Footballscience.net
As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.
Following studies were retrieved for this week:
#1 Psychophysiological Stress Markers During Preseason Among Elite Female Soccer Players
Reference: J Strength Cond Res. 2022 Jun 1;36(6):1648-1654. doi: 10.1519/JSC.0000000000003702. Epub 2020 Jul 16.
Authors: Renata Botelho, Cesar C C Abad, Regina C Spadari, Ciro Winckler, Márcia C Garcia, Ricardo L F Guerra
Summary: This study aimed to investigate changes and correlations between mood states and various physiological stress markers after a 7-week preseason period among elite female soccer players. Twenty-four elite female soccer players participated in this study (26.4 ± 3.7 years). Their internal training load, mood states, day and evening salivary testosterone and cortisol concentrations, blood creatine kinase concentration (CK), and heart rate variability (HRV) were assessed during the first week of preseason (PRE), and again 7 weeks after a systematic training period (END). After the preseason, there were significant increases in subject negative mood scales (p ≤ 0.03; Effect Size [ES] > 0.60), total mood scores (p = 0.01; QI = 100/0/0; ES = 1.32), day and evening testosterone and cortisol concentrations (p ≤ 0.03; ES > 0.54), and CK concentrations (p = 0.01; QI = 100/0/0; ES = 1.54). Correlations were found between cortisol and tension (r = 0.53 and 0.60; p ≤ 0.02), cortisol and confusion (r = 0.75; p = 0.01), and cortisol and the LF/HF index of HRV (r = -0.52; p = 0.04). Mood states (except vigor), salivary testosterone, and cortisol concentrations, as well as CK, showed significant changes after a 7-week systematic training system. The cortisol was the factor most highly related to various mood states (including tension and confusion), and with the HRV indices. Coaches and researchers can use these data to design, monitor, and control soccer training programs, in particular throughout the preseason period.
#2 Comparison of the H:Q Ratio Between the Dominant and Nondominant Legs of Soccer Players: A Meta-Analysis
Reference: Sports Health. 2022 May 26;19417381221095096. doi: 10.1177/19417381221095096.
Authors: Fabian D Lutz, Christopher J Cleary, Hannah M Moffatt, Violet E Sullivan, Dain P LaRoche, Summer B Cook
Summary: Soccer players often have a dominant (D) leg, which could influence the relative strength between the quadriceps and hamstrings. The hamstring-to-quadriceps (H:Q) ratio can be assessed on a dynamometer at various velocities to provide information on injury risk. The objective was to assess the concentric hamstrings and concentric quadriceps strength ratio (conventional H:Q ratio) assessed in D and nondominant (ND) legs at various speeds in male soccer players. A systematic literature search was completed from inception to 2020 in PubMed, Academic Search Ultimate, CINAHL, and SPORTDiscus. Keywords associated with the H:Q ratio were connected with terms for soccer players. Titles and abstracts were screened by 2 reviewers based on inclusion and exclusion criteria related to sex, playing level, language, and measurement. A total of 81 studies were reviewed and 17 studies (21%) were used. A meta-analysis with random effects modeling generated standardized mean differences with 95% CIs between legs and speeds was applied. A total of 38 cohorts were identified, with 14, 13, and 11 cohorts assessed at low, intermediate, and high velocities, respectively. The Quality Assessment Tool for Observational Cohort and Cross-sectional Studies from the National Institutes of Health was used. The mean H:Q ratio at low velocities was 59.8 ± 9.5% in D leg and 58.6 ± 9.9% in ND leg, 64.2 ± 10.7% (D) and 63.6 ± 11.3% (ND) at the intermediate velocity, and 71.9 ± 12.7% (D) and 72.8 ± 12.7% (ND) at the high velocity. Low, intermediate, and high velocities had small effects of 0.13, 0.10, and -0.06, respectively. Conventional H:Q ratios vary across velocities but did not differ between D and ND limbs in male soccer players. This study may provide the foundation to establish norms and clinically meaningful differences.
#3 Training soccer goalkeeping skills: Is video modeling enough?
Reference: J Appl Behav Anal. 2022 May 26. doi: 10.1002/jaba.937. Online ahead of print.
