Latest research in football - week 16 - 2023

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 Effects of plyometric training on kicking performance in soccer players: A systematic review and meta-analysis

Reference: Front Physiol. 2023 Apr 13;14:1072798. doi: 10.3389/fphys.2023.1072798. eCollection 2023.

Authors: Yeqin Zhang, Danyang Li, Miguel-Ángel Gómez-Ruano, Daniel Memmert, Chunman Li, Ming Fu

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Summary: This systematic review and meta-analysis aimed to determine the pooled effect size (ES) of plyometric training (PT) on kicking performance (kicking speed and distance) in soccer players depending upon some related factors (i.e., age, gender, skill level, and intervention duration). This study was carried out according to the PRISMA guidelines. Four electronic databases-EBSCO, PubMed, Scopus, and Web of Science-were searched for relevant studies. A total of n = 16 studies yielding 17 ES with n = 553 participants were finally included in the meta-analysis. A random-effects model was used to calculate Hedge's g with a 95% confidence interval (CI), which showed that plyometric training had a large-sized positive effect on soccer kicking performance (g = 0.979, 95% CI [0.606, 1.353], p < 0.001). Subgroup analyses were performed according to participants' characteristics (i.e., age, gender, skill level) and intervention duration, demonstrating no significant differences between these subgroups. The study pointed out that plyometric training is a generally effective method to improve soccer players' kicking performance, which plays a crucial role in passing and shooting actions during games. As for soccer players and strength and conditioning coaches, the plyometric training aiming to enhance kicking performance has valuable implications in practice. Therefore, besides well-known training methods like power training in the weight room, plyometric training could be incorporated into the overall strength and conditioning programs for soccer players to reach high standards of kicking performance.



#2 Association between internal load responses and recovery ability in U19 professional soccer players: A machine learning approach

Reference: Heliyon. 2023 Apr 13;9(4):e15454. doi: 10.1016/j.heliyon.2023.e15454. eCollection 2023 Apr.

Authors: Guglielmo Pillitteri, Alessio Rossi, Carlo Simonelli, Ignazio Leale, Valerio Giustino, Giuseppe Battaglia

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Summary: The objective of soccer training load (TL) is enhancing players' performance while minimizing the possible negative effects induced by fatigue. In this regard, monitoring workloads and recovery is necessary to avoid overload and injuries. Given the controversial results found in literature, this study aims to better understand the complex relationship between internal training load (IL) by using rating of perceived exertion (RPE), recovery, and availability (i.e., subjective players' readiness status). In this cross-sectional study, twenty-two-professional soccer players (age: 18.5 ± 0.4 years, height: 177 ± 6 cm, weight: 67 ± 6.7 kg) competing in the U19 Italian Championship were monitored using RPE scale to assess IL, and TreS scale to detect information about recovery and training/match availability during an entire season (2021-2022). Autocorrelation analysis showed a repeated pattern with 7 days lag (weekly microcycle pattern) for all the variables considered (i.e., TL, recovery, and availability). For recovery (r = 0.64, p < 0.001) and availability (r = 0.63, p < 0.001) the best lag for both of them is 1 day. It indicates that recovery and availability are related to the past day value. Moreover, TL was found to be negatively affected by recovery and availability of the current day (lag = 0 day). Cross-correlation analysis indicates that TL is negatively affected by recovery (r = 0.46, p < 0.001) and availability (r = 0.42, p < 0.001) of the current day (lag = 0 day). In particular, lower recovery and availability will result in following lower TL. Furthermore, we found that TL negatively affects recovery (r = 0.52, p < 0.001) and availability (r = 0.39, p < 0.01) of the next day (lag = 1 day). In fact, the higher the TL in a current day is, the lower the recovery and availability in the next day will be. In conclusion, this study highlights that there is a relationship between TL and recovery and that these components influence each other both on the same day and on the next one. The use of RPE and TreS scale to evaluate TL and recovery/availability of players allows practitioners to better adjust and schedule training within the microcycle to enhance performance while reducing injury risk.



#3 High-intensity Actions in Elite Soccer: Current Status and Future Perspectives

Reference: Int J Sports Med. 2023 May 2. doi: 10.1055/a-2013-1661. Online ahead of print.

