Background: Soccer coaching staffs may have difficulties in classifying properly the load accomplished during training sessions and understanding how players rate the effort and the training load during the micro-cycles. Objective: The aims of this study were to investigate if the features and duration of training tasks can automatically classify the different weekly training sessions into different clusters, and to describe and compare the features and duration of training tasks, rating of perceived exertion and training load from the different training sessions across both classifications (prescribed by staff per day vs. automatically per cluster). Methods: Eighteen elite youth male soccer players reported their rating of perceived exertion 10 min after each practice during twelve micro-cycles. In each micro-cycle, differentiated management of the task characteristics for each training day was implemented. A Random Forest Clustering was used to automatically assign each training session to one cluster and allowed to create similar groups and contrast them with the sessions prescribed by the coaching staff. Results: Proper manipulation of different variables of small-sided games (number of players, relative playing area per player, game orientation, training regimen) can automatically differentiate training sessions. Youth soccer players can also perceive each training session differently (p < .05). Conclusions: Using different formats of small-sided games in each training session may be interesting to modulate the player's perceived load during the micro-cycle. However, results should be interpreted with caution, due to representing a single team and coaching staff.

Background: Increases in early sport specialization, professionalization of youth sports, and leisure opportunities have led to growing numbers of youth dropping out of competitive sport. Understanding youth sport motivation and reasons for dropout is essential to crafting national federation policy, finance, and strategy decisions, as well as for clubs in aiding youth to reach their maximum potential. Objective: The study explored the leisure constraints perceived by former Czech youth football players as their main reasons for dropout. Based on leisure constraints theory, the hierarchical relationship between structural, intrapersonal, and interpersonal constraints was analyzed.Methods: A modified Czech version of Gould et al.'s Questionnaire of Reasons for Attrition (1982) was used to survey former Czech football players who dropped out between the ages of 13 and 18 years old. Data were analyzed using exploratory factor analysis and structural equation modeling to determine the relative prevalence of, and hierarchical relationship between, leisure constraints. Results: The participants' reasons for attrition were grouped into six factors corresponding to intrapersonal constraints (Low interest, Perceived low skills), interpersonal constraints (Team climate and the coach, Peer relationships) and structural constraints (Lacking family resources, External costs/low rewards). The participants most frequently reported interpersonal constraints (Team climate and the coach) and intrapersonal constraints (Low interest and Perceived low skills). Peer relationships significantly predicted intrapersonal constraints, including Perceived low skills (β = .482, p = .050) and Low interest (β = .914, p = .013); and Team climate and the coach significantly predicted Perceived low skills (β = .245, p = .036). Conclusions: Our results emphasize the importance of intrapersonal constraints and interpersonal constraints related to the team climate as the most significant reasons for dropout in Czech youth football. Based on these findings, we conclude that the coach, including coaching education, is the best place for the federation and clubs to address attrition in Czech football.

Background: The literature on performance analysis in team handball has increased at the top level, but there has been far less research published at the amateur level. Objective: The objectives of the present study were: (i) to compare handball game-related statistics by match result (winning and losing teams) for the men's and women's teams in an amateur league, (ii) to compare handball game-related statistics by gender, and (iii) to identify characteristics that discriminated performance in amateur men and women handball leagues. Methods: The game-related statistics of the 190 matches (113 men, 77 women) played in the 2018/19 Icelandic League by 12 men and 8 women teams were analysed. Their intra- and inter-observer internal consistency and reliability were at levels considered to be good or very good for the games of both genders. Differences in the game statistics between match outcomes (winning or losing teams for each gender) and between the genders were determined using the unpaired t-test or Mann-Whitney U test, and the corresponding effect sizes were calculated. Results: Large differences between the winning and losing teams were shown by shots, goalkeeper blocked shots, and 9 m shots for men, and by shots, goalkeeper blocked shots and 7 m shots for women. In the comparison between the genders, there were four variables that showed a moderate effect size (Cohen's d > 0.50). A discriminant analysis applying the sample-splitting method was performed for each gender to determine the game statistics that best characterized the match outcomes. The resulting predictive models correctly classified 84% of the matches using five variables for men and 87% of the matches using two variables for women. Conclusions: The results could be used to better understand the structure of the game in amateur leagues, and to improve the performance of teams.

