Reliability of estimating active drag in swimming using the assisted towing method with fluctuating speed

The reliability of active drag values was examined using a method that compared free swim speed with measurements taken by towing swimmers slightly faster than their maximum swim speed, while allowing their intra-stroke speed fluctuations. Twelve national age and open level swimmers were tested on two alternate days (Day 1 and Day 2). All participants completed four maximum swim speed, three passive drag and five active drag trials on each of the days. The reliability was determined using within-participant intra-class correlation coefficients (ICC) within each day and between the days. The ICCs for Day 1 and Day 2 were 0.82 and 0.85, respectively, while the comparison of the mean active drag values between days was 0.93. The data showed that the assisted towing method (ATM) with fluctuating speed was only moderately reliable within a single test. However, this method was more reliable when using the average value of active drag from both days (ICC = 0.93). This study identified that the ATM method with fluctuating speed had moderate reliability within-participant trials on values in a single day but high reliability for the average active drag values across different days.     

Relationship between physical activity,physical fitness and multiple metabolic risk in youths from Muzambinho's study

Negative associations between physical activity (PA), physical fitness and multiple metabolic risk factors (MMRF) in youths from populations with low PA are reported. The persistence of this association in moderately-to highly active populations is not, however, well established. The aim of the present study was to investigate this association in a Brazilian city with high frequency of active youths. We assessed 122 subjects (9.9?±?1.3 years) from Muzambinho city. Body mass index, waist circumference, glycaemia, cholesterolaemia, systolic and diastolic blood pressures were measured. Maximal handgrip strength and one-mile walk/run test were used. Leisure time PA was assessed by interview. Poisson regression was used in the analysis. The model explained 11% of the total variance. Only relative muscular strength and one-mile walk/run were statistically significant (p?相似文献   

Acute effects of exercise and active video games on adults’ reaction time and perceived exertion

The purpose of the present study was to examine the acute effects of resting, aerobic exercise practised alone, and aerobic exercise with active video games (AVG), on complex reaction time (CRT) and the post-exercise acute rate of perceived exertion (RPE) in young healthy adults. The experimental group was composed of 92 healthy young adults, 78 males and 13 females (age M?=?21.9?±?2.7 years) who completed two sessions, A and B. In session A, participants rode 30?min on an ergometer, while in session B they exercised for 30?min on an ergometer while playing an AVG on a Wii. The control group was composed of 30 young adults, 26 males and 4 females (age M?=?21.4?±?2.9 years) who rested for 30?min. In each session, a CRT task was performed before and after exercising or resting, and post-exercise global RPE was noted. Repeated measures general linear model (GLM) and Wilcoxon tests were performed. (1) Both aerobic exercise alone and aerobic exercise combined with AVG improved CRT, while resting did not; (2) aerobic exercise combined with AVG did not improve CRT more than aerobic exercise only; and (3) RPE was lower after aerobic exercise combined with AVG compared with aerobic exercise only. In young adults, exercise produces acute benefits on CRT, and practising exercise with AVG helps to decrease RPE.     

The peak velocity derived from the Carminatti Test is related to physical match performance in young soccer players

ABSTRACT

The aim of this study was to examine the relationship between the peak velocity derived from the Carminatti Test (T-CAR) (PV_T-CAR) and physical match performance in young soccer players. Thirty-three youth soccer players were recruited from 2 non-professional clubs. Friendly matches and small-sided game were performed. Physical match demands were assessed using Global Positioning System (GPS) technology. On a separate occasion, the players were submitted to the T-CAR. Players were categorised into 3 groups based on their T-CAR performance: Low (PV_T-CAR ≤ P33), Intermediate (P33 > PV_T-CAR < P66) and High (PV_T-CAR ≥ P66). The PV_T-CAR (15.5 ± 0.7 km·h^?1) was significantly related to high-intensity activities (HIA; r = 0.78, P < 0.001), high-intensity running (HIR; r = 0.66, P < 0.001), sprinting (r = 0.62, P < 0.001) and total distance (TD) covered (r = 0.47, P < 0.01) during friendly matches. The PV_T-CAR was strongly correlated with the amount of HIA (r = 0.81, P < 0.001), HIR (r = 0.85, P < 0.001) and TD covered (r = 0.81, P < 0.001) during small-sided game. No significant correlation was observed between the PV_T-CAR and distance of sprinting (r = 0.49, P = 0.067) during small-side game. Furthermore, players in the High group covered significantly more TD (10%) and did more HIA (42%), sprinting (31%) and HIR (25%) during friendly matches compared to the players classified as having Low performance on the T-CAR. These differences still remained after adjusting for chronological age (CA), maturity and body size. In conclusion, the current study gives empirical support to the ecological and construct validity of this novel field test (T-CAR) as an indicator of match-related physical performance in young soccer players during pubertal years.     

Effects of an intervention programme with teachers on the development of positive behaviours in Spanish physical education classes

Background: The physical education (PE) context has been emphasised as an ideal environment for developing positive behaviours among students. Under the Positive Youth Development paradigm, various initiatives have been conducted with the aim of promoting personal and social responsibility among adolescents. Self-Determination Theory has been widely used to analyse students’ motivational processes during PE classes.

Purpose: This study aimed to measure the effects of a multidisciplinary intervention with teachers on the development of positive behaviours in PE classes.

Participants: Twenty PE teachers participated in the study (M_age?=?35 years; SD?=?2.32) along with 777 of their students (M_age?=?12.81 years; SD?=?.93). The teachers (male?=?16; female?=?4) were between the ages of 29 and 48 years (M?=?35.2 years; SD?=?2.32). The students who participated in this study (male?=?377; female?=?400) were divided into 52 classes and were between the ages of 12 and 16 years (M?=?12.81; SD?=?.93).

