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Israel Halperin Dale W. Chapman David T. Martin Chris Abbiss 《Journal of sports sciences》2017,35(5):500-507
Research indicates that instructing athlete’s to focus on bodily movements (internal focus of attention [IFA]) may hinder performance, whereas instructing them to focus on the movement outcome (external focus of attention [EFA]) often enhances performance. Despite the importance of instructions in striking combat sports, limited research has examined the influence of IFA and EFA on performance in well-trained combat athletes. This study investigated the effects of different instructional cues on punching velocity (m · s?1) and normalised impact forces (N · kg?1) among intermediate (n = 8) and expert (n = 7) competitive boxers and kickboxers. Athletes completed three rounds of 12 maximal effort punches delivered to a punching integrator on three separate days. Day one was a familiarisation session with only control instructions provided. In the following two days athletes randomly received IFA, EFA or control instructions prior to each of the three rounds. Athletes punching with EFA were 4% faster and 5% more forceful than IFA (P < 0.05), and 2% faster and 3% more forceful than control (P < 0.05). Furthermore, experts punched 11% faster and with 13% greater force compared with intermediate athletes (P < 0.05). EFA led to a positive effect on punching performance and should be favoured over IFA and control instructions. 相似文献
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Israel Halperin Dale W. Chapman Kevin G. Thompson Chris Abbiss 《Journal of sports sciences》2019,37(1):59-66
Prior research indicates that providing participants with positive augmented feedback tends to enhance motor learning and performance, whereas the opposite occurs with negative feedback. However, the majority of studies were conducted with untrained participants performing unfamiliar motor tasks and so it remains unclear if elite athletes completing familiar tasks respond in a similar fashion. Thus, this study investigated the effects of three different versions of false-performance feedback on punching force (N), pacing (force over time) and ratings of perceived exertion (RPE) in 15 elite amateur male boxers. Athletes completed a simulated boxing bout consisting of three rounds with 84 maximal effort punches delivered to a punching integrator on four separate days. Day one was a familiarisation session in which no feedback was provided. In the following three days athletes randomly received false-positive, false-negative and false-neutral feedback on their punching performance between each round. No statistical or meaningful differences were observed in punching forces, pacing or RPE between conditions (P > 0.05; ≤ 2%). These null results could stem from the elite status of the athletes involved, the focus on performance rather than learning, or they may indicate that false feedback has a less potent effect on performance than previously thought. 相似文献
3.
This study aimed to (1) profile a professional boxer (23 years and 80 kg) with boxing-specific, muscle function, aerobic capacity and body composition tests, and (2) quantify how these measures varied during an 8-week preparation phase leading to, and post a state-Title Bout fought in the 76.2-kg class. A series of boxing-specific and muscle function tests were completed on 11 occasions: 9 prior and twice after the bout, each separated by approximately 2 weeks. The boxing test included 36 maximal punches (9 of each: lead and rear straights, lead and rear hooks) to a punching integrator measuring forces and velocity. Muscle function tests included countermovement jump, drop-jumps, isometric mid-thigh pull and isometric bench-press. Body composition was assessed using skin-fold measurements on three occasions and one dual energy X-ray absorptiometry scan. Aerobic capacity was assessed using 2 VO2 max tests. Leading up to the bout, performance decreased in isometric mid-thigh pull (8%), isometric bench-press (5%), countermovement jump (15%) and impact forces in 3 of 4 punches (4%–7%). Whereas measures of dynamic and isometric muscle function remained depressed or unchanged post competition, punching forces (6%–15%) and aerobic power (6%) increased. Data suggest the athlete may have super-compensated following rest as fatigue dissipated and further adaptation occurred. 相似文献
4.