Authors: Alexandra Capalbo, Raymond G Miltenberger, Jennifer L Cook
Summary: Scant literature exists assessing the effectiveness of video modeling (VM) alone in the sports literature. Further evaluations of VM to improve sports skills is warranted because VM is an accessible and efficient procedure that has successfully improved skills in other fields of practice (e.g., staff training, medical procedures). Additionally, behavior analysts have not evaluated interventions for improving goalkeeping skills for individual soccer players. Therefore, we replicated the 1 behavior-analytic sports study on VM (Quinn et al., 2020), using a multiple baseline design across behaviors to evaluate the effects of VM and VM + video feedback (VF) to train 3 goalkeeper skills to two 9-year-old soccer players. The results showed that, although VM had some effect on performance compared to baseline, VM + VF resulted in the robust outcomes necessary for proficient performance of the goalkeeper skills. We discuss the results and limitations.
#4 The effects of jump training on measures of physical performance, lower extremities injury incidence and burden in highly trained male soccer players
Reference: Res Sports Med. 2022 May 26;1-15. doi: 10.1080/15438627.2022.2079989. Online ahead of print.
Authors: Javier Sánchez-Sánchez, Luis Torres Martín, Rodrigo Ramirez-Campillo, Daniel Castillo, Javier Raya-González
Summary: This study aimed to analyse the effects of a 16-week jump training program on the physical performance and lower extremities injury profile in semi-professional male soccer players. Participants were randomly assigned to the control group (CG; n = 13; age = 21.7 ± 3.6 years) or the experimental group (EG; n = 10; age = 22.3 ± 3.5 years). Countermovement jump (CMJ) height (cm), 30 m linear sprint time (s) with split times at 10 m and 20 m distances, and change of direction speed (CODS; 10 + 10 m with 90° turn) time (s) with turns using the dominant or non-dominant leg, were assessed before and after the intervention. Lower extremity injuries sustained throughout the intervention period were collected. Significant within-group improvements were found in EG in CMJ (p = 0.01; effect size [ES] = 1.03; large). Additionally, between-group difference after intervention was found in CMJ (F = 4.42; p = 0.013) in favour of EG. Injury burden was 194.86 (CG) vs 71.37 (EG) days of absence/1,000 h (RR = 2.73; 95% CI 2.10-3.54; p < 0.001). No other significant within-group or between-group differences were found. In conclusion, compared to regular soccer training, jump training was effective to improve jumping ability and burden in soccer players.
#5 Intra- and Inter-Seasonal Fitness and Training Load Variations of Elite U20 Soccer Players
Reference: Res Q Exerc Sport. 2022 May 25;1-8. doi: 10.1080/02701367.2022.2074951. Online ahead of print.
Authors: Massimo Saccà, Danilo Bondi, Fabrizio Balducci, Cristian Petri, Giuseppe Mazza
Summary: Inherent physical and anthropometric traits of elite soccer players, influenced by nature and nurture, account for the emergence of performances across time. The present study aimed to evaluate inter- and intraseasonal differences and the influence of playing position on training and fitness metrics in talented young soccer players. A total of 74 male players from U20 teams of a single elite club were tested both at beginning, during, and at the end of three consecutive competitive seasons. Players under went anthropometric measurement and were tested for aerobic, jumping, and sprinting performances; the GPS-derived measures of metabolic power (MP) and equivalent distance index (ED) of every athlete were analyzed. Difference between teams emerged in Mognoni's test, while it did not in countermovement jump and anthropometrics. ED was different across seasons. The model selection criteria revealed that the Bosco-Vittori test achieved the best fit. BMI and countermovement jump (CMJ) increased, and fat mass decreased, during season; different intraseasonal trends for CMJ. MP was slightly greater in midfielder. Network approaches in modeling performance metrics in sports team could unveil original interconnections between performance factors. In addition, the authors support multiparametric longitudinal assessments and a huge database of sports data for facilitating talent identification.
#6 Examining the influence of the Get aHEAD Safely in Soccer™ program on head impact kinematics and neck strength in female youth soccer players
Reference: Res Sports Med. 2022 May 24;1-11. doi: 10.1080/15438627.2022.2079982. Online ahead of print.