Research design: A quasi-experimental design was used that consisted of a control group and three groups in which an intervention was developed. In the control group, the teachers did not receive any type of intervention; in the second group, the teachers received a training programme to develop strategies for supporting basic psychological needs and promoting positive behaviours; in the third group, the teachers received a didactic unit to promote positive behaviours; and in the last group the teachers received a combination of the two previous interventions.

Data analysis: A repeated-measures ANCOVA (analysis of covariance) was used for every dependent variable included in the study to analyse the effect of Group?×?Time interaction, including Gender and Grade Level as covariates. The fixed effects caused by Intercept, Group, Time, and the Group?×?Time interaction were calculated using compound symmetry as the type of covariance and restricted maximum likelihood as the estimation method.

Findings: By examining the differences between pre-test and post-test, it was determined that in comparison with the students in the control group, the students from the three experimental groups had generally improved scores on the variables related to positive behaviours, such as perceptions of the teacher's support, as well as the development of the targeted behaviours.

Conclusions: These results provide information about the efficacy of an intervention programme with teachers that consists of strategies for developing positive behaviour and support for basic psychological needs to promote the development of positive student behaviour.     

Yo-Yo Intermittent Endurance Test-Level 1 to monitor changes in aerobic fitness in pre-pubertal boys

The present study aimed to examine the performance and heart rate responses during the Yo-Yo Intermittent Endurance Test-Level 1 (Yo-Yo IE1) in children under the age of 10. One hundred and seven male children (7–9 years) performed the Yo-Yo IE1 at the beginning (M₁), middle (M₂) and end (M₃) of the school year. Data from individual heart rate curves of the Yo-Yo IE1 were analysed in order to detect the inflection point between an initial phase of fast rise in heart rate values and a second phase in which the rise of the heart rate values is much smaller. The distance covered in the Yo-Yo IE1 improved from M₁ to M₃ (884 ± 496 vs. 1032 ± 596 m; p < 0.05; d = 0.27), with intermediate values for M₂ (962 ± 528 m). Peak heart rate (HR_peak) decreased from M₁ to M₂ and M₃ (204 ± 9, 202 ± 9 and 200 ± 9 bpm, respectively; p < 0.05; d = 0.25–0.42). The 7th shuttle of the test (280 m), corresponding to 2.5 min, was identified as the inflection point between the two phases. Also, absolute heart rate at the 7th shuttle decreased progressively throughout the year (185 ± 9, 183 ± 10, and 179 ± 10 bpm; p < 0.05; d = 0.31–0.61). The present study provides evidence of the usefulness of a maximal as well as a submaximal version of Yo-Yo IE1 as a tool to monitor changes in aerobic fitness in pre-pubertal children.     

A Rationale for Public Library Civics Instruction

Statistics bear out the dire need for civic education and engagement within our nation’s libraries, those free and “equalizing” institutions that traditionally afforded opportunities assisting in the development of civically astute individuals. Per our founding principles, libraries and librarians remain responsible for instituting programming that assists in the development of capable citizens who actively participate in political life, hence ensuring the perpetuation and positive evolvement of our governmental system and its resulting law. Public and school libraries must return to a targeted emphasis on the provision of services that develop critical thinking opportunities steeped in civic intent and purpose. Examples include civic-oriented instruction, debate, communication, service and public policy facilitation, and forum building.     

Evolution in Freedom? The Meanings of ‘Free School’ in Chile

This article examines the background in which enterprises called free schools, as well as complementary educational activities, have taken root in Chile. Two kinds of recently burgeoning free schools are identified; one supplementing regular schooling with a social justice focus, and another that is a fully fledged alternative to other schooling. The history of freedom itself in Chile is explored from a historical perspective, contrasting somewhat with freedom as it is understood in more developed countries. Parallels to Anglophone free schools such as AS Neill’s Summerhill are also discussed, as well as the sociopolitical context in which Chilean free schools continue to develop.     

The influence of core teaching conceptions on teachers' use of inquiry teaching practices

This article investigates three teachers' conceptions and use of inquiry‐based instructional strategies throughout a professional development program. The professional development program consisted of a 2‐week summer inquiry institute and research experience in university scientists' laboratories, as well as three academic year workshops. Insights gained from an in‐depth study of these three secondary teachers resulted in a model of teacher conceptions that can be used to direct future inquiry professional development. Teachers' conceptions of inquiry teaching were established through intensive case–study research that incorporated extensive classroom observations and interviews. Through their participation in the professional development experience, the teachers gained a deeper understanding of how to implement inquiry practices in their classrooms. The teachers gained confidence and practice with inquiry methods through developing and presenting their institute‐developed inquiry lessons, through observing other teachers' lessons, and participating as students in the workshop inquiry activities. Data analysis revealed that a set of four core conceptions guided the teachers' use of inquiry‐based practices in their classrooms. The teachers' conceptions of science, their students, effective teaching practices, and the purpose of education influenced the type and amount of inquiry instruction performed in the high school classrooms. The research findings suggest that to be successful inquiry professional development must not only teach inquiry knowledge, but it must also assess and address teachers' core teaching conceptions. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 1318–1347, 2007     

Les représentations graphiques dans l’enseignement et l’apprentissage de l’electricité

The teaching of basic electricity uses many circuit diagrams. We present in this paper several experiments which show that no specific teaching about the decoding and understanding of the graphical information contained in these diagrams in made in class. On the contrary teaching reinforces the role of certain types of diagrams (canonical ones) which contribute to the organisation of students’ knowledge in the, form of prototypes. Thus diagrams become autonomous objects unrelated to concepts of electricity they are representing. We will present some experiments in the area of learning about electricity which aim at changing the usual classroom practices. They take into account the naive conceptions of students. Within this framework, graphical representations are used as a support for learning concepts of electricity.