373 research outputs found
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 Carterâs 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 swimmersâ 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 âtalentedâ 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, ÎČ=-0.62; M2: Da, ÎČ=-0.53; M3: ηp, ÎČ=0.59; M4: SF, ÎČ=-0.57; all P<0.001). The models' good-of-fit was 1.40â€x2/dfâ€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
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
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 swimmersâ 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 proïŹle of young swimmers: changes over a competitive season
The aim of this study was to analyze the changes in the hydrodynamic proïŹle of young swimmers over a competitive season and to compare the variations according to a well-designed training periodization. Twenty-ïŹve 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, swimmerâs added water mass, height, and trunk transverse surface area. Swimming efïŹciency was estimated by the speed ïŹuctuation, 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 signiïŹcant gender effect. Anthropometrics and inertial parameters plus dimensionless numbers increased over time. Swimming efïŹciency 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 ïŹow selected by each young swimmer
Training evaluation in male age-group swimmers
Monitoring the training process represents an important task during sports preparation. However, not always the applied protocols help to address the coachesâ concerns, namely regarding its complexity and difficulty to be used in large samples. Therefore, the aim of this study was to apply a simple protocol to control the training process in a group of male age-group swimmer
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 âscienceâ
community. Indeed, it is consensual that
biomechanical and energetic variables are
determinant for enhance performance
(Barbosa et al, 2010)
Effects of body fat and dominant somatotype on explosive strength and aerobic capacity trainability in prepubescent children
he purpose of this study was to analyze the influence of
body fat and somatotype on explosive strength and aerobic
capacity trainability in the prepubertal growth spurt, marked by
rapid changes in body size, shape, and composition, all of which
are sexually dimorphic. One hundred twenty-five healthy children
(58 boys, 67 girls), aged 10â11 years (10.8 6 0.4 years), who
were self-assessed in Tanner stages 1â2, were randomly
assigned into 2 experimental groups to train twice a week for
8 weeks: strength training group (19 boys, 22 girls), endurance
training group (21 boys, 24 girls), and a control group (18 boys,
21 girls). Evaluation of body fat was carried out using the method
described by Slaughter. Somatotype was computed according
to the Heath-Carter method. Increased endomorphy reduced the
likelihood of vertical jump height improvement (odds ratio [OR],
0.10; 95% confidence interval [CI], 0.01â0.85), increased
mesomorphy (OR, 6.15; 95% CI, 1.52â24.88) and ectomorphy
(OR, 6.52; 95% CI, 1.71â24.91) increased the likelihood of
sprint performance, and increased ectomorphy (OR, 3.84;
95% CI, 1.20â12.27) increased the likelihood of aerobic fitness
gains. Sex did not affect the training-induced changes in strength
or aerobic fitness. These data suggest that somatotype has
an effect on explosive strength and aerobic capacity trainability,
which should not be disregarded. The effect of adiposity
on explosive strength, musculoskeletal magnitude on running
speed, and relative linearity on running speed and aerobic
capacity seem to be crucial factors related to training-induced
gains in prepubescent boys and girls.info:eu-repo/semantics/publishedVersio
Conception, development and validation of a software interface to assess humanâs horizontal intra-cyclic velocity with a mechanical speedo-meter
The aim of this paper was to: (i) calibrate the SwimsportecÂź speedo-meter; (ii) concept and develop a softwareâs interface for it (iii) validate the full system. Calibration was done with an industrial robot. The robot armâs performed a linear and horizontal path at a uniform movement for a set of wide range of velocities (0.5<v<4.5m/s) being the tension data acquire for each specific linear velocity. Softwareâs interface was developed in LabVIEWÂź to acquire, display and process pair wises velocity-time data on-line during the subjectâs locomotion bout. To transfer data from speedo-meter to the software an acquisition card is used. System validation was done for a set of land-based human locomotion techniques (from slow walk to maximal running) in four subjects and comparing it with a Doppler radar gun. Linear regression models between speedo-meter system and radar gun where very high for both the coefficient of variation of the subjectâs
velocity within the full gait cycle and his maximal velocity.
The 95% of interval confidence agreement limits were very close together in both variables. More than 80% of the Bland-
Altman plots were with the 1.96 standard-deviation criteria used on regular basis as rule thumb for techniques validation
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