Authors: Victoria E Wahlquist, Joseph J Glutting, Thomas W Kaminski
Summary: The objective was to examine the efficacy of the Get aHEAD Safely in Soccer™ intervention on head impact kinematics and neck strength in female youth soccer players. The control group (CG) consisted of 13 players (age: 11.0 ± 0.4 yrs), while the experimental group (EG) consisted of 14 players (age: 10.6 ± 0.5 yrs). Head impact kinematics included peak linear acceleration (PLA), peak rotational acceleration (PRA), and peak rotational velocity (PRV). Pre- and post-season measures included strength measures of neck/torso flexion (NF/TF) and extension (NE/TE). Data were analysed using a multilevel linear model and ANOVA techniques. No differences in PLA, PRA, or PRV were observed between groups. The EG showed significant improvement in NF strength while the CG showed significant improvement in NE strength. Both groups significantly improved in TF pre- to post-season. The foundational strength components of the Get aHEAD Safely in Soccer program appear to show a benefit in youth soccer players beginning to learn the skill of purposeful heading.
#7 Descriptive trunk kinematics in healthy collegiate women's soccer players indicate trunk center of mass is laterally positioned prior to decelerating and cutting
Reference: J ISAKOS. 2022 Apr 4;S2059-7754(22)00019-0. doi: 10.1016/j.jisako.2022.03.002.
Authors: Celeste Dix, Amelia Arundale, Holly Silvers-Granelli, Adam Marmon, Ryan Zarzycki, Elisa Arch, Lynn Snyder-Mackler
Download link: https://www.jisakos.com/action/showPdf?pii=S2059-7754%2822%2900019-0
Summary: Trunk kinematics can contribute to lower extremity biomechanical risk factors for anterior cruciate ligament (ACL) injury. However, normative trunk kinematics during unilateral athletic tasks in a large population of "healthy" (no history of ACL injury and no known future ACL injury) women's soccer players have not been well-described. This study's purposes were to describe trunk kinematics in a population of 37 healthy collegiate women's soccer players completing a step-down, a deceleration, and a 90° cut, and to provide a reference for normative values. A cross-sectional cohort of 37 female soccer players were analysed for this study. Trunk forward flexion and lateral flexion were measured relative to the pelvis, and trunk centre of mass position was measured relative to the proximal tibia. Trunk kinematics were characterized by individual values at key events during the tasks and time-series curves normalized to 100% of the time. Participants demonstrated increasing trunk forward flexion with increasing knee flexion angle, small amounts of increasing ipsilateral trunk flexion with increasing peak knee abduction moment, and trunk centre of mass position that moved medially during the deceleration and cut tasks. Additionally, participants demonstrated peak trunk lateral flexion angles milliseconds before peak knee flexion angle. This study provides a reference for identifying aberrant trunk mechanics that may increase the risk for non-contact ACL injury.
#7 Real world complexities of periodization in a youth soccer academy: An explanatory sequential mixed methods approach
Reference: J Sports Sci. 2022 May 22;1-9. doi: 10.1080/02640414.2022.2080035. Online ahead of print.
Authors: Jake Pass, Lee Nelson, Greg Doncaster
Summary: The purpose of the study was to (1) assess the training load experienced during pre-season and in-season meso-cycles within youth academy soccer players and (2) investigate the extent to which the intended periodized approach was implemented, considering those factors that affected its realization. An explanatory sequential mixed-method design comprising two phases was adopted. Phase 1 encompassed the quantitative analysis of training load data, using 10 Hz GPS, and consisted of 17 youth academy soccer players (age 17 ± 1 yrs; stature 179 ± 9 cm; body mass 72 ± 9 kg), from a professional English soccer academy. Phase 2 involved the collection of qualitative data in relation to the data collected in phase 1 of the study. Three semi-structured interviews were conducted with the lead strength and conditioning coach at the same academy, to gain his reflections on the data, its alignments with desired outcomes, and factors that impacted on the enactment of the periodized training programme. The results provide original information on the training load experienced within a youth soccer academy and novel insights into the complex realities of enacting periodized training programmes in practice.
#8 Bilateral vs. Unilateral Countermovement Jumps: Comparing the Magnitude and Direction of Asymmetry in Elite Academy Soccer Players
Reference: J Strength Cond Res. 2022 Jun 1;36(6):1660-1666. doi: 10.1519/JSC.0000000000003679. Epub 2020 Jun 5.
