The aim of this study was to analyze the concurrent validity, test–retest reliability, and capacity to detect changes of four different portable devices used to measure a wide range of neuromuscular parameters derived from countermovement jump (CMJ). An accelerometric device (Myotest), a jump mat (Ergojump), an optical device (Optojump), and a smartphone app (MyJump) were simultaneously examined for concurrent validity against gold-standard measures (motion-capture system and a force platform). Twenty-two CMJ-derived variables were collected from 15 healthy male subjects (n = 60 CMJs). Contraction time (CT) and eccentric duration (EccD) measurements obtained from the Myotest were moderately to largely associated with and not different from force platform measurements (r = 0.31 to 0.64, ES = 0.11 to 0.18) and showed moderate test-retest reliability (intraclass correlation coefficient (ICC) = 0.92 to 0.97, coefficient of variation (CV) = 3.8 to 8.0%). Flight time (FT) and jump height (JH) from Ergojump, Optojump, and MyJump showed moderate to strong associations with gold-standard measurements (r = 0.57 to 0.98) and good test–retest reliability (ICC = 0.54 to 0.97, CV = 1.8 to 4.2). However, all portable devices underestimated JH (ES = 1.25 to 2.75). Independent of the instrument used, the analyzed CMJ variables showed good capacity to detect changes (standard error of measurement (SEM) < smallest worthwhile change (SWC)), with the exception of rate of force and rate of power development parameters, which showed marginal capacity (SEM > SWC). The Myotest is preferable to measure temporal parameters during ground contact, whereas Ergojump, Optojump, and MyJump devices may be preferable to measure FT and JH, with the Optojump being the most accurate.

Research in soccer has traditionally given more weight to players’ technical and tactical skills, but few studies have analyzed the motor skills that underpin specific motor actions. The objective of this study was to investigate the style of play of the world’s top soccer players, Cristiano Ronaldo and Lionel Messi, and how they use their motor skills in attacking actions that result in a goal. We used and improved the easy-to-use observation instrument (OSMOS-soccer player) with 9 criteria, each one expanded to build 50 categories. Associations between these categories were investigated by T-pattern detection and polar coordinate analysis. T-pattern analysis detects temporal structures of complex behavioral sequences composed of simpler or directly distinguishable events within specified observation periods (time point series). Polar coordinate analysis involves the application of a complex procedure to provide a vector map of interrelated behaviors obtained from prospective and retrospective sequential analysis. The T-patterns showed that for both players the combined criteria were mainly between the different aspects of motor skills, namely the use of lower limbs, contact with the ball using the outside of the foot, locomotion, body orientation with respect to the opponent goal line, and the criteria of technical actions and the right midfield. Polar coordinate analysis detected significant associations between the same criteria included in the T-patterns as well as the criteria of turning the body, numerical equality with no pressure, and relative numerical superiority.

The research about soccer defensive phase shows many limitations regarding the procedures and operational definitions. The aims of this paper are to create an observational instrument based on Dynamic Systems concepts and evidence sufficient content validity to adequately and reliably recode defensive soccer behaviours. For these, a five-stage development process for validity was followed: (1) an initial literature review, instrument development, observation training; (2) adapting an existing systematic observational instrument; (3) pilot study with non-experts; (4) content validity with experts (coaches and researchers) and (5) inter- and intra-observer reliability. Using Aiken’s V coefficient and its cut-off value to determine validity content, consensus was found (V > 0.67, n = 32, p < 0.05) for all items answered by participants in pilot study and for almost all subjects in the experts’ study (V > 0.69, n = 12, p < 0.05). Also, Cohen’s Kappa shows inter- and intra-reliability values of 0.87 and 0.90, respectively. The final model, entitled Theoretical Dynamic Model of Soccer Defence, and the observational instrument, named Soccer-Defence, with 14 criteria and category systems, and 106 categories, seems to be suitable for analysing the defensive process in soccer and could be used to find strengths or weaknesses of tactical–technical defensive patterns of play and to help coaches to better prepare their teams.

