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Selmi, O, Goncalves, B, Levitt, DE, Ouergui, I, Sampaio, J, and Bouassida, A. Influence of well-being indices and recovery state on the technical and physiological aspects of play during small-sided games. J Strength Cond Res 35(10): 2802-2809, 2021-Soccer players performing at high level are frequently exposed to periods of intense training, which can induce substantial stress and fatigue. These high-intensity stimuli likely lead to a lower state of well-being and poor recovery and, consequently, may affect players' performance. This study aimed to assess the influence of well-being indices (i.e., self-ratings of sleep, stress, fatigue, and delayed onset muscle soreness [DOMS]) and the total quality of recovery (TQR) on technical and physiological measures during soccer small-sided games (SSGs). Twenty male professional soccer players (age: 25.1 ± 1.0 years) performed four 25-minute SSG sessions. Well-being indices were collected before each SSG-session. Heart rate was continuously measured throughout each session, and the ratings of perceived exertion and blood lactate concentration were collected after each SSG. A hierarchical cluster analysis was performed across variables and cases to identify associations between variables and variability in players' responses between sessions. No significant correlations were found between well-being indices, TQR and physiological parameters. Total quality recovery was positively correlated with successful pass % (r = 0.27) and interceptions (r = 0.25) and negatively correlated with lost balls (r = -0.25). Fatigue and DOMS were negatively correlated with tackles (r = -0.29, r = -0.28, respectively), successful pass % (r = -0.58, r = -0.55, respectively) and interceptions (r = -0.25, r = -0.27, respectively), and positively correlated with lost balls (r = 0.32, r = 0.28, respectively). Results provide an alternative and complementary method to understand training responses and can be an objective tool to help create subgroups in training for optimizing performance. This study demonstrates the efficacy and utility of using simple well-being and recovery measures to help coaches monitor athlete readiness.

This study explored how the number of allowed ball touches per player possession affected the performance of different age groups (U9, U11, U13, U15, U17 and U19) during a Gk + 4vs4+Gk small-sided games. Each day, players randomly performed the following three conditions (for a total of 6 days): i) free-play (FP); ii) maximum of 2 touches (2 T); iii) 1 touch (1 T). Players’ positional data was used to compute time-motion and positional-related variables, while video analysis was used to capture technical performance. In general, no effects were identified in relation to the players distances (team centroid, opponents’ centroid, nearest teammate, and nearest opponent). There were small to moderate decreases in the longitudinal synchronization while playing with 1 T and 2 T in the U9 and U17, but a moderate increase in the U15. There was a general decrease in the distance covered and distance covered while running (small to moderate effects) when playing with limited touches in all age groups. Limiting the touches promoted small to moderate increases in the number of successful passes in the U9, U15, and U17 and a general increase in unsuccessful actions. Overall, playing with limited touches emphasized the passing skill while it also contributed to more unsuccessful actions and lower physical demands. As so, coaches may use the 2 T in young age groups (U9-U13) as they seem less able to successfully cope with 1 T, while using 1 T in older age groups due to their higher ability to interact with environmental information.

Team sports players are required to perform repeated bouts of short-term high-intensity actions during the games. The present study aimed to examine the effects of a novel repeated sprint ability protocol (20×15 m) and compare it with the impact of a more traditional repeated sprint ability protocol (10×30 m). Twelve male elite Lithuanian basketball players (age 21.0 ± 2.0 y, body height 1.90 ± 0,07 m, body mass 86.2 ± 5.8 kg and training experience 12.0 ± 1.9 y) competing in the Lithuanian National Basketball Championship participated in this study. Participants completed three bouts of each repeated sprint protocol interspersed with 5 minutes of recovery. Results showed that the 20×15 m protocol caused a significant decrease in total sprint time (most likely; mean changes (%) with ± 90% of confidence limits, -9.4%; ± 0.7%) and a large decrease in blood lactate (most likely, -39.2%; ±12.8%) compared to the 10×30 m protocol. Despite small differences, the fatigue index presented a similar trend (possibly decrease, -23.7%; ± 38.8%). The exercise heart rate showed a very similar trend with trivial differences between the two protocols. The 20×15 m protocol presented a lower heart rate during recovery with small magnitude. Overall, the present study showed that the 20×15 m protocol seemed to be more representative of the specific basketball demands. Coaches should be aware that RSA training during the in-season may be an adequate stimulus to improve high-intensity runs and muscle power in high-level players.

Vazquez-Guerrero, J, Reche, X, Cos, F, Casamichana, D, and Sampaio, J. Changes in external load when modifying rules of 5-on- 5 scrimmage situations in elite basketball. J Strength Cond Res 34(11): 3217-3224, 2020-Constraining tasks are very frequent during the team sports training process; however, most of the effects of these coaching decisions are unknown, which leads to less controlled performing environments, with less chances to promote improvements. The aim of this study was to determine the effects of modifying rules of 5-a-side scrimmage on the physical performance of professional basketball players. Data were collected from 12 elite male players (age, 29.6 ± 4.5 years; height, 1.99 ± 9.6 cm; body mass, 92.1 ± 11.9 kg) from the Spanish first Division of Basketball during thirty-three 5-on-5 scrimmage situations over a 18-week period. Physical demands were assessed using WIMU PRO Local Positioning System (Realtrack Systems, Almeria, Spain) and included total and speed-ranged distance covered, player load, peak speed, number of high-intensity actions, number of total and high-intensity accelerations and decelerations, and peak acceleration. A repeated-measures analysis of variance was used to test the differences in all variables, considering playing in half-court (HALF), half-court and transition (HTRAN), and full-court (FULL) conditions for the 5-on-5 scrimmage drill. Results showed that during the HALF condition, there was less distance covered (effect size [ES] = 3.55), lower peak speeds (ES = 3.00), less player load (ES = 2.79), lesser number of high-intensity actions (ES = 1.45), and lesser number of high-intensity accelerations (ES = 1.44) and decelerations (ES = 1.31) than in FULL. In HTRAN, players covered more distance (ES = 2.42), presented higher player load (ES = 1.88), higher intensity actions (ES = 1.02), and peak speed (ES = 4.22) than in HALF. In conclusion, physical demands can be modulated changing the rules and court size using 5-on-5 scrimmage situations, and this factor should be taken into account when designing training drills and when fine-tuning periodization.

The aim of this study was to identify the correspondence between the workload demands in training sessions and the game performance from elite basketball players, according to their specific positions. Data were collected from a professional men's basketball team competing in the Spanish Professional League and Euroleague. Players' activity during the training sessions was measured using WIMU PRO® and the game statistics were used as a measure of game performance. Cluster analysis allowed to classify the training workload and the game performance, whereas correspondence analysis allowed to explore their relationship. In essence, there was no correspondence from the higher workloads with the best performances, on the contrary, the small forwards' best performances corresponded to lower training workouts. Despite their importance, the external measures of load need to be complemented with additional (and valid) measures that can be translated to game performance.

This study aimed to identify the effects of manipulating the ball type in players’ physical, technical, creative and tactical performance in two small-sided games situations: 4-a-side and 6-a-side....

