Latest research in football - week 28 - 2022

#1 Absence of Injury Is Not Absence of Pain: Prevalence of Preseason Musculoskeletal Pain and Associated Factors in Collegiate Soccer and Basketball Student Athletes

Reference: Int J Environ Res Public Health. 2022 Jul 26;19(15):9128. doi: 10.3390/ijerph19159128.

Authors: Oluwatoyosi B A Owoeye, Jamil R Neme, Paula Buchanan, Flavio Esposito, Anthony P Breitbach

Summary: Unlike musculoskeletal (MSK) injuries, MSK pain is rarely studied in athletes. In this study, we examined the prevalence of preseason MSK pain in apparently healthy collegiate soccer and basketball players and its relationship with previous injuries (1-year history), among other factors. Ninety-seven eligible student athletes (mean age: 20.1 (SD: 1.6) years; 43% male; 53% soccer players) completed a baseline questionnaire comprising questions related to demographics, medical and 1-year injury history and any current MSK pain and the corresponding body location. The overall prevalence of preseason MSK pain was 26% (95% CI: 17-36%) and it did not differ by sex or sport. The back (6.2%) and knee (5.2%) regions were reported to be the most frequently affected body parts for preseason MSK pain. Athletes with a previous injury and with perception of incomplete healing had 3.5-fold higher odds (OR: 3.50; 95% CI: 1.28-9.36) of baseline MSK pain compared with those without a previous injury. One in four collegiate soccer and basketball players had preseason MSK pain. Collegiate sports medicine professionals should consider conducting routine preseason evaluations of MSK pain in their athletes and initiate appropriate interventions for the prevention of MSK pain and its potential consequences among athletes.

 

 

#2 Slow-Speed Compared With Fast-Speed Eccentric Muscle Actions Are Detrimental to Jump Performance in Elite Soccer Players In-Season

Reference: Int J Sports Physiol Perform. 2022 Jun 23;1-7. doi: 10.1123/ijspp.2021-0542. Online ahead of print.

Authors: Nick Segers, Mark Waldron, Louis P Howe, Stephen D Patterson, Jason Moran, Ben Jones, Dawson J Kidgell, Jamie Tallent

Summary: The purpose was to examine the effect of fast- versus slow-speed eccentric-muscle-action resistance training on lower-body strength, vertical jump height, sprint speed, and change-of-direction performance in elite soccer players during a competitive season. Twenty-two elite soccer players, from a single team, were randomly assigned to groups that undertook either 1- (fast speed) or 4-second (slow speed) eccentric resistance training during the in-season period. A 5-week program was conducted during an elite top-division European League soccer season. Performance measures including predicted 1-repetition-maximum back squat, countermovement jump, 20-m sprint, and change of direction were tested before and after the intervention period. Total match and training running distance and muscle soreness were also recorded during each week of the intervention. An analysis of covariance showed significant group effects (P = .01) for countermovement jump with a greater jump height in the 1-second fast-speed group postintervention (95% CI, 1.1-6.9 cm). Despite an overall increase in 1-repetition maximum pretraining to posttraining (95% CI, 10.0-15.3 kg, effect size 0.69), there were no significant differences (P > .05) between groups after the intervention. Similarly, there were no differences between groups for change of direction, 20-m sprint, or muscle soreness. Faster eccentric muscle actions may be superior for increasing movements in elite soccer players in-season.

 

 

#3 Effects of Far-Infrared Radiation-Lamp Therapy on Recovery From Simulated Soccer Match Running Activities in Elite Soccer Players

Reference: Int J Sports Physiol Perform. 2022 Jul 12;1-7. doi: 10.1123/ijspp.2022-0084. Online ahead of print.

