Latest research in football - week 4 - 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 The Level of Selected Blood Parameters in Young Soccer Players in Relation to the Concentration of 25(OH)D at the Beginning and End of Autumn

Reference: Biology (Basel). 2023 Jan 13;12(1):129. doi: 10.3390/biology12010129.

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

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Summary: This study aimed to demonstrate the changes of selected blood parameters in relation to 25(OH)D concentration during the autumn period in young soccer players. A total of 35 participants' results (age: 17.5 ± 0.6 years, body mass 71.3 ± 6.9 kg) were tested twice: in mid-September and in mid-December and divided into subgroups with regard to two criteria. First, according to the initial level of the 25(OH)D concentration (optimal group-ODG, suboptimal group-SDG), second, according to drops in 25(OH)D concentration (high drop group-HDG, low drop group-LDG). A significant decrease (p < 0.001) in the 25(OH)D concentration was reported in the total group (TGr) and in all subgroups. Blood parameters such as white blood cells, red blood cells, haemoglobin and haematocrit increased significantly (p < 0.05) in TGr during the analysed period of time. The analysis of changes in the lipid profile did not expose significant differences except triglycerides. The asparagine amino transferase and creatine kinase activity decreased significantly after autumn in all analysed groups. The declining level of 25(OH)D concentration should be compensated (e.g., with vitamin D supplementation) during autumn. Applied training loads could also influence the blood parameters variability in young soccer players. Regular measurements of 25(OH)D concentration are helpful in identifying potential drops and allows for the preparation of individual supplementation plans for the players.



#2 Effects of Biological Age on Athletic Adaptations to Combined Plyometric and Sprint with Change of Direction with Ball Training in Youth Soccer Players

Reference: Biology (Basel). 2023 Jan 12;12(1):120. doi: 10.3390/biology12010120.

Authors: Hamza Marzouki, Samar Sbai, Ibrahim Ouergui, Okba Selmi, Marilia S Andrade, Ezdine Bouhlel, Mabliny Thuany, Katja Weiss, Pantelis T Nikolaidis, Beat Knechtle

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Summary: There is evidence for the effectiveness of youth combined plyometric and sprint with change of direction (COD) training. However, the evidence is not well-known regarding the in-season effects of biological age (peak height velocity-PHV) on the motor adaptive processes following combined plyometric and COD with ball training (P-CODBT) in youth soccer players. This study aimed to examine the in-season effects of P-CODBT (8 weeks and twice a week) on the athletic performances of male youth soccer players, circa- and post-PHV. In a randomized controlled training study with pre-to-post measurements, forty-eight male players were assigned into two experimental (performing P-CODBT; n = 12 × circa-PHV and n = 12 × post-PHV) and two control groups (CONG; n = 12 × circa-PHV and n = 12 × post-PHV). The pre- and post-training participants were assessed for their anthropometric, linear sprinting with and without a ball, COD speed with and without a ball, vertical jump, dynamic balance, and endurance-intensive performances. After the intervention, the experimental condition induced significant (all p < 0.0001) and small to large effect size (ES = 0.263-3.471) additional gains only on explosive measures compared to CONG. Both the experimental (all p < 0.0001; ES = 0.338-1.908) and control (p = 0.011-0.0001; ES = 0.2-1.8) groups improved their athletic performances over the training period. The improvements generated by p-CODBT were not affected by biological age. In-season short-term P-CODBT (twice a week) could be safe way to generate benefits in explosive performances in youth soccer players, which are relevant components of match-winning actions in soccer.



#3 Factors influencing the implementation of the EuroFIT lifestyle change program in professional football clubs in Europe: a qualitative study in four European countries

Reference: Transl Behav Med. 2023 Jan 24;ibac100. doi: 10.1093/tbm/ibac100. Online ahead of print.

