Comparison of two measurement devices for obtaining horizontal force-velocity profile variables during sprint running

This study established the magnitude of systematic bias and random error of horizontal force-velocity (F-v) profile variables obtained from a 1080 Sprint compared to that obtained from a Stalker ATS II radar device. Twenty high-school athletes from an American football training group completed a 30 m sprint while the two devices simultaneously measured velocity-time data. The velocity-time data were modelled by an exponential equation fitting process and then used to calculate individual F-v profiles and related variables (theoretical maximum velocity, theoretical maximum horizontal force, slope of the linear F-v profile, peak power, time constant tau, and horizontal maximal velocity). The devices were compared by determining the systematic bias and the 95% limits of agreement (random error) for all variables, both of which were expressed as percentages of the mean radar value. All bias values were within 6.32%, with the 1080 Sprint reporting higher values for tau, horizontal maximal velocity, and theoretical maximum velocity. Random error was lowest for velocity-based variables but exceeded 7% for all others, with slope of the F-v profile being greatest at ±12.3%. These results provide practitioners with the information necessary to determine if the agreement between the devices and the magnitude of random error is acceptable within the context of their specific application.

The strength and conditioning practices and perspectives of soccer coaches and players

Strength and conditioning (S&C) is implemented across various sports and levels, but there is limited understanding of the personnel responsible for this, including their S&C practices and perspectives. Whereas recent evidence has shown that coaches and players are often tasked with the responsibility. Therefore, this study aimed to investigate: 1) the personnel responsible for delivering S&C across different levels of soccer, 2) the practices and perspectives of soccer coaches and players, and 3) to ascertain whether the practices employed align with contemporary evidence and guidelines. Forty-two soccer coaches and 30 soccer players completed an online survey with six sections: (a) informed consent, (b) background information, (c) education, qualifications, and prescription, (d) views on S&C, (e) exercise selection and preferences, and (f) issues and improvements. Frequency analysis was used to report responses to fixed-response questions and thematic analysis for open-ended questions. Most respondents reported S&C to be ‘important’ to ‘very important’ for all soccer, physical fitness, and injury parameters, with perspectives being predominantly aligned with S&C guidelines and research in soccer. Although S&C coaches were mostly responsible for delivering S&C sessions, over 60% of respondents disclosed S&C sessions were delivered independently or by support staff. This is problematic given only four coaches held S&C qualifications, and issues and improvements were mostly regarding a lack of S&C expertise and education. This study provides valuable information for S&C and soccer organizations. Particularly regarding the additional support required to ensure those responsible for delivering S&C in soccer have the appropriate knowledge and qualifications.

Development of a novel biofeedback system for the sprint start

This study developed and evaluated a novel concurrent biofeedback system for the sprint start. Previous studies have investigated sprint start biofeedback applications, but these have either not considered important kinematics, coaching implications or key motor learning principles. The biofeedback system was developed to convey rear knee angle information, obtained from 3D motion capture to novice participants as changes in the colour of an LED start line when they were in the “set” position. Based on initial user feedback, the system indicated whether the participants’ rear knee angles were within ± 2° of 130° (green) or not (red). A two-group experimental study was then employed to explore the acute responses of novices to the use of the biofeedback system during the sprint start. When exposed to biofeedback, the experimental group (EXP, n = 10) exhibited less deviation (4.0 ± 2.4°) from the target rear knee angle than they did in either a pre-test (11.9 ± 6.9°) or post-test (10.4 ± 4.4°) condition without biofeedback. The control group (CON, n = 10) with no biofeedback exhibited greater deviation from the target rear knee angle than the EXP group in all three condition blocks (pre-test = 21.8 ± 15.1°, no intervention = 15.6 ± 7.3°, post-test = 14.3 ± 6.5°) but the group × condition interaction effect was not significant (P = 0.210). The novel biofeedback system can be used to manipulate selected “set” position kinematics and has the potential to be incorporated with different input systems (e.g. inertial measurement units (IMUs)) or in longitudinal designs.