Authors: Chris Bishop, Will Abbott, Calum Brashill, Anthony Turner, Jason Lake, Paul Read
Summary: The aims of this study were to compare the magnitude and direction of asymmetry in comparable bilateral and unilateral countermovement jumps (CMJs). Forty-five elite academy soccer players from under-23 (n = 15), under-18 (n = 16), and under-16 (n = 14) age groups performed bilateral and unilateral CMJs as part of their routine preseason fitness testing. For the magnitude of asymmetry, no significant differences were evident for any metric between tests. However, the eccentric impulse asymmetry was significantly greater than mean force and concentric impulse in both bilateral and unilateral tests (p < 0.01). For the direction of asymmetry, Kappa coefficients showed poor levels of agreement between test measures for all metrics (mean force = -0.15, concentric impulse = -0.07, and eccentric impulse = -0.13). The mean jump data were also presented relative to the body mass for each group. For the bilateral CMJ, significant differences were evident between groups but showed little consistency in the same group performing better or worse across metrics. For the unilateral CMJ, eccentric impulse was the only metric to show meaningful differences between groups, with the under-18 group performing significantly worse than under-23 and under-16 players. This study highlights that despite the magnitude of asymmetry being similar for each metric between comparable bilateral and unilateral CMJs, consistency in the direction of asymmetry was poor. In essence, if the right limb produced the larger force or impulse during a bilateral CMJ, it was rare for the same limb to perform superior during the unilateral task. Thus, practitioners should be aware that bilateral and unilateral CMJs present different limb dominance characteristics and should not use 1 test to represent the other when measuring between-limb asymmetries.
#9 Effects of Repeated Sprint Training With Progressive Elastic Resistance on Sprint Performance and Anterior-Posterior Force Production in Elite Young Soccer Players
Reference: J Strength Cond Res. 2022 Jun 1;36(6):1675-1681. doi: 10.1519/JSC.0000000000004242. Epub 2022 Mar 11.
Authors: Johan Le Scouarnec, Pierre Samozino, Benoit Andrieu, Teddy Thubin, Jean-Benoit Morin, François B Favier
Summary: This study aimed to determine whether repeated sprint training with progressive high elastic resistance could improve sprint performance and anterior-posterior (AP) force production capacities of elite young soccer players. Seven elite U19 soccer players underwent 10 sessions of elastic-resisted repeated sprints on 8 weeks, whereas 8 U17 players from the same academy (control group) followed the same protocol without elastic bands. Sprint performance and mechanical parameters were recorded on a 30-m sprint before and after training. The control group did not show change for any of the measured variables. In contrast, the elastic-resisted training resulted in a significant improvement of the sprint time (-2.1 ± 1.3%; p = 0.026; Hedges' g = -0.49) and maximal velocity (Vmax; +3.9 ± 2%; p = 0.029; Hedges' g = 0.61) reached during the 30-m sprint. These enhancements were concurrent with an increase in the maximal power output related to AP force (Pmax; +4.9 ± 5.1%%; p = 0.026; Hedges' g = 0.42). Although the theoretical maximal AP force (F0) remained unchanged in both groups, there was a medium but nonsignificant increase in theoretical maximal velocity (V0; +3.7 ± 2.5%; p = 0.13; Hedges' g = 0.5) only in the elastic group. Therefore, the present results show that sprint capacity of elite young soccer players can be further improved by adding incremental resistance against runner displacement to raise the ability to produce AP force, rather at high velocity in the final phase of the acceleration.
#10 Regional Bioelectrical Phase Angle Is More Informative than Whole-Body Phase Angle for Monitoring Neuromuscular Performance: A Pilot Study in Elite Young Soccer Players
Reference: Sports (Basel). 2022 Apr 22;10(5):66. doi: 10.3390/sports10050066.
