Semi-professional Soccer Players Research Articles

Technical and Physical Load Variables at Different Positions in U18 Semi-Professional Soccer Players: Differences between the First and Second Half

Among the many factors that can affect men’s soccer performance, technical and tactical actions can obscure relevant game data, even affecting specialists in both the programming and design of training tasks. We aimed to evaluate the technical and physical load variables of different positions in U18 semi-professional soccer players and observe the differences between the first and second halves during 10 matches of the 2021/2022 Spanish Football U18 National League Championship. A total of 246 match records (10 matches) were collected from the 2021/2022 Spanish Football U18 National League Championship. Two teams participated, with a total of 49 athletes. Our study’s results indicate that, concerning technical performance, no significant differences between halves were found for goalkeepers, wingers, and forwards. However, significant declines were observed in the number of ball contacts, different actions per time, and possessions per time among central defenders, lateral defenders, and central midfielders. Regarding the observed physical load demands, it was noted that in outfield players, there was a significant decline in total distances covered at different speed thresholds, as well as a decrease in the number and distance of acceleration measures, most of which were lower in the second halves compared to the first, irrespective of playing positions. This study contributes to enhancing our understanding of the multifaceted dynamics of soccer performance and provides valuable insights for coaches, players, and researchers aiming to optimize player performance.

Biceps femoris muscle-tendon strain during an entire overground sprint acceleration: a biomechanical explanation for hamstring injuries in the acceleration phase

ABSTRACT The objectives of this study were to analyse the peak muscle-tendon (MT) strain of the hamstring during an entire acceleration sprint overground and examine their relationship with relative joint angles and segment orientation in the sagittal plane, which are the direct causes of MT strain. Kinematic data were recorded using a 3D inertial motion capture system in 21 male semi-professional soccer players during 40-metre overground sprint. Scaled musculoskeletal models were used to estimate peak MT strain in the hamstring over 16 steps. Biceps femoris long head (BFLH) exhibited the largest peaks in MT strain compared to semitendinosus (ST) and semimembranosus (SM) muscles across all the steps, with its overall strain decreased as the number of steps and maximum speed increased. Hip flexion angle was found to be a strong predictor (p < 0.001) of joint angles, being the orientation of the pelvis in the sagittal plane of the segment with the greatest influence (p < 0.001) on the peak MT strain of BFLH during sprinting. The current study provides a biomechanical explanation for the high proportion of hamstring injuries in the acceleration phase of sprinting.

Association between match-related physical activity profiles and playing positions in different tasks: A data driven approach

ABSTRACT Assessing the intensity characteristics of specific soccer drills (matches, small-side game, and match-based exercises) could help practitioners to plan training sessions by providing the optimal stimulus for every player. In this paper, we propose a data analytics framework to assess the neuromuscular or metabolic characteristics of a soccer-specific exercise in relation with the expected match intensity. GPS data describing the physical tasks’ external intensity during an entire season of twenty-eight semi-professional soccer players competing at the fourth Italian division were used in this study. A supervised machine-learning approach was tested in order to detect difference in playing positions in different sport-specific drills. Moreover, a non-supervised machine-learning model was used to profile the match neuromuscular and metabolic characteristics. Players’ playing positions during matches and match-based exercises are characterised by specific metabolic and neuromuscular characteristics related to tactical demands, while in the small-side game these differences are not detected. Additionally, our framework permits to evaluate if the match performance request is mirrored during training drills. Practitioners could evaluate the type of stimulus performed by a player in a specific training drill in order to assess if they reflect the matches characteristics of their specific playing position.

Effect of the role, playing position and the body characteristics on physical performance in female soccer players

The aims of this study were to know the physical demands according to the playing position and team role, and to assess the effect of the body characteristics on the physical performance of semi-professional female soccer players. Forty-five female semi-professional soccer players during 9 home-matches of the 2021–2022 season were analyzed and GPS devices (GPEXE ®) were used. ANCOVA tests were performed with playing time as covariate. The results showed greater physical demands in forwards and wide-midfielders and offensive role players. Total distance, metabolic power, accelerations, deaccelerations, and distance covered to medium and high speed obtained a strong effect size in these analyses according to the playing position. Furthermore, relationships between body weight and physical performance were found (p < 0.05). In conclusion, the main finding of this study showed that semi-professional female soccer players compete differently, caused by differentiated functions, evidenced in the playing positions and role in the team. Offensive role, forwards and wide-midfielder female players performed the highest physical demands in the competition. This study has shown relevant information for coaches, S&C coaches, and training staff of the semi-professional female soccer teams in order to propose new keys and ways of planning training sessions.

A Methodological Comparison of Protocols and Analytical Techniques to Assess the Outcome Measures ofSubmaximal Fitness Tests.