Authors: Alberto Filter, Jesús Olivares-Jabalera, Thomas Dos'Santos, Marc Madruga, JoséMaríaOliva Lozano, Alejandro Molina, Alfredo Santalla, Bernardo Requena, Irineu Loturco

Summary: Over the years, soccer has become more physically demanding; the number and frequency of high-intensity actions have increased, and these activities are decisive in determining the match outcome. Importantly, the reductionist approach commonly used to analyze high-intensity actions does not contemplate a more contextualized perspective on soccer performance. Traditionally, most investigations have only provided quantitative data regarding sprints (i. e. time, distances, frequency) without examining "how" (e. g. type of trajectory or starting position) and "why" (e. g. tactical role) soccer players sprint. In fact, other high-intensity actions, apart from running, are not even mentioned (i. e. curve sprints, change of direction, and specific-jump tasks). This has led to the use of tests and interventions that do not accurately reflect real game actions. Given the true technical-tactical-physical demands of each playing position, this narrative review collected a wide-spectrum of current soccer-related articles and provided a discussion regarding high-intensity actions, with a positional-based approach. In this narrative review, practitioners are encouraged to contemplate and consider the different elements that characterize high-intensity actions in soccer, in order to assess and train soccer players under a more sport-specific and integrative perspective.



#4 Reliability and validity of the 21-m shuttle-run test and its application to youth soccer players during the preseason training

Reference: Phys Act Nutr. 2023 Mar;27(1):55-59. doi: 10.20463/pan.2023.0007. Epub 2023 Mar 31.

Author: Kyeongho Byun

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Summary: This study has two purposes: first to assess the reliability and validity of the 21-m shuttle-run test (21-m SRT) and, second, to evaluate the practicality of the 21-m SRT for youth soccer players during preseason training. Twenty-seven youth soccer players (15.9 ± 0.7 yrs., males) participated in the present study. To assess the reliability of the test, each player performed the 21-m SRT twice, on separate days. Criterion validity of the 21-m SRT was determined by examining the relationship between directly measured V3 O2max and 21-m SRT performance. To test the practicality of the 21-m SRT, three 21-m SRTs and two graded exercise tests on a treadmill were performed by each youth soccer player during preseason training. Results revealed that the 21-m SRT has high correlation coefficients (r = 0.87) between test and retest and has moderate correlation coefficients (r = 0.465) between V3 O2max and SRT performance. As V3 O2max significantly increased after the training period, SRT performance (distance and heart rate immediately after the 67th shuttle run) also positively changed during the preseason training period. The 21-m SRT has high reliability with moderate validity, and it is an effective tool for coaches to examine aerobic capacity and the efficacy of a training program for youth soccer players during the preseason training period.



#5 Can the supplementation of vitamin D, sun exposure, and isolation during the COVID-19 pandemic affect the seasonal concentration of 25(OH)D and selected blood parameters among young soccer players in a one-year training season?

Reference: J Int Soc Sports Nutr. 2023 Dec;20(1):2206802. doi: 10.1080/15502783.2023.2206802.

Authors: Joanna Jastrzębska, Maria Skalska, Łukasz Radzimiński, Guillermo F López Sánchez, Lee Hill, Katja Weiss, Beat Knechtle

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Summary: This study examined the effect of vitamin D supplementation, sunlight radiationradiation, and home isolation during the COVID-19 pandemic on the seasonal changes in 25(OH)D concentration and selected biomarkers in young soccer players along a one-year training cycle. Forty elite young soccer players (age: 17.2 ± 1.16 years, body mass: 70.2 ± 5.84, and body height: 179.1 ± 4.26 cm) participated in the research. Only 24 players completed the measurements during all four time- points (T1-: September 2019, T2-: December 2019, T3-: May 2020, and T4-: August 2020) and were divided into two subgroups: supplemented group (GS) and placebo group (GP). Players from GS received 5,000 IU of vitamin D for 8 weeks (January-MarchJanuary-March 2020). Several biomarkers such as 25(OH)D, white blood cells (WBC), red blood cells (RBC), hemoglobin (HGB), muscle damage markersmarkers, and lipid profile were measured. AnalysisThe analysis of the total group demonstrated significant seasonal changes in 25(OH)D, HGB, asparagine aminotransferaseaminotransferase, and creatine kinase along the one1-year training cycle. The level of 25(OH)D concentrationinconcentration in T4 was significantly (p < 0.001, pη [ = 0.82) higher in both subgroups in comparison to T2 and T3. Moreover, the significant (p = 0.023) but poor (r = -0.23) correlation between 25(OH)D and WBC was calculated. Current research confirmed the significant seasonal changes in 25(OH)D concentration during four seasons. 8-weekEight-week vitamin D supplementation had no extended effect on the level of 25(OH)D concentration.



