The transfer of strength and power into the stroke biomechanics of young swimmers over a 34-week period

The purpose of this study was to learn the interplay between dry-land strength and conditioning, and stroke biomechanics in young swimmers, during a 34-week training programme. Twenty-seven swimmers (overall: 13.33 ± 0.85 years old; 11 boys: 13.5 ± 0.75 years old; 16 girls: 13.2 ± 0.92 years old) competing at regional- and national-level competitions were evaluated. The swimmers were submitted to a specific in-water and dry-land strength training over 34 weeks (and evaluated at three time points: pre-, mid-, and post-test; M1, M2, and M3, respectively). The 100-m freestyle performance was chosen as the main outcome (i.e. dependent variable). The arm span (AS; anthropometrics), throwing velocity (TV; strength), stroke length (SL), and stroke frequency (SF; kinematics) were selected as independent variables. There was a performance enhancement over time (M1 vs. M3: 68.72 ± 5.57 s, 66.23 ± 5.23 s; Δ = -3.77%; 95% CI: -3.98;-3.56) and an overall improvement of the remaining variables. At M1 and M2, all links between variables presented significant effects (p < .001), except the TV-SL and the TV-SF path. At M3, all links between variables presented significant effects (p ≤ .05). Between M1 and M3, the direct effect of the TV to the stroke biomechanics parameters (SL and SF) increased. The model predicted 89%, 88%, and 92% of the performance at M1, M2, and M3, respectively, with a reasonable adjustment (i.e. goodness-of-fit M1: χ2/df = 3.82; M2: χ2/df = 3.08; M3: χ2/df = 4.94). These findings show that strength and conditioning parameters have a direct effect on the stroke biomechanics, and the latter one on the swimming performance.We would like to thank the support of the University of Beira Interior and SantanderUniversities (Bolsa BIPD/ ICI-FCSH-Santander Universidades-UBI/2017)info:eu-repo/semantics/acceptedVersio

Assessment of the inter-lap stability and relationship between the race time and start, clean swim, turn and finish variables in elite male junior swimmers’ 200 m freestyle

The aims of this study were to: (1) assess the stability (mean and normative) of the lap performance, and a set of clean swim and turn variables of junior male swimmers in the 200 m freestyle, and; (2) verify the relationship between the start, clean swim, turn, and finish phases in the 200 m freestyle. Seventy-six individual races in the 200 m freestyle at the 2019 long-course LEN European Junior Championships were analysed. Start, clean swim, turn, and finish variables were assessed. The lap performance showed a significant variance. The highest variation was verified between the first and third lap (Coefficient of Variation = 7.37%). The clean swim and the total turn also presented a significant variance. Normative stability indicated a moderate to very-high stability for all variables. All phases of the race had significant correlations with the final race time (p < 0.001). The total turn (i.e., the total time spent to perform the turn), specifically turn #3, showed the largest correlation with the total race performance. The significant correlation between all phases of the race and the final race time indicates that coaches and swimmers should customise the swimmers’ preparation and race strategy at major international competitions, based on the individual characteristics of each swimmerTo LEN and Spiideo AB for providing the video clips. This project was supported by the National Funds through FCT - Portuguese Foundation for Science and Technology (UIDB/DTP/04045/2020)info:eu-repo/semantics/publishedVersio

The influence of anthropometric, kinematic and energetic variables and gender on swimming performance in youth athletes

The aim of this study was to assess the: (i) gender; (ii) performance and; (iii) gender versus performance interactions in young swimmers’ anthropometric, kinematic and energetic variables. One hundred and thirty six young swimmers (62 boys: 12.76 ± 0.72 years old at Tanner stages 1-2 by self-evaluation; and 64 girls: 11.89 ± 0.93 years old at Tanner stages 1-2 by self-evaluation) were evaluated. Performance, anthropometrics, kinematics and energetic variables were selected. There was a non-significant gender effect on performance, body mass, height, arm span, trunk transverse surface area, stroke length, speed fluctuation, swimming velocity, propulsive efficiency, stroke index and critical velocity. A significant gender effect was found for foot surface area, hand surface area and stroke frequency. A significant sports level effect was verified for all variables, except for stroke frequency, speed fluctuation and propulsive efficiency. Overall, swimmers in quartile 1 (the ones with highest sports level) had higher anthropometric dimensions, better stroke mechanics and energetics. These traits decrease consistently throughout following quartiles up to the fourth one (i.e. swimmers with the lowest sports level). There was a non-significant interaction between gender and sports level for all variables. Our main conclusions were as follows: (i) there are non-significant differences in performance, anthropometrics, kinematics and energetics between boys and girls; (ii) swimmers with best performance are taller, have higher surface areas and better stroke mechanics; (iii) there are non-significant interactions between sports level and gender for anthropometrics, kinematics and energetics

Is leg kicking workout position affecting kinematic and hydrodynamic variables in front-craw?