Authors: Tindaro Bongiovanni, Alessio Rossi, Athos Trecroci, Giulia Martera, F Marcello Iaia, Giampietro Alberti, Giulio Pasta, Mathieu Lacome
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9144460/pdf/sports-10-00066.pdf
Summary: The objective of this study was to investigate the association between regional and total phase angle (PhA) with lower-body neuromuscular performance in young elite soccer players. Sixteen elite male soccer players (14.3 ± 1.0 years) participated in this study. Lower (LPhA)- and upper (UPhA)-hemisome PhA together with whole-body PhA (WBPhA) were measured by a bioelectrical-impedance analysis (BIA), while appendicular arm and leg lean soft tissue (ALST and LLST, respectively) were estimated. Urine osmolarity (UOsm) and urine-specific gravity (USG) were also considered. Sprints over 10 m and 20 m and countermovement jump (CMJ) tests were employed to evaluate neuromuscular performance. LPhA (p = 0.003) and UOsm (p = 0.012) explained 62% of the variance in the 10 m sprint. UOsm (p = 0.001) and both LPhA (p < 0.001) and WBPhA (p = 0.024) explained 81% of the total variance in the 20 m sprint. The CMJ height was affected by LPhA (p < 0.001) and UOsm (p = 0.024), which overall explained 68% of its variance (p < 0.05), while 93% of the CMJ power variance was explained by LPhA (p < 0.001), ALST (p < 0.001), and WBPhA (p = 0.011). Regional PhA is a relevant and non-invasive tool to monitor lower-body neuromuscular performance in elite youth soccer. Specifically, LPhA may be favored over WBPhA as more informative.
#11 An Examination of Relative Age and Athlete Dropout in Female Developmental Soccer
Reference: Sports (Basel). 2022 May 20;10(5):79. doi: 10.3390/sports10050079.
Authors: Kristy L Smith, Patricia L Weir
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9148022/pdf/sports-10-00079.pdf
Summary: Sport dropout rates among children and youth are a concern for researchers and policy makers. The impact of relative age effects (RAEs) on dropout trends has not been adequately examined in female samples. The purpose of this study was to longitudinally examine dropout in a female soccer cohort in Ontario, Canada. Registration entries for a one-year cohort were examined across a seven-year period (n = 9908; age 10-16 years). A chi-square analysis established the presence of RAEs in the initial year of registration. Survival analyses assessed the impact of relative age, competition level, and community size on athlete dropout. A median survival rate of four years was observed for players born in the first quartile, while all remaining quartiles had a median survival of three years. Community size did not predict dropout in this analysis; however, competition level was a significant predictor, with competitive players being more likely to remain engaged vs. recreational players (55.9% vs. 20.7%). The observed trends are likely to have a significant impact from both a healthy development and systems perspective (e.g., economic/market loss). Intervention is needed to mitigate current dropout trends in female athletes. Practical applications are discussed.
#12 Multiagent off-screen behavior prediction in football
Reference: Sci Rep. 2022 May 23;12(1):8638. doi: 10.1038/s41598-022-12547-0.
Authors: Shayegan Omidshafiei, Daniel Hennes, Marta Garnelo, Zhe Wang, Adria Recasens, Eugene Tarassov, Yi Yang, Romuald Elie, Jerome T Connor, Paul Muller, Natalie Mackraz, Kris Cao, Pol Moreno, Pablo Sprechmann, Demis Hassabis, Ian Graham, William Spearman, Nicolas Heess, Karl Tuyls
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9126960/pdf/41598_2022_Article_12547.pdf
Summary: In multiagent worlds, several decision-making individuals interact while adhering to the dynamics constraints imposed by the environment. These interactions, combined with the potential stochasticity of the agents' dynamic behaviors, make such systems complex and interesting to study from a decision-making perspective. Significant research has been conducted on learning models for forward-direction estimation of agent behaviors, for example, pedestrian predictions used for collision-avoidance in self-driving cars. In many settings, only sporadic observations of agents may be available in a given trajectory sequence. In football, subsets of players may come in and out of view of broadcast video footage, while unobserved players continue to interact off-screen. In this paper, we study the problem of multiagent time-series imputation in the context of human football play, where available past and future observations of subsets of agents are used to estimate missing observations for other agents. Our approach, called the Graph Imputer, uses past and future information in combination with graph networks and variational autoencoders to enable learning of a distribution of imputed trajectories. We demonstrate our approach on multiagent settings involving players that are partially-observable, using the Graph Imputer to predict the behaviors of off-screen players. To quantitatively evaluate the approach, we conduct experiments on football matches with ground truth trajectory data, using a camera module to simulate the off-screen player state estimation setting. We subsequently use our approach for downstream football analytics under partial observability using the well-established framework of pitch control, which traditionally relies on fully observed data. We illustrate that our method outperforms several state-of-the-art approaches, including those hand-crafted for football, across all considered metrics.