Authors: Femke van Nassau, Anita Huis, Irene van de Glind, Eivind Andersen, Christopher Bunn, Cindy M Gray, Kate Hunt, Judith G M Jelsma, Willem van Mechelen, Heather Morgan, Øystein Røynesdal, Hugo V Pereira, Hidde P van der Ploeg, Glyn C Roberts, Marlene N Silva, Marit Sørensen, Sally Wyke, Maria W G Nijhuis-van der Sanden, Theo van Achterberg

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Summary: This paper investigated facilitators and barriers to implementing the European Football Fans in Training program (EuroFIT) in professional sports clubs in England, the Netherlands, Norway, and Portugal. We analyzed qualitative data collected at clubs that delivered EuroFIT, based on semi-structured interviews with coordinating staff (n = 15), coaches (n = 16), and focus group interviews with participants (n = 108), as well as data from clubs that considered delivering EuroFIT in the future, based on interviews with staff (n = 7) and stakeholders (n = 8). Facilitators for implementation related to the content and structure of the program, its evidence-base, and the context for delivery in the football stadia. Financial and human resources were both facilitators and barriers. Further barriers were mostly practical, relating to human resources and infrastructure. Major differences between countries related to experience and commitment to running community projects, and differences in infrastructure, financing, and human resources. Professional football clubs' ability to support health promotion efforts depended on their ethos and the financial and human resources available to them. Overall, the EuroFIT program was well received by clubs, coaches, participants, and stakeholders, which was reflected by the many facilitators supporting sustained implementation. For sustainable implementation, it is crucial that clubs and their stakeholders engage fully with the EuroFIT program and understand that for an adequate program delivery their views (ethos) and ways of working influence the implementation and thereby the effectiveness of EuroFIT. An important prerequisite for future roll out of EuroFIT would be a strong EuroFIT delivery partner organization to ensure financial and human resources while overseeing and guiding the quality of delivery in clubs.



#4 Football movement profile analysis and creatine kinase relationships in youth national team players

Reference: Physiol Int. 2023 Jan 24. doi: 10.1556/2060.2023.00160. Online ahead of print.

Authors: György Szigeti, Gábor Schuth, Tamás Kovács, Péter Revisnyei, Alija Pasic, Ádám Szilas, Tim Gabbett, Gábor Pavlik

Summary: Creatine kinase (CK) is widely used as a monitoring tool to make inferences on fatigue and readiness in elite soccer. Previous studies have examined the relationship between CK and GPS parameters, however these metrics may not accurately describe the players' load during soccer-specific movements. Football Movement Profile (FMP) monitoring is a viable option for such purposes, providing solely inertial sensor-based data and categorizing movements according to intensity (very low, low, medium, high) and movement type (running-linear locomotive, dynamic - change of direction or speed). We investigated the relationship between the FMP distribution of youth (U16-U21) national team soccer players and the absolute day-to-day change in CK. We applied Spearman's correlations, principal component analysis and K-means clustering to classify players' CK responses according to their specific FMP. Moderate to large negative associations were found between very low intensity FMP parameters and CK change (r = -0.43 ± 0.12) while large positive associations were identified between CK change and other FMP metrics (r = 0.62 ± 0.12). Best fitting clustering methods were used to group players depending on their CK sensitivity to FMP values. Principal component analysis explained 83.0% of the variation with a Silhouette score of 0.61 for the 4 clusters. Our results suggest that soccer players can be clustered based on the relationship between FMP measures and the CK change. These findings can help to plan soccer training or recovery sessions according to the desired load on skeletal muscle, as FMP monitoring might bridge the limitations of GPS telemetry.



#5 An evaluation of the quality of CPR chest compressions performed on football-equipped and obese simulation manikins

Reference: Prehosp Emerg Care. 2023 Jan 24;1-11. doi: 10.1080/10903127.2023.2172494. Online ahead of print.

