The effect of different foot and hand set-up positions on backstroke start performance

Foot and hand set-up position effects were analysed on backstroke start performance. Ten swimmers randomly completed 27 starts grouped in trials (n = 3) of each variation, changing foot (totally immersed, partially and totally emerged) and hand (lowest, highest horizontal and vertical) positioning. Fifteen cameras recorded kinematics, and four force plates collected hands and feet kinetics. Standardised mean difference and 95% confidence intervals were used. Variations with feet immersed have shown lower vertical centre of mass (CM) set-up position (0.16 m), vertical impulse exerted at the hands, horizontal and vertical impulse exerted at the feet (0.28, 0.41, 0.16 N/BW.s, respectively) than feet emerged with hands horizontal and vertically positioned. Most variations with feet partially emerged exhibited higher and lesser vertical impulse exerted at hands than feet immersed and emerged (e.g. vertical handgrip, 0.13, 0.15 N/BW.s, respectively). Variation with feet emerged and hands on the lowest horizontal handgrip depicted shorter horizontal (0.23, 0.26 m) and vertical CM positioning at flight (0.16, 0.15 m) than the highest horizontal and vertical handgrip, respectively. Start variations have not affected 15-m time. Variations with feet partially or totally emerged depicted advantages, but focusing on the entry and underwater biomechanics is relevant for a shorter start time.     

Interdisciplinary therapy changes superoxide dismutase activity and adiponectin in obese adolescents: a randomised controlled trial

The objective of this study is to evaluate the effect of interdisciplinary therapy in the parameters of the oxidative stress and the anti-inflammatory responses of obese adolescents. We selected 57 participants, who were randomly divided into 2 groups: interdisciplinary therapy group and a control group. After 6 months of intervention, 17 participants of the interdisciplinary therapy group and 8 of the control group returned for re-evaluation. The interdisciplinary therapy group participated in a treatment with 4 weekly sessions of exercise, a weekly group therapy session and a weekly nutritional education session. Blood parameters of oxidative stress and anti-inflammatory response were evaluated. The results demonstrated that there were significant increases in the interdisciplinary therapy group for superoxide dismutase activity (6.56 ± 3.22 to 11.40 ± 7.49) and ferric-reducing antioxidant potential concentration (532.91 ± 106.48 to 573.25 ± 112.57), although adiponectin levels did not reduce (40.9 ± 29.34 to 49.05 ± 41.22). A significant decrease in nitrite levels was also found (14.23 ± 8.48 to 11.45 ± 6.05). In the control group, significant reduction was found in adiponectin (31.56 ± 18.88 to 18.01 ± 11.66). This study suggests that interdisciplinary therapy for 6 months was effective in improving the anti-inflammatory responses and the antioxidant defences in obese adolescents.     

Movement velocity as a measure of exercise intensity in three lower limb exercises

The purpose of this study was to investigate the relationship between movement velocity and relative load in three lower limbs exercises commonly used to develop strength: leg press, full squat and half squat. The percentage of one repetition maximum (%1RM) has typically been used as the main parameter to control resistance training; however, more recent research has proposed movement velocity as an alternative. Fifteen participants performed a load progression with a range of loads until they reached their 1RM. Maximum instantaneous velocity (V_max) and mean propulsive velocity (MPV) of the knee extension phase of each exercise were assessed. For all exercises, a strong relationship between V_max and the %1RM was found: leg press (r²_adj = 0.96; 95% CI for slope is [?0.0244, ?0.0258], P < 0.0001), full squat (r²_adj = 0.94; 95% CI for slope is [?0.0144, ?0.0139], P < 0.0001) and half squat (r²_adj = 0.97; 95% CI for slope is [?0.0135, ?0.00143], P < 0.0001); for MPV, leg press (r²_adj = 0.96; 95% CI for slope is [?0.0169, ?0.0175], P < 0.0001, full squat (r²_adj = 0.95; 95% CI for slope is [?0.0136, ?0.0128], P < 0.0001) and half squat (r²_adj = 0.96; 95% CI for slope is [?0.0116, 0.0124], P < 0.0001). The 1RM was attained with a MPV and V_max of 0.21 ± 0.06 m s^?1 and 0.63 ± 0.15 m s^?1, 0.29 ± 0.05 m s^?1 and 0.89 ± 0.17 m s^?1, 0.33 ± 0.05 m s^?1 and 0.95 ± 0.13 m s^?1 for leg press, full squat and half squat, respectively. Results indicate that it is possible to determine an exercise-specific %1RM by measuring movement velocity for that exercise.     

