Key determinants of time to 5 m in different ventral swimming start techniques

The aim of this study was to determine the biomechanical parameters that explain ventral start performance in swimming. For this purpose, 13 elite swimmers performed different variants of the ventral start technique. Two-dimensional video analyses of the aerial and underwater phases were used to assess 16 kinematic parameters from the starting signal to 5?m, and an instrumented starting block was used to assess kinetic data. A Lasso regression was used to reduce the number of parameters, providing the main determinants to starting performance, revealing different combinations of key determinants, depending on the variant (r²?≥?0.90), with flight distance being the most relevant to all variants (r?≤??0.80; p?r?=??0.79; p?r?≤?0.61; p?r²?=?0.66) or block time and flight distance (r²?=?0.83). These data provide relevant contributions to the further understanding of the biomechanics of swimming starts as well as insights for performance analysis and targeted interventions to improve athlete performance.     

Demand drops and innovation investments: Evidence from the Great Recession in Spain

The Great Recession, which began in 2008, brought about large contractions in aggregate consumption in many countries. In this research, we study the impact of heterogeneous decreases in demand on innovation investments by analyzing the evolution of innovation investments in a panel of Spanish manufacturing firms during the 2004–2013 period. We proxy heterogeneous variation in demand with net exit rates in the productive stratum of each firm, defined as the group of firms in the same industry and size class. These net exit rates are computed considering all firms in the stratum, including firms that are determined to be non-innovative firms. To support the identification strategy, we show that exit rates do not capture idiosyncratic unobservable characteristics among innovative firms. In addition, we control for the effect of time-varying credit constraints. We find that a one standard deviation increase in exit rates is associated with reductions of 1.5% in the share of firms investing in innovation. The drop is larger for smaller firms, which also experience greater decreases in sales. Since smaller firms are most sensitive to demand drops, they are the natural candidates to be the target of policies devoted to increasing R&D activities during crises. As additional analysis, we study firms’ perceptions of the main obstacles to innovation to find that net exit rates capture the heterogeneous variation in demand, rather than credit constraints. Finally, when analyzing the exit patterns of firms in the sample, we confirm that the net exit rate in a firm's stratum does not drive the exit of firms in our sample.     

Enhancing the Popularity and the Relevance of Science Teaching in Portuguese Science Classes

PARSEL Project emerged from the urgent need to overcome the problem of lack of scientific literacy in the population, which should be a priority in a society where science occupies a central place. Indeed, nowadays for any citizen to participate in a responsible and informed way in society he has to be scientifically acknowledgeable. Nevertheless, not only are scientific levels low in the general population, but also there is an increasing number of students who avoid science and technology courses and related professions. Within this context, PARSEL aims at raising science and scientific courses’ popularity and relevancy as well as at enacting teachers’ professional development. In order to achieve these goals, the PARSEL group developed 54 pan-European modules, which were tested and evaluated by several teachers in several European countries and Israel. Teachers maintained a close relationship with the university, were highly encouraged to appropriate the modules and to adapt them to their local conditions and, also to discuss and share their experiences. In Portugal, modules were tested by a group of eight teachers, and their students. This paper presents data concerning teachers’ evaluation. Data was collected by means of interviews, observation and written documents and reveals that teachers positively evaluated PARSEL’s impact on their own professional development. Furthermore, they considered modules as well as the teaching-learning approach essential for making science learning relevant and popular for their students.     

International student mobility in a German and Portuguese university: Which factors in the host institution matter?

In a globalising world, international mobility in higher education is an important phenomenon for students and higher education institutions. It is therefore essential to understand the factors that determine international students' satisfaction with higher education institutions that serve as hosts. Through research of an exploratory, quantitative nature, this study presents results from a survey among 289 incoming international students in two universities in Germany and Portugal. Our findings show that the factor we define as educational experience was an important determinant of student satisfaction. Furthermore, the appraisal of academic reputation is dependent on the university. We conclude that satisfaction with academic factors is more important for international students than satisfaction with non-academic aspects.     

Accuracy of Actigraph inclinometer to classify free-living postures and motion in adults with overweight and obesity

Sedentary behaviour (SB) is an independent health risk-factor and interrupting SB seems to be beneficial. SB is both defined by posture and intensity, thus objective measurement of postures remains a priority. The ActivPAL inclinometer (AP) has been used as a reference for postural estimation, but information on the validity of the Actigraph inclinometer (AG_incl) is scarce. We compared postural estimation from waist-worn AG_incl against thigh-worn AP, under free-living. Data from 10 participants (50.4 ± 11.4 years) were used and each 15s-block from 60-valid days was matched for the devices’ comparison. At group level, no differences were found for SB and standing-time between inclinometers (p ≥ 0.05). AG_incl underestimated stepping-time by 26.3 min and overestimated SB-to-upright transitions by 200.7 occasions (p < 0.05). Inter-individual variability was higher for SB and standing-time, and AG_incl was in better agreement with AP for the stepping-time (area under the ROC curve = 0.98, with 100% sensitivity and 94% specificity; CCC = 0.44). These results highlight potential error in estimating individual postures using AG_incl in overweight/obese adults and provide insights on the differences of using specific criteria on data-analysis. Our findings suggest that at the group level, AG_incl provides similar estimates compared to AP for SB and standing-time, but not for SB-to-upright transitions or stepping-time. (ClinicalTrials.govID:NCT02007681)     