The aims of this study were to examine the medium-term effects of previous experiences during early stages of sport development on physical capacities of under-13 (U-13) talented basketball players and, to identify variables that discriminated under-14 (U-14) national team training camp selection. Anthropometrical and physical measurements were collected during a basketball training camp. Previous sport experiences (6-10 years), maturity offset, power outputs for jumping and sprinting were determined. A cluster analysis was used to allocate the subjects according to their different levels of sport experiences (more specialized vs. less specialized) to allow creating a dummy variable for the subsequent analysis of the physical variables. A stepwise discriminant analysis was computed to identify the construct that best classifies selected and non-selected players for U-14 national team training camp. The less specialized group outscored more specialized in all physical parameters, irrespectively of gender. The Abalakov Jump Peak Power and Predicted Adult Height (PAH) could successfully discriminate selected from non-selected players for U-14 national team training camp in boys and PAHin girls. The diversified and non-specific sport stimulus during early ages seem to be determinant to the acquisition and development of fundamental movement skills of talented basketball players.

Sedentary behavior (SED) and physical activity (PA) are distinct behavioral domains that must be considered before interpreting individual profiles, particularly for amateur athletes which are considered active. The aim was to describe the PA and SED of master amateur runners and footballers, the main individual and team sports. Sixteen male runners and 13 footballers (42 ± 6.9 and 43.9 ± 3.9 years) were monitored for 7 days using triaxial accelerometers (30 Hz). The median (interquartile range) of up to 10 min of moderate-to-vigorous PA (MVPA bouts) was similar among runners and footballers [33.3 (56.0) and 32.5 (47.8) min/day, respectively] and achieved the recommended activity level. Vigorous PA levels were achieved, but were higher for runners than footballers [9.8 (59.5) and 1.6 (3.9) min/day, respectively]. Week-day differences for runners and footballers were found for light [202.0 (139.1) and 261.3 (115.3) min/day, P = 0.001], moderate [47.7 (59.8) and 103.3 (82.7) min/day, P

This study aimed to describe professional soccer players’ training responses during a competitive season and to investigate the relationship between these responses with wellbeing and recovery indices. Thirteen professional soccer players from the same Spanish Second Division team were monitored during a sixteen-week in-season period. Players’ external loads were analyzed using global positioning measurement units (GPS). Additionally, subjective reporting of sleep quality, sleep duration, fatigue, muscle soreness, and stress were assessed with a customized wellness questionnaire at the beginning of each training session. A two-step cluster analysis identified profiles of different training responses generally described as lower-demand sessions, intermediate-demand sessions, running-based sessions, and sprint-based sessions; which were discriminated by different total distance covered and high-intensity actions. Interestingly, no probabilistic interactions were found between these training responses with wellbeing and recovery markers (i.e., Bayes factor < 1 suggesting no evidence, for all the variables). These findings may raise concerns about using self-reporting tools, as they show that players’ wellness data is probably not accounted for when coaching staff plan and optimize the training process. However, results should be interpreted with caution, due to representing a single team and coaching staff.

This study aimed to quantify and assess the relationship of young soccer players' off-training physical activity (PA) and training responses on sleep quality. Eleven adolescent soccer players (13 ± 0.5 years old) were monitored during weekdays for four consecutive weeks, throughout soccer practice days. Off-training PA and sleep quality were assessed using 100 Hz tri-axial accelerometers and training responses analyzed using 20 Hz global positioning measurement units. A cluster analysis classified all cases into three different dimensions, (1) off-training PA, (2) training responses and (3) sleep quality. For each dimension, the most important variables for classifying the cases into clusters were sedentary PA and moderate-to-vigorous PA; total distance covered and impacts; and sleep onset latency and sleep fragmentation index, respectively. Afterwards, a correspondence analysis was used to identify whether off-training PA and training responses affected sleep quality. Results exposed that high to medium off-training PA combined with medium to high training responses may have decreased sleep quality. Conversely, no correspondence was observed between off-training PA and training responses, with higher sleep quality. This study emphasizes the importance of sports organizations adopting a holistic approach to youth soccer players’ development, that appropriately considers the inter-relationship between lifestyle, performance and health-related information.

Research in football has been embracing the complex systems paradigm in order to identify different insights about key determinants of performance. The present study explored the multifractal properties of several football-related scenarios, as a candidate method to describe movement dynamics. The sample consisted of five footballers that were engaged in six different training situations (jogging, high intensity interval protocol, running circuit, 5 vs. 5, 8 vs. 8 and a 10 vs. 10 small-sided game). All kinematic measures were collected using a 100 Hz wireless and wearable inertial measurement unit (WIMUPRO&copy, ). Data were processed using a discrete wavelet leader transform in order to obtain a spectrum of singularities that could best describe the movement dynamics. The Holder exponent for each of all six conditions revealed mean values h &lt, 0.5 indicating presence of long memory with anti-correlated behavior. A strong trend was found between the width of the multifractal spectrum and the type of task performed, with jogging showing the weakest multifractality ∆h = 0.215 &plusmn, 0.020, whereas, 10 vs. 10 small-sided game revealed the strongest ∆h = 0.992 &plusmn, 0.104. The Hausdorff dimension indicates that a maximal fluctuation rate occurs with a higher probability than that of the minimal fluctuation rate for all tasks, with the exception of the high intensity interval protocol. Moreover, the spectrum asymmetry values of jogging, running circuit, 5 vs. 5, 8 vs. 8 and 10 vs. 10 small-sided games reveal their multifractal structures are more sensitive to the local fluctuations with small magnitudes. The multifractal analysis has shown a potential to systematically elucidate the dynamics and variability structure over time for the training situations.

The study aimed to identify how the manipulation of knowledge regarding a training task duration constrains the pacing and tactical behaviour of soccer players when playing small-sided games (SSG). Twenty professional and experienced soccer players participated in a cross-sectional field study using three conditions: not informed on the duration of the SSG, which ended after 20 min (Unknown Condition), briefed about playing the SSG for 10 min, but after they completed the 10-min game, they were requested to complete another 10 min (Partial Condition) and informed before that they would play for 20 min (Known Condition). A global positioning system was used to measure the total distance covered and distances of different exercise training zones (walking to sprinting) and to access the dynamic players positioning through the distance from each player to all the teammates and opponents. Additionally, approximate entropy was measured to identify the regularity pattern of each gathered individual variable. The results indicate that the first 10 min of each scenario presented a higher physical impact independently of the initial information. During this time, the tactical behaviour also revealed higher variability. An increase in the distance of the teammates during the second period of 10-min for the Known scenario was also found, which may result from a lower pacing strategy. This study showed that the prior knowledge of the task duration led to different physical and tactical behaviours of the players. Furthermore, the relationship between the physical impact and the regularity of team game patterns should be well analysed by the coach, because the physical impact may be harmful to the development of the collective organization of the team.

The aim of this study was to identify relationships between the variation of match variables and football team’s match performance. Data from all 768 matches played at the group stage of UEFA Champions League from 2009-2010 to 2016-2017 seasons were analyzed. The correlations between the coefficient of variation of twenty match variables and the points of group stage were calculated. Autocorrelation function was used to identify the relationships between coefficients of variation of variables. Moreover, a generalized linear model was employed to identify the linear relationships between coefficients of variation and the probability of qualifying to the knockout stage. Inferences were made using the non-clinical magnitude-based inferences and evaluated by the smallest worthwhile change. Results showed that qualified teams showed more stable match performance on variables related to goal scoring, attacking and passing, while non-qualified teams displayed more stable match performance on variables related to defending. The coefficients of variation of variables related to goal scoring, attacking and passing had negative relationships with match performance, while variables related to defending displayed positive relationships. Findings of this study can provide useful information about the stability of match variables, contributing to the development of specific training interventions to enhance team’s performance in key indicators.

