Habitat choice and female preference in a polymorphic stickleback population

Background: A small pond, c. 90 years old, near Bern, Switzerland contains a population of threespine stickleback (Gasterosteus aculeatus) with two distinct male phenotypes. Males of one type are large, and red, and nest in the shallow littoral zone. The males of the other are small and orange, and nest offshore at slightly greater depth. The females in this population are phenotypically highly variable but cannot easily be assigned to either male type. Question: Is the existence of two sympatric male morphs maintained by substrate-associated male nest site choice and facilitated by female mate preferences? Organisms: Male stickleback caught individually at their breeding sites. Females caught with minnow traps. Methods: In experimental tanks, we simulated the slope and substrate of the two nesting habitats. We then placed individual males in a tank and observed in which habitat the male would build his nest. In a simultaneous two-stimulus choice design, we gave females the choice between a large, red male and a small, orange one. We measured female morphology and used linear mixed effect models to determine whether female preference correlated with female morphology. Results: Both red and orange males preferred nesting in the habitat that simulated the slightly deeper offshore condition. This is the habitat occupied by the small, orange males in the pond itself. The proportion of females that chose a small orange male was similar to that which chose a large red male. Several aspects of female phenotype correlated with the male type that a female preferred

Somatotype is more interactive with strength than fat mass and physical activity in peripubertal children

The purpose of this study was to analyse the interaction between somatotype, body fat and physical activity in prepubescent children. This was a cross!sectional study design involving 312 children (160 girls, 152 boys) aged between 10 and 11.5 years old (10.8 ± 0.4 years old). Evaluation of body composition was done determining body mass index and body fat by means of skin!fold measurements, using the method described by Slaughter. Somatotype was computed according to the Carter’s method. Physical activity was assessed with the Baecke questionnaire. The physical activity assessment employed sets of curl!ups, push!ups, standing broad jump, medicine ball throw, handgrip strength and Margaria!Kalamen power stair. There were negative associations for body fat, endomorphy and mesomorphy with curl!ups, push!ups and broad jump tests and positive associations with ball throw, handgrip strength and Margaria! Kalamen power tests. The associations for ectomorphy were the inverse of those for endomorphy and mesomorphy. Non obese children presented higher values for curl!ups, push!ups and standing broad jump. In medicine ball throw, handgrip strength and Margaria!Kalamen power test obese children presented higher scores, followed by children who were overweight. The mesoectomorphic boys and ectomesomorphic girls performed higher in all tests. The morphological typology presented more interactions with strength than % of body fat and physical activity. These data seem to suggest that the presence/absence of certain physical characteristics is crucial in the levels of motor provision in prepubescent children

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

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

The influence of a specific high intensity circuit training during physical education classes in children’s physical activity and body composition markers

Physical activity plays a paramount role on children growth and schools emerged as a key setting for promoting physical activity during childhood. The aim of this study was to verify the effects of a high intensity circuit training performed during regular physical education classes at schools. One hundred and five children aged 11–14 years (71 boys and 34 girls) were evaluated. The participants were split into a control group (boys: N = 47; girls: N = 16) and an experimental group (boys: N = 24; girls: N = 18). Besides the normal physical education classes, the experimental group also performed a high intensity circuit training for eight weeks, twice a week, at the beginning of the lesson. A pre- post-test was performed. Cardiorespiratory (20 m shuttle run test ) and a set of strength variables were evaluated. Percentage of fat mass was used as a somatic indicator. The 20 m shuttle run test presented a significant time effect, but not a time X sex, time X group, and time X weight status interactions. Conversely, the strength variables presented a significant time X group interaction (significant differences between groups). Percentage of fat mass presented a significant time effect, but not a significant time X group interaction. Data showed that adding a high intensity circuit training to physical education classes would result in a significant increase in muscular fitness performance in children, but cardiorespiratory fitness may not present the same magnitude of improvement. High intensity circuit training programs (performed during regular physical education classes at schools) seem to present a positive and significant effect in physical fitness parameters as well as reducing the percentage of fat mass.This work is supported by national funds (FCT - Portuguese Foundation for Science and Technology) under the project UIDB/DTP/04045/2020info:eu-repo/semantics/publishedVersio

The influence of a specific high intensity circuit training during physical education classes in children’s physical activity and body composition markers

Physical activity plays a paramount role on children growth and schools emerged as a key setting for pro- moting physical activity during childhood. The aim of this study was to verify the effects of a high intensi- ty circuit training performed during regular physical education classes at schools. One hundred and five children aged 11–14 years (71 boys and 34 girls) were evaluated. The participants were split into a control group (boys: N = 47; girls: N = 16) and an experimental group (boys: N = 24; girls: N = 18). Besides the normal physical education classes, the experimental group also performed a high intensity circuit training for eight weeks, twice a week, at the beginning of the lesson. A pre- post-test was performed. Cardiorespiratory (20 m shuttle run test ) and a set of strength variables were evaluated. Percentage of fat mass was used as a somatic indicator. The 20 m shuttle run test presented a significant time effect, but not a time X sex, time X group, and time X weight status interactions. Conversely, the strength variables presented a significant time X group interaction (significant differences between groups). Percentage of fat mass presented a significant time effect, but not a significant time X group interaction. Data showed that adding a high intensity circuit training to physical education classes would result in a significant increase in muscular fitness performance in children, but cardiorespiratory fitness may not present the same magnitude of improvement. High in- tensity circuit training programs (performed during regular physical education classes at schools) seem to present a positive and significant effect in physical fitness parameters as well as reducing the percentage of fat mass.This work is supported by national funds (FCT - Portuguese Foundation for Science and Technology) under the project UIDB/DTP/04045/2020.info:eu-repo/semantics/publishedVersio

Relationship between thrust, anthropometrics, and dry-land strength in a national junior swimming team

Objectives: This study aimed to (i) assess an anthropometric and thrust inter-limb asymmetry, and; (ii) determine the contribution of anthropometrics, and dry-land upper-body strength and power to the thrust of talented adolescent swimmers. Methods: Eighteen talented adolescent swimmers (12 boys and 6 girls: 15.81 ± 1.62 years old) were evaluated. A set of anthropometric, dry-land upper-body strength and power, and in-water thrust were assessed. Results: Despite the fact that the dominant side presented higher values in anthropometrics (except for the hand surface area) and thrust, non-significant inter-limb differences were found. The symmetry index indicated a symmetry between upper-limbs. Hierarchical linear modeling retained as main predictors of each upper-limb thrust the respective hand surface area (dominant upper limb: estimate = 0.293, 95CI: 0.117; 0.469, p = 0.005; non-dominant upper limb: estimate = 0.295, 95CI: 0.063; 0.526, p = 0.025). The full stroke cycle retained the upper-body dry-land strength as main predictor (estimate = 0.397, 95CI: 0.189; 0.605, p = 0.002). Conclusion: The hand surface area and upper-body strength were the main predictors of each upper-limb and full stroke cycle thrust, respectively. Hence, coaches and practitioners should aim to carefully maximize the hand surface area (by finger spreading) while performing the stroke, as well as dry-land upper-body strength in order to enhance the performanceThis 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 the European Union through the COMPETE 2020 Programme (POCI-01-0145-FEDER-006969). We would like also to thank the support of the University of Beira Interior and Santander Universities (Bolsa BIPD/ICIFCSH-Santander Universidades-UBI/2017).info:eu-repo/semantics/publishedVersio

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

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

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)