Authors: Jennifer A Longo, Katie J Lyman, Thomas A Hanson, Bryan Christensen, Gianluca Del Rossi

Summary: Protective athletic equipment may hamper the delivery of effective chest compressions. Unfortunately, an algorithm for managing cardiac arrest emergencies with equipment-laden athletes has yet to be established by national CPR certifying agencies. Further, athletes classified as being overweight or obese carry adipose in the thoracic region, which has been reported to inhibit the ability of rescuers to provide quality chest compressions. Thus, the purpose of this study was two-fold. The first purpose was to assess the ability of emergency responders to perform CPR chest compressions on an obese manikin. The second purpose was to analyze the effect of American football protective equipment on the performance of chest compressions by emergency responders. Fifty emergency responders completed four 2-minute bouts of compression-only CPR. The scenarios included performing chest compressions on both traditional and obese CPR manikins, and performing chest compressions over a set of shoulder pads/chest protector that is used in the sport of American football on both traditional and obese manikins. The most notable outcomes in this study were related to chest compression depth, which fell well below the minimum recommended depth published by the American Heart Association in all conditions. Mean compression depth was significantly lower when performed on the obese manikin (avg over pads = 32.8, SD = 9.2 mm; avg no pads = 38.2, SD = 9.1 mm) compared to the traditional manikin (avg over pads = 40.0, SD = 10.9 mm; avg no pads = 40.8, SD = 14.8 mm), with statistical analyses revealing a significant effect due to both manikin size (p < 0.001) and the presence of equipment (p = 0.003), and a statistically significant interaction effect (p = 0.035). Chest recoil data revealed a statistically significant effect due to both manikin size (p = 0.017) and the presence of chest/shoulder safety pads (p = 0.003). Within this sample of emergency responders, chest compressions were adversely affected both by the equipment and obesity. Additionally, the traditional manikin received comparable chest compressions regardless of the presence or absence of football protective equipment, albeit both conditions resulted in poor depth performance.



#6 The Qatar 2022 World Cup warm-up: Football goal-scoring evolution in the last 14 FIFA World Cups (1966-2018)

Reference: Front Psychol. 2023 Jan 4;13:954876. doi: 10.3389/fpsyg.2023.954876. eCollection 2022.

Authors: Branimir Mićović, Bojan Leontijević, Milivoj Dopsaj, Aleksandar Janković, Zoran Milanović, Amador Garcia Ramos

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Summary: The aim of this study was to elucidate pattern of attacking actions leading up to goal scoring during the 14 FIFA World Cups from 1966 to 2018. The study analysed 1881 goals scored during a total of 732 matches. We employed observational methodology design. Before goal analysis began, it was developed the observing protocol in which data related to selected variables, by system of notation, was entered after reviewing each individual goal scoring action. The analysis of all video material was carried out independently by four experienced examiners (three of them are Ph.D in sports science and one is Ph.D. candidate in sports science with at least 7 years of coaching and experience as analyst in football). The inter-and intra-observer reliability presented good level of agreement. The kappa values ranged from 0.82 (goal scoring through open play) to 1.00 (action leading up to goal), showing a very high agreement for all performance variables. Interclass correlation was very high (ICC = 0.966, 95% upper and lower confidence intervals were between 0.933 and 1.00). A statistically significant trend (p < 0.05) from 1966 to 2018 was identified towards a higher relative frequency of goals scored from set play and collective actions from open play. The Chi-square did not reveal significant differences in the frequency of goal scoring patterns and goal-scoring zones. The results also revealed that the majority of goals were scored between the 76th and 90th minutes of a match (22.7%), from open play (70.5%), inside the penalty area (54.7%), one touch finishing (62.5%), and collective attacks in open play (55.8%). These findings may provide a possible strategic direction for improving goal-scoring performance in football, as well as practical implementation in World Cup tournament preparation.



#7 Relationship between Repeated Sprint Ability, Countermovement Jump and Thermography in Elite Football Players

Reference: Sensors (Basel). 2023 Jan 5;23(2):631. doi: 10.3390/s23020631.