The aim of the present study was to identify and describe players’ performances in NBA games using individual and team-based game variables. The sample was composed by 535 balanced games (score differences below or equal to eight points) from the regular season (n=502) and the playoffs (n=33). A total of 472 players were analysed. The individual-based variables were: minutes on court, effective field-goal percentage, free-throws/field-goals ratio, offensive rebound percentage, turnover percentage and playing position. The team-based variables were: team points minus opponent’s points (on and off court), NET score (player’s on values minus his/her off values), maximum negative and positive point difference, team’s winning percentage, game pace, defensive and offensive ratings. A two-step cluster analysis was performed to identify the player’s profiles during regular season and playoff games. The results identified five performance profiles during regular season games and four performance profiles during playoff games. The profiles identified were mainly characterized by the game quarter and the negative NET indicator (players’ performance on court minus their performance off court) in regular season games and the positive NET indicator during playoff games and second and third game-quarters. Coaching staffs can fine-tune these profiles to develop more team-specific models and, conversely, use the results to monitor and rebuild team formation under the constrained dynamics of the game and competition stages.

This study aimed to identify the game-related statistics that discriminated between Euroleague basketball players and European basketball players playing in the NBA, when competing in the same event (EuroBasket 2015). There was a total of 78 matches played by 24 teams in two groups of analysis: NBA, participants in the European Championship who played in the NBA season of 2014-2015 (n = 26); Euroleague, participants in the European Championship who played in the Euroleague season of 2014-2015 (n = 82). The players’ performance variables were normalized to the time they spent on the court. To identify which variables best discriminated between the NBA and the Euroleague performance profiles, a descriptive discriminant analysis was conducted. Structure coefficients (SC) from the matrix greater than |0.30| were interpreted as meaningful contributors to discriminating between the groups. The results revealed a significant function (p = 0.008, canonical correlation of 0.51, Λ = 0.74, reclassification = 84.2%) and substantial performance differences in game-related statistics much related to the influence of body size (body height and mass), such as two-point field goals made (SC = 0.42) and missed (SC = 0.40), free-throws made (SC = 0.55), defensive rebounds (SC = 0.62), blocks (SC = 0.48) and suffered fouls (SC = 0.34). No differences were found at the level of game-related statistics indirectly related to perception, such as assists, turnovers or steals. Also, the greater body size in NBA players was likely related to higher variability in performance, thus, being an important topic for coaches and recruiters to analyse.

Objectives This study described the variability in acceleration during a resistance training task, performed in horizontal inertial flywheels without (NOBALL) or with the constraint of catching and throwing a rugby ball (BALL). Design and methods Twelve elite rugby players (mean ± SD: age 25.6 ± 3.0 years, height 1.82 ± 0.07 m, weight 94.0 ± 9.9 kg) performed a resistance training task in both conditions (NOBALL AND BALL). Players had five minutes of a standardized warm-up, followed by two series of six repetitions of both conditions: at the first three repetitions the intensity was progressively increased while the last three were performed at maximal voluntary effort. Thereafter, the participants performed two series of eight repetitions from each condition for two days and in a random order, with a minimum of 10 min between series. The structure of variability was analysed using non-linear measures of entropy. Results Mean changes (%; ±90% CL) of 4.64; ±3.1 g for mean acceleration and 39.48; ±36.63 a.u. for sample entropy indicated likely and very likely increase when in BALL condition. Multiscale entropy also showed higher unpredictability of acceleration under the BALL condition, especially at higher time scales. Conclusions The application of match specific constraints in resistance training for rugby players elicit different amount of variability of body acceleration across multiple physiological time scales. Understanding the non-linear process inherent to the manipulation of resistance training variables with constraints and its motor adaptations may help coaches and trainers to enhance the effectiveness of physical training and, ultimately, better understand and maximize sports performance.

This study aimed to compare youth football players' performance during two small-sided games with different pitch orientation: i) 40x30m and ii) 30x40m formats. Twenty under-15 players (age = 14.1 ± 0.5 years) participated in nine GK+4vs4+GK situations in each format, with the duration of six minutes each. Positional data were collected using individual GPS units, and computed for tactical and physical performance indicators. The SSG were video recorded, using notational analysis for collecting technical indicators. A novel method that incorporates time dependent notational information with spatiotemporal data was used to compute multidimensional parameters. Standardised effect sizes and non-clinical magnitude-based inferences were used to compare formats. Results showed that players covered more distance at higher intensities, presented more passes and dribbles and were more synchronised in the longitudinal axis while playing in the 40x30m pitch. In the 30x40m pitch, results showed a lower distance between team centroids, higher number of shots, more lateral passes and a wider team positioning. Multidimensional indicators, as players position and distance to the closest defender while shooting, revealed a more constant distance between attacker and defender in the 40x30m pitch. These results highlight the importance of integrating information from different indicators for a contextually valid information.

The purpose of this study was to describe the dynamics of a repeated sprint ability (RSA) cycling protocol in young elite basketball players. Twenty-two elite male basketball players (aged 18.3±0.6 years; training years 9.1±1.3 years) performed 3 bouts of a repeated sprint ability (RSA) protocols, consisting of 5 x 6-s cycling sprints with a 24-s rest interval between sprints. The work decrement during the first trial was high (14.1±4.8%) and after 5-minute rest did not change significantly. The total work decreased by 5.5% in the second work interval and by 2.9% in the third interval. During the 5-minute passive rest, young basketball players’ peak power recovered about 90% of the initial levels. It is suggested that rest intervals are sufficient to continue the game with adequate performance potential. A reduction in work decrement, while maintaining the capacity of all sprints, is needed to achieve a higher repeated sprint ability. Resumen El propósito de este estudio fue describir la dinámica de un protocolo de esprines repetidos en jóvenes jugadores de baloncesto. Veintidós jugadores de baloncesto masculino (con edades comprendidas entre 18,3 ± 0,6 años, años de entrenamiento de 9,1 ± 1,3 años) realizaron 3 series de un protocolo de esprín repetido, consistiendo en 5 esprines en cicloergometro de 6-s con de descanso de 24-s entre esprints. La disminución del trabajo durante la primera serie fue alta (14.1 ± 4.8%) y después de 5 minutos de descanso no cambió significativamente. El trabajo total disminuyó en un 5.5% en la segunda serie y en un 2.9% en la tercera. Durante el descanso pasivo de 5 minutos, la potencia máxima de los jóvenes jugadores de baloncesto recuperó aproximadamente hasta un 90% de los niveles iniciales. Se sugiere que los intervalos de descanso sean suficientes para continuar el juego con un potencial de rendimiento adecuado. Se necesita una reducción en el decremento del trabajo, mientras se mantiene la capacidad de todos los esprines, para optimizar esta capacidad de rendimiento tan importante en baloncesto.

