Influence of regression model and incremental test protocol on the relationship between lactate threshold using the maximal-deviation method and performance in female runners     

Fabiana Andrade Machado  Fábio Yuzo Nakamura  Solange Marta Franzói De Moraes 《Journal of sports sciences》2013,31(12):1267-1274

Abstract

This study examined the influence of the regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and the endurance performance. Sixteen non-competitive, recreational female runners performed a discontinuous incremental treadmill test. The initial speed was set at 7 km · h^?1, and increased every 3 min by 1 km · h^?1 with a 30-s rest between the stages used for earlobe capillary blood sample collection. Lactate-speed data were fitted by an exponential-plus-constant and a third-order polynomial equation. The lactate threshold was determined for both regression equations, using all the coordinates, excluding the first and excluding the first and second initial points. Mean speed of a 10-km road race was the performance index (3.04 ± 0.22 m · s^?1). The exponentially-derived lactate threshold had a higher correlation (0.98 ≤ r ≤ 0.99) and smaller standard error of estimate (SEE) (0.04 ≤ SEE ≤ 0.05 m · s^?1) with performance than the polynomially-derived equivalent (0.83 ≤ r ≤ 0.89; 0.10 ≤ SEE ≤ 0.13 m · s^?1). The exponential lactate threshold was greater than the polynomial equivalent (P < 0.05). The results suggest that the exponential lactate threshold is a valid performance index that is independent of the initial intensity of the incremental test and better than the polynomial equivalent.  相似文献   

Technical and physical match performance of teams in the 2018 FIFA World Cup: Effects of two different playing styles     

Qing Yi  Miguel A. Gómez  Lei Wang  Guohu Huang  Hengliang Zhang 《Journal of sports sciences》2013,31(22):2569-2577

ABSTRACT

In order to investigate the effect of playing styles on the match performance of football teams, data were analysed on 18 technical performance-related variables and 8 physical performance-related variables from 59 matches in the 2018 FIFA World Cup. A k-means cluster analysis was conducted to classify all match observations into two clusters of tactical approach in order to identify the playing styles of teams (characterised as direct-play, possession-play and mixed-play). Separate Poisson regression models were run in the generalised mixed linear modelling to examine the differences in technical and physical performance between teams classified as using different playing styles when facing different opponents. Results showed that possession-play characterised teams achieved higher values in all the variables related to goal scoring, attacking and passing (ES: 0.32 ~ 1.27) and covered more distance in sprints and high-intensity running (ES: 0.33 ~ 0.47) than direct-play characterised teams. Both possession- and direct-play characterised teams achieved higher values in passing, pass accuracy and delivery into the attacking third playing against direct-play characterised teams than playing against possession-play characterised sides (ES: 0.22 ~ 0.98). These findings may provide insights into the establishment of performance profiles of teams with different tactical styles and the development of specific training drills to optimise playing style.  相似文献   

Ageing of brazilwood dye in wool – a chromatographic and spectrometric study     

Ana Manhita  Vanda Santos  Helena Vargas  António Candeias  Teresa Ferreira  Cristina Barrocas Dias 《Journal of Cultural Heritage》2013,14(6):471-479

Brazilwood was used in this work to dye wool mordanted with different amounts of copper(II) sulfate, alum and iron(II) sulfate. Two different dyeing methods were used: premordanting (MD) and simultaneous mordanting (M+D) procedures. In order to evaluate the influence of the mordant ion in the brazilein chromophore photodegradation, samples were subjected to artificial light ageing. Color measurements were made and, for the first time, LC-DAD-ESI-MS was used for chromophore analysis of the dyed fibers before and after light exposure. Mordant ion quantification was done after fiber acid digestion, by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and flame atomic absorption spectroscopy (FAAS). Mordant metal ion, mordant bath concentration and dyeing procedure were found to have strong influence in the wool fiber hues. Color variation was more pronounced in the alum dyed samples. Overall, mordant quantification showed that the amount of metal ions found in the fibers is very small when compared to the original concentrations of the dyeing bath, being Cu the ion with greater affinity for the wool fibers. MD dyeing procedure yielded fibers with larger amounts of mordant metal ions and higher chromophore peak areas. Higher amounts of brazilein were extracted from wool mordanted with copper(II) sulfate. Finally, chromatographic analysis of the brazilwood dyed samples before and after light exposure resulted in the detection of Type C compound as an outcome of the photodegradation process.  相似文献   

Preservation of a two-wing Lorenz-like attractor with stable equilibria     

L.J. Ontañón-García  E. Campos-Cantón 《Journal of The Franklin Institute》2013,350(10):2867-2880

In this paper, we present the preservation of a two-wing Lorenz-like attractor when in the Lorenz system a feedback control is applied, making two of its equilibria a sink. The forced system is capable of generating bistability and the trajectory settles down at one stable equilibrium point depending on the initial condition when the forced signal is zero. Due to a variation in the coupling strength of the control signal the symmetric equilibria of the Lorenz system move causing the basins of attraction to be the dynamic bounded regions that change accordingly. Thus, the preservation of a two-wing Lorenz-like attractor is possible using a switched control law between these dynamic basins of attraction. The forced switched systems also preserve multistability regarding the coupling strength and present multivalued synchronization according to the basin of attraction in which they were initialized. Bifurcations of the controlled system are used to exemplify the different basins generated by the forcing. An illustrative example is given to demonstrate the approach proposed.  相似文献   