Authoritarianism, perceived threat and exclusionism on the eve of the Disengagement: Evidence from Gaza 总被引：1，自引：0，他引：1
Canetti D Halperin E Hobfoll SE Shapira O Hirsch-Hoefler S 《Int J Intercult Relat》2009,33(6):463-474
Major political events such as terrorist attacks and forced relocation of citizens may have an immediate effect on attitudes towards ethnic minorities associated with these events. The psychological process that leads to political exclusionism of minority groups was examined using a field study among Israeli settlers in Gaza days prior to the Disengagement Plan adopted by the Israeli government on June 6, 2004 and enacted in August 2005. Lending credence to integrated threat theory and to theory on authoritarianism, our analyses show that the positive effect of religiosity on political exclusionism results from the two-staged mediation of authoritarianism and perceived threat. We conclude that religiosity fosters authoritarianism, which in turn tends to move people towards exclusionism both directly and through the mediation of perceived threat. 相似文献
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Sweat lactate reflects eccrine gland metabolism. However, the metabolic tendencies of eccrine glands in a hot versus thermoneutral environment are not well understood. Sixteen male volunteers completed a maximal cycling trial and two 60-min cycling trials [30°C?=?30±1°C and 18°C?=?18±1°C wet bulb globe temperature (WBGT)]. The participants were requested to maintain a cadence of 60 rev?·?min?1 with the intensity individualized at ～ 90% of the ventilatory threshold. Sweat samples at 10, 20, 30, 40, 50 and 60?min were analysed for lactate concentration. Sweat rate at 30°C (1380±325?ml?·?h?1) was significantly greater (P<0.05) than at 18°C (632±311?ml?·?h?1). Sweat lactate concentration was significantly greater (P<0.05) at each time point during the 18°C trial, with values between trials tending to converge across time. During the 30°C trial, both heart rate (20, 30, 40, 50 and 60?min) and rectal temperature (30, 40, 50 and 60?min) were significantly higher than in the 18°C trial. Higher sweat lactate concentrations coupled with lower sweat rates may indicate a greater relative contribution of oxygen-independent metabolism within eccrine glands during exercise at 18°C. Decreases in sweat lactate concentration across time suggest either greater dilution due to greater sweat volume or increased reliance on aerobic metabolism within eccrine glands. The convergence of lactate concentrations between trials may indicate that time-dependent modifications in sweat gland metabolism occur at different rates contingent partially on environmental conditions. 相似文献
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Israel Halperin Brandon W. Collins Michael Monks Chris T. Compton Joseph D. Yetman Angela Loucks-Atkinson 《European Journal of Sport Science》2018,18(7):994-1003
Purpose: To compare the physiological and perceptual responses of the upper and lower body to all-out cyclical sprints with short or long rest periods between sprints.Methods: Ten recreationally trained males completed four 10?×?10?s sprint protocols in a randomized order: upper body with 30?s and 180?s of rest between sprints, and lower body with 30?s and 180?s of rest between sprints. Additionally, maximum voluntary contractions (MVC) were measured at pre-sprint and post-sprints 5 and 10. Normalized (% of first sprint) peak power, MVC, heart rate (HR) and rating of perceived exertion (RPE) were compared between upper and lower body within the same recovery period, and absolute values (Watts, bpm, RPE scores) were compared within the same body part and between recovery periods.Results: Trivial differences were identified in normalized peak power, HR and RPE values between the upper and lower body in both recovery conditions (<2%, d?≤?0.1), but MVC forces were better maintained with the upper body (～9.5%, d?=?1.0) in both recovery conditions. Absolute peak power was lower (～147?Watts, d?=?1.3), and HR was higher (～10?bpm, d?=?0.73) in the 30?s compared to 180?s condition in both the upper and lower body whereas RPE scores were similar (<0.6?RPE units, d?≤?0.1). Despite the reductions in peak power, MVC forces were better maintained in the 30?s condition in both upper (2.5?kg, d?=?0.4) and lower (7.5?kg, d?=?0.7) body.Conclusions: Completing a commonly used repeated sprint protocol with the upper and lower body results in comparable normalized physiological and perceptual responses. 相似文献
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The intensification of online disclosure of personal information, coupled with the ability to link personal information to those who disclose it, poses important questions regarding the benefits and risks associated with sharing of personal data. This article examines the manifestation of these concerns in news media. Guided by framing theory, it seeks to ascertain the prevailing frames for personal information sharing and to determine whether such framing facilitates debate on issues related to self-disclosure. Articles published in top Israeli online newspapers were analyzed (n = 609). Findings show that the individual user, the state, and corporations are framed as key actors that shape online self-disclosure practices and their outcomes. Furthermore, the individual user, while portrayed as chief actor, is seen as the weakest player. 相似文献
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Mogamat Razeen Davids Usuf Chikte Karen Grimmer‐Somers Mitchell L Halperin 《British journal of educational technology : journal of the Council for Educational Technology》2014,45(2):367-381
The usability of computer interfaces may have a major influence on learning. Design approaches that optimize usability are commonplace in the software development industry but are seldom used in the development of e‐learning resources, especially in medical education. We conducted a usability evaluation of a multimedia resource for teaching electrolyte and acid‐base disorders by studying the interaction of 15 medical doctors with the application. Most of the usability problems occurred in an interactive treatment simulation, which was completed successfully by only 20% of participants. A total of 27 distinct usability problems were detected, with 15 categorized as serious. No differences were observed with respect to usability problems detected by junior doctors as compared with more experienced colleagues. Problems were related to user information and feedback, the visual layout, match with the real world, error prevention and management, and consistency and standards. The resource was therefore unusable for many participants; this is in contrast to good scores previously reported for subjective user satisfaction. The findings suggest that the development of e‐learning materials should follow an iterative design‐and‐test process that includes routine usability evaluation. User testing should include the study of objective measures and not rely only on self‐reported measures of satisfaction. 相似文献
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Ruth Halperin 《Learning, Media and Technology》2017,42(3):279-294
Scholars in the field of educational technology have been calling for robust use of social theory within learning technology research. In view of that, interest has been noted in applying Giddens’ structuration theory to the understanding of human interaction with technology in learning settings. However, only few such attempts have been published to date with recent reviews indicating the scarcity of structurational accounts from the educational technology field. Addressing this gap and advancing a critical use of the theory in the field, an attempt is made in this paper to lend coherency to structuration-based research into learning technology. Specifically, a critical consideration of the structurational Practice Lens is offered drawing from its application in a case study that explored technology-mediated learning practices in the institutional context of higher education. Conceptual and analytical aspects are addressed with a view to augment the framework, and to extend its relevance and applicability in educational technology research. 相似文献