Background: Stability is one of the key demands in human locomotion including running. Various kinematical analytical approaches are adopted to investigate the running strategies; nevertheless, the impacts of running speeds on the variability of angles in individual lower limbs joints is still unclear. Objective: This study was aimed to investigate the impact of various running speeds on linear and non-linear variability of the hip, knee and ankle joints movement. Methods: Twenty-three collegiate athletes (13 females, 10 males, age 22.04 ± 3.43 years, body mass 62.14 ± 9.26 kg, height 168.29 ± 7.06 cm) ran at preferred running speed, 20% lower, and 20% higher than preferred running speed on a treadmill and their lower limbs joints kinematics were recorded using myoMOTION system at the sampling frequency of 200 Hz. The repeated measure analysis of variance test was adopted to investigate the linear (mean and standard deviation) and non-linear (Lyapunov exponent) variability of the hip, knee and ankle angle in sagittal, frontal and transverse planes throughout the running cycle. Results: No significant difference was observed between the lower limbs joint angles variability in linear analysis, while the Lyapunov exponent of the hip (p = .008, ηp2 = .338), knee (p = .002, ηp2 = .249) joints in the sagittal plane significantly increased as running speed increased. Conclusions: Findings of this study revealed that the hip and knee joints respond with more freedom of movement in the sagittal plane while walking speed increases, although nonlinear approaches were the only ones capable of detecting it. Given that speed changes might reduce body stability, it appears that these joints are attempting to maintain body stability by regulating internal body system perturbations by increasing their variability.

Background: Athletes, who engage in combat sports, perform often several matches in a day during competitions. For this reason, recovery is a very important factor between matches. There are many different recovery methods applied by athletes and it is very important to know which one is more suitable for anaerobic performance. Objective: The aim of this study was to investigate the effects of different recovery methods on anaerobic performance in combat sports athletes. Methods: Thirteen experienced international level elite combat sports athletes (age 20.5 ± 1.6 years, body height 175.3 ± 4.5 cm, body mass 73.8 ± 7.9 kg, body fat 11.4 ± 3.9%, training experience 7.5 ± 3.4 years) have participated voluntarily in this study. Athletes were involved in passive recovery (PR), cold water immersion (CWI) and active recovery (AR) methods after countermovement jump and Wingate anaerobic test. Also, body temperature and rating of perceived exertion were evaluated. In this study, a randomized crossover design was used and applications lasted three days. All measurements were performed at three different times (baseline, 1st and 2nd session) in a day. Two-way analysis of variance with repeated measures was used for statistical analysis. Results: For the countermovement jump there was a significant increase after CWI and AR. A significant decrease was found in the Fatigue index after CWI recovery. Body temperature was increased after CWI, AR, and PR. Rating of perceived exertion has increased in AR. Moreover, there were no significant differences were found in peak power and mean power. Conclusions: The results indicate that during intermittent recovery, CWI positively impacted countermovement jump and fatigue index. Also, AR has positively affected countermovement jump performance, while negatively affected the rating of perceived exertion. Thus our findings suggest that 10 min of CWI and AR can be adopted in competitions when successive matches take place.

Background: In contrast to strongly established views on the development of tonic, top-down controlled alertness, a small number of neurobehavioral and neurophysiological studies deal with the developmental trajectory of exogenously driven phasic alertness during childhood. Objective: The current study aimed to examine the age and sex effects on phasic alerting during late childhood, and to analyse the degree of association between tonic and phasic alertness at the behavioural level. Methods: Three age groups of typically developing children, aged 10, 11 and 12 years (N = 59, 27 boys, 32 girls) performed a computer-based simple hand-eye reaction test of alertness that involved 28 trials with and 28 trials without a warning signal. Results: The results showed a moderate decrease of mean reaction time in both the alert and non-alert conditions with age. However, the alert effect calculated as the difference in reaction times achieved in alert and non-alert conditions was not affected by age and sex. Conclusions: In contrast to previous suggestions on possible continuing improvement in phasic alertness during late childhood, the current study suggested that the neurocognitive function of transient enhancement in attentional alertness (phasic alertness) does not change and it is stabilized in this developmental period. In addition, this function does not differ between males and females in childhood.

Background: Injury is one of the risks of performing regular sports activities, which causes mild to severe physical discomfort and emotional distress for athletes. Objective: As there is not much research on the psychological aspects of pain perception of athletes, the main purpose of this study was to investigate differences in pain coping styles according to gender and type of sport. Methods: The sample consisted of 147 athletes (101 men, 46 women) who reported a previous sports-related injury, with an average age of 20.82 ± 1.61 years, involved in individual (n = 59) and team (n = 88) sports. The pain perception was evaluated by Sports Inventory for Pain (SIP15) comprised of three subscales: coping by direct action, catastrophizing, and somatic awareness. Results: We found that men perceive pain in sport more intensely and sensitively than women (p = .01, r = .21). Nevertheless, men consider pain to be more bearable and give up less than women (p = .05, r = .16). In individual and team sports, we did not find significant differences in response to painful stimuli, but in terms of giving up due to the perceived pain, the athletes of individual sports scored higher values than athletes of team sports (p = .04, r = .17). In coping by direct action, we also did not find significant differences between gender or types of sports. Conclusions: The results of our research suggest that pain perception is one of the factors influencing giving up in the sport. Therefore, we recommend that this aspect be considered in psychological preparation and that the efforts of sports psychologists should focus on eliminating escape reactions, especially for women, which would contribute to higher mental resilience and effective management of painful obstacles. We also recommend implementing psychological preparation aimed at overcoming pain more in individual sports, because it seems that individual athletes can handle pain much more difficultly than collective athletes.