The Beginnings of Hockey in 1930s Galicia (Spain): A Female Phenomenon     

Cristina López-Villar 《国际体育史杂志》2013,30(9):1133-1157

This article considers the early days of field hockey in Galicia from the perspective of a female phenomenon, as in this region women's teams emerged before those of their male counterparts. The fact that women were the first to play field hockey in Galicia, and formed the driving force behind this sport in the north-west of the Iberian Peninsula offers an interesting insight into the phenomenon of sport in 1930s Spain. The prevalence of Galician hockey teams and the presence of Galician players in international competitions provide ample evidence for this research. This article discusses the history of field hockey in Galicia, taking into account the influences of precursors. It also analyses the socialising aspect for women of participation in clubs and other activities related to hockey, as well as the role of sport in the creation of female sporting identities and the initiatives led by the women themselves. The text includes images with the objective of making the protagonists of the dissemination of women's sport in Spain more visible.  相似文献   

Developmental foundations of physiological dynamics among mother–infant dyads: The role of newborn neurobehavior     

Mengyu Gao  Bailey Speck  Brendan Ostlund  Dylan Neff  Nila Shakiba  Robert D. Vlisides-Henry  Parisa R. Kaliush  Nicolette C. Molina  Leah Thomas  K. Lee Raby  Sheila E. Crowell  Elisabeth Conradt 《Child development》2022,93(4):1090-1105

This study tested whether newborn attention and arousal provide a foundation for the dynamics of respiratory sinus arrhythmia (RSA) in mother–infant dyads. Participants were 106 mothers (M_age = 29.54) and their 7-month-old infants (55 males and 58 White and non-Hispanic). Newborn attention and arousal were measured shortly after birth using the NICU Network Neurobehavioral Scale. Higher newborn arousal predicted a slower return of infant RSA to baseline. Additionally, greater newborn attention predicted mothers’ slower return to baseline RSA following the still-face paradigm, and this effect only held for mothers whose infants had lower newborn arousal. These findings suggest that newborn neurobehavior, measured within days of birth, may contribute to later mother–infant physiological processes while recovering from stress.  相似文献   

The transformation of doctoral education: a systematic literature review     

Cardoso  Sónia  Santos  Sandra  Diogo  Sara  Soares  Diana  Carvalho  Teresa 《Higher Education》2022,84(4):885-908

Higher Education - Framed by a wide range of factors, doctoral education has undergone a deep transformation, especially in the last two decades. The aim of this systematic literature review was to...  相似文献   

Emotional profiles regarding maths among primary school children – A two-year longitudinal study     

Mata  Lourdes  Monteiro  Vera  Peixoto  Francisco  Santos  Natalie Nóbrega  Sanches  Cristina  Gomes  Marta 《European Journal of Psychology of Education - EJPE》2022,37(2):391-415

Learning maths is challenging for many primary school students, and teachers must understand students’ learning and emotional processes specific to learning maths. The current research, grounded in control-value theory, focused on achievement emotions regarding maths. Primary school students (N?=?71) were studied with the primary objective of examining the longitudinal trajectories of achievement emotions of third graders over two years. The Portuguese Achievement Emotions Questionnaire for Elementary Students was administered biannually to assess enjoyment, anxiety, and boredom regarding maths. The results indicate that enjoyment decreased and boredom increased over time, revealing three emotional profiles: positive, negative and moderate. The positive profile showed the highest scores in maths achievement. Profile membership was moderately stable and became increasingly stable and structured. In examining the complexity of students’ emotional profiles and processes, the importance of understanding them to enhance educational support, development, and learning was highlighted.

  相似文献   

A Mirage of Change: Visibility of Politicians on TVE during the 2015 and 2016 General Elections     

José María García-de-Madariaga  José Antonio Navarro Moreno  Agustín Olmo López 《Journalism Practice》2020,14(3):339-357

ABSTRACT

The use of strategies to enhance the media visibility of politicians intensifies above all at election time and their focus is chiefly television due to the fact that it still has the greatest power to sway voters. Thus, based on a content analysis of the evening news on Televisión Española (TVE) and 18 semi-structured in-depth interviews with professionals working at the Spanish public broadcaster, the airtime that politicians were given was established to assess whether it had fulfilled its obligation as regards independence and pluralism at two crucial moments for Spanish politics: the period prior to the election calls, the pre-campaign periods and the official campaigns before the general elections held on 20 December 2015 and 26 June 2016. Both were unique in their own way: on the one hand, the debut of new political parties with the potential to win a large number of seats in Parliament; and, on the other, despite the fact that in just six months the party in power had lost its absolute majority and there were still no visible signs of change at TVE, it is still worth examining the variations in news treatment prior to both elections.  相似文献   

Breaking away to find a way: poverty and school failure in a Spanish adolescent life-history     

I. Calderón-Almendros 《British Journal of Sociology of Education》2011,32(5):745-762

This article is part of a biographical research study, and explores the social path that an adolescent from a marginal background in Malaga (Spain) has travelled throughout his life. The research shows a class differentiation that divides society in two: you, who control the means of production, impose your culture, and define the policy and the school; and we, who live in poor houses and districts, learn in the street and do things that are worthy of punishment – the bad ones. School failure, the result and cause of this division, leads to social failure, provoking ‘guerrillas against the good ones’ (teachers, peers, guards, police, judges, etc.) of youngsters who have learned to devalue themselves as people and as a group: youngsters who have to break away to find a way.  相似文献