Performance in team sports is the expression of complex, dynamic, interactive, and multidimensional processes. It is now well-established that optimum recovery after practice or match is a key factor of team sport performance. During season and tournaments, improving recovery could offer an advantage for following performance. As a consequence of the professionalization of different roles in staffs, new particular roles have been developed within the team sports physician core in order to improve recovery protocols. Presently, scientific literature presents a big amount of methods used to enhance recovery based on the type of practice, time between session or competitions and equipment and/or staff accessible. These practices, usually used by teams are related to: ergonutritional, water therapy, massages techniques, stretching compression garments, sleep strategies and psychological implements. Besides, travel fatigue has been recognized by athletes and coaches as a challenging problem that could benefit from practical solutions. Nowadays, players have to play a lot of matches without enough time to recover among them, therefore the use of well-managed recovery can lead to a competitive advantage. Although the main purpose of applied sport sciences investigation is to categorize the protocols as well as providing approaches for individual recovery, the stages to recognize the most appropriate recovery plans in the field of team sports come from the analysis of the individual parameters. Sin financiación No data JCR 2018 0.313 SJR (2018) Q3, 107/209 Physical Therapy, Sports Therapy and Rehabilitation, 171/289 Orthopedics and Sports Medicine No data IDR 2018 UEM

The aim of this study was: (i) to group basketball players into similar clusters based on a combination of anthropometric characteristics and playing experience; and (ii) explore the distribution of players (included starters and non-starters) from different levels of teams within the obtained clusters. The game-related statistics from 699 regular season balanced games were analyzed using a two-step cluster model and a discriminant analysis. The clustering process allowed identifying five different player profiles: Top height and weight (HW) with low experience, TopHW-LowE; Middle HW with middle experience, MiddleHW-MiddleE; Middle HW with top experience, MiddleHW-TopE; Low HW with low experience, LowHW-LowE; Low HW with middle experience, LowHW-MiddleE. Discriminant analysis showed that TopHW-LowE group was highlighted by two-point field goals made and missed, offensive and defensive rebounds, blocks, and personal fouls; whereas the LowHW-LowE group made fewest passes and touches. The players from weaker teams were mostly distributed in LowHW-LowE group, whereas players from stronger teams were mainly grouped in LowHW-MiddleE group; and players that participated in the finals were allocated in the MiddleHW-MiddleE group. These results provide alternative references for basketball staff concerning the process of evaluating performance.

Purpose: This study aimed to explore whether the outcome of professional football matches is affected by changes in intra-team movement synchronization. Methods: Positional data from 77 players wer...

This study aimed to assess the effects of the total quality of recovery and well-being indices (self-ratings of sleep during the preceding night, stress, fatigue and delayed onset muscle soreness) on rating of perceived exertion (RPE) and physical enjoyment (PE) during small-sided games. A total of 20 professional soccer players (25 ± 0.8 years) completed four 5-a-side game sessions of 25-min duration each (4 × 4 min work with 3-min passive recovery in-between). All variables were collected before each game session with the exception of RPE and Physical Activity Enjoyment Scale that were collected after. The results demonstrate that recovery state and pre-fatigue states were not contributing signals of affected internal intensity and enjoyment of players. The study established the objectivity and utility of RPE as a useful tool for determining internal intensity during soccer-specific training as well as PE for assessing emotional response during exercise or training session.

The aim of this study was to identify the effects of a differential-learning program, embedded in small-sided games, on the creative and tactical behavior of youth soccer players. Forty players from under-13 (U13) and under-15 (U15) were allocated into control and experimental groups and were tested using a randomized pretest to posttest design using small-sided games situations.The experimental group participated in a 5-month differential-learning program embodied in small-sided games situations, while the control group participated in a typical small-sided games training program. In-game creativity was assessed through notational analyses of the creative components, and the players' positional data were used to compute tactical-derived variables.The findings suggested that differential learning facilitated the development of creative components, mainly concerning attempts (U13, small; U15, small), versatility (U13, moderate; U15, small), and originality (U13, unclear; U15, small) of players' actions. Likewise, the differential-learning approach provided a decrease in fails during the game in both experimental groups (moderate). Moreover, differential learning seemed to favor regularity in pitch-positioning behavior for the distance between players' dyads (U13, small; U15, small), the distance to the team target (U13, moderate; U15, small), and the distance to the opponent target (U13, moderate; U15, small).The differential-learning program stressed creative and positional behavior in both age groups with a distinct magnitude of effects, with the U13 players demonstrating higher improvements over the U15 players. Overall, these findings confirmed that the technical variability promoted by differential learning nurtures regularity of positioning behavior.

espanolEl objetivo del presente estudio fue describir las respuestas fisiologicas y tecnico-tacticas en mujeres jovenes durante juegos reducidos (SSG) de baloncesto 3 contra 3 con y sin el estimulo verbal del entrenador y el bote. Seis jugadoras de baloncesto (edad: 14.3 ± 0.5 anos; altura: 167.8 ± 0.8 cm; peso: 56.5 ± 5.7 kg) tomaron parte del estudio piloto. Los juegos fueron grabados en video y despues las demandas tecnicas fueron registradas con software ad hoc de observacion. El pico de frecuencia cardiaca maxima se incremento de la serie 1 a la 3 durante el SSG con bote y estimulo del entrenador, asi como en el SSG sin bote y presencia del entrenador. Con el estimulo del entrenador se produjo mayores respuestas de frecuencia cardiaca y esfuerzo percivido que sin bote y estimulo del entrenador. No hubo diferencias en las acciones tecnicas, excepto en el numero de rebotes ofensivos que fue mayor en la tarea con estimulo del entrenador. En conclusion, el SSG con estimulo verbal deberia elegirse para centrarse en la carga fisiologica, mientras que el que se realiza sin el, puede ser util para mejorar el comportamiento colectivo, sin limitaciones en la carga fisiologica. EnglishThe aim of the present study was to describe the physiological and technical responses in young female during a basketball 3 vs. 3 small-sided games (SSG) with and without verbal coach encouragement and dribbling. Six young female basketball players (age: 14.3 ± 0.5 years; height: 167.8 ± 0.8 cm; body mass: 56.5 ± 5.7 kg) were recruited to participate in the present pilot study. The games were video recorded and afterwards the technical demands were notated with observational ad hoc software. The peak of maximum heart rate was increased from set 1 to set 3 during both the SSG with dribble and coach encouragement, as well as in the SSG without dribble and coach presence. With coach encouragement caused greater responses of heart rate and rate of perceived exertion than without both dribble and coach encouragement. There were no differences in technical actions, exception of the number of offensive rebounds showing a higher number in the coach encouragement task. In conclusion, the SSG with verbal encouragement should be selected to focus in physiological load, and SSG without might be useful to enhance collective behavior, without limitations in physiological load.

This study aimed to identify changes in tactical, physical and physiological performances in large-sided games during the preseason of elite footballers. Thirty professional football players participated in several GK+8vs.8+GK large-sided games across the first four weeks of the season. Players were monitored by GPS units and heart rate monitors to quantify physical, physiological and tactical performances. The variables were compared according to the preseason period, players' positioning and professional experience. The training situation promoted similar physiological responses during the first and the last training period. However, players were revealed to have higher levels of positional synchronization during the last preseason period, indicating an improved tactical performance. Tactical variables seem to reflect the improvement of players' performance during the preseason, measured in large-sided games situation, while affecting both physical and physiological demands. These results highlight the potential of positioning derived variables, concurrently to physical and physiological variables, for football training optimization.

