Estimating fat-free mass in elite youth male soccer players: cross-validation of different field methods and development of prediction equation

This study determined the most effective field method for quantifying fat-free mass (FFM) in elite youth male soccer players compared to dual X-ray absorptiometry (DXA) values and to develop prediction equations for FFM based on anthropometric variables. Forty-one male elite-standard youth soccer players, ages 16.2–18.0 years, undertook FFM assessments including bioelectrical impedance analysis, and different skinfold-based prediction equations. DXA provided a criterion measure of FFM. Correlation coefficients, bias, limits of agreement, and differences were used as validity measures, and regression analyses to develop soccer-specific prediction equations. Slaughter et al (1988), Durnin and Wormersley (1974), and Sarria et al (1998) equations showed the lowest biases, and no significant, standardized, and substantial differences against DXA. The new youth soccer-specific anthropometric equation explained 91% of the DXA-derived FFM variance using three circumferences, eight skinfolds, and one bone breadth. All field methods compared in this study may not be adequate for estimating FFM in elite youth male soccer players, except the equations of Slaughter et al (1988), Durnin and Wormersley (1974), and Sarria et al (1998). We recommend the use of the new soccer-specific equation proposed in this study as a valid alternative to DXA to quantify FFM among elite youth male players.     

Cross-curricular skills development in final-year dissertation by active and collaborative methodologies

European Frame for Higher Education has led universities to adapt their teaching schemes. Degrees must train students in competences including specific and cross-curricular skills. Nevertheless, there are important limitations to follow skill improvement through the consecutive academic years. Final-year dissertation (FYD) offers the opportunity to assess these aspects so linked to the professional requirements. The experience reported here offers an alternative methodology for the FYD in order to reinforce cross-curricular skills and substitute the classic final evaluation schemes. A new protocol for the FYD was defined and tested in the Degree in Human Nutrition and Dietetics, with the participation of students and lecturers from different disciplines. The new methodology included collaborative activities that required students active implication and participation. New cross-curricular skills not considered before were included and evaluated in a continuous way: analysis and critical attitude, as well as team working. Obtained data revealed an improvement over cross-curricular skills. Student–student cooperation resulted in significant contributions to enhance FYD quality. The new methodology was satisfactorily valued by students. The main keys for the successful implementation of this protocol were the followings: encouragement of teachers and students, coordination, information and communication technologies, and clear guidelines.     

Oxidative stress in elite athletes training at moderate altitude and at sea level

Using a controlled parallel group longitudinal trial design, we investigated the effects of different training interventions on the prooxidant/antioxidant status of elite athletes: living and training at moderate altitude for 3 (Hi-Hi3) and 4 weeks (Hi-Hi), and for 4 weeks too, living high and training high and low (Hi-HiLo) and living and training at sea level (Lo-Lo). From 61 swimmers, 54 completed the study. Nitrites, carbonyls, and lipid peroxidation (LPO) levels were assessed in plasma. Enzymatic antioxidants glutathione peroxidase (GPx) and glutathione reductase (GRd), and non-enzymatic antioxidants total glutathione (GST), reduced glutathione (GSH) and oxidized glutathione (GSSG) were analysed in the erythrocyte fraction. At the end of the intervention, nitrites levels were similar in all altitude groups but higher than in the Lo-Lo controls (P?=?.02). Hi-HiLo had greater GPx activity than Hi-Hi and Hi-Hi3 during most of the intervention (P?≤?.001). GRd activity was higher in Lo-Lo than in Hi-Hi at the end of the training camp (P?≤?.001). All groups showed increased levels of LPO, except Lo-Lo, and carbonyls at the end of the study (P?≤?.001). Training at altitude for 3 or 4 weeks drives oxidative stress leading to cellular damage mainly by worsening the antioxidant capacities. The GSSG/GSH ratio appears to be related to perceived exertion and fatigue. The stronger antioxidant defence showed by the Hi-HiLo group suggests an inverse relationship between redox alterations and performance. Further studies are required to investigate the role of oxidative stress in acclimatization, performance, and health.     

