Effect of a specific concurrent water and dry-land training over a season in young swimmers’ performance

The aims of this study were to assess over a full season: (i) the effect of a combined dry-land strength and conditioning and in-water program on the swimming performance of young swimmers; (ii) the effect of such program on the performance determinants; (iii) the effect of the training periodization designed. A longitudinal research design assessing an age-group of young swimmers over a season was carried out. Methods: Twenty-seven young swimmers (12 boys: 13.55±0.72-y; 15 girls: 13.16±0.93-y; both sexes in Tanner stages 2-3) were evaluated in three moments over 40 weeks. The 100-m freestyle performance, body mass, height, arm span (anthropometrics), stroke frequency, stroke length, swimming velocity, intracyclic swimming velocity (kinematics), stroke index, propelling efficiency (efficiency), squat jump, countermovement jump, and throw velocity (strength and conditioning) were assessed. A cluster analysis was computed to classify the swimmers. For the “talented” swimmers, the performance and all determinants, but the squat and countermovement jumps improved between the first and last evaluation moments. Both in-water and dry-land strength and conditioning features were responsible for the cluster discrimination in each one of the evaluation moments. All three clusters were also characterized by a mix of technical and strength & conditioning features. This highlights swimming performance as a holistic phenomenon (i.e. multiple determinants) where shifting occur in the interplay among the performance determinant according to the training periodization.info:eu-repo/semantics/publishedVersio

Evaluation of different cell disruption processes on encysted cells of Haematococcus pluvialis: effects on astaxanthin recovery and implications for bio-availability

Although Haematococcus pluvialis is one of the most importantnatural sources of the carotenoid astaxanthin as a pigmentor for theaquaculture industry, the thick sporopollenin cell wall in the cysts hindersastaxanthin extraction and its subsequent bio-availability to fish. A rangeof physical and chemical processes were tested to promote the disruptionof the encysted cells. The efficacy of these processes was evaluated interms of astaxanthin recovery, which was assessed by determining theextent of leaching of astaxanthin into an organic solvent. The processestested were: autoclave 30 min, 121 °C, 1 atm; HCl 0.1 M, 15min and 30 min; NaOH 0.1 M, 15 min and 30 min; enzymatictreatment with a mixture of 0.1% protease K and 0.5% driselase in aphosphate buffer, pH 5.8, 30 °C, for one hour; spray drying, inlet180 °C, outlet 115 °C; and mechanical disruption, with acell homogeniser developed for this purpose. The mechanical(homogenisation) and autoclave treatments were the most effective in termsof extraction and availability

Longitudinal modeling in sports: young swimmers' performance and biomechanics profile

The aims was to model a latent growth curve of young swimmers' performance over a season and its relationship with biomechanics, quantify the direct effect of the exogenous variables selected on performance across a season and analyze the sex effect on the performance growth. Fourteen boys (12.33±0.65 years) and 16 girls (11.15±0.55 years) were evaluated. Performance, stroke frequency, speed fluctuation, arm's propelling efficiency, active drag, active drag coefficient and power to overcome drag were collected in four different moments of the season. Latent growth curve modeling was computed to understand the longitudinal variation of performance (endogenous variables) over the season according to the biomechanics (exogenous variables). Latent growth curve modeling showed a high inter- and intra-subject variability in the performance growth. Sex had a significant effect at the baseline and during the performance growth. In each evaluation moment, different variables had a meaningful effect on performance (M1: Da, β=-0.62; M2: Da, β=-0.53; M3: ηp, β=0.59; M4: SF, β=-0.57; all P<0.001). The models' good-of-fit was 1.40≤x2/df≤3.74 (good-reasonable). Latent modeling is a comprehensive way to gather insight about young swimmers' performance over time. Different variables were the main responsible for the performance improvement. A gender gap, intra- and inter-subject variability was verified

Data modeling for inter- and intra-individual stability of young swimmers’ performance: a longitudinal cluster analysis

The aims of this study were to classify, identify and follow-up young swimmers' performance and its biomechanical determinants during two competitive seasons (in seven different moments of assessment-M), and analyze the individual variations of each swimmer. Method: Thirty young swimmers (14 boys: 12.70 +/- 0.63 years-old; 16 girls: 11.72 +/- 0.71 years-old) were recruited. A set of anthropometric, kinematic, efficiency, hydrodynamic and mechanical power variables were assessed. Results: The cluster solution (i.e., number of ideal clusters for this sample) resulted in three clusters, which were named as: cluster 1 ("talented"), cluster 2 ("proficient"), and cluster 3 ("non-proficient"). The performance improved between moments of assessment in all clusters (cluster 1-M1: 68.07 +/- 6.62s vs M7: 61.46 +/- 3.43s; cluster 2-M1: 73.14 +/- 4.87s vs M7: 65.33 +/- 2.97s; cluster 3-M1: 82.60 +/- 4.18s vs M7: 70.09 +/- 3.48s). Anthropometric features also increased between moments of assessment, and remaining biomechanical variables (kinematic, efficiency, hydrodynamic and mechanical power) also increased between M1 and M7, in all clusters. Cluster 1 increased their swimmer's membership between M1 and M7 (4 to 11), cluster 2 decreased (12 to 5), and cluster 3 maintained (14). Conclusion: It can be concluded that the cluster formation depends on different determinant factors during two competitive seasons, and young swimmers are prone to change from one cluster to another over this period of timeThis project was supported by the National Funds through FCT - Portuguese Foundation for Science and Technology [UID/DTP/04045/2019], and the European Fund for regional development (FEDER) allocated by European Union through the COMPETE 2020 Programme [POCI-01-0145-FEDER-006969].info:eu-repo/semantics/publishedVersio