Authors: Chung-Chan Hsieh, Kazunori Nosaka, Tai-Ying Chou, Sheng-Tsung Hsu, Trevor C Chen

Summary: The authors investigated whether far-infrared radiation (FIR) lamp therapy would reduce muscle damage and enhance recovery from multiple soccer-match-related running activities. Twenty-four elite female soccer players (20-24 y) were assigned into a FIR or a sham treatment group (n = 12/group). They performed a daily 90-minute Loughborough Intermittent Shuttle Test (LIST) for 6 consecutive days. Maximal voluntary contraction torque of the knee extensors (KEs) and flexors, muscle soreness, plasma creatine kinase activity, countermovement jump, and several other performance measures (eg, 30-m dash, Yo-Yo Intermittent Recovery Test Level 1) were taken before the first LIST, 1 hour after each LIST, and 24, 48, 72, 96, and 120 hours after the last LIST. All participants received a 30-minute FIR or sham treatment on KEs and knee flexors, respectively, at 2 hour after each LIST and 25, 49, 73, and 97 hours after the last LIST. All measures changed significantly (P < .05) at 1 hour after the first LIST without difference (P > .05) between groups. Maximal voluntary contraction torque (eg, the largest decrease of KE for FIR: 13% [4%], sham: 25% [5%]), countermovement jump height (4% [3%] vs 14% [4%]), and other performance measures (eg, Yo-Yo Intermittent Recovery Test: 11% [5%] vs 26% [5%]) decreased less, and peak muscle soreness (eg, KE: 26 [9] vs 51 [18] mm) and plasma creatine kinase activity (172 [32] vs 1289 [610] IU/L) were smaller for the FIR than for the sham group (P < .05), and they returned to the baseline earlier (P < .05) for the FIR group. These results suggest that the FIR therapy provided potent effects on reducing accumulated muscle damage and enhancing recovery.

 

 

#4 A Data Analytics Approach to Assess the Functional and Physical Performance of Female Soccer Players: A Cohort Design

Reference: Int J Environ Res Public Health.  2022 Jul 22;19(15):8941. doi: 10.3390/ijerph19158941.

Authors: Francisco Tomás González-Fernández, Alfonso Castillo-Rodríguez, Lorena Rodríguez-García, Filipe Manuel Clemente, Ana Filipa Silva

Summary: The aim of this study was twofold: (i) to observe the individual results of fitness status [countermovement jump (CMJ)], hop test, linear sprinting time, stride frequency, stride distance, force-power-velocity, peak power maximal and maximal speed, and repeated sprint ability (RSA) and functional performance (overhead squat, single-leg squat test, dumbbell hip-hinge, Thomas test, hip extension, and internal and external hip rotators) and (ii) to analyze the relationship between anthropometrical measures and values of fitness status with % of difference in the Thomas test, hip extension, and internal and external hip rotators. The study followed a cohort design. Sixteen female soccer players competing in the second division of the Spanish league were monitored during the first days of the pre-season. These players were evaluated three times during the preseason of the cohort period. The dataset showed a negative moderate correlation between time and percentage of difference in hip angle and another positive moderate correlation between maximal sprint and percentage of difference in hip angle (r = -0.54, p = 0.02 and r = 0.53, p = 0.04), respectively. The correlations of stride time and distance with hip extension are interesting, as professional soccer players should have higher levels of hip flexor flexibility during the stride phase, recoil of the instep kick action.

 

 

#5 Leg dominance and performance in change of directions tests in young soccer players

Reference: Sci Rep. 2022 Jul 28;12(1):12900. doi: 10.1038/s41598-022-17245-5.

Authors: Filipe Manuel Clemente, Francisco Tomás González-Fernández, Gabriel García-Delgado, Rui Silva, Ana Filipa Silva, Hadi Nobari, Moisés Falces-Prieto

