Physical fitness performance, playing position and competitive level attained by elite junior soccer players

The aim of this study was to look into the alleged impact of the physical fitness performance of elite junior soccer players on the professional career according to playing position. The physical tests (sprint test, countermovement jump [CMJ], and maximal aerobic speed [MAS]) performed by 165 players enrolled in the junior team of a Spanish 1st Division club (1998-2010) were evaluated. Players were classified as those who were promoted to the reserve team (Reserve Team) and those who were not (non-Reserve Team), and as those who were promoted to the Spanish 1st/2nd Divisions (PFL) and those who were not (NPFL) until the 2020-2021 season. Overall, no significant differences (p>.05) were found between the Reserve Team and non-Reserve Team or between the PFL and NPFL players in neuromuscular performance. Aerobic fitness was greater (p<.05; ES = .79 ± .60 , moderate; mean difference = 3.0%) for the Reserve Team lateral midfielders in comparison to that for the non-Reserve Team. The results suggest that the impact of physical fitness on the promotion of elite junior soccer players is limited.

Notational analysis in female grand slam tennis competitions

Grand Slam tennis tournaments are played on different surfaces. The aims of the present study were to analyse the technical differences in the Grand Slam tournaments (Australian Open or AO, Roland Garros or RG, Wimbledon or W, and the United States Open or US), as well as to establish differences between winning and losing players. A total of 580 sets in 248 matches played in Grand Slams between 2017 and 2018 were analysed. To observe differences between the tournaments, a one-way analysis of variance (Kruskal Wallis) with the Bonferroni post-hoc test was performed. Univariate (Wilcoxon test) analysis of data was carried out to show the differences between the winning and losing performances of sets. Players who had more aces, points won on the 1st serve, winning shots and net points won more matches in the AO, W and US than in the RG (p<.05). However, in RG, players won more receiving points (43.56% of the points played) with chances to break the opponents’ service game. The results also showed that the winning players were superior in both service and receiving, and the most influential variables on the outcome of the match were percentage of receiving points won, break points won, and percentage of points won on the first serve. Such knowledge may have implications in the design of appropriate game strategies and specific training sessions to improve performance in professional women’s tennis.

The effects of eccentric training on hamstring muscle architecture

The architectural features of the hamstring muscle group are important to prevent injury or to reduce the risk of re-injury. Besides, eccentric training is often used in the rehabilitation of hamstring injuries. The aim of this systematic review was to examine the changes created by eccentric training on hamstring muscle architecture and to determine the minimal values of training duration and intensity for requiring functional changes. The research was conducted on the PubMed, Scopus, Web of Science, COCHRANE, CINAHL, and Pedro databases. Full-text studies examining the effect of eccentric training on at least one parameter of the hamstring muscle architecture were included in the review. Studies on cadavers and animals and studies involving different types of training combined with eccentric training were excluded. Twelve of the 7954 studies met the set criteria. According to the results, eccentric training undoubtedly increases fiber length. However, the pennation angle tends to decrease. On the other hand, muscle thickness and cross-sectional area tends to increase depending on the eccentric training. Although the frequency, number of sets and number of repetitions in sets were similar in the examined studies, muscle architecture changes were different. We think that eccentric training duration and the number of repetitions in total or per training session seem to have an impact on muscle architecture. In order to determine the minimal eccentric training program that can create these changes, quality research is needed to examine the duration, intensity and methods of eccentric training.

Concurrent Validity and Reliability of the Load-Velocity Relationship to Predict the One-Repetition Maximum during Three Weightlifting Derivatives

The study investigated the concurrent validity and reliability of the load-velocity relationship to predict the one-repetition maximum (1RM) of the power clean from the knee (PCK), high pull from the knee (HPK), and mid-thigh clean pull (MTCP). For each exercise, 12 participants performed two 1RM sessions tests and two sessions to measure the barbell’s load-velocity relationship at 30, 45, 60, 75, and 90% of 1RM. The velocity recorded at each load was used to establish the linear regression equation and, consequently, to predict 1RM value. A low validity between the 1RM direct test and predicted 1RM was observed for PCK (typical error [TE]=3.96 to 4.50 kg, coefficient of variation [CV]=4.68 to 5.27%, effect size [ES]=-0.76 to -0.58, Bland-Altman bias [BAB]=9.83 to 11.19 kg), HPK (TE=4.58 to 5.82 kg, CV=6.44 to 8.14%, ES=-0.40 to -0.39, BAB=3.52 to 4.17 kg), and MTCP (TE=6.33 to 8.08 kg, CV=4.78 to 6.16%, ES=-0.29 to -0.19, BAB=3.98 to 6.17 kg). Adequate reliability was observed for the 1RM direct test and for the predicted 1RM. However, based on Bland-Altman limits of agreement, lower measurement errors were obtained for the 1RM direct test in comparison to the predicted 1RM for all the exercises. In conclusion, the load-velocity relationship was not able to predict 1RM values with high accuracy in the PCK, HPK, and MTCP. Moreover, the 1RM direct test was the most reliable for PCK, HPK and MTCP.

Training habits in professional soccer players during COVID-19 confinement

The pandemic caused by COVID-19 has led to an unprecedented situation, forcing governments to take urgent measures and confine the population. These measures have also affected sports. Soccer competitions and training sessions were interrupted worldwide, causing the need to adapt training sessions to the new situation. The objective of this study is to observe and analyse training habits carried out during the COVID-19 confinement by Spanish professional soccer players of both sexes. An o bservational study was based on an ad-hoc telematic questionnaire during the COVID-19 state of alarm in Spain. The results showed that strength and conditioning training was of great importance in the training habits developed during the COVID-19 confinement, fundamentally that of strength and endurance capacities. Specificity was low as conditional capabilities were affected by contextual limitations. The findings of this study yielded very useful information related to the training habits of professional soccer players of both sexes and offered an unpublished reference database that could be used to address training planning at specific periods of the year (transition, vacations, emergencies, ...), with the aim of resuming competitive activity in the best conditions.

