高强度间歇训练的科学与实践:应用考量与关键指标

高强度间歇训练(HIIT)是以≥无氧阈或最大乳酸稳态的负荷强度进行多次持续时间为几秒到几分钟的练习,并且每 2.次练习之间安排不足以使练习者完全恢复的静息或低强度练习的训练方法。进入2 1.世纪以来,HIIT受到了训练科学与实践领域的密切关注,越来越多的教练员在训练实践中开始采用HIIT来提升运动员的竞技表现。然而,HIIT不只是“高强度”和“间歇”这么简单,其效果和价值的发挥需要考虑诸多因素。本文基于《高强度间歇训练的科学与应用:训练安排的解决方案》一书内容,分别从形式和目标类型、应用的整体框架、应用情境、同期化训练、关键指标 5.个方面对HIIT进行了论述,旨在为教练员和科研人员在训练实践当中应用HIIT并发挥HIIT的价值提供参考     

Friendship moderates prospective associations between social isolation and adjustment problems in young children

This longitudinal study investigated prospective links between social isolation and adjustment problems among 166 (77 girls, 89 boys) Finnish children ages 7 to 9. Peer nominations for social engagement and self-reports of internalizing and externalizing problems were collected in the spring of the 1st and 2nd grade. Friendship moderated prospective associations between peer and adjustment variables. Among friended children, there were no prospective associations between social isolation and either internalizing or externalizing problems. Among unfriended children, initial social isolation was positively linked to subsequent increases in internalizing and externalizing problems, and initial internalizing and externalizing problems predicted subsequent increases in social isolation. The findings suggest that friendship buffers against the adverse consequences associated with being isolated and presenting adjustment difficulties.     

Practical precooling: effect on cycling time trial performance in warm conditions

The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test (VO2(peak) 71.4 +/- 3.2 ml x kg(-1) x min(-1)) and four approximately 40 min laboratory cycling time trials in a heat chamber (34.3 degrees C +/- 1.1 degrees C; 41.2% +/- 3.0% rh) using a fixed-power/variable-power format. Cyclists prepared for the time trial using three techniques administered in a randomised order prior to the warm-up: (1) no cooling (control), (2) cooling jacket for 40 min (jacket) or (3) 30-min water immersion followed by a cooling jacket application for 40 min (combined). Rectal temperature prior to the time trial was 37.8 degrees C +/- 0.1 degrees C in control, similar in jacket (37.8 degrees C +/- 0.3 degrees C) and lower in combined (37.1 degrees C +/- 0.2 degrees C, P < 0.01). Compared with the control trial, time trial performance was not different for jacket precooling (-16 +/- 36 s, -0.7%; P = 0.35) but was faster for combined precooling (-42 +/- 25 s, - .8%; P = 0.009). In conclusion, a practical combined precooling strategy that involves immersion in cool water followed by the use of a cooling jacket can produce decrease in rectal temperature that persist throughout a warm-up and improve laboratory cycling time trial performance in warm conditions.     

Searching high and low: what types of firms use universities as a source of innovation?

This paper examines the factors that influence why firms draw from universities in their innovative activities. The link between the universities and industrial innovation, and the role of different search strategies in influencing the propensity of firms to use universities is explored. The results suggest that firms who adopt “open” search strategies and invest in R&D are more likely than other firms to draw from universities, indicating that managerial choice matters in shaping the propensity of firms to draw from universities.     

The benefits of multi-year research experiences: differences in novice and experienced students' reported gains from undergraduate research

This mixed-methods study explores differences in novice and experienced undergraduate students' perceptions of their cognitive, personal, and professional gains from engaging in scientific research. The study was conducted in four different undergraduate research (UR) programs at two research-extensive universities; three of these programs had a focus on the biosciences. Seventy-three entry-level and experienced student researchers participated in in-depth, semi-structured interviews and completed the quantitative Undergraduate Research Student Self-Assessment (URSSA) instrument. Interviews and surveys assessed students' developmental outcomes from engaging in UR. Experienced students reported distinct personal, professional, and cognitive outcomes relative to their novice peers, including a more sophisticated understanding of the process of scientific research. Students also described the trajectories by which they developed not only the intellectual skills necessary to advance in science, but also the behaviors and temperament necessary to be a scientist. The findings suggest that students benefit from multi-year UR experiences. Implications for UR program design, advising practices, and funding structures are discussed.     

Students’ Choice and Social Selection

In democratic countries, students make individual choices of courses of higher education; psychological theories have tried to explain the logic of these choices. The “flow” of young people into different courses of education and different parts of the labour market can also be viewed as a social process which can be studied sociologically. But both the psychological and the sociological theories are incomplete. The article tries to integrate the two kinds of theories using inspiration from the “structuration theory” of A. Giddens. Empirical support to the theory is given through a sketch of the history of the Danish admission policy and as a review of a survey of the choice of higher education by Danish students. The article concludes with proposals for further research.     

The role of lead users in knowledge sharing

This paper introduces a model of knowledge sharing in an online community of practice that suggests that knowledge contributions will be made by those who possess the relevant knowledge. For them, matching a ready-made solution to a problem is low cost. We hypothesize that lead users – due to their characteristics – are likely to possess more relevant solution knowledge and thus be centrally involved in contributing knowledge. Our results support the hypothesis by showing that lead user characteristics relate positively to making contributions to the community. In addition, we find that search and integration of knowledge from different external sources of relevance to the community positively moderates knowledge contributions by lead users.     

Conflict Resolution Among Preschool Children: The Appeal of Negotiation in Hypothetical Disputes

Young children's preferences for conflict management strategies were assessed with hypothetical puppet interviews. A total of 48 children enrolled in a university nursery school were each presented 12 vignettes depicting common peer conflicts. Vignettes varied as a function of conflict issue (roles and possessions) and peer friendship status (friends and nonfriends). Three conflict resolution strategies were contrasted: negotiation, power assertion, and disengagement. The results indicated an overwhelming preference for negotiation. In contrast, power assertion was the least desirable means of resolving disputes. No differences emerged as a function of conflict issue or friendship status. Neither were there differences according to the age or sex of the subject. The findings indicate that young children evince a similar preference for resolving conflicts through negotiation and cooperation as has been reported in studies of older children and adolescents.     

A Test of the Bistrategic Control Hypothesis of Adolescent Popularity

Resource Control Theory (Hawley, 1999) posits a group of bistrategic popular youth who attain status through coercive strategies while mitigating fallout via prosociality. This study identifies and distinguishes this bistrategic popular group from other popularity types, tracing the adjustment correlates of each. Adolescent participants (288 girls, 280 boys; M_age = 12.50 years) completed peer nominations in the Fall and Spring of the seventh and eighth grades. Longitudinal latent profile analyses classified adolescents into groups based on physical and relational aggression, prosocial behavior, and popularity. Distinct bistrategic, aggressive, and prosocial popularity types emerged. Bistrategic popular adolescents had the highest popularity and above average aggression and prosocial behavior; they were viewed by peers as disruptive and angry but were otherwise well-adjusted.