Summary: The present study aimed to examine the influence of leg dominance on the change of direction (COD) performance. In this study participated 94 healthy young highly trained male soccer players belonging from two categories (n = 27 vs. n = 67; 14.81 ± 0.40 vs. 16.64 ± 1.25 years of age; 170.61 ± 5.61 vs. 173.73 ± 7.19 cm of height; 64.74 ± 8.44 vs. 66.70 ± 7.95 kg of weight, for U16 and U18, respectively). Fitness assessments were performed two times in a period of three months, and included: (1) anthropometry measures, (2) 30-15 IFT, (3) 10-m sprint test, (4) 505-COD test, 90° COD test and cross-over hop test. A paired sample t-test was performed to evaluate the asymmetries at the intragroup level in each of the COD's tests. A symmetry index was used to analyse the asymmetries between categories, and an independent sample t-test was used to compare the variability between the two categories in each of the three tests performed. The effect size was also evaluated. Analysis demonstrated that evidence a trend for a better performance with the preferred leg in the cross-over hop and 505-COD tests, and with the non-dominant leg in the 90° COD. However, in the intragroup analysis, only the 505-COD test registered differences, and no differences were notice din the intergroup comparison. Only in the 505-COD test the percentage of variability (CV) was statistically significant (7.03 ± 4.18% vs. 4.03 ± 2.02% from U16 and U18, respectively). In sum, bilateral differences were noticed in the intragroup comparison, although only in 505-COD test the leg dominance showed to influence performance. In the intergroup analysis any difference was noticed between age categories.

 

 

#6 The FIFA 11+ Kids Injury Prevention Program Reduces Injury Rates Among Male Children Soccer Players: A Clustered Randomized Controlled Trial

Reference: Sports Health. 2022 Jul 28;19417381221109224. doi: 10.1177/19417381221109224.

Authors: Wesam Saleh A Al Attar, Mario Bizzini, Hosam Alzahrani, Saud Alarifi, Hussain Ghulam, Mashaer Alyami, Msaad Alzhrani, Ross H Sanders

Summary: The Fédération Internationale de Football Association (FIFA) 11+ Kids is an exercise-based injury prevention program developed by an international group of experts to prevent injuries among child soccer players. It was hypothesized that the FIFA 11+ Kids program would be more effective than performing a typical warm-up regimen in reducing overall injuries among soccer players aged 7 to 13 years. A total of 94 boys' soccer teams, including 780 players, were randomly allocated into an experimental or control group. Complete datasets were collected from 45 teams (377 players) and 43 teams (363 players) in the experimental and control groups, respectively. The experimental group underwent the FIFA 11+ Kids program as a warm-up during training sessions and matches at least twice a week, and the control group continued performing their usual warm-ups. Participants were prospectively followed during 1 season (6 months). The primary outcomes included the incidence of overall and recurrent injuries and their mechanism and severity. The secondary outcome was the rate of compliance with the intervention program. A total of 43 injuries were reported in the experimental group in 50,120 hours of exposure (0.85 injuries/1000 exposure hours). A total of 86 injuries were reported in the control group in 42,616 hours of exposure (2.01 injuries/1000 exposure hours). The injury risk ratio was 0.43 (0.29-0.61), suggesting that the experimental group experienced 57% fewer injuries than those in the control group. The FIFA 11+ Kids program reduced overall injury rates in children playing soccer more than the usual warm-ups. The results of this study provide evidence for children's coaches to consider including the FIFA 11+ Kids program in their warm-up regimen. Such a program may prevent injury risk and decrease absenteeism and injury-related financial burdens.

 

 

#7 Defining movement strategies in soccer instep kicking using the relationship between pelvis and kick leg rotations

Reference: Sports Biomech. 2022 Jul 29;1-12. doi: 10.1080/14763141.2022.2106297. Online ahead of print.

Authors: Simon Augustus, Penny E Hudson, Neal Smith

Summary: Growing evidence suggests skilled ball kickers use distinct pelvis and kick leg strategies to achieve successful performance. However, since the interaction between different strategies remains unexplored, the aims of this study were to a) examine relationships between pelvis and kick leg rotations in male players performing soccer instep kicks and b) classify different 'types' of kickers based on the observed movement strategies. Twenty semi-professional players performed kicks for maximal speed and accuracy, and kick leg and pelvis kinematics were analysed using 3D motion capture (1000 Hz). A strong relationship was found between change in pelvis transverse angular velocity and thigh-knee angular velocity ratio upon ball contact (r = 0.76, p < 0.001), and participants were categorised by their location on kick leg (thigh-knee) and pelvis (maintainer-reverser) continuums. Knowledge of a player's preferred strategy can inform departure from 'one size fits all' technical and conditioning training practices towards more individualised approaches. For example, pelvis maintainer-thigh dominant kickers might benefit from focus towards the concentric capabilities of the hip flexors, whereas reverser-knee dominant kickers might benefit from developing the ability to decelerate the pelvis and thigh to induce motion-dependent angular acceleration of the lower leg towards the ball.