Changes in rearfoot strike patterns over childhood

Rearfoot strike (RFS) in children running produces impact forces that give rise to a transient stress wave traveling through the body. It could contribute to the development of injuries. The purpose of this study was to determine RFS prevalence during childhood while running at a self-selected velocity in a prospective longitudinal cohort study. A total of 175 children (68 girls), aged 6 to 14 years, participated in this study. The sample was divided into three age groups (age in 2016): 6-8 years, 9-11 years, and 12-14 years which were analysed three years later (2019). 2D video-based was used to record the RFS Taking into account all samples, in the jogging trial the prevalence of RFS (an average of both feet) was 86.9% in 2016 and 94.7% three years later; in the running trial the prevalence was 82.6 and 94.4%, respectively. In all samples a significant increase of RFS prevalence was found in both the jogging and running trials for both feet over three years (jogging, left foot, p=.011, right foot, p=.023; running, left foot, p=.001, right foot, p<.001). In girls, there were no significant differences in any conditions. In boys, a significant increase of RFS prevalence was found after three years in both feet (p<.01) in the running trial. This study shows that RFS prevalence in children increases with age and the results may be used to characterize typical running development in children population.

Getting back to the event: COVID-19, attendance and perceived importance of protective measures

Current COVID-19 realities impose additional challenges to sporting event organisers who now have to consider and include new protective measures for the safety and security of both active and passive participants. This study focuses on event consumers and issues related to their intention to attend future sporting events and their perception of how important they find some of the safety-related protective measures when attending sporting events following the COVID-19 crisis. Based on the empirical study of residents from one Middle East and two European countries, the results suggest that, once all restrictions on movement and sporting event attendance is allowed to resume, most of the respondents will attend events in their home country within few weeks. In addition, the respondents from a country that experienced more severe consequences of the pandemic perceive all protective measures as more important than respondents from countries that were less affected.

The influence of expertise and experimental paradigms on the visual behavior of tennis athletes in returning a serve

To return a serve, one must pick up information from the server’s kinematics and anticipate the ball trajectory. Although the perceptual requirements are important, the literature diverges in terms of the differences between experts and novices as well as the importance of the experimental paradigm (in-situ vs. video-based) for the results. This study aimed to address both concerns. We compared experts’ (n=7, 20.6±1.1 year of age) and novices’ (n=7, 20.0±0.4 years of age) visual pattern when returning a serve (Experiment 1) and the influence of the experimental paradigm in experts (Experiment 2). Experts fixated more and longer the upper body and ball, while novices showed a more distributed pattern and with longer fixations outside of the server’s body. Also, the pattern was different when comparing in-situ and laboratory settings, differing mainly in fixation frequency. The influence of expertise was observed in qualitative (relative) and quantitative (absolute) measures of visual behavior with the setting having an important influence. Thus, studies should be as close to the actual situation if trying to understand experts’ behavior.

Understanding of dropping out of sports in adolescence

The aim of the research was to test the hierarchical model of intrinsic and extrinsic motivation (HMIEM) as a model for understanding the process of dropping out of sports in adolescence. The task oriented motivational climate created by a coach was defined as the social factor, whereas the satisfaction of need for competence and enjoyment were the psychological mediators of amotivation. Cognitive outcome was defined as the intention to drop out of sports. The sample consisted of 383 respondents, 49.9% boys and 50.1% girls from Serbia, average age 13.74 years, who actively played volleyball, basketball, and handball. Results of the structural modelling equation analysis confirmed that the HMIEM represented a good model for understanding the process of dropping out, and that it explained 18.9% of the intention to drop out of sports in adolescence. Athletes who perceive their coach’s behaviour as non-supportive, rigid, primarily focused on achievement, will have sense of incompetence and will lack enjoyment while doing sport. Unsatisfied needs then lead to the development of amotivation – the lack of reasons to do sports, and to the intention to drop out of sports. These results represent a further step towards creating educational programmes for youth sport that might prevent dropping out of sport in adolescence.

Manipulating the Pitch Size Constrains the Players’ Positioning during Unbalanced Soccer Small-Sided Games Played by Different Age Groups

We aim to investigate the impact of variable soccer pitch sizes on the position of players during unbalanced small-sided games (SSGs) and compare the responses of players from two different age groups. Forty-eight young players (n = 24 under-13 and n = 24 under-14) took part in the study and played 3 vs. 3 + 1 SSGs on two different pitch sizes (smaller: 36 x 27 m / 139m2 per player; and larger: 40 x 29 m / 166 m2 per player). Players’ positions on the pitch (length, width, length-to-width ratio, stretching index, and spatial exploration index) were assessed by the positional data provided by global position system devices and were compared within age groups and between game formats using a two-way analysis of variance. Results showed higher values of spatial exploration index in the larger SSGs than in the smaller format (p<.001). Moreover, a higher length (p<0.001) and length-to-width ratio (p<.001) was observed in the younger group. Finally, the larger format presented higher values of SEI and stretching index, independent of the age group (p<.001). In the smaller format, U-14 players presented a higher stretching index, while in the larger format U-13 players presented higher values in the same variable. We conclude that enlarging the pitch size constrains players’ behaviour during SSGs, and older players are more able to deal with this more complex task context than younger ones.