The aim of this study was to compare heart rate (HR), rating of perceived exertion (RPE), and technical-tactical actions during small-sided games (SSGs) played without (CTR), with internal (IW), and with IW and external (IEW) wildcard players. A total of 22 young male soccer players (age 17.2 ± 0.9 years) randomly completed six 4vs4 SSG situations. The control conditions occurred with goals scored without goalkeeper (4vs4-NO) and with goalkeeper (4vs4-GK). During the experimental conditions, the situations incorporated 2 IW (4vs4+2IW-NO, 4vs4+2IW-GK) and 2 IEW (4vs4+2IW+2IEW-NO, 4vs4+2IW+2IEW-GK). Processed results did not include data from goalkeepers, IW, and IEW players. The HR was divided in intensity-zones (Z1, Z2, and Z3, for80%, 80-90%, and90% of maximal HR, respectively) and the analyzed technical-tactical actions were the pass, dribbling, collective success, and pause. The effects of IW and IEW were analyzed through repeated measures analysis of variance. During 4vs4+2IW+2IEW-NO, greater time was recorded in Z1 (p ≤ 0.05) compared with 4vs4-NO and 4s4+2IW-NO. During 4vs4+2IW+2IEW-GK, greater time was recorded in Z1 and less in Z3 (p ≤ 0.05) compared with 4vs4-GK. Greater RPE was reported in 4vs4-NO (p0.01) and 4vs4+2IW-NO (p0.01) compared with 4vs4+2IW+2IEW-NO, and during 4vs4-GK (p0.01) than 4vs4+2IW+2IEW-GK. Greater number of dribbling situations were recorded during 4vs4-NO (p ≤ 0.05) compared with 4vs4+2IW+2IEW-NO. In conclusion, compared with the control condition of 4vs4, the incorporation of IEW reduced HR, RPE, and dribbling actions.

The aim of this study was to explore the differences in technical, tactical and movement performance of professional male tennis players in Grand Slams, according to player's experience and relative quality. Match data of 1188 players competing in 2015–2017 Grand Slam tournaments were collected. Experience and relative quality (RQ) were used to classify players via cluster analysis, based on Cubic Clustering Criterion. Afterwards, a descriptive discriminant analysis was performed to identify the most important variables that best predict player clusters in each Grand Slam, and two discriminant functions were generated (p < 0.01). High-experienced Higher RQ Players (n = 337) outperformed other players in serve and return (fewer double faults, more second serve and return points won), rally winners and breaking opportunities while covering longer distance. Experienced Higher RQ Players (n = 267) hit faster serves and more aces, played more aggressively when returning (more return winners and unforce...

Objectives: This study aimed to identify whether the structure underlying the on-field interpersonal positioning tendencies of soccer players might discriminate the length of ball possession sequences.Methods: Data were gathered using GPS during 5-a-side games performed by under-19 elite soccer players.Results: The results revealed significant differences between clusters in almost all the variables, assuring that the regularity of the distance to centroid accurately discriminated the short from the long sequences of play. Also, the analyses revealed moderate significant interaction between Type of Relation (intra-team vs. inter-team) Sequences of Play (short vs. long) independently of the variable taken as criterion to divide the clusters.Conclusions: Regularity of intra- and inter-team interpersonal coordination is able to discriminate short and long sequences of play during SSG. Generally, short sequences of play displayed higher irregularity than the longer sequences. In the long sequence, int...

The aim of this study was to (i) identify technical and physical performances of basketballers according to playing position in strong and weak teams, and (ii) describe variability in game-togame performance according to game outcome, location, quality of teams and opposition. Performance-related variables of all the 699 matches of regular season 2015–2016 in the National Basketball Association were analysed. All the comparisons were performed using magnitude-based inferences. As could be expected, results showed that technical and physical performances differed between players of strong and weak teams. In technical aspect, forwards and centres from strong teams made more three-point field goals, but fewer two-point field goals, than their counterparts from weak teams. Interestingly, forwards and guards from strong teams covered shorter distances and lower speeds than their peers from weak teams. In addition, the threepoint field goals made and attempted presented high variability. Game location generally had no significant impact on the variability of players’ performance. Guards exhibited relatively lower variability in technical and physical variables in comparison with players from other positions. Exploring the difference and variability of technical and physical performances of basketballers allows fine-tuning of practice and game plans in order to build up optimal winning strategies.

The purpose of this study was two-step: (1) classify ball possession (BP) according to the duration and number of passes and (2) identify which tactical variables most discriminate the different BP. We obtained 527 BPs from four official matches of the Brazilian Soccer Championship 2016. Forty-one "notational", "space occupation", and "displacement synchronization" predictor variables were used. The BPs were classified into three groups: short (11.07 ± 4.49 s, 1.93 ± 0.99 passes), medium (26.83 ± 7.33 s, 5.41 ± 1.84 passes), long (55.50 ± 14.97 s, 12.11 ± 4.61 passes). Discriminant analysis identified the five most relevant variables to describe each group: coefficient of variation (CV) of the defensive team's synchronization-Y, CV defensive team´s synchronization-X, successful pass last third, CV distance between offensive team's centroid and target, mean of the offensive team's width. The approach highlights important variables and could benefit the description of offensive and defensive game sequences to provide precise knowledge on the process.

Baptista, J, Travassos, B, Gonçalves, B, Mourão, P, Viana, JL, and Sampaio, J. Exploring the effects of playing formations on tactical behavior and external workload during football small-sided games. J Strength Cond Res 34(7): 2024-2030, 2020-This study aimed to identify the effects of playing formations on tactical behavior and external workload during football small-sided games. Twenty-three semiprofessional footballers integrated 3 different playing formations in a 7-a-side small-sided game, according to their specific player positions: team 4:3:0 (4 defenders and 3 midfielders); team 4:1:2 (4 defenders, 1 midfielder, and 2 forwards); and team 0:4:3 (4 midfielders and 3 forwards). Based on players' movement trajectories, the following individual and collective tactical variables were calculated: total distance covered and distance covered while walking, jogging, running, and sprinting, distance from each player to both own-team centroid and opponent-team centroid, individual area, team length, team width, and surface area. Approximate entropy was computed to identify the regularity of each variable. The team 4:3:0 promoted players' space exploration with moderate physical efforts. The team 4:1:2 promoted compactness and regularity of the team with increase in the physical efforts. The team 0:4:3 promoted team balance and adaptability on space coverage with increase in physical efforts. Concluding, different playing formations support different game dynamics, and variations on external load were directly linked with the variations on tactical behavior. The analysis of tactical behavior through quantification of variability of patterns of play and quantification of distance covered at different velocities were the most useful information for the analysis of the effects of practice task manipulations. Therefore, in a practical sense, strength and conditioning coaches should plan and monitor these tasks in interaction with the head coaches. info:eu-repo/semantics/publishedVersion

Performance analysis research in association football has recently cusped a paradigmatic shift in the way tactical behaviours are studied. Based on insights from system complexity research, a growing number of studies now analyse tactical behaviours in football based on the collective movements of team players. The aim of this systematic review is to provide a summary of empirical research on collective tactical behaviours in football, with a particular focus on organising the methods used and their key findings. A systematic search of relevant English-language articles was performed on one database (Web of Science Core Collection) and one search engine (PubMed), based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. The keywords ‘football’ and ‘soccer’ were each paired with all possible combinations of the following keywords: ‘collective movement behaviour’, ‘collective behaviour’, ‘tactical behaviour’, ‘interpersonal coordination’, ‘space’, ‘Voronoi’, ‘synchronisation’, ‘tactical analysis’, ‘constraints’, ‘ecological dynamics’, and ‘dynamic positioning’. Empirical studies that were related to tactical analyses of footballers’ positional data were sought for inclusion and analysis. Full-text articles of 77 studies were reviewed. A total of 27 tactical variables were identified, which were subsequently organised into 6 categories. In addition to conventional methods of linear analysis, 11 methods of nonlinear analysis were also used, which can be organised into measures of predictability (4 methods) and synchronisation (7 methods). The key findings of the reviewed studies were organised into two themes: levels of analysis, and levels of expertise. Some trends in key findings revealed the following collective behaviours as possible indicators of better tactical expertise: higher movement regularity; wider dispersion in youth players and shorter readjustment delay between teammates and opponents. Characteristic behaviours were also observed as an effect of playing position, numerical inequality, and task constraints. Future research should focus on contextualising positional data, incorporating the needs of coaching staff, to better bridge the research-practice gap.