Effect of two different intensity distribution training programmes on aerobic and body composition variables in ultra-endurance runners

The aim of this study was to compare the effects of two different intensity distribution training programmes (polarized (POL) and threshold (THR)) on aerobic performance, strength and body composition variables in ultra-endurance runners. Twenty recreationally trained athletes were allocated to POL (n?=?11; age: 40.6?±?9.7 years; height: 175.4?±?7?cm; weight: 73.5?±?10.8?kg; fat mass 18.4?±?6.0%; VO₂max: 55.8?±?4.9?ml/kg/min) or THR group (n?=?9; age: 36.8?±?9.2 years; height: 178.5?±?4.2?cm; weight: 75.5?±?10.4?kg; fat mass 14.9?±?5.3%; VO₂max: 57.1?±?5.2?ml/kg/min) and performed the 12 weeks training programme. Both programmes had similar total time and load but a different intensity distribution (POL?=?79.8?±?2.1% in Zone 1; 3.9?±?1.9% in Zone 2; 16.4?±?1.5% in Zone 3; THR?=?67.2?±?4.6% in Zone 1; 33.8?±?4.6% in Zone 2; 0% in Zone 3). Body composition, isokinetic strength and aerobic running performance were measured before and after each programme. Both groups decreased fat mass after training (POL= Δ–11.2%; p?=?.017; ES?=?0.32; THR= Δ–18.8%; p?p?=?0.003; ES?=?0.71) and 12?km/h (Δ–4.5%; p?=?.026; ES?=?0.73) and running time to exhaustion (Δ2.4%; p?=?.011; ES?=?0.33). No changes were observed in strength and no significant differences were observed between the group in any variable. Compared with THR distribution, 12 weeks of POL training efficiently improves aerobic performance in recreational ultra-endurance runners.     

Calibration of context-specific survey items to assess youth physical activity behaviour

This study tests calibration models to re-scale context-specific physical activity (PA) items to accelerometer-derived PA. A total of 195 4th–12th grades children wore an Actigraph monitor and completed the Physical Activity Questionnaire (PAQ) one week later. The relative time spent in moderate-to-vigorous PA (MVPA_%) obtained from the Actigraph at recess, PE, lunch, after-school, evening and weekend was matched with a respective item score obtained from the PAQ’s. Item scores from 145 participants were calibrated against objective MVPA_% using multiple linear regression with age, and sex as additional predictors. Predicted minutes of MVPA for school, out-of-school and total week were tested in the remaining sample (n = 50) using equivalence testing. The results showed that PAQ β-weights ranged from 0.06 (lunch) to 4.94 (PE) MVPA_% (P < 0.05) and models root mean square error ranged from 4.2% (evening) to 20.2% (recess). When applied to an independent sample, differences between PAQ and accelerometer MVPA at school and out-of-school ranged from ?15.6 to +3.8 min and the PAQ was within 10–15% of accelerometer measured activity. This study demonstrated that context-specific items can be calibrated to predict minutes of MVPA in groups of youth during in- and out-of-school periods.     

Biomechanics,energetics and coordination during extreme swimming intensity: effect of performance level

The present study aimed to examine how high- and low-speed swimmers organise biomechanical, energetic and coordinative factors throughout extreme intensity swim. Sixteen swimmers (eight high- and eight low-speed) performed, in free condition, 100-m front crawl at maximal intensity and 25, 50 and 75-m bouts (at same pace as the previous 100-m), and 100-m maximal front crawl on the measuring active drag system (MAD-system). A 3D dual-media optoelectronic system was used to assess speed, stroke frequency, stroke length, propelling efficiency and index of coordination (IdC), with power assessed by MAD-system and energy cost by quantifying oxygen consumption plus blood lactate. Both groups presented a similar profile in speed, power output, stroke frequency, stroke length, propelling efficiency and energy cost along the effort, while a distinct coordination profile was observed (F_{(3, 42)} = 3.59, P = 0.04). Speed, power, stroke frequency and propelling efficiency (not significant, only a tendency) were higher in high-speed swimmers, while stroke length and energy cost were similar between groups. Performing at extreme intensity led better level swimmers to achieve superior speed due to higher power and propelling efficiency, with consequent ability to swim at higher stroke frequencies. This imposes specific constraints, resulting in a distinct IdC magnitude and profile between groups.