression levels were assessed 12 weeks after intervention and 24–28 weeks after randomization. Thirty-seven participants were recruited and 30 completed the intervention. At 12 weeks, the groups differed significantly in daily steps (adjusted average difference, 2488 steps; 95% confidence interval [CI], 803 to 4172; p = 0.005) and in the 6MWT (adjusted average difference, 21.9 m; 95% CI, 6.6 to 37.3; p = 0.006). These differences were not significant 24–28 weeks after randomization. The program was effective in increasing daily steps of adults with moderate to severe asthma 12 weeks after intervention.  相似文献   

Effect of contact and no-contact small-sided games on elite handball players     

Antonio Dello Iacono  Domenico Martone  Alessandro Moura Zagatto  Yoav Meckel  Mahmood Sindiani  Mirjana Milic 《Journal of sports sciences》2018,36(1):14-22

This study aimed to investigate the effect of contact (C-SSG) and no-contact (NC-SSG) handball small-sided games (SSGs) on motion patterns and physiological responses of elite handball players. Twelve male handball players performed 10 C-SSG and 10 NC-SSG while being monitored through the heart rate (HR) and rate of perceived exertion (RPE) as physiological responses and time-motion activities profile using video-match analysis. Both game conditions resulted in similar HR responses (P > 0.05), but the NC-SSG led to a higher RPE scores. The time-motion activity analysis featured NC-SSG with a greater amount of walking (855.6 ± 25.1 vs. 690.6 ± 35.2 m) and backward movements (187.5 ± 12.3 vs. 142.5 ± 8.7 m) combined with fast running (232.3 ± 8.5 vs. 159.7 ± 5.7 m) and sprinting (79.5 ± 4.7 vs. 39.7 ± 3.7 m) activities (P < 0.001). Conversely, C-SSG had a higher percentage of jogging and sideway movements associated with greater frequency of jumping (0.87 ± 0.09 vs. 0.31 ± 0.06 nr) and physical contact (1.82 ± 0.55 vs. 0.25 ± 0.03 nr) events (P < 0.001). No between-regimen differences were found for the number of throws (P = 0.745). In addition, the RPE was significantly correlated with fast running relative distances (r = 0.909, P < 0.001) and sprinting relative distances (r = 0.939, P < 0.001). In conclusion, this investigation showed that both C-SSG and NC-SSG in team handball can effectively represent specifically oriented exercises, according to the sport-task and the performance demands.  相似文献   

Effects of inspiratory muscle training in professional women football players: a randomized sham-controlled trial     

Bruno Archiza  Daniela Kuguimoto Andaku  Flávia Cristina Rossi Caruso  José Carlos Bonjorno Jr.  Cláudio Ricardo de Oliveira  Paula Angélica Ricci 《Journal of sports sciences》2018,36(7):771-780

This study was conducted to determine the effects of inspiratory muscle training (IMT) on respiratory and peripheral muscles oxygenation during a maximal exercise tolerance test and on repeated-sprint ability (RSA) performance in professional women football players. Eighteen athletes were randomly assigned to one of the following groups: SHAM (n = 8) or IMT (n = 10). After a maximal incremental exercise test, all participants performed (on a different day) a time-to-exhaustion (Tlim) test. Peripheral and respiratory muscles oxygenation by near-infrared spectroscopy, breath-by-breath ventilatory and metabolic variables, and blood lactate concentration were measured. The RSA test was performed on a grass field. After a 6 week intervention, all athletes were reevaluated. Both groups showed increases in inspiratory muscles strength, exercise tolerance and RSA performance, however only the IMT group presented lower deoxyhemoglobin and total hemoglobin blood concentrations on intercostal muscles concomitantly to an increased oxyhemoglobin and total hemoglobin blood concentrations on vastus lateralis muscle during Tlim. In conclusion, these results may indicate the potential role of IMT to attenuate inspiratory muscles metaboreflex and consequently improve oxygen and blood supply to limb muscles during high-intensity exercise, with a potential impact on inspiratory muscle strength, exercise tolerance and sprints performance in professional women football players.  相似文献   

An investigation into turn-away among information technology professionals in Brazil     

Eduardo Ramos  Luiz Antonio Joia 《The Journal of High Technology Management Research》2013,24(1):30-41

Two important problems have been observed fairly frequently among information technology (IT) professionals, namely turn-over – where the IT professional moves to another company but still remains in the IT sector – and turn-away, in which the IT professional abandons the area in order to occupy a position in a different area, either in the same company or in another, sometimes assuming a managerial function. Few research papers were found with respect to the latter phenomenon. Based on that, the main thrust of this work is to understand how and why IT professionals in Brazil abandon their area, identifying typical characteristics in their career transition. Thus, from a literature review about career development and the analysis of the data collected, eight research hypotheses were developed in order to be analyzed by the researchers. A multiple case study method with several units of analysis was applied in two large companies in Brazil. In-depth interviews were conducted with IT professionals who had migrated to other areas within their organizations, they being considered the unit of analysis. The results accrued from this research reveal that IT professionals in Brazil need to have more growth opportunities than either their companies have been able to offer them or it is possible to offer within the technical arena.  相似文献