Are the new starting block facilities beneficial for backstroke start performance?

We aimed to analyse the handgrip positioning and the wedge effects on the backstroke start performance and technique. Ten swimmers completed randomly eight 15 m backstroke starts (four with hands on highest horizontal and four on vertical handgrip) performed with and without wedge. One surface and one underwater camera recorded kinematic data. Standardised mean difference (SMD) and 95% confidence intervals (CI) were used. Handgrip positioning did not affect kinematics with and without wedge use. Handgrips horizontally positioned and feet over wedge displayed greater knee angular velocity than without it (SMD = ?0.82; 95% CI: ?1.56, ?0.08). Hands vertically positioned and feet over wedge presented greater take-off angle (SMD = ?0.81; 95% CI: ?1.55, ?0.07), centre of mass (CM) vertical positioning at first water contact (SMD = ?0.97; 95% CI: ?1.87, ?0.07) and CM vertical velocity at CM immersion (SMD = 1.03; 95% CI: 0.08, 1.98) when comparing without wedge use. Swimmers extended the hip previous to the knee and ankle joints, except for the variant with hands vertically positioned without wedge (SMD = 0.75; 95% CI: ?0.03, 1.53). Swimmers should preserve biomechanical advantages achieved during flight with variant with hands vertically positioned and wedge throughout entry and underwater phase.     

Feasibility and students' preliminary views on parkour in a group of primary school children

Background: Adventure education is an instructional model where students participate in adventurous activities to acquire physical, cognitive, and affective skills. It also has strong connections with cooperative learning. Parkour is a fast-growing sport practiced by thousands of youngsters all over the world. The media does not portray it as an educational content, but resourcefulness, maturity, cooperation, and respect are among its basic principles. It also appears to have a direct connection with risk-taking, self-discipline, and autonomy.

Purpose: The purpose of this paper is to assess students' ideas, views, and/or feelings after experiencing a parkour learning unit.

Participants and settings: The research project was conducted in an intact, sixth-grade physical education class in an elementary school located in the northern part of Spain. A total of 26 students with ages ranging between 11 and 12 years (mean age 11.4?±?0.6) participated in the study. There were 14 boys and 12 girls.

Data collection: At the end of the intervention programme, all participating students were asked to ‘Describe your feelings, your thoughts, and your ideas on the parkour learning unit that you just experience in physical education'.

Data analysis: MAXQDA 11, a qualitative software package, was used to assist with data management. All participants' answers were analysed via thematic content analysis and constant comparison.

Findings: Five major categories emerged from data analysis: enjoyment, fear, social skills, problem-solving skills, and integration. Our findings agree with previous researchers who believe that parkour could be considered an educational content due to all the different positive outcomes that it brings to the physical education class. It seems to promote the development of social and problem-solving skills in the students. Both are competences that should be encouraged and fostered in our youngsters. Furthermore, it is considered a fun activity, it promotes students' integration, and it teaches them how to cope with fear.

Conclusion: In contrast to popular views portrayed by the media, the sport of parkour can be a safe, educational content. School cannot turn its back on sports or contents whose popularity is rapidly increasing.     

Developing audience awareness in writing

Beginning writers need to consider their audience; but this is only possible when the writer has reached a certain stage of cognitive development, as it is necessary to consider an absent reality (e.g. an audience reading the piece at a later point). Adapting the text to the audience is only possible when the physical task of writing becomes automatic and the writer is no longer absorbed by it. Then the writer is free to pay attention to other aspects of the task without overloading cognitive processes. Procedural facilitation involves the use of external aids to support a simplified version of the processes used by expert writers. It may function as a way of enabling beginning writers to adapt what they write for their audiences. At the same time, as this task becomes automatic, it may be seen as a way of promoting writing development. A quasi–experimental study is described in which a procedural facilitation strategy is used to promote writing skills, in particular, the skill of suiting the text to the communicative context. The study was with fifth and ninth grade Portuguese students. The results of the post–test show significant progress for the experimental groups in contrast to the control groups.     