Authors: Carlos Majano, Jorge García-Unanue, Antonio Hernandez-Martin, Javier Sánchez-Sánchez, Leonor Gallardo, Jose Luis Felipe

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Summary: Football is a very demanding sport which requires players to exert maximum effort, producing fatigue and eventually injuries. Thermography can be used to detect fatigue and prevent its consequences through thermal asymmetries in the bilateral body areas; however, its adequacy for elite footballers has not been widely studied. Therefore, the objective of the present investigation was to determine the suitability of thermography to detect fatigue in male football players. For this reason, twenty participants were gathered into a pair of subgroups (low [&lt;0.2 °C] vs. high thermal asymmetry [≥0.2 °C]) based on a thermography session of the lower limbs (thighs, calves, and hamstrings). After the thermography session, players performed CMJs before and after an RSA test (6 × 30 m/20″). A mixed two-way analysis of variance and Bonferroni post hoc pairwise comparisons were undertaken to analyse the results. No significant differences (p &gt; 0.05) were found in any of the RSA test variables between low and high thermal asymmetry groups for thighs and calves. On the other hand, the low thermal asymmetry hamstring group reported a smaller percentage difference in sprints for the first sprint (%Diff) and a larger percentage difference in sprints two and three with respect to the best sprint (%Best). For CMJs, the low thermal asymmetry hamstring group reported significantly higher values post-RSA test, indicating better performance. Accordingly, thermography can provide information about performance in CMJ and RSA tests through hamstring asymmetries over 0.2 °C. Meanwhile, larger asymmetries than 0.2 °C in calves and thighs do not seem to be related to performance in these tests; therefore, coaches should consider if it is optimal to align players with high hamstring asymmetries.



#8 Weekly External Load Performance Effects on Sports Injuries of Male Professional Football Players

Reference: Int J Environ Res Public Health. 2023 Jan 8;20(2):1121. doi: 10.3390/ijerph20021121.

Authors: Francisco Martins, Adilson Marques, Cíntia França, Hugo Sarmento, Ricardo Henriques, Andreas Ihle, Marcelo de Maio Nascimento, Carolina Saldanha, Krzysztof Przednowek, Élvio Rúbio Gouveia

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Summary: One of the most challenging issues professional football players face throughout their careers is injuries. Those injuries often result from suboptimal training programs that were not designed according to the players' individual needs. This prospective study aimed to examine in detail the effects of sports injuries on professional football players' weekly external load performances. Thirty-three male professional football players were monitored using 10-Hz Global Positioning System (GPS) units (Apex pro series, StatSports) during an entire season. The variables considered in the analysis were total distance (TD), high-speed running (HSR), accelerations (ACC), and decelerations (DEC). The comparisons were made between the four-week block before injury (-4T), four-week block after return (+4T), and players' season averages (S). Players displayed significantly higher values of TD, HSR, ACC, and DEC in the -4T, compared to the other two moments (+4T and S). Furthermore, the comparison between the +4T and S showed no significant variations in the GPS metrics. It was shown that a significant increase in players' weekly external load performance over a four-week period may have a negative effect on the occurrence of injuries from a professional football standpoint. Future research should consider the effects of injury severity on players' external load variations.



#9 Muscle Contractile Properties Measured by the Tensiomyography (TMG) Method in Top-Level Football Players of Different Playing Positions: The Case of Serbian Super League

Reference: Int J Environ Res Public Health. 2023 Jan 4;20(2):924. doi: 10.3390/ijerph20020924.

Authors: Lazar Pajović, Lazar Toskić, Veroljub Stanković, Ljubiša Lilić, Borislav Cicović

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Summary: The aim of this study is to investigate the differences in muscle contractile properties measured by the TMG method between top-level football players of different playing positions. The sample consisted of 57 football players from the Serbian Super League, divided into three groups: defenders-DF, midfielders-MF, and forwards-FW. Muscles included in the study were the Rectus Femoris (RF), Vastus Medialis (VM), Vastus Lateralis (VL), Biceps Femoris (BF), and Semitendinosus (ST) of the right (R) and left (L) leg. The TMG parameters used in this study were contraction time (Tc), delay time (Td), relaxation time (Tr), maximal displacement (Dm), and sustain time (Ts). The ANOVA results showed that differences in TMG parameters between top-level football players of different playing positions are small and exist only in the Tr of RF (F = 4.658, p = 0.014), BF (F = 4.433, p = 0.016), and ST muscle (F = 3.808, p = 0.028), and the Tc (F = 3.214, p = 0.048) and Td (F = 3.705, p = 0.031) of the VM muscle. All differences were detected between DF and FW players, and all differences were in the left (non-dominant) leg. The results obtained in this study indicate that the training and selection process in football, from the aspect of functional and mechanical muscle properties, should be similar for all players, regardless of playing position. It has been shown that TMG has relatively low sensitive strength for detecting differences between football players of different playing positions.