Swimming training includes leg kicking workouts, whereas swimmerschoose betweenhead out (RO) or headin (HI) position holding afllitter kick board. Ourobjective was to characterize andanalyse differences between the t\vo legkicking positions in Swimming Vdocity (Y, 1n m/s), lntra-cyclic variation of the horizontal velocity (dv, dimensionless), Active Drag (D, in N), Hydrodynamic Coefficient (CD •. dimensionless), Mechanical Power (P, in W) andfrontal surfacearea (FSA, ia m2). Thirteen swimmers (15.3 ± 2,9 years~old) participated in thisstudy. Frontal surface area was calculated according to the proposal of Morais et aI. (201l)byphotogrammetry. Aftefa standard warmup, swimmers performed 4x25mbouts at maximum velocity as follows: i) 2XcrawI HO Ieg-kick; ii) 2XcrawI HI Ieg-kick. ln the first bout ofeach the V and the dv were measured usingaspeedmeter cable that Was attached to lhe swimmer's hip (Barbosaet aI., 2013). In the secondbout CD was obtained through the velocity perturbation method (Kolmogorov and Duplishcheva, 1992).info:eu-repo/semantics/publishedVersio

Linking selected variables with direct and indirect effect on young swimmer's performance

One of the main goals of swimming research is to identify the scientific domains and/or variables that predict swimming performance in children (i.e., young athletes) in the perspective of detecting future talents (1). Nevertheless, research in young athletes should be less invasive, expensive and timeconsuming than in adult/elite counterparts (2). In this sense, several authors (2-4) on regular basis estimate and/or measure variables in different scientific domains (i.e., anthropometric, hydrodynamic, kinematical and energetic) that are easy to collect and might predict performance and/or detect talented swimmers.info:eu-repo/semantics/publishedVersio

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

Widespread intron retention in mammals functionally tunes transcriptomes

© 2014 Braunschweig et al.; Published by Cold Spring Harbor Laboratory Press. This article is distributed exclusively by Cold Spring Harbor Laboratory Press for the first six months after the full-issue publication date (see http://genome.cshlp.org/site/misc/terms.xhtml). After six months, it is available under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/.Alternative splicing (AS) of precursor RNAs is responsible for greatly expanding the regulatory and functional capacity of eukaryotic genomes. Of the different classes of AS, intron retention (IR) is the least well understood. In plants and unicellular eukaryotes, IR is the most common form of AS, whereas in animals, it is thought to represent the least prevalent form. Using high-coverage poly(A)(+) RNA-seq data, we observe that IR is surprisingly frequent in mammals, affecting transcripts from as many as three-quarters of multiexonic genes. A highly correlated set of cis features comprising an "IR code" reliably discriminates retained from constitutively spliced introns. We show that IR acts widely to reduce the levels of transcripts that are less or not required for the physiology of the cell or tissue type in which they are detected. This "transcriptome tuning" function of IR acts through both nonsense-mediated mRNA decay and nuclear sequestration and turnover of IR transcripts. We further show that IR is linked to a cross-talk mechanism involving localized stalling of RNA polymerase II (Pol II) and reduced availability of spliceosomal components. Collectively, the results implicate a global checkpoint-type mechanism whereby reduced recruitment of splicing components coupled to Pol II pausing underlies widespread IR-mediated suppression of inappropriately expressed transcripts.This work was supported by grants from the Canadian Institutes of Health Research and Canadian Cancer Society (B.J.B.); EMBO long-term fellowships (U.B. and T.G.-P.); Human Frontier Science Program Organization long-term fellowships (U.B. and M.I.); an OSCI fellowship (T.G.-P.); CIHR postdoctoral and Marie Curie IOF fellowships (N.L.B.-M.); and an NSERC studentship (E.N.).info:eu-repo/semantics/publishedVersio

Afasia y depresión post-ictus: una relación predictiva

Introducción/objetivos: La depresión se ha mostrado como la complicación psiquiátrica postictus más común, y la que se asocia con un pronóstico peor. Todavía existe incerteza en cuanto a su etiología y factores de riesgo. Algunos factores son reconocidos: gravedad del ictus, grado de discapacidad y déficit cognitivo. Por ello, es urgente definir nuevos factores que faciliten un diagnóstico temprano, lo cual puede disminuir los efectos negativos sobre el proceso de rehabilitación. Objetivos: Determinar la incidencia de la depresión post-ictus (DPI) y estudiar las variables descritas en la literatura como posibles factores predictores de la DPI: sexo, edad, tipo de ictus, lateralidad, territorio vascular y presencia de afasia. Material y métodos: Estudio longitudinal retrospectivo incluyendo a todos los pacientes admitidos en una planta de Medicina Física y Rehabilitación con el diagnóstico de ictus de novo durante dos a˜nos. Inicialmente se incluyeron 144 pacientes. Los criterios de exclusión fueron «ictus previo», «enfermedad psiquiátrica previa con alteración del humor» y «medicación antidepresiva en el momento del ictus». La n final fue de 111 pacientes. Resultados: La incidencia de DPI fue de 38,7%. La presencia de afasia se mostró asociada significativamente con la depresión (p = 0,05). No hubo relación con el tipo de afasia. Los otros predictores analizados no mostraron correlación estadísticamente significativa. Conclusiones: Este estudio establece la afasia como un factor predictivo de DPI. La elevada incidencia de la DPI en esta población concuerda con los estudios existentes. Adicionalmente se necesitan más estudios, no solo para aumentar el conocimiento de los factores de riesgo para la DPI, sino también para mejorar los resultados de los programas de rehabilitación