Purpose: This study aimed to compare players' performances when manipulating the external markings of the pitch during football small-sided games. Methods: Ten under-15 players performed a 5-a-side (plus goalkeepers) under three conditions: (i) Lines, the game was played in a pitch in which the external boundaries were painted with full lines; (ii) Dashed, the game was played in a pitch in which the external boundaries were painted with dashed lines; (iii) Corners, the game was played in a pitch were the external boundaries were delimited by one marker at each pitch corner. Players' positional data was used to compute tactical and time-motion variables. Also, technical analysis was comprised using video footage. Results: Results showed similar tactical, physical and technical performances between the Lines and Dashed conditions. In contrast, the Lines condition showed small higher effects than Corners scenario in the time spent synchronized in longitudinal and lateral displacements, game pace, total distance covered, distance covered while jogging, number successful dribbles and shots on target. The Lines scenario has also revealed a lower effective playing space, distance covered at walking and running and a lower number of passes (small effects) compared to Corners. Conclusions: These results highlight that these changes in informational perception constraints modify players movement behavior. Accordingly, pitches with more visible boundaries were likely to decrease team dispersion, which may optimize team synchrony and technical performances, while decreasing the distance covered at higher speeds. Coaches may use this information to modify the types of pitch external boundaries markings, exposing the players to different environmental information.

PurposeThe aim of this study was to describe the physical demands during U18 elite basketball games according to the game quarter and to identify a smaller subset of variables and threshold scores that distinguish players' physical performance in each quarter.MethodsData was collected from ninety-four players who participated in the study (age: 17.4 ± 0.74 years; height: 199.0 ± 0.1 cm; body mass: 87.1 ± 13.1 kg) competing in the Euroleague Basketball Next Generation Tournament. Players' movements during the games were measured using a portable local positioning system (LPS) (WIMU PRO®, Realtrack Systems SL, Almería, Spain) and included relative distance (total distance / playing duration), relative distance in established speed zones, high-intensity running (18.1-24.0 km·h-1) and sprinting (> 24.1 km·h-1). player load, peak speed (km·h-1) and peak acceleration (m·s-2) number of total accelerations and total decelerations, high intensity accelerations (> 2 m·s-2) and decelerations (< -2 m·s-2).ResultsThere was an overall decrease in distance covered, player load, number of high intensity accelerations and decelerations between the first and last quarter of the games in all playing positions. A classification tree analysis showed that the first quarter had much influence of distance covered (above 69.0 meters), distance covered 2 m·s-2), whereas the fourth quarter performance had much influence of distance covered (below 69.0) and distance covered 12.1-18.0 km·h-1.ConclusionsA significant reduction in physical demands occurs during basketball, especially between first and last quarter for players in all playing positions during basketball games of under 18 elite players.

Purpose: To describe and identify individual trends and changes in training load, neuromuscular readiness, and perceptual fatigue measures in 2 youth elite long jumpers, finalists at the European Athletics U18 (Under 18) Championships (athlete A, female, age 16.5 y, long-jump record 6.25 m; athlete B, male, age 16.0 y, long-jump record 7.28 m). Methods: Data were collected from both training sessions and athletics competitions during a 16-week period, divided into a preparation (weeks 1–8) and a competitive phase (weeks 9–16). Training load was computed through training diaries (training time, sprint, jumping, and weights volume). The countermovement jump and the 10-to-5 repeated-jump test were executed on a weekly basis to assess neuromuscular readiness, and perceptual fatigue measures were collected through a wellness questionnaire. Statistical analysis was conducted using a magnitude-based decisions approach. Results: The results highlighted a decrease in training load during the competitive period with moderate to large differences for training time, sprint, and jump volume. Moreover, data showed an upward trend and very likely higher scores in vertical-jump performance across the competitive phase together with a very likely lower perceptual fatigue. Conclusions: This scenario seemed to be favorable to achieve competition performance very close to the personal record during the competitive season. This study provided an example of application of a comprehensive monitoring system with young athletes involved in track-and-field jumping events.

The aims of this study were (a) to compare players' physical demands between different playing positions in elite U18 basketball games and (b) to identify different clusters of performance. Data were collected from 94 male subjects (age: 17.4 ± 0.7 years), competing in a Euroleague Basketball Tournament. Guards covered a greater relative distance than centres and forwards (small to moderate effect). Forwards and guards had more peak accelerations, high accelerations and high decelerations than centres (moderate to large effects). A cluster analysis allowed to classify all cases into three different groups (Lower, Medium and Higher activity demands), containing 37.4%, 52.8% and 9.8% of the cases, respectively. The high accelerations, high decelerations, peak accelerations and total distance covered were the variables that most contributed to classify the players into the new groups. The percentage of cases distributed in the clusters according to playing position, game type (worst vs worst, mixed opposition, best vs best) and team were different. Centres have lower physical demands specially related with the number of accelerations and decelerations at high intensity and the peak acceleration when compared with guards. Each team has a different activity profile, that does not seem to influence the tournament outcome.

This study aimed to identify how playing basketball with two additional baskets influences the players' technical, physiological, physical and especially, positional performance. Fourteen youth players performed eight 5vs.5 simulated basketball games, four with the two official baskets and four with two-extra official baskets, each one placed in the court restricted area. The variables collected were technical (field-goals made and missed, offensive and defensive rebounds, steals, passes, dribble-drive, give-and-go and ball possessions), physiological (heart rate monotony and sample entropy), workload (total distance covered and distance covered at different velocities) and positioning-related (distance to the nearest opponent, distance to the nearest teammate, stretch-index and distance between centroids). The results showed that the four-baskets games favoured the emergence of individual behaviours, increasing the game' physical demands and promoting a collective dispersion, which might impair team playing. Conversely, when playing with two-baskets, there was less distance between teammates. In conclusion, this study has clear implications for practice as it emphasizes that coaches can manipulate the number of baskets to modulate training workload and promote different individual and team behaviours.

The study was aimed to explore distinct players' groups according to their anthropometric and individual features, and to identify the key performance indicators that discriminate player groups. Match statistics, anthropometric and personal features of 1188 male players competing during 2015-2017 main draw Grand Slam singles events were collected. Height, weight, experience, handedness and backhand style were used to automatically classify players into different clusters through unsupervised learning model. Afterwards, 29 match variables were analysed through MANOVA and discriminant analysis in order to evaluate the different match performance among player groups and to identify the key performance indicators that best differentiate player clusters in each Grand Slam. The analysis revealed the existence of four clusters, they were classified as Big-sized Right Two-handed Players (