#10 Effects of a Football Simulated Exercise on Injury Risk Factors for Anterior Cruciate Ligament (ACL) Injury in Amateur Female Players

Reference: Biology (Basel). 2023 Jan 12;12(1):124. doi: 10.3390/biology12010124.

Authors: Harriet Ferguson, Jessica Piquet, Monèm Jemni, Anne Delextrat

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Summary: Females are more at risk of Anterior Cruciate Ligament (ACL) injuries than males; however, there is limited literature on neuromuscular risk factors such as angle-specific hamstring/quadriceps functional strength ratios (Hecc/Qcon) and rate of torque development (RTD) in female footballers. The aim of this study was to investigate the effects of fatigue on these neuromuscular risk factors. Thirty-three amateur players (20.3 ± 2.0 years old, 1.67 ± 9.31 m, 63.4 ±8.1 kg, 23.6 ± 5.7% body fat) performed strength assessments of the quadriceps (concentrically, Qcon) and hamstrings (eccentrically, Hecc) on both legs on an isokinetic dynamometer, before and immediately after a football-specific exercise. Results showed significantly lower peak Hecc (-15.1 to -15.5%), peak Hecc/Qcon (-8.8 to -12.9%) and RTD (-14.0 to -17.0%) for hamstring eccentric contractions after fatigue in the dominant and non-dominant legs. Furthermore, significant decreases in Hecc/Qcon were observed at 10° only in the dominant leg (-15.5%), and at 10°, 20° and 30° in the non-dominant leg (-15.1 to -21.8%). These results suggest a reduced capacity of the hamstrings to stabilise the knee joint with fatigue. Unlike results previously shown on men, the non-dominant leg seemed more affected, highlighting the need to consider specific prevention measures in females.



#11 Do Repeated Sprints Affect the Biceps Femoris Long Head Architecture in Football Players with and without an Injury History?-A Retrospective Study

Reference: Biology (Basel). 2023 Jan 8;12(1):96. doi: 10.3390/biology12010096.

Authors: Ricardo Pimenta, Hugo Antunes, Tomás Lopes, António Veloso

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Summary: The aim of this study was to compare the biceps femoris long head (BFlh) architecture between football players with (twelve) and without (twenty) history of BFlh injury before and after a repeated sprint task. Fascicle length (FL), pennation angle (PA) and muscle thickness (MT) were assessed at rest and in the active condition before and after the repeated sprint protocol. Athletes with previous BFlh injury showed shorter FL at rest (p = 0.014; η2p = 0.196) and active state (p &lt; 0.001; η2p = 0.413), and greater PA at rest (p = 0.002; η2p = 0.307) and active state (p &lt; 0.001; η2p = 0.368) before and after the task. Intra-individual comparisons showed that injured limbs have shorter FL at rest (p = 0.012; η2p = 0.519) and in the active state (p = 0.039; η2p = 0.332), and greater PA in passive (p &lt; 0.001; η2p = 0.732) and active conditions (p = 0.018; η2p = 0.412), when compared with contralateral limbs. Injured players, at rest and in the active condition, display shorter BFlh FL and greater PA than contralateral and healthy controls after repeated sprints. Moreover, the BFlh of injured players presented a different architectural response to the protocol compared with the healthy controls.



#12 How Football Players' Age Affect Passing Patterns of Play According to Field Location

Reference: Children (Basel). 2023 Jan 13;10(1):157. doi: 10.3390/children10010157.

