Tentativa preliminar para desenvolver um modelo de análise (path-flow) da performance em jovens nadadoras

O objectivo do presente trabalho foi desenvolver um modelo de análise da performance (path flow) em jovens nadadoras, com base em parâmetros antropométricos, hidrodinâmicos, biomecânicos e bioenergéticos

Using lean thinking principles to reduce wastes in reconfiguration of car radio final assembly lines

Assembly lines are production systems designed to be oriented to the product and well known to be highly productive. Nevertheless, during this time-frame the product volumes could decrease and the assembly lines, previously very productive and efficient, becomes unproductive and inefficient. This happens in the car electronics components company where this study took place that due to customer's demand decrease, produced volumes also decreased and provoked the appearance of wastes related with too much occupied space, unbalanced workstations, more capacity than needed, outdated standard work sheets, bottlenecks, to conclude, too many non-added value activities. This paper presents a reconfiguration proposal for two final assembly lines with the goal of adapt physically the lines to the actual production volumes and eliminate the existing wastes. The proposed reconfiguration translates into very positive gains for the company, namely, the release of 22% of the space occupied by the production lines, a reduction in the number of operators, a 50% increase in productivity for each of the lines and an increase in the utilization rate (23% for line 1 and 13% for line 2). In total, the monetary gains associated with these improvements were, approximately, of 125,600 m.u. per year.Special thanks to engineer Hugo Moreira for all the advice given for the development of this project. Also, thanks to the company for all the cooperation and opportunity to apply knowledge acquired during the academic years. This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019

A path-flow analysis model for active drag force determinant variables in age-group swimmers

The goal of competitive swimming is to travel the event distance as fast as possible. The identification of the parameters that predict swimming performances is one of the main aims of the swimming “science” community. Indeed, it is consensual that biomechanical and energetic variables are determinant for enhance performance (Barbosa et al, 2010)

How informative are the vertical buoyancy and the prone gliding tests to assess young swimmers hydrostatic and hydrodynamic profiles?

The aim of this research was to develop a path-flow analysis model to highlight the relationships between buoyancy and prone gliding tests and some selected anthropometrical and biomechanical variables. Thirty-eight young male swimmers (12.97 ± 1.05 years old) with several competitive levels were evaluated. It were assessed the body mass, height, fat mass, body surface area, vertical buoyancy, prone gliding after wall push-off, stroke length, stroke frequency and velocity after a maximal 25 [m] swim. The confirmatory model included the body mass, height, fat mass, prone gliding test, stroke length, stroke frequency and velocity. All theoretical paths were verified except for the vertical buoyancy test that did not present any relationship with anthropometrical and biomechanical variables nor with the prone gliding test. The good-of-fit from the confirmatory path-flow model, assessed with the standardized root mean square residuals (SRMR), is considered as being close to the cut-off value, but even so not suitable of the theory (SRMR = 0.11). As a conclusion, vertical buoyancy and prone gliding tests are not the best techniques to assess the swimmer’s hydrostatic and hydrodynamic profile, respectively

Young swimmers’ kinematic and hydrodynamic detraining between a two seasons’ break

Young swimmers usually have sever-al weeks of school break in the sum-mer. During such period no swim training is conducted until the begin-ning of the next season. According to training principles, the prolonged absence of a regular ex-ternal load may decrease the form status built up in a previous training period. Since the major focus of swim training in children is their technical enhancement, it is ex-pected that some adaptations will occur namely in kinematics and hy-drodynamic outcomes.info:eu-repo/semantics/publishedVersio

Variability in young swimmer’ performance and its determinant factors: a two-year follow-up

Predicting sports performance and identifying talented athletes at early ages seems to be a challenging task for practioners and researchers. Based on this, the follow-up of individual pathway to exper?se should be a regular procedure among sports practioners.info:eu-repo/semantics/publishedVersio

Path-flow analysis model for anthropometric, hydrodynamic and biomechanical variables in age-group swimmers

The goal of competitive swimming is to travel the event distance as fast as possible. The identification of the parameters that predict swimming performances is one of the main aims of the swimming “science” community

Path-flow analysis model for anthropometric, hydrodynamic and biomechanical variables in age-group swimmers

The aim of this research was to develop a path-flow analysis model for age-group swimmer’s speed based on anthropomeric, hydrodynamic and biomechanical determinants

Characterization of speed fluctuation and drag force in young swimmers: a gender comparison

The aim of this study was to compare the speed fluctuation and the drag force in young swimmers between genders. Twenty-three young pubertal swimmers (12 boys and 11 girls) volunteered as subjects. Speed fluctuation was measured using a kinematical mechanical method (i.e., speedo-meter) during a maximal 25-m front crawl bout. Active drag, active drag coefficient and power needed to overcome drag were measured with the velocity perturbation method for another two maximal 25 m front crawl bouts with and without the perturbation device. Passive drag and the passive drag coefficient were estimated using the gliding decay velocity method after a maximal push-off from the wall while being fully immersed. The technique drag index was also assessed as a ratio between active and passive drag. Boys presented meaningfully higher speed fluctuation, active drag, power needed to overcome drag and technique drag index than the girls. There were no significant gender differences for active drag coefficient, passive drag and passive drag coefficient. There were positive and moderate- strong associations between active drag and speed fluctuation when controlling the effects of swim velocity. So, increasing speed fluctuation leads to higher drag force values and those are even higher for boys than for girls

Is the underwater gliding test a valid procedure to estimate the swimmers’ drag?

The aim of this study was to develop a structural equation model for underwater gliding distance based on its determinant variables, in order to confirm whether it is an informative test of young swimmers’ hydrodynamic profile. Methods: Twenty-three subjects (twelve boys and eleven girls with a mean age of 13.61 ± 0.83 years old) were evaluated. The following were determined: (i) the underwater gliding distance; (ii) the squat jump performance; (iii) the passive drag; (iv) the passive drag coefficient; (v) the trunk transverse surface area and; (vi) the gliding velocity. Results: The underwater gliding distance was significantly correlated with the squat jump (rs = 0.47; p = 0.038) and with the coefficient of passive drag (rs = -0.55; p < 0.01) but not with passive drag (rs = 0.41; p = 0.09). The overall model explained 45% of the underwater gliding distance (x2/df = 3.138). Conclusion: The underwater gliding distance seems to be more dependent from the squat jump than from the passive drag. Therefore it seems as if the underwater gliding test is not representative of the swimmers’ passive drag or his /her passive drag coefficient