#6 Effectiveness of Injury Prevention Programs With Core Muscle Strengthening Exercises to Reduce the Incidence of Hamstring Injury Among Soccer Players: A Systematic Review and Meta-Analysis

Reference: Sports Health. 2023 May 4;19417381231170815. doi: 10.1177/19417381231170815.

Authors: Wesam Saleh A Al Attar, Mohamed A Husain

Summary: Muscles in the hamstring group are frequently injured in sporting activities. Injury prevention programs (IPPs), including eccentric training of the hamstrings, have proven to be of great value in decreasing the injury rate of hamstring muscles. The aim was too examine the effectiveness of IPPs that include core muscle strengthening exercises (CMSEs) in reducing hamstring injury rates. This systematic review with meta-analysis was based upon the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search was conducted for relevant studies published from 1985 to 2021 using the following databases: Cochrane Library, MEDLINE, AMED, PubMed, Web of Science, and Physiotherapy Evidence Database (PEDro). The initial electronic search found 2694 randomized controlled trials (RCTs). After removing duplicate entries, 1374 articles were screened by their titles and abstracts, and 53 full-text records were assessed, of which 43 were excluded. The remaining 10 articles were reviewed in detail, from which 5 studies met our inclusion criteria and were included in the current meta-analysis. Two researchers independently completed the abstract review and performed full-text reviews. A third reviewer was consulted to reach a consensus if any discrepancies were noted. Details were recorded about the participants, methodological aspects, eligibility criteria, intervention data, and outcome measures, including age; number of subjects in the intervention/control group; number of injuries in each group; and the duration, frequency, and intensity of the training conducted in the intervention. The pooled results of 4728 players and 379,102 exposure hours showed 47% hamstring injury reduction per 1000 h of exposure in the intervention group compared with the control group with an injury risk ratio of 0.53 (95% CI [0.28, 0.98], P = 0.04). The results indicate that CMSEs incorporated with IPPs reduce susceptibility and risk of hamstring injuries in soccer players.



#7 Prediction of Shooting Events in Soccer Videos Using Complete Bipartite Graphs and Players' Spatial-Temporal Relations

Reference: Sensors (Basel). 2023 May 5;23(9):4506. doi: 10.3390/s23094506.

Authors: Ryota Goka, Yuya Moroto, Keisuke Maeda, Takahiro Ogawa, Miki Haseyama

Summary: In soccer, quantitatively evaluating the performance of players and teams is essential to improve tactical coaching and players' decision-making abilities. To achieve this, some methods use predicted probabilities of shoot event occurrences to quantify player performances, but conventional shoot prediction models have not performed well and have failed to consider the reliability of the event probability. This paper proposes a novel method that effectively utilizes players' spatio-temporal relations and prediction uncertainty to predict shoot event occurrences with greater accuracy and robustness. Specifically, we represent players' relations as a complete bipartite graph, which effectively incorporates soccer domain knowledge, and capture latent features by applying a graph convolutional recurrent neural network (GCRNN) to the constructed graph. Our model utilizes a Bayesian neural network to predict the probability of shoot event occurrence, considering spatio-temporal relations between players and prediction uncertainty. In our experiments, we confirmed that the proposed method outperformed several other methods in terms of prediction performance, and we found that considering players' distances significantly affects the prediction accuracy.



#8 Decision-Making Time and Neuromuscular Coordination in Youth and Senior Soccer Goalkeepers

Reference: Sensors (Basel). 2023 May 4;23(9):4483. doi: 10.3390/s23094483.