 

 

#8 A Very Low Volume of Nordic Hamstring Exercise Increases Maximal Eccentric Strength and Reduces Hamstring Injury Rate in Professional Soccer Players

Reference: J Sport Rehabil. 2022 Jul 13;1-6. doi: 10.1123/jsr.2021-0445. Online ahead of print.

Authors: Jean-Philippe Cadu, Valentin Goreau, Lilian Lacourpaille

Summary: The aim of this study was to determine whether the inclusion of a very low volume (1 set of 3 maximal repetitions) of eccentric-biased Nordic hamstring program of 21 weeks induced an increase in maximal eccentric strength and whether its magnitude was influenced by the compliance rate. The secondary aim of this study was to determine whether this eccentric-biased Nordic hamstring program was effective at reducing hamstring injury rate. Twenty-three professional soccer players formed the experimental group and undertook regular in-season hamstring strength training and monitoring for 21 weeks. Data from 23 players in the immediately preceding cohort (previous year) were included as a control group. The subdivision of the experimental group revealed that the high compliance subgroup (∼13 d between sessions) exhibited higher changes in maximal eccentric strength compared with the low compliance group (∼24 d between sessions; +26.5%; 95% confidence interval, 7.1%-45.9%; P < .001; g = 1.2). Five hamstring injuries (22%) were recorded in the experimental group and 9 (39%) in the control group, corresponding to a nonsignificant 2.7-fold lower risk (P = .12) of suffering hamstring injury in the experimental group. The current study demonstrates that the inclusion of a very low volume of eccentric-biased Nordic hamstring program for 21 weeks induced an increase in maximal eccentric strength (∼15%) in professional soccer players, the magnitude of which depended on the players' compliance. We also found that this program was efficient (2.7-fold lower risk), although nonsignificant, at reducing hamstring injury rate in professional soccer players.

 

 

#9 Effects of Warm-Up Training on Psychomotor Vigilance and Repeated-Sprint Ability of Professional Soccer Referees: A Pilot Study

Reference: Motor Control. 2022 Jul 21;1-18. doi: 10.1123/mc.2022-0037. Online ahead of print.

Authors: Mateu Busquets-Ferrer, Francisco Tomás González-Fernández, Filipe Manuel Clemente, Alfonso Castillo-Rodriguez

Summary: For this research, we analyzed the immediate effects of warm-up condition (WC) or without warm-up condition (WWC) on amateur referees' physical and cognitive functioning. Eight professional soccer referees from the Balearic Committee of Football Referees were the participants of this study. Body composition characteristics were measured and the scores on three tests were recorded: the Yo-Yo intermittent recovery, repeated-sprint ability, and psychomotor vigilance task. Regarding results, the psychomotor vigilance task was performed better after warm-up training (p = .002, η2 = .79) with faster reaction times following WC (M = 318.2, SD = 27.1 ms) than WWC (M = 334.9, SD = 26.1). Similarly, the referees' performance was better on the repeated-sprint ability test after WC (p = .002, d = 0.53) than WWC, with minimum and average power values higher after WC (M = 626.77, SD = 112.57) than WWC (M = 562.35, SD = 79.63). We conclude that re-warm-up training may mitigate the vigilance performance changes caused by effects of rest on soccer referees.

 

 

#10 Quantification of Pre-Season and In-Season Training Intensity across an Entire Competitive Season of Asian Professional Soccer Players

Reference: Healthcare (Basel). 2022 Jul 23;10(8):1367. doi: 10.3390/healthcare10081367.