Effects of different sprint training programs with ball on explosive, high-intensity and endurance-intensive performances in male young soccer players

This study compared the effects of different sprint ball-based training programs on fitness-related performances in youth soccer players. Forty male players (age: 15.2 ± 0.6 yrs) participated in a short-term (8 weeks) randomized parallel fully controlled training study, with pre-to-post measurements. Players were randomly assigned to 3 sprint ball-based training groups: training with combined sprint (performing linear and change of direction sprints; CST), or using linear sprint (LST), or performing sprint with change of direction (CODT) and to a control group (CONT). Pre- and post-training players completed a test battery involving linear sprinting (10 and 20 m, and flying 10 m), 505 test (COD), 15 m test with ball (CODB), countermovement jump test (CMJ test) and maximal oxygen consumption (VO2max). All physical performance’ variables improved after the training intervention (all p < 0.05; ES ≥ 0.2). No main effect of groups was observed in linear sprinting, CMJ and VO2max (p > 0.05; ES < 0.2). A training group main effect was found (p < 0.0001; ES = 0.50) for COD with CODT induced better performance than LST and CONT (all p <0.0001; ES > 0.8). Also, a training group main effect (p = 0.009; ES = 0.35) was found for CODB with CODT elicited better performance than LST and CONT (all p = 0.001; ES > 0.80). Our findings suggest that ball-based training programs were more effective to improve fitness levels in youth players during the in-season period and that CODT modality was more effective to improve COD and CODB performances.

Oliver’s four-factor model: Validation through causality

While there has been a growing interest in sports analysis in recent years, much research first focused on a classical statistical approach and later on an artificial intelligence approach. This article aims instead to propose a causal inference approach to sports analysis. In particular, the present article intends to review the famous four-factor model proposed by Dean Oliver for assessing the winning ability of National Basketball Association (NBA) teams through a causal inference approach. A structural equation model is used to validate Oliver’s model. The present paper considers the winning percentage and the factors’ statistics over entire seasons from [Formula: see text] to [Formula: see text]. The statistics for the [Formula: see text] season are considered only on a subset of the games. This is because the games played in the Orlando bubble under the particular COVID-19 situation have been regarded as outliers compared to the games played in the other NBA seasons, hence they have not been taken into account. The second goal of the article is to analyse if the fitting ability of the four-factor model changes when it is fitted over the pre[Formula: see text] and post[Formula: see text] basketball eras datasets, considering the year [Formula: see text] as the turning point for the NBA playing style.

Breaking up the play: The relationship between legal stops and winning in team handball

The purpose of this study was to examine the relationship between legal stops and winning in team handball. Real-time analysis was performed on all games played in the Icelandic elite division for both males and females (regular season and playoffs) between 2017–2021 (854 games [570 male games, 284 female games], 32,392 legal stops in total). Legal stops were assessed as any physical action by a defensive player that resulted in the stop of play, without the defensive player being penalized or the offensive player receiving a 7-meter throw. The results from a multinomial logistic regression analysis indicated that legal stops were significantly associated with winning games in the male league. No statistically significant relationship was found between illegal stops and game outcome for either sex. However, 2-minute suspensions were found to be positively associated with winning in the male league.

Small-sided games do not replicate all external and internal loads of a football match-play during pre-season: A case study

This study investigated the differences in external and internal load during pre-season training sessions carried out with different SSGs and a friendly match in top-class professional football players. The study was conducted over a full pre-season. Participants were 9 male top-class professional football players (25 ± 5 years; 74 ± 8 kg; 177 ± 8 cm). The following variables were measured: training session duration (min), average heart rate (bpm), total distance (m), distance covered per minute (m/min), the total number of accelerations > 2.5 m/s2, number of accelerations > 2.5 m/s2 per minute, average distance of accelerations (m), the average value of acceleration (m/s2). One-way ANOVA was performed to analyze the variance of all evaluated variables. No differences were found in the average accelerations (m/s2) (0.128) among all the training formats. Moderate differences were found in number of accelerations > 2.5 m/s2 per minute (η2 = 0.396, moderate effect) and average distance of accelerations (η2 = 0.545). Strong differences were found in HR (η2 = 0.788, large effect), total distance (η2 = 0.797, strong effect), distance per minute (η2 = 0.775 strong effect), total number of accelerations > 2.5 m/s2 (η2 = 0.699 strong effect). Significant correlations were found just for the number of accelerations > 2.5 m/s2 and the number of accelerations > 2.5 m/s2 per minute with the 4v4, 8v8 and the FM (r = 0.828–0.890, r2 = 69% – 79%; p < 0.01). External and internal loads differ across different SSGs and a FM during the pre-season training sessions.