Submaximal fitness test (SMFT) outcome measures are frequently collected with a wide array of technologies and methodological approaches. To examine the test-retest reliability of various SMFT outcome measures derived from different protocols and analytical techniques. Twenty-six semiprofessional adult soccer players performed 3 SMFT protocols, including 2 continuous (3min, 11 and 12.8km·h-1) and 1 intermittent (4 × 50m, 18km·h-1) twice, each separated by 7days. Heart-rate (HR) indices (exercise HR, HR recovery)and scapula-mounted (PlayerLoad vector magnitude) and foot-mounted (flight time and contact time, stride length) microelectrical mechanical system-derived variables were collected using different time frames and analytical approaches adopted in the literature and practice. Absolute reliability was quantified as the group mean difference, typical error of measurement, also expressed as the coefficient of variation (where appropriate) and standardized units (ie,d). Intraclass correlation coefficient was used to quantify relative reliability. The highest degrees of reliability were evident for exercise HR (typical error: 1.0%-1.6% points), the vertical component of PlayerLoad (expressed in arbitrary units; coefficient of variation: 5.5%-7.0%), and contact time (coefficient of variation: 1.5%-3.0%). These estimates were not influenced by SMFT protocol or analytical approach. All other measures displayed poorer reliability and/or were different between protocols and analytical methods. SMFT protocols impact the test-retest reliability of various outcome measures; however, exercise HR, verticalPlayerLoad, and contact time (derived from foot-mounted micro-electrical mechanical systems) appear to have stable measurement properties to assist the assessment of aerobic capacity and lower-limb neuromuscular status, respectively.

Differences between U23 and older semi-professional soccer players in perfectionism and passion: exploring determinant relationship between variables.

Abundant studies have pointed out that perfectionism and passion are interrelated and that they both can influence performance in a variety of contexts, including sports, however, research on how these variables interact and might affect performance in team sports, such as soccer, is still scarce. The aim of this study is to analyze differences in perfectionism and passion between under-23 years-old (U23) and older semi-professional soccer players, as well as to study the possible relationship between these two psychological variables. Participants (N = 130 healthy semi-professional Spanish soccer players) were divided into two equivalent groups according to the participants age, U23 (N = 65; 21.58 ± 1.91 years) and older than 24 years (N = 65; 30.03 ± 3.72 years) and completed self-reports on perfectionism and passion. Independent samples t-test determined significant differences between the U23 Group and the >24 Group in perfectionism global score and concern over mistakes (maladaptive perfectionism), and in time, value, and passion. Multiple regression analyses revealed that obsessive passion predicted maladaptive subdimensions of perfectionism, while harmonious passion predicted adaptive perfectionism. U23 soccer players show higher levels of maladaptive perfectionism, time, value, and passion in relation with soccer than older players, probably because at this stage pressure to become professionals and to develop their technical, tactical, and physical skills is higher than in later stages. Identifying differences between different age groups can help professionals in tailoring their interventions and strategies to address the specific needs of athletes at different stages of development more effectively, and to optimize mental focus, reduce stress, to promote a healthy mindset for optimal performance in soccer players, furthermore, the study of moderating effects of factors such as team dynamics or coaching styles on these constructs is advised.

Small-sided-games with coaches' verbal encouragement have a positive effect on aerobic performance, mood state, satisfaction and subjective effort in male semi-professional soccer players

The study aimed to examine the impact of high-intensity Small-Sided Games (SSGs) with coaches’ verbal encouragement (VE) on soccer players’ aerobic performance, mood state, satisfaction and subjective effort. Forty-three semi-professional male soccer players were randomly assigned to three distinct groups: a control group (CG, n = 14), an experimental group with verbal encouragement (EGVE, n = 14), and an experimental group without verbal encouragement (EGNE, n = 15). Participants performed the VAMEVAL aerobic test, Total-Mood-Disorder (TMD), and the Satisfaction Scale for Athletes (SSA) tests before and following the 6-week SGGs program that included ten training sessions. Rating of Perceived Exertion (RPE) was collected 5-minutes post-training session. The SGGs program with coaches’ VE showed a significant improvement in maximal aerobic velocity (MAV) and TMD scores (p &lt; 0.05). Except for the SSA scores (p = 0.268), the percentage of change was higher for MAV (p = 0.001; d: 1.36–1.48 (large)) and TMD scores (p = 0.001; d: 1.45–1.48 (large)) in the EGVE group when compared with the other groups (i.e., EGNE and CG). Overall, RPE scores were significantly higher (p ˂ 0.05; d: 0.99–5.00 (large)) in the EGVE group than other groups. The present study highlights the positive effects of integrating SSGs with coaches VE to improve aerobic performance and mental well-being of semi-professional soccer players. Nevertheless, notably the SSA did not exhibit a statistically significant difference. Furthermore, the experimental EGVE group reported elevated RPE, potentially suggesting that SSGs may entail greater physical and mental challenges, yet may yield more sport-specific outcomes for soccer players.

Dietary intake and adherence to the Mediterranean diet in semi-professional female soccer players: a cross-sectional study.