Young swimmers' anthropometrics, biomechanics, energetics, and efficiency as underlying performance factors: a systematic narrative review

Introduction: In youth swimming, researchers are interested in understanding how anthropometry and parameters related to swimming technique (biomechanics, energetics, and efficiency) influence the performance. However, there is not any review in the literature that consolidates the body of knowledge of this topic. The objective of this study was to review systematically the current body of work on the influence of determinant factors related to swimming technique (biomechanics, energetics, and efficiency) and anthropometry in the young performance of swimmers. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to identify relevant studies. Results: After screening, 240 studies were analyzed and 59 related to swimming performance, and its determinant factors were retained for synthesis. Studies revealed a high-quality index by PEDro scale (mean score was 7.17 ± 1.40). Twenty-five studies were longitudinal designs and the remaining 34 cross-sectional designs. Most of the studies (N = 39, 66.1%) reported concurrently two or more determinant factors (anthropometrics, biomechanics, energetics, and efficiency). Conclusion: Youth swimming research relies on a multifactorial assessment. From the synthesis, it is possible to conclude that the performance of young swimmers is characterized by a multifactorial, holistic, and dynamic phenomenon. Better performance has always been related to better swimming technique and higher anthropometrics. This suggests that both anthropometrics (i.e., nature) and training (i.e., nurture) play key roles in the swimming performance of young swimmers.This work is supported by national funds (FCT—Portuguese Foundation for Science and Technology) under the project UIBD/DTP/04045/2020.info:eu-repo/semantics/publishedVersio

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

Comparison of the start, turn and finish performance of elite swimmers in 100 m and 200 m races

The main aim of this study was to compare the start, turn, and finish performance of 100 m and 200 m events in the four swimming strokes in elite swimmers of both sexes. The performances of all 128 finalists (64 males and 64 females) of the 100 m, and 200 m events at a major championship were analyzed. A set of variables related to the start, turn, and finish were assessed. In the start a significant and moderate race effect was verified in both sexes (100 m vs 200 m). It was highest in butterfly events (males: Δ = 9.81%, p = 0.046, η2 = 0.60; females: Δ = 7.96%, p < 0.001, η2 = 0.75). In the turn a significant and moderate-strong race effect was verified in all strokes in both sexes, the highest being in butterfly (males: Δ = 12.26%, p < 0.001, η2 = 0.93; females: Δ = 10.74%, p < 0.001, η2 = 0.92). The finish had a significant and moderate race effect in butterfly and in breaststroke (females). The underwater variables were found to be the main contributors to a faster start. Over the turn, key determinants were the surface variables. As for the finish, mixed results were observed. It can be suggested that the underwater profile was the main determinant in starting, whereas the surface profile was the main determinant in turning. Therefore, coaches are advised to focus on such race phases to enhance the total race time.Our thanks to LEN and Spiideo AB for providing the video clips. This work is supported by national funding through the Portuguese Foundation for Science and Technology, I.P., under project UIDB/04045/2020. We would also like to thank the University of Beira Interior and Santander Universities (Bolsa BIPD/ICIFCSH-Santander Universidades-UBI/2017) for their support. The experiments comply with the current laws of the country in which they were performed. The authors have no conflict of interest to declare.info:eu-repo/semantics/publishedVersio

Determinant factors of long-term performance development in young swimmers

To develop a performance predictor model based on swimmers’ biomechanical profile, relate the partial contribution of the main predictors with the training program, and analyze the time effect, sex effect, and time × sex interaction. 91 swimmers (44 boys, 12.04 ± 0.81 y; 47 girls, 11.22 ± 0.98 y) evaluated during a 3-y period. The decimal age and anthropometric, kinematic, and efficiency features were collected 10 different times over 3 seasons (ie, longitudinal research). Hierarchical linear modeling was the procedure used to estimate the performance predictors. Performance improved between season 1 early and season 3 late for both sexes (boys 26.9% [20.88;32.96], girls 16.1% [10.34;22.54]). Decimal age (estimate [EST] –2.05, P < .001), arm span (EST –0.59, P < .001), stroke length (EST 3.82; P = .002), and propelling efficiency (EST –0.17, P = .001) were entered in the final model. Over 3 consecutive seasons young swimmers’ performance improved. Performance is a multifactorial phenomenon where anthropometrics, kinematics, and efficiency were the main determinants. The change of these factors over time was coupled with the training plans of this talent identification and development program.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

Hydrodynamic profile of young swimmers: changes over a competitive season

The aim of this study was to analyze the changes in the hydrodynamic profile of young swimmers over a competitive season and to compare the variations according to a well-designed training periodization. Twenty-five swimmers (13 boys and 12 girls) were evaluated in (a) October (M1); (b) March (M2); and (c) June (M3). Inertial and anthropometrical measures included body mass, swimmer’s added water mass, height, and trunk transverse surface area. Swimming efficiency was estimated by the speed fluctuation, stroke index, and approximate entropy. Active drag was estimated with the velocity perturbation method and the passive drag with the gliding decay method. Hydrodynamic dimen- sionless numbers (Froude and Reynolds numbers) and hull velocity (i.e., speed at Froude number = 0.42) were also calculated. No variable presented a significant gender effect. Anthropometrics and inertial parameters plus dimensionless numbers increased over time. Swimming efficiency improved between M1 and M3. There was a trend for both passive and active drag increase from M1 to M2, but being lower at M3 than at M1. Intra-individual changes between evaluation moments suggest high between- and within-subject variations. Therefore, hydrodynamic changes over a season occur in a non-linear fashion way, where the interplay between growth and training periodization explain the unique path flow selected by each young swimmer