Authors: Nuno Coito, Hugo Folgado, Diogo Monteiro, Bruno Travassos

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Summary: This study aimed to characterize the passing patterns that support collective tactical behaviour in football players of different ages (U15, U17, and U19) in different field zones. Two hundred and twenty-eight male players, divided into U15, U17, and U19, participated in the study. Cluster analysis was used to group the passes into three sizes (short, medium, and long). The chi-square test was used to analyse the effect of player age on game-passing patterns in each field zone. The results revealed that long and medium passes were used more in areas close to the goals and short passes in the middle area of the field, concerning all ages (p &lt; 0.001). Furthermore, the analysis of the relative distance between the ball carrier and the receiver indicated that older players (U17 and U19) used more distant players to pass the ball in medium and long passes. These results can help coaches design small-sided games according to the players' ages and adjust to the field's space and the numerical relationship, thus creating a greater transfer from training to competition.



#13 Agility Skills, Speed, Balance and CMJ Performance in Soccer: A Comparison of Players with and without a Hearing Impairment

Reference: Healthcare (Basel). 2023 Jan 13;11(2):247. doi: 10.3390/healthcare11020247.

Authors: Hakan Yapici, Yusuf Soylu, Mehmet Gulu, Mehmet Kutlu, Sinan Ayan, Nuray Bayar Muluk, Monira I Aldhahi, Sameer Badri Al-Mhanna

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Summary: This study investigates the differences in agility, speed, jump and balance performance and shooting skills between elite hearing-impaired national team soccer players (HISP) and without-hearing-impairment elite soccer players (woHISP). Players were divided into two groups, the HISP group (n = 13; 23.5 ± 3.1 years) and the woHISP group (n = 16; 20.6 ± 1.4 years), and were tested in three sessions, seven apart, for metrics including anthropometrics, speed (10 m, 20 m and 30 m), countermovement jump (CMJ), agility (Illinois, 505, zigzag), T test (agility and shooting skills), and balance. The results showed that 30 m, 20 m and 10 m sprint scores, agility/ skills (sec), shooting skills (goals), zigzag, Illinois, and 505 agility skills, and countermovement jump scores were significantly lower among players with hearing impairments (p &lt; 0.05). There were no significant T test differences between HISP and woHISP (p &gt; 0.05). The HISP showed right posterolateral and posteromedial, and left posterolateral and posteromedial scores that were lower than the woHISP group (p &lt; 0.05). Anterior scores were not significantly different between each leg (p &gt; 0.05). In conclusion, the HISP group showed higher performance scores for speed (10 m, 20 m and 30 m), CMJ, agility (Illinois, 505, zigzag) and T test (sec and goals), but not balance. Hearing-impaired soccer players are determined by their skill, training, and strategy, not their hearing ability.



#14 Does Inspiratory Muscle Training Affect Static Balance in Soccer Players? A Pilot Randomized Controlled Clinical Trial

Reference: Healthcare (Basel). 2023 Jan 14;11(2):262. doi: 10.3390/healthcare11020262.

Authors: Silvana Loana de Oliveira-Sousa, Martha Cecilia León-Garzón, Mariano Gacto-Sánchez, Alfonso Javier Ibáñez-Vera, Luis Espejo-Antúnez, Felipe León-Morillas

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Summary: Inspiratory muscle training (IMT) is effective in improving postural stability and balance in different clinical populations. However, there is no evidence of these effects in soccer players. A single-blind, two-arm (1:1), randomized, placebo-controlled pilot study on 14 soccer players was performed with the main aim of assessing the effect of IMT on static balance, and secondarily, of examining changes in the respiratory muscle function. The experimental group (EG) received an IMT program with progressive intensity, from 20% to 80%, of the maximal inspiratory pressure (MIP). The sham group (SG) performed the same program with a fixed load of 20% of the MIP. Static balance and respiratory muscle function variables were assessed. A two-factor analysis of variance for repeated measures was used to assess differences after training. Statistical significance was set at p &lt; 0.05. Significant increases were observed in the EG on length of sway under eyes open (from 2904.8 ± 640.0 to 3522.4 ± 509.0 mm, p = 0.012) and eyes closed (from 3166.2 ± 641.3 to 4173.3 ± 390.8 mm, p = 0.004). A significant increase in the maximal voluntary ventilation was observed for both groups (EG p = 0.005; SG p = 0.000). No significant differences existed between the groups. IMT did not improve the static balance in a sample of soccer players. Conducting a high-scale study is feasible and could refine the results and conclusions stemming from the current pilot study.