Authors: Hadi Nobari, Akhilesh Kumar Ramachandran, João Paulo Brito, Rafael Oliveira

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9330844/pdf/healthcare-10-01367.pdf

Summary: The aim of this study was to quantify the training load in two microcycles (Ms) from pre- and another two from in-season and to analyze playing position influences on the load experienced by professional soccer players. Nineteen Asian athletes, including four central defenders, four wide defenders, six central midfielders, three wide midfielders, and two strikers participated in this study. The micro-electromechanical system was used to collect training duration, total distance, and data from Zone 1 (0-3.9 km·h-1), Zone 2 (4-7.1 km·h-1), Zone 3 (7.2-14.3 km·h-1), Zone 4 (14.4-19.7 km·h-1), and Zone 5 (&gt;19.8 km·h-1), heart rate maximum (HRmax), and average (HRavg). The load was reduced on the last day of the Ms, with the exception of Zone 5, in M1, where higher values were found on the last day. Significant differences were observed between central and wide defenders for distance covered in Zone 4 (effect-size: ES = -4.83) in M2 and M4 (ES = 4.96). Throughout all the Ms, a constant HRmax (165-188 bpm) and HRavg (119-145 bpm) were observed. There was a tendency to decrease the load on the last day of the Ms. In general, there were higher external training loads in Ms from the pre-season than in-season. Wide defenders and wide midfielders showed higher distances covered with high-intensity running.

 

 

#11 Regional Lean Soft Tissue and Intracellular Water Are Associated with Changes in Lower-Body Neuromuscular Performance: A Pilot Study in Elite Soccer Players

Reference: Eur J Investig Health Psychol Educ. 2022 Jul 22;12(8):882-892. doi: 10.3390/ejihpe12080064.

Authors: Tindaro Bongiovanni, Grant Tinsley, Giulia Martera, Carmine Orlandi, Federico Genovesi, Giuseppe Puleo, Alessio Rossi, Athos Trecroci

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9332301/pdf/ejihpe-12-00064.pdf

Summary: The assessment of body composition over a competitive season provides valuable information that can help sports professionals to evaluate the efficacy of training and nutritional strategies, as well as monitoring athletes' health status. The purpose of this study was to examine the association of changes in body composition and hydration status with changes in lower-body neuromuscular performance in soccer. Twenty-two male professional soccer players (mean ± SD; age: 26.4 ± 4.8 years; height: 184.3 ± 5.7 cm; body mass: 81.1 ± 6.5 kg; body fat: 11.6 ± 1.5%) took part in the study, for which they were tested at the initial and final stage of the competitive season. Total (whole body) and regional (arms and legs) lean soft tissue (LST) were estimated to obtain the body composition profile. Total body water (TBW) content, including extracellular (ECW) and intracellular (ICW) water, was obtained to monitor players' hydration status. Countermovement jump (CMJ) height, power, and strength were used to derive players' lower-body neuromuscular performance. The results showed that changes in legs LST and ICW significantly (p &lt; 0.01) explained (r2 = 0.39) the improvements in CMJ height, power, and strength from the initial to the final stage of the season. Given the high demand imposed on the lower limbs during a soccer season, being more susceptible to change compared to whole-body LST, assessing regional LST and ICW would be more appropriate to provide extended information on players' readiness.

 

 

#12 A Metabolomic Approach and Traditional Physical Assessments to Compare U22 Soccer Players According to Their Competitive Level

Reference: Biology (Basel). 2022 Jul 25;11(8):1103. doi: 10.3390/biology11081103.

Authors: João Pedro da Cruz, Fábio Neves Dos Santos, Felipe Marroni Rasteiro, Anita Brum Marostegan, Fúlvia Barros Manchado-Gobatto, Claudio Alexandre Gobatto

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9331507/pdf/biology-11-01103.pdf