#13 Return to Play Prediction Accuracy of the MLG-R Classification System for Hamstring Injuries in Football Players: A Machine Learning Approach
Reference: Sports Med. 2022 May 24. doi: 10.1007/s40279-022-01672-5. Online ahead of print.
Authors: Xavier Valle, Sandra Mechó, Eduard Alentorn-Geli, Tero A H Järvinen, Lasse Lempainen, Ricard Pruna, Joan C Monllau, Gil Rodas, Jaime Isern-Kebschull, Mourad Ghrairi, Xavier Yanguas, Ramon Balius, Adrian Martinez-De la Torre
Summary: Muscle injuries are one of the main daily problems in sports medicine, football in particular. However, we do not have a reliable means to predict the outcome, i.e. return to play from severe injury. The aim of the present study was to evaluate the capability of the MLG-R classification system to grade hamstring muscle injuries by severity, offer a prognosis for the return to play, and identify injuries with a higher risk of re-injury. Furthermore, we aimed to assess the consistency of our proposed system by investigating its intra-observer and inter-observer reliability. All male professional football players from FC Barcelona, senior A and B and the two U-19 teams, with injuries that occurred between February 2010 and February 2020 were reviewed. Only players with a clinical presentation of a hamstring muscle injury, with complete clinic information and magnetic resonance images, were included. Three different statistical and machine learning approaches (linear regression, random forest, and eXtreme Gradient Boosting) were used to assess the importance of each factor of the MLG-R classification system in determining the return to play, as well as to offer a prediction of the expected return to play. We used the Cohen's kappa and the intra-class correlation coefficient to assess the intra-observer and inter-observer reliability. Between 2010 and 2020, 76 hamstring injuries corresponding to 42 different players were identified, of which 50 (65.8%) were grade 3r, 54 (71.1%) affected the biceps femoris long head, and 33 of the 76 (43.4%) were located at the proximal myotendinous junction. The mean return to play for grades 2, 3, and 3r injuries were 14.3, 12.4, and 37 days, respectively. Injuries affecting the proximal myotendinous junction had a mean return to play of 31.7 days while those affecting the distal part of the myotendinous junction had a mean return to play of 23.9 days. The analysis of the grade 3r biceps femoris long head injuries located at the free tendon showed a median return to play time of 56 days while the injuries located at the central tendon had a shorter return to play of 24 days (p = 0.038). The statistical analysis showed an excellent predictive power of the MLG-R classification system with a mean absolute error of 9.8 days and an R-squared of 0.48. The most important factors to determine the return to play were if the injury was at the free tendon of the biceps femoris long head or if it was a grade 3r injury. For all the items of the MLG-R classification, the intra-observer and inter-observer reliability was excellent (k > 0.93) except for fibres blurring (κ = 0.68). The main determinant for a long return to play after a hamstring injury is the injury affecting the connective tissue structures of the hamstring. We developed a reliable hamstring muscle injury classification system based on magnetic resonance imaging that showed excellent results in terms of reliability, prognosis capability and objectivity. It is easy to use in clinical daily practice, and can be further adapted to future knowledge. The adoption of this system by the medical community would allow a uniform diagnosis leading to better injury management.
#14 Impact of Match Type and Match Halves on Referees' Physical Performance and Decision-Making Distance in Chinese Football Super League
Reference: Front Psychol. 2022 May 9;13:864957. doi: 10.3389/fpsyg.2022.864957. eCollection 2022.