Background: Vertical jump height and body height are almost universally recognised as determinant factors in elite volleyball performance. Objective: The purpose of this study was to assess the correlation between basic anthropometric parameters (body height and body weight) and jumping performance in a group of 16 female volleyball players (age 19.14 ± 5.52 years, height 1.80 ± 0.06 m, weight 69.81 ± 6.85 kg) and in a control group of 15 female university students (age 22.90 ± 0.83 years, height 1.70 ± 0.05 m, weight 61.70 ± 8.23 kg). Methods: The Quattro Jump 9290BA force platform system (Kistler, Winterthur, Switzerland) was used to test jumping performance in single vertical jumps (squat jump, countermovement jump) and 45-s continuous jumps. In single jumps, jump height was analysed and during the 45-s continuous jumps the maximal and mean jump height, the average contact time and the fatigue index were evaluated. The efficiency of the conversion of mechanical work into mechanical energy at the moment of take-off was calculated. Results: No significant influence of body height and body weight was found in the jumping performance in the squat jump and countermovement jump. In continuous jumps, a significant correlation was found between body height and fatigue index in the volleyball players. In the control group, in most of the tests moderate correlation between body height and jump height was observed. In the volleyball players, rather low values of efficiency of take-off (23.67 ± 2.64%) were calculated. The values in the control group were even lower. Conclusions: Nowadays, many volleyball coaches choose individuals mainly according to body height, but it is important that the talent identification process should also consider jumping abilities in the simple jumps and in continuous jumps. All these parameters should help coaches choose the right players for the appropriate position and role in the team.

Background: The Greek bibliography does not provide researchers with a credible measurement instrument that can estimate satisfaction as a multi-dimensional concept, in the frame of a physical education lesson. Objective: The main aim of this study was to cross-validate the Greek version of the Physical Activity Class Satisfaction Questionnaire (PACSQ) in a Greek educational context. The internal consistency of the PACSQ was also examined as well as the levels of satisfaction, gender, and grade of studies as factors that differentiate lesson satisfaction from lesson attendance. Methods: A total of 459 elementary school students (220 boys and 239 girls) aged between 11 and 12 years, across the country joined in the study. The Greek version of PACSQ was used. The statistical analysis included descriptive analysis, confirmatory factor analysis, reliability analysis and discriminant and convergent validity, and one-way multivariate analysis of variance. Results: The results of the confirmatory factor analysis demonstrated that the hypothesized model produced a significant χ2 (3311.55), normed fit index (.95) and comparative fit index (.96). The root mean square error of approximation (.62) was also considered to assess the degree of fit of the model. Composite reliability (≥ .879) and variance extracted (≥ .586) of all dimensions of the PACSQ demonstrated an acceptable reliability coefficient. Conclusions: From the analysis of the results, we came to the following conclusions. The PACSQ constitutes an instrument credible enough to measure the satisfaction of elementary school male and female students. Students seem to be quite satisfied by the cognitive process. Gender is a differentiation factor only as far as Normative Success is concerned. Students in the 6th grade (12 years old) appear to be more satisfied by their participatiοn in a physical education lesson.

Background: It has been suggested that velocity-based training (VBT) improves real-life performance in sports, such as jumping, but studies rarely examined the associations between variables derived during VBT (VBT-variables) and jumping performances. Objective: The aim of this study was to investigate the associations between VBT-variables derived during deadlift exercise executed at different loads and anthropometric variables, and vertical and horizontal jump performance in young athletes. Methods: Seventeen youth soccer players (16-18 years old) were included. Predictors were body height, body mass, body fat percentage, and VBT-variables (force, power, and velocity) measured at different loads (45%, 55%, 65%, 75%, 85%, and 95%) of a one-repetition maximum deadlift (1RM). Criteria included tests of vertical and horizontal jumping performance. Results: The VBT-variables are more strongly correlated with horizontal jumps (Pearson's r up to .81) than vertical jumps (Pearson's r up to .75). The VBT-variables for the deadlift recorded at lower loads stronger correlated with jumping performance than the VBT-variables recorded at higher loads. Conclusions: Results of the study suggest that light-to-moderate loads (45%-65% of 1RM) maximize power output and are therefore more strongly related to jumping performance in youth athletes. Further intervention studies aimed at the improvement of jumping performances using the VBT are warranted.