Summary: The purpose of this study was to use traditional physical assessments combined with a metabolomic approach to compare the anthropometric, physical fitness level, and serum fasting metabolic profile among U22 soccer players at different competitive levels. In the experimental design, two teams of male U22 soccer were evaluated (non-elite = 20 athletes, competing in a regional division; elite = 16 athletes, competing in the first division of the national U22 youth league). Earlobe blood samples were collected, and metabolites were extracted after overnight fasting (12 h). Untargeted metabolomics through Liquid Chromatograph Mass Spectrometry (LC-MS) analysis and anthropometric evaluation were performed. Critical velocity was applied to determine aerobic (CV) and anaerobic (ARC) capacity. Height (non-elite = 174.4 ± 7.0 cm; elite = 176.5 ± 7.0 cm), body mass index (non-elite = 22.1 ± 2.4 kg/m2; elite = 21.9 ± 2.3 kg/m2), body mass (non-elite = 67.1 ± 8.8 kg; elite = 68.5 ± 10.1 kg), lean body mass (non-elite = 59.3 ± 7.1 kg; elite = 61.1 ± 7.9 kg), body fat (non-elite = 7.8 ± 2.4 kg; elite = 7.3 ± 2.4 kg), body fat percentage (non-elite = 11.4 ± 2.4%; elite = 10.5 ± 1.7%), hematocrit (non-elite = 50.2 ± 4.0%; elite = 51.0 ± 4.0%), CV (non-elite = 3.1 ± 0.4 m/s; elite = 3.0 ± 0.2 m/s), and ARC (non-elite = 129.6 ± 55.7 m; elite = 161.5 ± 61.0 m) showed no significant differences between the elite and non-elite teams, while the multivariate Partial Least Squares Discriminant Analysis (PLS-DA) model revealed a separation between the elite and non-elite athletes. Nineteen metabolites with importance for projection (VIP) &gt;1.0 were annotated as belonging to the glycerolipid, sterol lipid, fatty acyl, flavonoid, and glycerophospholipid classes. Metabolites with a high relative abundance in the elite group were related in the literature to a better level of aerobic power, greater efficiency in the recovery process, and improvement of mood, immunity, decision making, and accuracy, in addition to acting in mitochondrial preservation and electron transport chain maintenance. In conclusion, although classical physical assessments were not able to distinguish the teams at different competitive levels, the metabolomics approach successfully indicated differences between the fasting metabolic profiles of elite and non-elite teams.

 

 

#13 Soccer Scoring Techniques-A Biomechanical Re-Conception of Time and Space for Innovations in Soccer Research and Coaching

Reference: Bioengineering (Basel). 2022 Jul 23;9(8):333. doi: 10.3390/bioengineering9080333.

Authors: Gongbing Shan, Xiang Zhang

Download link: https://www.mdpi.com/2306-5354/9/8/333/htm

Summary: Scientifically, both temporal and spatial variables must be examined when developing programs for training various soccer scoring techniques (SSTs). Unfortunately, previous studies on soccer goals have overwhelmingly focused on the development of goal-scoring opportunities or game analysis in elite soccer, leaving the consideration of player-centered temporal-spatial aspects of SSTs mostly neglected. Consequently, there is a scientific gap in the current scoring-opportunity identification and a dearth of scientific concepts for developing SST training in elite soccer. This study aims to bridge the gap by introducing effective/proprioceptive shooting volume and a temporal aspect linked to this volume. The SSTs found in FIFA Puskás Award (132 nominated goals between 2009 and 2021) were quantified by using biomechanical modeling and anthropometry. This study found that players' effective/proprioceptive shooting volume could be sevenfold that of normal practice in current coaching. The overlooked SSTs in research and training practice are commonly airborne and/or acrobatic, which are perceived as high-risk and low-reward. Relying on athletes' talent to improvise on these complex skills can hardly be considered a viable learning/training strategy. Future research should focus on developing player-centered temporal-spatial SST training to help demystify the effectiveness of proprioceptive shooting volume and increase scoring opportunities in soccer.

 

 

#14 Supportive Communities: Conceptualizing Supportive Structures for Coaches' Learning and Well-Being in Community Youth Soccer

Reference: Int J Environ Res Public Health. 2022 Jul 6;19(14):8249. doi: 10.3390/ijerph19148249.