Authors: Jinying Jiang, Huanmin Ge, Lida Du, Miguel-Angel Gomez, Bingnan Gong, Yixiong Cui
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9125187/pdf/fpsyg-13-864957.pdf
Summary: The purpose of this study was to explore how Chinese Football Super League (CSL) referees' physical performance and decision-making distance varied according to match type and match halves. Data from 107 matches played by top-4 ranked and bottom-4 ranked teams during 2018-2019 CSL seasons were collected. Level of matches was classified into three groups: (a) upper-ranked (top-4) teams against top-4 teams, (b) top-4 teams against lower-ranked teams (bottom-4), and (c) bottom-4 teams against bottom-4 teams. Two-way ANOVA and Scheirer-Ray-Hare test were used to examine the statistical differences of referees' physical and spatial related distance variables among different match levels and halves. The Euclidean distance to the ball at the following three variables were statistically different among three match types: clearance (p = 0.03, E2RER2 = 0.03), running with the ball (p = 0.01, E2RER2 = 0.04), and shot off target (p = 0.04, E2RER2 = 0.03). In addition, referees' distance to the ball at three events were statistically different between both match halves: pass (p < 0.001, r = 0.69), reception (p < 0.001, r = 0.76), and running with the ball (p < 0.001, r = 0.77). The total running distance was statistically different between both match halves (p = 0.001, d = 0.05). The findings indicated that although CSL referees showed little difference in physical performance when officiating matches of three competitive levels and two halves, distinct rhythms of competitions determined that they needed to adjust running strategies to maintain proper distance to the ball. This study implied that the CSL referees' match performance was affected by the teams' style of play and match status.
#15 Examining the Mental Health Status of Referees in the Turkish Professional Football League
Reference: Sci Med Footb. 2022 May 27. doi: 10.1080/24733938.2022.2084150. Online ahead of print.
Authors: Yavuz Lima, Sergen Devran, Nazlı Deniz Öz, Tom Webb, Bülent Bayraktar
Summary: The purpose of the study was to evaluate the mental health (MH) status of referees who officiate in the Turkish professional football leagues. An online survey was sent to all referees in the Turkish professional football leagues (n=630) incorporating standardized scales assessing depression, anxiety, and stress. A total of 433 referees participated in the study, yielding a response rate of 68.7%. Younger referees (18-27 years) reported higher depression (p=0.01), anxiety (p<0.01), and stress (p<0.01) scores than older (>38 years) refereees. Depression, anxiety, and stress scores of single referees were higher compared to married referees (all p<0.01). Lower-level referees reported higher depression (p<0.01), anxiety (p=0.01), and stress (p<0.01) scores than their higher-level counterparts. Higher depression, anxiety, and stress scores were also associated with less income, performance concerns, severe injury history, and inadequate social support. MH problems in referees were associated with a wide range of variables including younger age, being single, refereeing at lower-levels, performance concerns, and inadequate social support. In light of these results, MH assessments should be undertaken with referees to detect which officials are at greater risk of MH problems. Doing so will help to enable appropriate and timely MH interventions.
#16 Players with high physical fitness are at greater risk of injury in youth football
Reference: Scand J Med Sci Sports. 2022 May 27. doi: 10.1111/sms.14199. Online ahead of print.
Authors: Mari Leppänen, Aliisa Uotila, Kari Tokola, Hannele Forsman-Lampinen, Urho M Kujala, Jari Parkkari, Pekka Kannus, Kati Pasanen, Tommi Vasankari
Summary: The aim of this study was to investigate physical fitness, football-specific skills and their association with injury risk in youth football. Altogether 447 male and female players aged 9 to 14 years (median 12 years) participated in performance tests and prospective follow-up. The physical fitness tests included five-jump test for distance, 30-m sprint, football-specific figure of eight agility, countermovement jump, and Yo-Yo intermittent endurance test level 1. The football-specific skill tests included dribbling and passing tests. Injuries and exposure were registered during the 20-week follow-up. Our candidate risk factors were low/high level of physical fitness measured with a composite score of physical fitness tests and low/high level of football-specific skills measured with a composite score of dribbling and passing tests. Secondarily, we investigated performance in individual tests and their association with injury risk. During the follow-up, players reported 565 injuries (264 acute and 301 overuse injuries). High level of physical fitness was associated with increased rate of all injuries (age-, sex- and mean team exposure - adjusted IRR 1.28, 95% CI 1.04-1.58). The level of football-specific skills had no influence on the overall injury rate. Burden of overuse injuries, but not acute injuries was significantly higher in most fit players compared with the players in the reference group (IRR 2.09, 95 % CI 1.04-4.24). In conclusion, most fit players were at greater risk of sustaining injuries in youth competitive football.
