The Influence of Antenna Height on the Measurement of Collective Variables Using an Ultra-Wide Band Based Local Positioning System in Team Sports

Ultra-wide band (UWB) based local positioning systems (LPS) are based on devices and a portable antenna set. The optimal installation height of the antennae is crucial to ensure data accuracy. Collective variables are metrics that consider at least two pairs of coordinates, which may lead to lower precision than an individual one. Therefore, the aim of this study was to compare the influence of antenna height with collective metrics using a UWB (i.e., IMU; WIMU PRO™, RealTrack Systems, Almeria, Spain) based LPS. Data acquisition was carried out in a basketball court measuring 28 × 15 m. Five devices were used; one of which was carried by a healthy and well-trained athlete (age: 38 years, mass: 76.34 kg, height 1.70 m), while each of the remaining four was positioned on a tripod in one of the four corners of the court. Four kinds of variables were extracted: (1) static distances, (2) dynamic distances, (3) static areas and (4) dynamic areas in all antenna installation modes of 0.15, 1.30 and 2.00 m. The results showed that the antenna of 1.30 m provided better accuracy for all measures (% difference range from −0.94 to 1.17%) followed by the antenna of 2.00 m (% difference range from −2.50 to 2.15%), with the antenna of 0.15 m providing the worst accuracy level (% difference range from −1.05 to 3.28%). Overall, the measurements of distance metrics showed greater accuracy than area metrics (distance % difference range from −0.85 to 2.81% and area % difference range from −2.50 to 3.28). In conclusion, the height of the antennae in basketball courts should be similar to the height at which the devices are attached to a player’s upper back. However, as the precision is sensitive to the magnitude of the measure, further studies should assess the effects of the relative height of antennae in team sports with greater playing spaces.This work is funded by Fundação para a Ciência e Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020

Smartphone Use Among High Level Swimmers Is Associated With Mental Fatigue and Slower 100- and 200- but Not 50-Meter Freestyle Racing

Discovering any performance degradation effect of racing swimmers' use of social media smartphone apps might lead to new training and race preparation protocols, including pre-meet smartphone avoidance. This study's objective was to analyze the performance effects of using smartphone social media apps on the 50, 100, and 200-m freestyle among 25 high-level swimmers. Each participant performed the three race distances in two conditions: with smartphone app exposure (50-MF, 100-MF, and 200-MF) and without (50-CON, 100-CON, and 200-CON). We randomized the order of these two conditions across participants. While smartphone app use was not associated with statistically significant performance differences on the shortest race (50CON versus 50MF), a repeated measures ANOVA showed a significant condition x time interaction for the swimmers'100-m freestyle performance (p = 0.01), with a significantly slower performance following smartphone app use evident in the last half of this race (p = 0.02) but not in the first half (p = 0.41). We also found a condition x time interaction in the same direction (slower for swimmers who used the smartphone app) for the 200-m freestyle performance (p = 0.01), with the slower performance occurring in the second (p = 0.01) but not the first (p = 0.91), third (p = 0.07) or fourth (p = 0.06)quarters of this race. Thus, prolonged smartphone social media app use was associated with reduced performance from elite swimmers on the 100- and 200- but not the 50-m freestyle

Within-Session Sequence of the Tennis Serve Training in Youth Elite Players

[EN] The influence of muscular fatigue on tennis serve performance within regular training sessions is unclear. Therefore, the aim of the present study was to examine the within-session sequence of the tennis serve in youth tennis. Twenty-five young male (14.9 ± 0.9 years) and fe- male (14.5 ± 0.9 years) players participated in this within-subject crossover study, and they were randomly but sex-matched assigned to different training sequences (serve exercise before tennis training (BTS) or after tennis training (ATS)). Pre- and post-tests included serve velocity performance and accuracy, shoulder strength, and range-of-motion (ROM) performance (internal/external rota- tion). Results showed that after one week of serve training conducted following the ATS sequence, significant decreases were found in serve performance (e.g., speed and accuracy), with standardized differences ranging from d = 0.29 to 1.13, as well as the shoulder function (strength [d = 0.20 to 1.0] and ROM [d = 0.17 to 0.31]) in both female and male players, compared to the BTS sequence. Based on the present findings, it appears more effective to implement serve training before the regular tennis training in youth players. If applied after training, excessive levels of fatigue may cause shoulder imbalances that could be related to an increased injury risk.SIThe authors are grateful to all the athletes who took part in this study

How does curve sprint evolve across different age categories in soccer players?