#15 Psychological Intervention Based on Mental Relaxation to Manage Stress in Female Junior Elite Soccer Team: Improvement in Cardiac Autonomic Control, Perception of Stress and Overall Health

Reference: Int J Environ Res Public Health. 2023 Jan 4;20(2):942. doi: 10.3390/ijerph20020942.

Authors: Eleonora Pagani, Naomi Gavazzoni, Giuseppina Bernardelli, Mara Malacarne, Nadia Solaro, Emanuele Giusti, Gianluca Castelnuovo, Piero Volpi, Giulia Carimati, Daniela Lucini

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Summary: Chronic stress may represent one of the most important factors that negatively affects the health and performance of athletes. Finding a way to introduce psychological strategies to manage stress in everyday training routines is challenging, particularly in junior teams. We also must consider that a stress management intervention should be regarded as "efficacious" only if its application results in improvement of the complex underlying pathogenetic substratum, which considers mechanistically interrelated factors, such as immunological, endocrine and autonomic controls further to psychological functioning and behavior. In this study, we investigated the feasibility of implementing, in a standard training routine of the junior team of the Italian major soccer league, a stress management program based on mental relaxation training (MRT). We evaluated its effects on stress perception and cardiac autonomic regulation as assessed by means of ANSI, a single composite percentile-ranked proxy of autonomic balance, which is free of gender and age bias, economical, and simple to apply in a clinical setting. We observed that the simple employed MRT intervention was feasible in a female junior soccer team and was associated with a reduced perception of stress, an improved perception of overall health, and a betterment of cardiac autonomic control. This data may corroborate the scientific literature that indicates psychological intervention based on MRT as an efficacious strategy to improve performance, managing negative stress effects on cardiac autonomic control.



#16 Dynamometric Strength Profile of Hip Muscles in Youth Soccer Players

Reference: Int J Environ Res Public Health. 2023 Jan 11;20(2):1291. doi: 10.3390/ijerph20021291.

Authors: Guido Contreras-Díaz, Luis Javier Chirosa-Ríos, Ignacio Chirosa-Ríos, Antonio Riego-Ruiz, Leonardo Intelangelo, Marcelo Tuesta-Roa, Jorge Morales-Zúñiga, Daniel Jerez-Mayorga

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Summary: Soccer is the most widely practiced sport in the world, demanding high-speed activities such as jumps, sprints and changes of direction. Therefore, having optimal levels of muscle strength improves performance and reduces the injury rate. The objectives of our study were (i) to determine the dynamometric profile of hip muscle strength in young soccer players by position, evaluated at different isokinetic speeds, (ii) to describe the conventional and functional unilateral muscle strength ratios, (iii) to analyze the bilateral balance. Thirty-seven male soccer players (age 17.02 ± 0.92 years) participated in the study. Strength assessment was performed with a functional electromechanical dynamometer, and concentric and eccentric strength of abductors, adductors, extensors and hip flexors were measured bilaterally at 0.5 m/s and 1 m/s. For eccentric right hip abduction at 0.5 m/s, defenders are significantly stronger than midfielders (p = 0.013) and stronger than forwards (p = 0.140). For eccentric right hip adduction at 0.5 m/s, defenders are significantly stronger than midfielders (p = 0.005) and stronger than forwards (p = 0.253), as for eccentric right hip adduction at 1 m/s, defenders are significantly stronger than midfielders (p = 0.014) and stronger than forwards (p = 0.084). There is a significant effect for the conventional strength ratio of left abduction/adduction at 1 m/s. The conventional strength ratio of forwards is significantly higher than that of defenders (p = 0.045) and higher than that of midfielders (p = 0.152).