Reliability assessment and correlation analysis of 3 protocols to measure trunk muscle strength and endurance

Different methods have been developed to quantify trunk muscle strength and endurance. However, some important protocol characteristics are still unclear, hindering the selection of the most suitable tests in each specific situation. The aim of this study was to examine the reliability and the relationship between 3 representative tests of the most common type of protocols used to assess trunk muscle strength and endurance. Twenty-seven healthy men performed each test twice spaced 1 month apart.Trunk strength and endurance were evaluated with an isokinetic dynamometer and 2 field tests including Biering-Sørensen test and Flexion–rotation trunk test.

All tests showed a good relative consistency (intraclass correlation coefficient [ICC]> 0.75), except for the isokinetic endurance variables which had low–moderate reliability (0.37 < ICC > 0.65). Absolute reliability seemed slightly better in the isokinetic protocol than in the field tests, which showed about 12% of test–retest score increase. No significant correlations were found between test scores.

After a familiarisation period for the field tests, the 3 protocols can be used to obtain reliable measures of trunk muscle strength and endurance. Based on the correlation analysis, these measures are not related, which highlights the importance of selecting the most suitable trunk test for each situation.     

Antecedents of continued use intention of e-hailing apps from the passengers' perspective

E-Hailing Apps (EHA) – mobile device software to order any form of transportation pick up – have become very popular in society due to the swift proliferation of smartphones worldwide. Thus, the scope of this article is to ascertain the antecedents of continued use intention of EHA from the passengers' standpoint. To achieve this, a meta-model was developed via a theoretical background based on theories of information system adoption, diffusion of innovation, trust in virtual environments and user satisfaction, as well as research hypotheses. By applying structural equation modelling in data collected via a web survey, the theoretical meta-model and research hypotheses were tested. It was established that perceived utility, compatibility, relative advantage and trust are antecedents of user satisfaction with EHA, this factor being an antecedent of the continued use intention of same. Lastly, it was found that subjective norms have a direct and statistically significant impact on the continued use intention of EHA.     

Assessing students’ perception of parental career-related support: development of a new scale and a new taxonomy

The object of this study was to assess students' perceptions of their parents’ career-related behaviours and their influence on the students’ behaviours. In study 1 (528 students), we developed the SIL Scale (support, interference and lack of engagement), a nine-item questionnaire applied to educational and job contexts. In study 2 (1204 students), we tested a person-centred approach and developed a new model called the WID Types (willing, involved and in difficulty), which identifies three clusters of students. The associations between the clusters and career choice difficulties, level of career exploration and stage of the vocational choice confirmed its validity.     

Constructing Explanations in Science: Informal Formative Assessment Practices Among Science Teachers of English Learners

Research in Science Education - Informal formative assessments (IFAs) are classroom interactions teachers use to gather information about their students’ learning, interpret it, and act on...     

A probabilistic model for analysing the effect of performance levels on visual behaviour patterns of young sailors in simulated navigation

Abstract

The visual behaviour is a determining factor in sailing due to the influence of the environmental conditions. The aim of this research was to determine the visual behaviour pattern in sailors with different practice time in one star race, applying a probabilistic model based on Markov chains. The sample of this study consisted of 20 sailors, distributed in two groups, top ranking (n = 10) and bottom ranking (n = 10), all of them competed in the Optimist Class. An automated system of measurement, which integrates the VSail-Trainer® sail simulator and the Eye Tracking System^TM was used. The variables under consideration were the sequence of fixations and the fixation recurrence time performed on each location by the sailors. The event consisted of one of simulated regatta start, with stable conditions of wind, competitor and sea. Results show that top ranking sailors perform a low recurrence time on relevant locations and higher on irrelevant locations while bottom ranking sailors make a low recurrence time in most of the locations. The visual pattern performed by bottom ranking sailors is focused around two visual pivots, which does not happen in the top ranking sailor's pattern. In conclusion, the Markov chains analysis has allowed knowing the visual behaviour pattern of the top and bottom ranking sailors and its comparison.