Authors: Krister Hertting, Karin Grahn, Stefan Wagnsson

Download link: https://www.mdpi.com/1660-4601/19/14/8249/htm

Summary: Sweden has an extensive culture of community club sports for children and youths, based on voluntary leadership. Being a voluntary coach can be stressful and can affect coaches' well-being. Since voluntary coaching is closely connected to and conditioned by family life and civil occupation, coaches need support for practical issues as well as for developing their coaching assignment in relation to the constantly changing conditions within sports for children and youths. The aim of this paper was to conceptualize and problematize the supportive structures in everyday activities, in order to promote learning and well-being and to prevent mental health issues. This paper is conceptual and based on a paradigm case. The starting point is communities of practice (CoP) and how CoPs can contribute to the development of supportive structures for coaches in youth sports. In conclusion, a CoP is dependent on negotiation within the coaching team as well as on facilitating factors that can add knowledge, perspectives, and experiences to the CoP. The facilitating factors mean that a CoP has the potential to be health-promoting for both coaches and players. Hence, it is important to create conditions, structures, and support-such as policies, practice-based education, mentorship, and facilitators.

 

 

#15 Rapid Prediction of Retina Stress and Strain Patterns in Soccer-Related Ocular Injury: Integrating Finite Element Analysis with Machine Learning Approach

Reference: Diagnostics (Basel). 2022 Jun 23;12(7):1530. doi: 10.3390/diagnostics12071530.

Authors: Yasin Shokrollahi, Pengfei Dong, Mehmet Kaya, Donny W Suh, Linxia Gu

Download link: https://www.mdpi.com/2075-4418/12/7/1530/htm

Summary: Soccer-related ocular injuries, especially retinal injuries, have attracted increasing attention. The mechanics of a flying soccer ball have induced abnormally higher retinal stresses and strains, and their correlation with retinal injuries has been characterized using the finite element (FE) method. However, FE simulations demand solid mechanical expertise and extensive computational time, both of which are difficult to adopt in clinical settings. This study proposes a framework that combines FE analysis with a machine learning (ML) approach for the fast prediction of retina mechanics. Different impact scenarios were simulated using the FE method to obtain the von Mises stress map and the maximum principal strain map in the posterior retina. These stress and strain patterns, along with their input parameters, were used to train and test a partial least squares regression (PLSR) model to predict the soccer-induced retina stress and strain in terms of distributions and peak magnitudes. The peak von Mises stress and maximum principal strain prediction errors were 3.03% and 9.94% for the frontal impact and were 9.08% and 16.40% for the diagonal impact, respectively. The average prediction error of von Mises stress and the maximum principal strain were 15.62% and 21.15% for frontal impacts and were 10.77% and 21.78% for diagonal impacts, respectively. This work provides a surrogate model of FE analysis for the fast prediction of the dynamic mechanics of the retina in response to the soccer impact, which could be further utilized for developing a diagnostic tool for soccer-related ocular trauma.

 

 

#16 Goal or Miss? A Bernoulli Distribution for In-Game Outcome Prediction in Soccer

Reference: Entropy (Basel). 2022 Jul 13;24(7):971. doi: 10.3390/e24070971.

Authors: Wendi Yao, Yifan Wang, Mengyao Zhu, Yixin Cao, Dan Zeng

Download link: https://www.mdpi.com/1099-4300/24/7/971/htm

Summary: Due to a colossal soccer market, soccer analysis has attracted considerable attention from industry and academia. In-game outcome prediction has great potential in various applications such as game broadcasting, tactical decision making, and betting. In some sports, the method of directly predicting in-game outcomes based on the ongoing game state is already being used as a statistical tool. However, soccer is a sport with low-scoring games and frequent draws, which makes in-game prediction challenging. Most existing studies focus on pre-game prediction instead. This paper, however, proposes a two-stage method for soccer in-game outcome prediction, namely in-game outcome prediction (IGSOP). When the full length of a soccer game is divided into sufficiently small time frames, the goal scored by each team in each time frame can be modeled as a random variable following the Bernoulli distribution. In the first stage, IGSOP adopts state-based machine learning to predict the probability of a scoring goal in each future time frame. In the second stage, IGSOP simulates the remainder of the game to estimate the outcome of a game. This two-stage approach effectively captures the dynamic situation after a goal and the uncertainty in the late phase of a game. Chinese Super League data have been used for algorithm training and evaluation, and the results demonstrate that IGSOP outperforms existing methods, especially in predicting draws and prediction during final moments of games. IGSOP provides a novel perspective to solve the problem of in-game outcome prediction in soccer, which has a potential ripple effect on related research.