OBJECTIVES: The XXI Century Academy was a 6- year state-initiated intervention program that served as an alternative to basketball clubs for players in the u-14 and u-18 age groups in Spain, under guidelines established by the Spanish Basketball Federation. It was an important and unique project on talent development in basketball. To the best of the authors' knowledge, no evidence has been reported on long-term athlete development programs in basketball worldwide. The main aim of this report is to describe the design and evaluation methods used for the XXI Century Academy as a long-term intervention program in the elite Spanish Basketball Academy, aiming to prepare basketball players to compete at the elite level. METHODS: The monitoring time lasted from 1996 to 2001. A total of 55 players were assigned to the intervention groups based on age, position, maturation level, and country of origin. During this process, participants competed in up to two categories in addition to playing competitive official matches worldwide in international tournaments in their categories and with the national team in the European and World Championships (u-14 - u-18). Participants included 1 NBA player, 3 national A Team players, 10 ACB (First Spanish League) players, 5 LEB (second League) players and 39 LEB-2 EBA (third League) players. Assessments took place in a High-Performance Sports Center (CPT FADURA-GETXO- Basque Government, Getxo, Vizcaya, Spain) and consisted of health questionnaires, anthropometric measures, blood parameters, maturation level, birth age, fitness tests, training volume and intensity, physical activity, technical and tactical training, dietary intake, supplementation and injuries. Each player was assessed 4 times per year (September, December, April, June) for 4 years (16 data points). RESULTS: This is a purely methodological paper describing the design and evaluation methods used in the XXI Century Project, which will be used as a basis for future reporting of results. Therefore, the results of the project will be reported in subsequent publications. CONCLUSION: The viability of the Century XXI Project protocols has been described. This national project of training in basketball closely replicates the physical and technical match-play conditions for professionals and may constitute a useful training tool.

The aim of the current study was (i) to identify how important was a good season start in relation to elite handball teams’ performance, and (ii) to examine if this impact was related to the clubs’ financial budget. The match performances and annual budgets of all teams were collected from the Spanish Professional Handball League during ten seasons. The dependent variable was the difference between the ranking of each team in accordance to the annual budget and the ranking of each team at the end of the season. A k-means cluster analysis classified the clubs according to their budget as High Range Budget Clubs (HRBC), Upper-Mid Range Budget Clubs (UMRBC), Lower-Mid Range Budget Clubs (LMRBC) and Low Range Budget Clubs (LRBC). Data were examined through linear regression models. Overall, the results suggested that the better the team performance at the beginning of the season, the better the ranking at the end of the season. Each position in the ranking above expected in accordance to the budget of the teams in Rounds 3, 4 or 5 improved by 0.47, 0.50 or 0.49, respectively, in the ranking at the end of the season (p

Optimizing collective behaviour helps to increase performance in mutual tasks. In team sports settings, the small-sided games (SSG) have been used as key context tools to stress out the players' awareness about their in-game required behaviours. Research has mostly described these behaviours when confronting teams have the same number of players, disregarding the frequent situations of low and high inequality. This study compared the players' positioning dynamics when manipulating the number of opponents and teammates during professional and amateur football SSG. The participants played 4v3, 4v5 and 4v7 games, where one team was confronted with low-superiority, low- and high-inferiority situations, and their opponents with low-, medium- and high-cooperation situations. Positional data were used to calculate effective playing space and distances from each player to team centroid, opponent team centroid and nearest opponent. Outcomes suggested that increasing the number of opponents in professional teams resulted in moderate/large decrease in approximate entropy (ApEn) values to both distance to team and opponent team centroid (i.e., the variables present higher regularity/predictability pattern). In low-cooperation game scenarios, the ApEn in amateurs' tactical variables presented a moderate/large increase. The professional teams presented an increase in the distance to nearest opponent with the increase of the cooperation level. Increasing the number of opponents was effective to overemphasise the need to use local information in the positioning decision-making process from professionals. Conversely, amateur still rely on external informational feedback. Increasing the cooperation promoted more regularity in spatial organisation in amateurs and emphasise their players' local perceptions.

Summary Aim The aim of this study was to compare the effects of a 4-week combined sloped training program with a standard flat training program performed by basketball players. Methods A total of 31 male elite youth basketball players were randomly allocated into an experimental (SLOPE, n = 15, age 13.4 ± 0.4 y, height 168.8 ± 14.2 cm, weight 52.6 ± 12.7 kg) and control training group (FLAT, n = 16, age 12.9 ± 0.3 y, height 169.5 ± 9.3 cm, weight 56.2 ± 11.3 kg). A pre- to post-test design was used to explore the effects in performance variables. Results The comparison between groups showed moderate higher values in FLAT training group for standing height jump (differences in groups means: % [90% confidence intervals], −10.2% [−14.9% to −5.3%]) and reaction time (5.8% [1.3% to 10.5%]). On the other hand, SLOPE training promoted a small improve in anaerobic-alactic power (W/kg) (3.4% [−1.2% to 8.1%]). The FLAT group presented small improvements in peak power (W), (−9.2% [−15.0% to −3.0%]) and moderate in relative peak power (W/kg) (−9.8% [−15.3% to −4.0%]). Power results suggested a more efficient movement pattern, probably due to a better propulsive phase supported by an improved ability to produce equivalent levels of force in a shorter period of time. Despite the identified benefits of combined uphill/downhill/flat training method, results suggest that young non-familiarize players need a progressive reduction of training load to optimize performance. These results represent important evidence into the planning guidelines of strength and conditioning coaches to support daily planning by choosing the most appropriate tasks to enhance players’ performance.

The use of unstable surfaces during resistance training has demonstrated a maintenance or reduction on force production. However, the use of unstable surface on force variability has not been assessed using non-linear methods that may be better suited to detect changes in movement variability throughout a given movement. Consequently, this study compared the use of stable vs unstable surfaces on force variability during bilateral squats performed with an inertial flywheel device (Eccoteck, Byomedic System SCP, Spain). Twenty healthy men (mean ± SD: age 22.9 ± 2.9 years, height 1.81 ± 0.7 m, body mass 76.4 ± 7.6 kg and 1RM back squat 110.9 ± 19.7 kg) with a minimum of four years in resistance training performed six sets of six repetitions of squats at maximal concentric effort with one minute rest between sets. Force output on the vertical axes was measured using a strain gauge and the results were processed using nonlinear sample entropy (SampEn). Results showed no differences for any of the dependent variables between stable and unstable conditions. SampEn showed no differences between conditions (chi-squared = 0.048 P = 0.827), while Forcemean and SampEn presented a small correlation (r = 0.184; p < 0.01). No changes in entropy were found over the course of the series. Together, these results suggest that the structure of force variability between stable and unstable surfaces are similar. This lack of difference between surfaces may be due to postural and anticipatory adjustments. Consequently, by introducing unstable surfaces to the flywheel bilateral squat exercise, practitioners may not observe changes in Forcemean and force variability when compared to stable surface training suggesting that increased training volumes or intensity may be required during unstable environments to cause a desired training stimulus.

If done properly, physical exercise can help maintain fitness and health. The benefits of physical exercise could be increased with real time monitoring by measuring physical exercise intensity, which refers to how hard it is for a person to perform a specific task. This parameter can be estimated using various sensors, including contactless technology. Physical exercise intensity is usually synchronous to heart rate; therefore, if we measure heart rate, we can define a particular level of physical exercise. In this paper, we proposed a Convolutional Neural Network (CNN) to classify physical exercise intensity based on the analysis of facial images extracted from a video collected during sub-maximal exercises in a stationary bicycle, according to standard protocol. The time slots of the video used to extract the frames were determined by heart rate. We tested different CNN models using as input parameters the individual color components and grayscale images. The experiments were carried out separately with various numbers of classes. The ground truth level for each class was defined by the heart rate. The dataset was prepared to classify the physical exercise intensity into two, three, and four classes. For each color model a CNN was trained and tested. The model performance was presented using confusion matrix as metrics for each case. The most significant color channel in terms of accuracy was Green. The average model accuracy was 100%, 99% and 96%, for two, three and four classes classification, respectively.