: Research has shown that soccer players regularly execute curved sprints during matches. The purpose of this study was to determine the age-related effects on curve sprint (CS) performance to both sides, asymmetry, and association with linear sprint (LS). Eighty-four soccer players (aged 16.1 ± 1.6 categorized in U15, U17, and U20) were recruited, who performed CS and LS tests. One-way analysis of variance (ANOVA) and effect size (ES) were used to compare CS performance between age categories, and relationships between physical performance measures were calculated using Pearson’s correlation coefficient. The main findings of this study were that: 1) there were significant differences in the “good” side CS among age groups (p < 0.001; ES from moderate to large), but not in the “weak” side CS, 2) curve asymmetry was significantly higher in U20 than U15 (p < 0.05; ES large) and U17 players (p < 0.05; ES moderate), and 3) relationships between CS and LS times decreased with age (from significant and very large [p 0.05]). This study highlights the importance of assessing and training CS in different age categories, an action that becomes less correlated with LS as age increases, with the aim of mitigating the increase in asymmetries as a result of the specialization process, focusing interventions mainly on improving the CS “weak” sideThanks to all the participants in this study, to Football Science Institute, and to the soccer clu

Short-term effects of repeated-sprint training on vertical jump ability and aerobic fitness in collegiate volleyball players during pre-season

International Journal of Exercise Science 15(6): 1040-1051, 2022. The aim of this study was to assess the effect of repeated-sprint training (RST) on vertical jump ability and aerobic power in college volleyball players. Nineteen male volleyball players, aged between 18-24 years, were randomized into the RST group (RST; n = 10) and control group (CG; n = 9). The RST included 2-3 sets of 6x30m all-out sprints, twice per week, in addition to the regular training routine. The control group performed only the regular volleyball training sessions (i.e. mainly of technical-tactical drills). All players performed a maximal graded treadmill test, vertical countermovement jump (CMJ), and repeated-vertical jump ability (RVJA) test before and after 6-weeks of the training program. The following variables were determined from the RVJA: peak (RVJApeak), average (RVJAmean), and rate of decrement (RVJADec). A two-way ANOVA with repeated measures showed an interaction effect on CMJ (F(1,17) = 6.92; p = 0.018; η2 = 0.289), RVJApeak (F(1,17) = 4.92; p = 0.040; η2 = 0.225), maximal oxygen uptake (F(1,17) = 9.29; p = 0.007; η2 = 0.353) and maximal speed attained in the treadmill test (F(1,17) = 8.66; p = 0.009; η2 = 0.337), with significant improvements only on the RST group. In conclusion, RST, twice per week, improved RVJA and aerobic power in comparison to regular skill-based volleyball training

Satisfaction of Body Image in Adolescents With Different Maturity Stages

Introduction: Adolescence is a period marked by intense body modifications that occur differently according to the maturational stage and sex, which can generate different body image perceptions.Objective: This study aims to compare and associate body image satisfaction in different maturational stages. Methods: Overall, 207 adolescents of both sexes aged 10-12 years were evaluated. Maturation was estimated through an equation predictive of skeletal age and for the body image evaluation, the scale of silhouettes was used. The statistical tests used were chi-square and logistic regression (odds ratio) with respective confidence intervals (95% CI).Results: There was a prevalence of body image dissatisfaction of 63.8% (p &lt;0.001). In both sexes, subjects with accelerated maturation had greater body image dissatisfaction (girls p = 0.0, boys p = 0.04), and desire to reduce their silhouette scale (p &lt;0.001). Subjects with accelerated maturation were 2.88 more likely (CI 95% 1.03 - 8.05) of having body image dissatisfaction when compared to normal maturation; however, when adjusting for body mass index, the association lost its significance. Conclusion: It could be concluded that body dissatisfaction perceived by young individuals is independent of sex, and there is an association between accelerated maturational stage 2.88 times higher than in the normal maturational stage in relation to body dissatisfaction, in which the body mass index appears to be the main predictor for body dissatisfaction

Fatores motivacionais em paratletas com deficiência visual e motora praticantes de natação e atletismo