Understanding the pedagogical practice in futsal teaching and learning process based on the TGfU approach

The aim of the current study is to understand the pedagogical practice of coaches of youth futsal players based on the TGfU approach. Action Research (AR) approach, developed according to the planning, teaching, observing and reflecting spiral steps, was applied for the teaching of futsal for 12 children aged 9–11 years. An eight-member research group (five student coaches, one research coach and two university professors) was subjected to the same practice. Information was collected from class planning meetings, diagnostic assessment and field diaries of participant and non-participant observers. Based on results, changes in the pedagogical practice were aimed at helping players understanding and using actions to support futsal improvements. AR application also highlighted the emerging understanding about student-coach practices, the influence of coaches who adopt reflective practices or not; and the relevance of using critical player observation at the time of reflecting on how to develop supportive pedagogical practices. Results have shown that the pedagogical practice of coaches has changed over time. The researcher-coach practice and the assistant coach (student-coach 1) was influenced by the perceptions of student-coaches and reflections made in meetings.

Asymmetry in internal oblique muscle thickness: Not the key to a cricket fast bowler's performance

Purpose Previous studies found that trunk muscle asymmetry may play a role in preventing injury in cricket fast bowlers, while the association with bowling performance has not been investigated. This study aims to describe the side-to-side differences in trunk muscle thickness and determine the association between bowling performance and these side-to-side differences in trunk muscle thickness in adolescent fast bowlers. Methods In this observational cross-sectional study, bowling performance, namely ball release speed and bowling accuracy, was recorded in adolescent fast bowlers. Ultrasound imaging measured external oblique, internal oblique, transversus abdominis and lumbar multifidus muscle thickness. Results Fast bowlers (n = 46) with a mean age of 15.9 (±1.2) years participated. On the non-dominant side, the external oblique and internal oblique at rest were thicker than on the dominant side (external oblique: p = 0.011, effect size = 0.27; internal oblique: p < 0.0001, effect size = 0.40), while the transversus abdominus ( p = 0.72, effect size = 0.19) and lumbar multifidus ( p = 0.668, effect size = 0.04) were symmetrical. Weak correlations existed between bowling performance and the side-to-side differences in the thickness in all muscles, except for two moderate correlations: 1. The smaller the side-to-side difference in absolute thickness of the external oblique when contracted, the faster the ball release speed (Spearman's (ρ) = −0.455, p = 0.002). 2. Also, a smaller side-to-side difference in external oblique contraction ratio (Spearman's (ρ) = −0.495, p = 0.0001) was associated with faster ball release speed. Conclusions No relationship between bowling performance and side-to-side differences in internal oblique muscle thickness could be established, while more symmetrical external oblique muscles may be linked to faster ball release speeds.

The content and load of preseason field-based training in a championship-winning professional rugby league team: A case study

This study reports on the content and periodisation of the preseason field-based training for a professional rugby league team. Thirty professional male rugby league players (26 ± 5 years, 180.9 ± 6.5 cm, 94 ± 9 kg) completed an 8-week preseason. Global positioning system devices and heart rate were used to monitor physical and physiological responses of different field-based training components (speed, conditioning, rugby skill and game-based training). Rugby skill training contributed the most to the total distance covered, conditioning was the greatest contributor to high-speed running (>15 km/h) and game-based training provided the greatest high metabolic distance (>20 W/kg) and overall external load. Game-based training provided the greatest time with heart rate ≥80% estimated maximum. The weekly preseason cycle had lower loads on Monday and Thursday whereas Tuesday and Friday produced the highest loads. The preseason described herein adopted a progressive overload comprising a weekly undulating cycle. This study emphasises how skill and games-based training contributes significantly to the overall load of a professional rugby league team's preseason with more traditional conditioning promoting high-speed running load and high metabolic load.