In soccer, understanding of collective tactical behaviour has become an integral part in sports analysis at elite levels. Evolution of technology allows collection of in-creasingly larger and more specific data sets related to sport activities in cost-effective and accessible manner. All this information is minutely scrutinized by thousands of analysts around the globe in search of an-swers that can in the long term help increase the performance of indi-viduals or teams in their respective competitions. As the volume of data increases in size, so does the complexity of the problem and the need for suitable tools that leverage the cognitive load involved in the inves-tigation. It is proven that visualization and computer-vision techniques, correctly applied to the context of a problem, help data analysts focus on the relevant information at each stage of the process, and generally lead to a better understanding of the facts that lie behind the data. In the current study, we presented a software prototype capable of assisting researchers and performance analysts in their duty of studying group collective behavior in soccer games and trainings. We used geospatial data acquired from a professional match to demonstrate its capabilities in two different case studies. Furthermore, we successfully proved the efficiency of the different visualization techniques implemented in the prototype and demonstrated how visual analysis can effectively improve some of the basic tasks employed by sports experts on their daily work, complementing more traditional approaches.

The present study aims to identify the accuracy of the NBN23&reg, system, an indoor tracking system based on radio-frequency and standard Bluetooth Low Energy channels. Twelve capture tags were attached to a custom cart with fixed distances of 0.5, 1.0, 1.5, and 1.8 m. The cart was pushed along a predetermined course following the lines of a standard dimensions Basketball court. The course was performed at low speed (&lt, 10.0 km/h), medium speed (&gt, 10.0 km/h and &lt, 20.0 km/h) and high speed (&gt, 20.0 km/h). Root mean square error (RMSE) and percentage of variance accounted for (%VAF) were used as accuracy measures. The obtained data showed acceptable accuracy results for both RMSE and %VAF, despite the expected degree of error in position measurement at higher speeds. The RMSE for all the distances and velocities presented an average absolute error of 0.30 &plusmn, 0.13 cm with 90.61 &plusmn, 8.34 of %VAF, in line with most available systems, and considered acceptable for indoor sports. The processing of data with filter correction seemed to reduce the noise and promote a lower relative error, increasing the %VAF for each measured distance. Research using positional-derived variables in Basketball is still very scarce, thus, this independent test of the NBN23&reg, tracking system provides accuracy details and opens up opportunities to develop new performance indicators that help to optimize training adaptations and performance.

The study aimed to compare footballers' performances when playing with teammates and opponents from the same age group with performances when playing with teammates and opponents of different age groups. Three football matches were played: i) under-15 (U15) players played with each other; ii) under-17 (U17) players played with each other; and iii) players under the age of 15 and 17 played with each other in two equivalent mixed age teams. The players' physical performance was measured using the distances covered at different speed categories and tactical behaviour was assessed using several positioning-derived variables. The results showed that, when playing in the mixed age condition, the U15 players increased the distance covered in sprinting intensity (18.1%; +/- 21.1%) and the U17 players increased the distance covered in jogging zones (6.8%; +/- 6.5%). The intra-team movement synchronization in longitudinal and lateral displacements was higher when U15 players confronted peers of the same age, in the first half (-13.4%; +/- 2.0%, -20.3%; +/- 5.7% respectively), and when U17 players confronting the mixed group, in both halves (-16.9%; +/- 2.5%, 9.8%; +/- 4.0% and 7.9%; +/- 5.7%, 10.6% +/- 4.4%, respectively). The differences between age groups and the mixed condition may be connected with the level of players' tactical expertise and adaptive positioning according to the dynamic environmental information. In general, these results suggest that mixing the age groups may be useful to promote a wider range of training session stimuli in these young football players.

Facial expression analysis has a wide area of applications including health, psychology, sports etc. In this study, we explored different methods of automatic classification of exercise intensities using facial image processing of a subject performing exercise on a cycloergometer during an incremental standardized protocol. The method can be implemented in real time using facial video analysis. The experiments were done with images extracted from a 12 min HD video collected in laboratorial normalized settings (TechSport from the University of Tras-os-Montes e Alto Douro) with a static camera (90° angle with face and camera). The time slot for video to extract images for a particular class of exercise intensity is correspondence to the incremental heart rate. The facial expression recognition has been performed mainly in two steps: facial landmark detection and classification using the facial landmarks. Luxand application was used to detect 70 landmarks were detect using the adaptation of code available in Luxand application and we applied machine learning classification algorithms including discriminant analysis, KNN and SVM to classify the exercise intensities from the facial images. KNN algorithms presents up to 100% accuracy in classification into 2 and 3 classes. The distances between a lowermost landmark of the faces, which is indicated in landmark number 11 in the Luxand application, and the 26 landmarks around mouth were calculated and considered as features vector to train and test the classifier. Separate experiments were done for classification into two, three, and four classes and the accuracy of each algorithm was analyzed. From the overall results, classification into two and three classes was easy and resulted in very good classification performance whereas the classification with four classes had poor classification performance in each algorithm. Preliminary results suggest that distinguishing more levels of exertion, might require additional feature variables.

This study identified temporal effects (immediate, short-term, and medium-term effect) of team timeouts on elite handball scoring performance in reference to several situational variables that may influence performance: match status, game location, quality of the opposition, game period, and game type. The sample consisted of 646 team timeouts from 142 close games (score differences less than or equal to five goals) of the 2011/2012 men’s Spanish Professional Handball League (ASOBAL League). For each team timeout, the goals scored and conceded within the previous and post timeout 1st, 3rd and 5th ball possessions were recorded for the teams that called a timeout and for their opponents. Multiple linear regression models were used for analysis. The results showed positive effects on goals scored for the teams that called a timeout, with increases of 0.59, 1.40 and 1.85 goals for the periods within the previous and post team timeout 1st, 3rd and 5th ball possessions. Conversely, significant negative effects on goals scored were found for the opposing teams, with decreases of 0.59, 1.43 and 2.04 goals for the same periods, respectively. Unexpectedly, the influence of situational variables on scoring performance of the teams was only registered for certain game periods. These findings could be useful for a better team timeout management during games and competitions.

The aims of this study were to compare the training load intended by a coach with the training load perceived by the players, over a 45-week professional futsal team season and to compare the variation of session rating of perceived exertion (sRPE) across different periods of the season. Eighteen Brazilian professional futsal players participated in the study. The players' rating of perceived exertion (RPE) and coach's rating of intended exertion (RIE) were collected daily throughout the study. To compare the sRPE variation, the season was divided into 4 periods as follows: preseason (PRE-SEASON), first competitive period (COMP1), intercompetition period (INTER-COMP), and second competitive period (COMP2). Based on the cluster analyses, the training sessions were classified into 3 different intensity zones (low, moderate, and high). In all the season periods and intensity zones, the players' RPEs were lower than the coach's RIE. In the low-intensity zone, the INTER-COMP demonstrated higher sRPE values than did the other periods. In the moderate-intensity zones, the INTER-COMP and COMP2 were similar. Finally, for the high-zone intensity, the PRE-SEASON demonstrated higher values than did the other periods. We concluded that the coach overestimated the training load reported by the players in almost all intensity training zones and season periods. The RPE scale does not seem to be a suitable tool when used by the coach for intended training load. Therefore, technical staff should constantly review the training goals in each season period through daily training load control, always taking into consideration the possibilities and limitations of the RPE method.