Diversas modalidades esportivas buscaram se adaptar com o intuito de agregar um maior número de pessoas com deficiência física a sua prática, nesse contexto o estudo da motivação é um dos que mais ganha espaço na Psicologia do Esporte. O objetivo deste estudo foi verificar os fatores motivacionais em paratletas com deficiência visual e motora praticantes de natação e atletismo. O estudo caracteriza-se como descritivo, de delineamento transversal. A amostra foi composta por 30 paratletas do sexo masculino, idade (34,1±7,9 anos), portadores de deficiência visual e motora, praticantes de natação (n=13) e de atletismo (n=17). O instrumento utilizado foi o Questionário de Motivação para Atividades Desportivas (QMAD). Foi verificado que o domínio “Atividade em Grupo†apresentou maior escore para a modalidade natação (83,3±11,8) e atletismo (78,9±19,6). Através do teste de Mann Withney foi verificado que os paratletas da natação (81,4±6,7) se diferenciaram significativamente dos paratletas de atletismo (75,5±7,5) no domínio “Status†(p<0,05), demonstrando que os nadadores foram mais incisivos nas questões relacionadas aos aspectos como, ganhar, fazer alguma coisa em que se é bom, receber prêmios, ter a sensação de ser importante, ser conhecido e ser reconhecido e ter prestígio, uma vez que participam da prática esportiva de alto rendiment

Maturational stages: comparison of growth and physical capacity indicators in adolescents

Introduction: The identification of physical capacity is an important marker related to healthy behavior during childhood and adolescence, in which some factors appear to contribute to motor performance such as maturation and hormonal levels. Objective: To compare growth indicators, physical capacity and hormonal markers according to gender and maturational stage in adolescents. Methods: Eighty-nine adolescents of both genders aged 10-13 years participated in the study. Sexual maturation was evaluated using the Tanner’s self-evaluation method. Physical capacity (explosive strength of upper and lower limbs, upper limb velocity and agility) and hormonal markers (testosterone and estradiol) were evaluated through the chemiluminescence method. Results: In the comparison by gender, girls had higher weight (p = 0.023), height (p = 0.018) and fat percentage values (p = 0.001), while boys presented better motor performance for the explosive strength of upper limbs (p = 0.005) and lower limbs (p = 0.011), agility (0.018) and upper limb velocity (p = 0.014). Regarding maturational stage, boys did not present differences in any variable analyzed; (Stage V versus I), height (stage III, IV and V versus I) and upper limb explosive strength (stage III and IV versus I). Conclusion: Growth, weight and height, as well as explosive strength of upper limbs were higher in girls at more advanced maturational stages and appear to be gender dependent

Validation of automated apparatus for upper limb velocity testing

The purpose of this paper was to validate the ability of automated devices to measure the velocity of the upper limbs. Thus, 144 students, from 8 to 17 years old, both sexes, participated in the study in a social project in the city of Natal/RN. The Automated Tapping Test (AATT) was developed following the dimensions of the original EUROFIT test, but built out of metal parts, so that the calibration was more accurate and could be read as an electronic signal by the integrated circuit. The upper limb velocity test was applied in three steps: before performing the original test, all participants underwent a laterality check and then motor practice similar to the original test. After 30 minutes, the first step in the pattern established by the EUROFIT test battery was performed and 30 minutes later, the third stage, with the AATT. The measurement reliability of the automated apparatus was tested through intraclass correlations and a strong intraclass interaction coefficient of r = 0.901 was found. In conclusion, the AATT was found to be accurate and efficient as to what it is proposed to evaluate, being able to minimize the intra-evaluator error and to assist professionals in the sports

Relationship between bone age, hormonal markers and physical capacity in adolescents

Introduction: Physical capabilities are an important parameter of the functional development of adolescents, not only by chronological age but also by their maturational state, as individuals with the same chronological age can have different performance to their less mature counterparts. Objective: To compare and relate the physical capabilities and hormonal markers according to sex and maturity of adolescents. Methods: The sample consisted of adolescents of both sexes, aged 10 to 14 years. We evaluated the maturity achieved by a predictive equation of skeletal age, physical capabilities (explosive power of upper and lower limbs, velocity of upper limbs and agility) and hormonal markers (testosterone and oestradiol) via chemiluminescence. Results: Females showed more advanced maturational status, higher weight, body height and oestradiol levels; males performed better in the explosive force of upper and lower limbs, upper limb speed, agility and testosterone levels. In the normal maturational state males showed greater skeletal age, body weight, body height, explosive strength of upper and lower limbs, and testosterone levels; the females in the normal maturational state had higher skeletal age, body weight, body height, explosive upper limb strength and oestradiol levels. In the male correlation analysis, bone age was related to the explosive strength of upper and lower limbs and testosterone; while bone age in females was related to explosive upper limb strength and oestradiol. Conclusion: It is concluded that maturation, testosterone and oestradiol levels play an important role in the physical aspects and performance of motor skills of adolescents, especially in upper limb force which was more related to the maturation obtained by skeletal age of males and females