Authors: Katarzyna Piechota, Edyta Majorczyk

Summary: The aim of this study was to compare soccer goalkeepers' decision-making times following a shot on goal and to determine goalkeepers' movement pattern structures using EMG in a typical game situation (two-on-one). Two groups of goalkeepers (n = 60) took part in the study: Group A, the senior group (22.00 ± 2.35 years of age), and Group B, the youth group (15.38 ± 1.32 years of age). The goalkeepers' decision-making times were measured by using EMG from the moment the attacker struck the ball until the completion of the saving action by the goalkeeper. Subsequently, the goalkeepers' movement pattern structure was determined (for both Groups A and B), and the values of muscle bioelectrical tension during a typical defensive situation in training conditions were revealed. The findings clearly indicate a significantly (p = 0.001) shorter decision-making time in experienced goalkeepers (250-260 ms) than in novices (300-320 ms). In addition, the movement pattern structure confirmed the hypotheses on the economization of effort and the visual-muscular coordination of the postural muscles (calf muscles) that affect soccer goalkeepers. The study also demonstrated a lower bioelectric tension of the gastrocnemius muscle (GAS.MED. RT-p = 0.008; GAS.LAT. RT-p = 0.030) in the expert goalkeepers.



#9 Maturity-associated variation in the body size, physical fitness, technical efficiency, and network-based centrality measures in young soccer players

Reference: Sci Rep. 2023 May 11;13(1):7693. doi: 10.1038/s41598-023-34833-1.

Authors: Paulo Henrique Borges, Julio Cesar da Costa, Luiz Fernando Ramos-Silva, Vanessa Menezes Menegassi, Gibson Moreira Praça, Felipe Arruda Moura, Enio Ricardo Vaz Ronque

Summary: This study aimed to observe the relationships between the maturity status on the network-based centrality measures of young athletes in small-sided soccer games (SSG). The study included 81 male players (14.4 ± 1.1 years). Measurements included height, sitting height, body mass, and bone age (TW3 method). The applied protocols were the following: Countermovement Jump (CMJ), Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1), Repeated Sprints Ability (RSA), observational analysis of techniques, and interactions performed by players in SSG. The relationship between the set of evaluated variables within each maturity status was obtained from the correlational analysis of networks (P < 0.05). The maturity status explained a significant portion of the variance in body mass (η2 = 0.37), height (η2 = 0.30), sitting height (η2 = 0.30), and performance on the YYIRT1 (η2 = 0.08), CMJ (η2 = 0.14), and RSA (η2 = 0.13). No effect of maturity status on network-based centrality measures of young athletes was identified (P > 0.05). For the late maturity group, there was a correlation between the degree of centrality and physical growth indicators (rmean = 0.88). For players with maturation "on time", physical growth indicators relate to the degree of prestige (rmean = 0.36). It is concluded that body size and bone age impact how late and on-time maturity groups interact within the match.



#10 Reliability of individual acceleration-speed profile in-situ in elite youth soccer players

Reference: J Biomech. 2023 May;153:111602. doi: 10.1016/j.jbiomech.2023.111602. Epub 2023 Apr 26.

Authors: P Clavel, C Leduc, J-B Morin, M Buchheit, M Lacome

Summary: The aims of this study were to describe differences in the acceleration-speed (A-S) profile in-situ and to assess the week-to-week reliability of the A-S profile in-situ over a given training cycle of elite youth soccer players, in relation to the number of sessions included and analyse the effect of the inclusion or not of a specific sprint session. In this retrospective study, 18 male elite U19 football players (179.4 ± 7.1 cm; 69.0 ± 9.5 kg) participated. GPS data collected from three consecutive typical training weeks were used to calculate different combinations of A-S profile in-situ variables (theoretical maximal acceleration [A0], theoretical maximal speed [S0] and the slope of the acceleration-speed [ASslope]). The number (and content) of sessions affected mainly S0 while A0 remained similar with or without a sprint session. The reliability of the A-S profile in-situ is more related to the spread of points rather than a specific number of sessions (and thus points) and was improved when a high percentage of maximum speed (i.e. ≥ 95%) was reached. The present study showed low week-to-week variability for A0, S0 and ASslope. However, practitioners need to make sure that the values cover a sufficient range of raw data [20-95% of maximum speed] to build a clear and consistent linear regression, and in turn extrapolate meaningful A-S profile values.



#11 Effects of cold water immersion and protein intake combined recovery after eccentric exercise on exercise performance in elite soccer players

Reference: J Exerc Rehabil. 2023 Apr 27;19(2):126-133. doi: 10.12965/jer.2244596.298. eCollection 2023 Apr.