Ecological dynamics of continuous and categorical decision-making: The regatta start in sailing

Abstract

Ecological dynamics of decision-making in the sport of sailing exemplifies emergent, conditionally coupled, co-adaptive behaviours. In this study, observation of the coupling dynamics of paired boats during competitive sailing showed that decision-making can be modelled as a self-sustained, co-adapting system of informationally coupled oscillators (boats). Bytracing the spatial–temporal displacements of the boats, time series analyses (autocorrelations, periodograms and running correlations) revealed that trajectories of match racing boats are coupled more than 88% of the time during a pre-start race, via continuous, competing co-adaptions between boats. Results showed that both the continuously selected trajectories of the sailors (12 years of age) and their categorical starting point locations were examples of emergent decisions. In this dynamical conception of decision-making behaviours, strategic positioning (categorical) and continuous displacement of a boat over the course in match-race sailing emerged as a function of interacting task, personal and environmental constraints. Results suggest how key interacting constraints could be manipulated in practice to enhance sailors' perceptual attunement to them in competition.     

Unveiling the Colours of Cellulose Nitrate Black and White Film-based Negatives in Colonial Photography

ABSTRACT

Aiming at contributing to the preservation of black and white (B&W) film-based negatives held by Portuguese archives, four photographic collections from the first half of the twentieth century were selected for study. During the macro assessment of the collections the preservation condition and hues found in photographic negatives from the Elmano Cunha e Costa (ECC) were noticed, distinguishing this collection from the remaining ones. Additional attention was given considering that the ECC collection was formed in a colonial context in the 1930s, while the others were formed on the Portugal mainland. The ECC collection results from an ethnographic survey of Angolan tribes recorded with B&W film-based negatives. In this collection, sets of negatives with pink, lemon yellow, greenish, orange brownish, and red brownish hues were found. To identify the origin of such hues, the image layer was analysed by microscale energy-dispersive X-ray fluorescence (μ EDXRF) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Additionally, to assess the base decay and its effect on the formation of hues, the plastic supports were characterized by Fourier transform infrared microscopy (μ FTIR). To complement the assessment of the film-base decay, pH was measured by using combined microelectrodes. The identification of mercury, iodine, chromium, and iron by μ EDXRF allowed correlation of the hues found in the negatives with chemical corrective treatments performed to improve the image quality. SEM-EDX confirmed those results and proved that the elements found were in the photographic emulsion layer. The results obtained are relevant since the hues identified may now be used as markers to indicate the technical work performed on colonial photography. Additionally, the visual and molecular assessment of the negatives’ supports (good to fair condition) allow proposing that the original storage conditions may have had a beneficial contribution to their present condition.     

Insights into user engagement on social media. Case study of a higher education institution

ABSTRACT

The interactions of users in social networks have been analyzed in the literature as sources of information on their ability to generate engagement among stakeholders in higher education institutes, which make more tactical than strategic use of social networks. This study helps identify which variables generate greater participation in Instagram users, providing strategic proposals for digital marketing. From the codification of all the publications published by a university in a social network site during the period of one year, a comparative analysis was carried out through a multivariate model. The results provide important and timely implications for both universities and higher education professionals. Our findings suggest that higher education marketing specialists should develop stronger and more consistent communication strategies to establish more valuable relationships with stakeholders. The administrators of the social networks of higher education institutions can find patterns in those publications that generate a greater participation in this study.     

Interrupting commemoration: thinking with art,thinking through the strictures of Argentina's Espacio para la memoria

Recently, a few buildings within the Espacio para la memoria in Buenos Aires have been designated as a UNESCO Centre where, amongst other educational activities, evidentiary materials of the past repression are to be stored and displayed. Another building in the complex houses a Community Centre operated by the Mothers of the Plaza de Mayo, where the mandate is to learn about and continue the revolutionary ideals of those disappeared during the repression. Amid these commemorative projects, designating a space for exhibiting art presents a significant opportunity for posing difficult questions, which go beyond the terms of information and idealization. Through a close reading of Diana Dowek's art exhibit, ‘A Long March’, the paper invites us to consider how art can draw out a particular haunting temporality that holds the present open to provocative questions that are difficult to pose and sustain amid the strictures of this commemorative site.