Researchers in soccer match analysis have been using limited procedures to express the dynamics of the game and mainly focus on the attack. Therefore, the aims of this paper were to detect the successful teams’ ball recovery defensive patterns of play and study the influence of tactical modelling, halves, match status, opponent quality and stage competition on those patterns. The sample consisted of 1323 situations of defensive ball possession of the semi-finalist teams from the 2014 FIFA World Cup play-offs, which was collected by a valid and reliable observational instrument (Soccer-Defence). The Kruskal-Wallis H, Mann-Whitney U, Chi-square, Z-, multinomial logistic regression tests and sequential analysis (p < .05; z > 1.96) were used accordingly to test the differences and associations among and within teams of tactical modelling, tactical-technical behaviours and contextual variables to ball recovery. We found that among teams ball recovery differed in duration; H(3) = 14.958, p = .002. Germany were more likely to perform ball recovery by the goalkeeper than Argentina (p = .04; OR = 0.47) or the Netherlands (p < .05; OR = 0.50). Nevertheless, Brazil was the least likely to concede a shot off goal. Teams facing lower-ranked opponents were 0.63 times less likely to perform ball recovery by interception (p <.001). Additionally, sequential analysis illustrated that teams varied between central and lateral high-pressure zones before ball recovery in lower zones of the field. Finally, coaches could use such findings to design training exercises, create their own style of play, and set strategies.

This study protocol describes a systematic method to identify, collect and rank sports science and medicine interventions most associated with optimising team performance in elite football in observational studies. While numerous interventions, such as conditioning or injury prevention programmes, protective equipment, training periodisation, tactical decision-making, supplements, medication and hydration administration, have been associated with football players and team performance enhancement, there is a need to prioritise them to save resources and increase the efficiency of applications. Nevertheless, previous literature has shown that systematic reviews in elite football often need more protocol registration and have limited procedures, synthesis and practical implications directly applicable to the field. Therefore, this protocol outlines a comprehensive process developed following the Cochrane Collaboration and Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement comprising the following stages: (1) research question formulation and preliminary study, (2) eligibility criteria, (3) search strategy, (4) study selection, (5) data collection, (6) data assessment and (7) data synthesis and statistical analysis. It also presents a data quality standard process incorporating human and large language models reviewers and a detailed flow diagram for selecting suitable quantitative synthesis and ranking techniques. It includes meta-regression, pairwise, network, Bayesian or hierarchical meta-analysis options. The project associated and pre-registration of the protocol is available on the Open Science Framework (https://osf.io/tzcxq/).

To identify key training load (TL) and intensity indicators in ice hockey, practice, and game data were collected using a wearable 200-Hz accelerometer and heart rate (HR) recording throughout a four-week (29 days) competitive period (23 practice sessions and 8 competitive games in 17 elite Danish players (n = 427 observations). Within-individual correlations among accelerometer- (total accelerations [Acc_tot], accelerations >2 m·s^-2 [Acc2], total accelerations [Dec_tot], decelerations <- 2 m·s^-2 [Dec2]), among HR-derived (time >85% maximum HR [t85%HR_max], Edwards' TL and modified training impulse) TL indicators, and between acceleration- and HR-derived TL parameters were large to almost perfect (r = 0.69-0.99). No significant correlations were observed between accelerometer- and HR-derived intensity indicators. Three between- and two within-components were found. The K-means++ cluster analysis revealed five and four clusters for between- and within-loadings, respectively. The least Euclidean distance from their centroid for each cluster was reported by session-duration, Acc_tot, Dec2, TRIMP_MOD, %t85HR_max for between-loadings, whereas session-duration, Acc2, t85HR_max and Dec2/min for within-loadings. Specific TL or intensity variables might be relevant to identify similar between-subject groups (e.g. individual player, playing positions), or temporal patterns (e.g. changes in TL or intensity over time). Our study provides insights about the redundancy associated with the use of multiple TL and intensity variables in ice hockey.