#17 Relationship between Body Composition and Specific Motor Abilities According to Position in Elite Female Soccer Players

Reference: Int J Environ Res Public Health. 2023 Jan 11;20(2):1327. doi: 10.3390/ijerph20021327.

Authors: Mima Stanković, Ilma Čaprić, Dušan Đorđević, Stefan Đorđević, Adem Preljević, Admira Koničanin, Džejla Maljanović, Hamza Nailović, Iso Muković, Igor Jelaska, Goran Sporiš

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Summary: Contemporary top-division soccer is characterized by high-intensity activity throughout the entire match, which also requires high levels of a wide range of the players' functional and motor abilities. Furthermore, motor and functional requirements vary in relation to the players' position on the pitch. In view of the above, the objective of this study was to determine any differences in body composition and specific motor abilities in relation to position. Twenty elite female soccer players (age: 20.90 ± 3.70 years; height: 166.95 ± 5.83 cm; weight: 58.97 ± 7.50 kg; training experience: 9.50 ± 4.11 years) were recruited for the purpose of this study. Based on their position within the team, the players were divided into three groups: defenders (N-7), midfielders (N-6), and forwards (N-7). The instruments used included the InBody770 (for body composition assessment), Optojump and Polar for the assessment of specific motor abilities. The results obtained indicate a strong link between the parameters body composition and specific motor abilities; however, the level of significance varies, as do the variables concerning specific motor abilities and body composition in relation to the players' position on the pitch. In accordance with these results, coaches and others working in the soccer industry should be apprised of the necessity of a tailored approach when it comes to planning the development of specific motor abilities, as well of with the importance of balanced body composition as prerequisites for achieving top results.



#18 Relationship between Objective and Subjective Fatigue Monitoring Tests in Professional Soccer

Reference: Int J Environ Res Public Health. 2023 Jan 14;20(2):1539.  doi: 10.3390/ijerph20021539.

Authors: João Lourenço, Élvio Rúbio Gouveia, Hugo Sarmento, Andreas Ihle, Tiago Ribeiro, Ricardo Henriques, Francisco Martins, Cíntia França, Ricardo Maia Ferreira, Luís Fernandes, Pedro Teques, Daniel Duarte

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Summary: Studying fatigue is challenging because it is influenced by physiological, psychological, and sociological states. Fatigue can be assessed objectively or subjectively, but the literature has difficulty understanding how an analytical test relates to a response via a questionnaire. Thus, the purpose of this study was to evaluate the relationships between objective fatigue variables (Squat Jump (SJ) and Countermovement Jump (CMJ)) measured on day-2 to the game and subjective fatigue (Rating Perceived Exertion (RPE) measured on day-3 to the game and Hooper Index (HI) measured on day-2). The sample comprised 32 professional football players from the First Portuguese League aged 25.86 ± 3.15 years. The Spearman correlations and regression analyses were used to study the relationships between the variables. The results showed statistically significant (p &lt; 0.05) but small correlations (0.113-0.172) between several objective metrics and the subjective metrics evaluated. In addition, we found two weak models with statistical significance (p &lt; 0.05) between the dependent objective variables (contact time, height, and elasticity index) and the HI (R2 = 3.7%) and RPE (R2 = 1.6%). Also, nine statistically significant (p &lt; 0.05) but weak models were observed between the subjective dependent variables (HI and RPE) and contact time (R2 = 1.8-2.7%), flight time (R2 = 1.1-1.9%), height (R2 = 1.2-2.3%), power (R2 = 1.4%), pace (R2 = 1.2-2.1%), and elasticity index (R2 = 1.6%). In conclusion, objective and subjective fatigue-monitoring tests in professional soccer do not measure identical but rather complementary aspects of fatigue, and therefore, both need to be considered to gain a holistic perspective.


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