Authors: Hyoung-Won Kim, Chang-Hwa Joo

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Summary: The purpose of this study is to analyze the effects of the combined recovery method of cold water immersion (CWI) and protein supplement intake after eccentric exercise that causes muscle fatigue in elite soccer players. Eleven semiprofessional soccer players participated in this study. Participants were divided into CWI group, combined protein and CWI group (PCWI), and passive resting group (CON). The participants completed the eccentric exercise for one hour and performed one of three recovery methods. The muscle strength of the quadriceps and hamstring muscles significantly decreased at 48-hr postexercise compared to before exercise in all recovery groups (P<0.05), with no significantly different between the recovery groups. The time required to sprint 40 m was significantly longer in all groups at 24 hr and 48 hr after exercise than before exercise (P<0.05). The vertical jump height was significantly decreased at 48 hr after exercise compared to before exercise in the CON and CWI groups (P<0.05). The muscle soreness values were higher at 6 hr, 24 hr, and 48 hr after exercise than before exercise in all groups (P<0.001). The perceived recovery quality was reduced after exercise in the PCWI (P<0.01) and CON groups (P<0.001) compared to before exercise; it was unchanged in the CWI group. The recovery quality decreased at 6 hr, 24 hr, and 48 hr after exercise in all recovery groups (P<0.01). In conclusion, the combined recovery method was less effective than CWI alone for the recovery of exercise performance.



#12 Return to Play and Performance After Anterior Cruciate Ligament Reconstruction in the National Women's Soccer League

Reference: Orthop J Sports Med. 2023 May 4;11(5):23259671231164944. doi: 10.1177/23259671231164944. eCollection 2023 May.

Authors: Varag Abed, Ajith Dupati, Gregory S Hawk, Darren Johnson, Caitlin Conley, Austin V Stone

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Summary: The anterior cruciate ligament (ACL) is commonly injured in elite-level female athletes, which usually requires ACL reconstruction (ACLR). The aim was to analyze return to play (RTP) and changes in performance of players in the National Women's Soccer League (NWSL) after ACLR. NWSL players who sustained an ACL tear and underwent surgery between the 2013 and 2020 seasons were identified by multiple online resources. Players were classified as forwards, defenders, midfielders, and goalkeepers. RTP was assessed according to games played, games started, percentage of minutes played, plus/minus net per 90 minutes (a measure of a player's contribution to their team's performance while on the field), goals scored, and assists. A subanalysis was performed based on the median age at the time of the injury (≤24 vs ≥25 years). Nonparametric testing methods were used throughout the analysis. A total of 30 NWSL athletes were included. Midfielders had the highest percentage of injuries (n = 11; 36.7%), followed by forwards (n = 10; 33.3%). Overall, 27 players returned to the NWSL at a median of 12.1 months (IQR, 10.9-14.3 months), constituting a 90.0% RTP rate. There was a significant decrease in the percentage of minutes played from 1 year before the injury to 1 year after the injury (median, 87.9% [IQR, 80.7%-90.6%] vs 25.1% [IQR, 16.3%-57.2%], respectively; P = .031). Forwards and midfielders had a significant decrease in the number of assists from 1 year before the injury to 1 year after the injury (median, 3.0 [IQR, 1.0-3.0] vs 0.0 [IQR, 0.0-1.0], respectively; P = .037) as well as the number of goals scored when averaging across 2 seasons before the injury to 2 seasons after the injury (median, 3.0 [IQR, 1.5-5.5] vs 1.0 [IQR, 0.5-3.5], respectively; P = .031). On subanalysis, older players started in significantly more games (median, 12.0 [IQR, 3.8-18.5] vs 3.0 [IQR, 0.5-6.0], respectively; P = .048) and had a higher percentage of minutes played (median, 63.0% [IQR, 18.8%-77.3%] vs 14.9% [IQR, 2.0%-21.2%], respectively; P = .046) at 1 year after the injury versus younger players. There was a 90.0% RTP rate after ACLR in the NWSL. Players who returned to the NWSL had a lower percentage of minutes played in their first year after RTP, with older players starting in more games and having a greater percentage of minutes played. Compared with preinjury performance, forwards and midfielders had a significant decrease in the number of assists at 1 year after the injury as well as the number of goals scored at 2 years after the injury.



#13 Exploring the role of socioeconomic status and psychological characteristics on talent development in an English soccer academy

Reference: Sci Med Footb. 2023 May 10. doi: 10.1080/24733938.2023.2213191. Online ahead of print.

Authors: Adam L Kelly, Craig A Williams, Daniel T Jackson, Jennifer Turnnidge, Matthew J Reeves, James H Dugdale, Mark R Wilson

Summary: Social factors and psychological characteristics can influence participation and development in talent pathways. However, the interaction between these two factors is relatively unknown. The aim of this study was to investigate the implications of socioeconomic status and psychological characteristics in English academy soccer players (n=58; aged 11 to 16 years). To assess socioeconomic status, participants' home postcodes were coded according to each individual's social classification and credit rating, applying the UK General Registrar Classification system and CameoTM geodemographic database, respectively. Participants also completed the six factor Psychological Characteristics for Developing Excellence Questionnaire (PCDEQ). A classification of 'higher-potentials' (n=19) and 'lower-potentials' (n=19) were applied through coach potential rankings. Data were standardised using z-scores to eliminate age bias and data were analysed using independent sample t-tests. Results showed that higher-potentials derived from families with significantly lower social classifications (p=0.014) and reported higher levels for PCDEQ Factor 3 (coping with performance and developmental pressures) (p=0.007) compared to lower-potentials. This study can be used to support the impetus for researchers and practitioners to consider the role of social factors and psychological characteristics when developing sporting talent. For example, facilitating player-centred development within an academy and, where necessary, providing individuals with additional support.



#14 Severe CTE and TDP-43 pathology in a former professional soccer player with dementia: a clinicopathological case report and review of the literature

Reference: Acta Neuropathol Commun. 2023 May 10;11(1):77. doi: 10.1186/s40478-023-01572-3.

Authors: Suzan van Amerongen, Suzie Kamps, Kyra K M Kaijser, Yolande A L Pijnenburg, Philip Scheltens, Charlotte E Teunissen, Frederik Barkhof, Rik Ossenkoppele, Annemieke J M Rozemuller, Robert A Stern, Jeroen J M Hoozemans, Everard G B Vijverberg

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Summary: In the last decades, numerous post-mortem case series have documented chronic traumatic encephalopathy (CTE) in former contact-sport athletes, though reports of CTE pathology in former soccer players are scarce. This study presents a clinicopathological case of a former professional soccer player with young-onset dementia. The patient experienced early onset progressive cognitive decline and developed dementia in his mid-50 s, after playing soccer for 12 years at a professional level. While the clinical picture mimicked Alzheimer's disease, amyloid PET imaging did not provide evidence of elevated beta-amyloid plaque density. After he died in his mid-60 s, brain autopsy showed severe phosphorylated tau (p-tau) abnormalities fulfilling the neuropathological criteria for high-stage CTE, as well as astrocytic and oligodendroglial tau pathology in terms of tufted astrocytes, thorn-shaped astrocytes, and coiled bodies. Additionally, there were TAR DNA-binding protein 43 (TDP-43) positive cytoplasmic inclusions in the frontal lobe and hippocampus, and Amyloid Precursor Protein (APP) positivity in the axons of the white matter. A systematic review of the literature revealed only 13 other soccer players with postmortem diagnosis of CTE. Our report illustrates the complex clinicopathological correlation of CTE and the need for disease-specific biomarkers.



#15 College Soccer Student-Athletes Demonstrate Differences in Self-Reported Athlete Health When Grouped by Match Volume

Reference: J Sport Rehabil. 2023 May 9;1-8. doi: 10.1123/jsr.2022-0266. Online ahead of print.

Authors: Brett S Pexa, Justin P Waxman, Audrey E Westbrook, Kevin R Ford

Summary: Physical changes following activity are well documented, but there is limited information about self-reported outcomes around competitive matches. High training volumes and poor recovery could predispose athletes to overuse injury. The purpose of this study was to identify the changes in daily athlete health measures before, during, and after the day of each match in high- and low-volume groups. Fifty-five soccer athletes (age: 19.8 [1.2] y, 26 males, 29 females) provided daily measures of readiness, physical fatigue, mental stress, sleep quality, and soreness intensity match days, days 1 (D01) and 2 (D02) following matches, and standard practice days. Participants were grouped into high volume and low volume, based off the minutes played during the season. Soreness increased, readiness decreased, and fatigue increased on D01 compared with match days (P < .008) in the high-volume group. Between groups, the high-volume group demonstrated higher soreness on D01 and D02, lower readiness on D01 and D02, and lower fatigue on D01, compared with the low-volume group (P < .008). Soccer athletes demonstrate significant changes in self-reported athlete health variables around competitive matches. These changes are similar to physical outcomes, potentially indicating that the athlete health variables may be used to track athlete recovery from competition, potentially limiting the impact of overuse injuries.



#16 Dietary intakes and daily distribution patterns of macronutrients in youth soccer players

Reference: Front Nutr. 2023 Apr 20;10:1134845. doi: 10.3389/fnut.2023.1134845. eCollection 2023.

Authors: Diogo V Martinho, Robert J Naughton, César Leão, João Lemos, Adam Field, Ana Faria, André Rebelo, Élvio R Gouveia, Hugo Sarmento

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Summary: There has been an abundance of dietary analysis research conducted on adult male soccer players, while studies on youth players are lacking. Furthermore, the daily distribution of energy and macronutrient intake throughout the day has been reported to influence training adaptations, but this is often not considered in the literature. This study aims to quantify daily energy and macronutrient intake and assess their distribution over 5 days, and compare daily energy intakes and predicted daily energy expenditure in under-16 male soccer players. The sample included 25 soccer participants aged 14.8-15.7 years. Five-day self-reported food diaries were used to record the food/drink consumption. Intake was analyzed for total daily energy, macronutrient intakes, and distribution among meals (breakfast, lunch, dinner, and snacks). Daily energy expenditure was predicted by resting energy expenditure and physical activity levels developed for youth sports participants. The mean total energy intake was 1,928 ± 388 kcal∙day-1, whereas the estimated daily energy expenditure was 3,568 kcal∙day-1. Relative daily protein intakes were lower at breakfast, morning snack, afternoon snack, and night snack compared to lunch and dinner. Youth soccer players do not appear to meet energy requirements and daily CHO guidelines. Fluctuations in protein intake throughout the day were noted and may influence training adaptations (i.e., muscle protein synthesis and recovery).



#17 Soccer heading immediately alters brain function and brain-muscle communication

Reference: Front Hum Neurosci. 2023 Apr 20;17:1145700. doi: 10.3389/fnhum.2023.1145700. eCollection 2023.

Authors: Johnny V V Parr, Liis Uiga, Ben Marshall, Greg Wood

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Summary: There is growing evidence of a link between repetitive soccer heading and the increased incidence of neurodegenerative disease. Even a short bout of soccer heading has been shown to impair cognitive performance and disrupt movement control. However, a greater understanding of the mechanisms behind these immediate impairments is needed. The current study attempted to identify how a short bout of soccer heading alters brain function and brain-muscle communication during a movement task. Sixty soccer players were exposed to either an acute bout (i.e., 20 balls thrown underarm) of soccer heading (n = 30) or a control condition where participants (n = 30) headed soccer balls in virtual reality (VR). Before and after heading, we measured cognitive performance on the King-Devick test, as well as electromyography (EMG), electroencephalography (EEG) and brain-muscle communication (i.e., corticomuscular coherence; CMC) during a force precision task. Following the heading protocol, the VR group improved their cognitive performance whereas the Heading group showed no change. Both groups displayed more precise force contractions at post-test. However, the VR group displayed elevated frontal theta activity and global increases in alpha and beta activity during the contraction task, whereas the Heading group did not. Contrary to our expectations, the Heading group displayed elevated CMC, whereas the VR group showed no change. Our findings indicate a short bout of soccer heading may impair cognitive function and disrupt the organization of efficient neural processes that typically accompany motor skill proficiency. Soccer heading also induced corticomuscular hyperconnectivity, which could represent compensatory brain-muscle communication and an inefficient allocation of increased task-related neuromuscular resources. These initial findings offer insights to the mechanisms behind the impairments experienced after a short bout of repetitive soccer heading.


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