Adequate energy and nutrient intakes in athletes contribute to optimal performance and recovery, decrease the risk of injury, and help preserve athletes' health. The Mediterranean diet (MD) is considered suitable for covering the nutritional needs of athletes, while contributing to improve eating habits. The aim of the present study was to investigate the energy and nutrient intakes of semi-professional female soccer players and their adherence to the MD, during the competitive season. A cross-sectional observational study was conducted on twenty-three female soccer players, who were invited to fill in a 3-day food diary twice, one month apart, to assess their energy and nutrient intakes and a validated questionnaire (MEDI-LITE) to evaluate their adherence to MD. Exercise energy expenditure during three training and match-play days was monitored by GPS. On average, the participants consumed 1,981 kcal/day, with 44% of their energy deriving from carbohydrates, 21% from protein, and 34% from fat; the mean MD adherence score was 10.1 ± 1.8, corresponding to a good MD adherence. A substantial percentage of athletes were at risk of insufficient nutrient intakes for vitamin D (100%), iodine (87%), potassium (87%), vitamin E (39%), iron and zinc (17 and 30%, respectively). The evaluation of the dietary intake in female soccer players showed energy deficiency in relation to training level, mainly due to the insufficient intake of carbohydrates, and micronutrient deficiencies. The technical staff should promote adequate consumption of starchy foods in female athletes and emphasize the importance of a proper distribution of energy intake among different eating occasions, including snacks. Periodic monitoring of the nutritional status of micronutrients (vitamin D and some minerals) could help reduce deficiency risk. Over all, nutrition education to improve eating habits of athletes seems worthy of attention, in order to preserve athletes' health and performance.

Effects of 8 weeks pre-season training on physical fitness, heart rate variability and cognition in women soccer players

The aim of this study was to explore the variations (pre-post) of (i) Anthropometric measures: weight, body mass index, lean and muscle mass, (ii) Physical fitness: countermovement jump (CMJ) and VO2max, (iii) heart rate variability (HRV) (recumbent and sitting): mean RR, RMSSD, NN50 and NN50 %, (iv) Psychomotor Vigilance Task, and v) SART: ACC Go, ACC NoGo and reaction times in semi-professional women soccer players from the second division of the Spanish League. The analysis indicated that lean mass improved after the observation period (p = .05, d = −0.38), while no other significant changes in anthropometric measures were observed. Additionally, CMJ and aerobic power were also improved (p<.01, d>0.50). The RMSSD [recumbent (d = −0.73) and sitting (d = −0.52)] and NN50 [recumbent (d = −0.69) and sitting (d = −0.70)] increased after the period of observation (p < .05). Reaction time also significantly improved after the period of observation [PVT (d = 0.42) and SART (d = −0.89)]. Correlations performed between measures revealed that smaller body mass and body mass index were largely associated with greater NN50 (r < 0.83, p = .001). Additionally, greater CMJ and aerobic fitness were associated with greater HRV [recumbent (r = −51, p = .001) and sitting (r = −0.60, p = .01). The main findings of this study were that there was no relationship between cognitive performance and physical fitness, but HRV was related to body composition and physical fitness during the pre-season in women soccer players.

A Foucauldian Autoethnographic Account of a Male Former Soccer Player’s Move to Coaching Female Players: A Call to Problematize the Importation of Gendered Assumptions During a Common Coaching Transition

It has frequently been observed that the disproportionate number of male coaches within women’s soccer is problematic, not least, because it limits the opportunities for the progression of female coaches. Despite this, the transition from “male former player to male coach of female players” is one that remains common, is likely to continue, yet is not widely discussed in the sport/coach transition literature. This is an oversight given the numerous problematic outcomes that are routinely connected to the presence of male coaches in women’s sport. In this confessional, analytical autoethnography, we build upon our existing work regarding coaching women’s soccer that has been informed by Michel Foucault’s conceptual framework. Precisely, we use a collection of creative narrative reflections to discuss the first author’s transition from that of a British semiprofessional soccer player context, to an Assistant Coach of a female soccer team in a North American varsity program. In so doing, we trace and map some of the (problematic) learned gendered assumptions which initially shaped and guided the first author’s coaching assumptions, relationships, approaches, and practices within this context, before unpacking some of the challenges he navigated along the way (with varying degrees of success). We end by summarizing our paper and a call to male coaches working with female athletes to reflect on how “thinking with Foucault” might help them to coach in more ethical and gender-responsive ways by both problematizing imported gendered assumptions and developing active allyship practices.

Is a Maximal Strength-Training Program Effective on Physical Fitness, Injury Incidence, and Injury Burden in Semi-Professional Soccer Players? A Randomized Controlled Trial.

The aims of the study were to analyze the effects of a 12-week maximal strength- training program on injury incidence, injury burden, and physical fitness in semi-professional soccer players and to compare the perceived exertion load and well-being state between injured and non-injured soccer players. Twenty semi-professional male soccer players participated in this study. Participants were randomly allocated to an experimental group (EG, n = 10 players), who performed a maximal strength-training program, or to a control group (CG, n = 10 players), who only performed their regular soccer training. Physical fitness was measured at baseline and after the training program. In addition, the injury incidence, burden, training/match load, and the state of well-being of the players were recorded. The EG showed significant improvements in vertical jumps, change in direction ability, linear sprints, repeated sprint ability, isometric strength (p < 0.003; effect size = 1.78-11.86), and quadriceps-hamstring imbalance in both legs (p < 0.001; effect size = 2.37-3.71) in comparison to the CG. In addition, the EG players showed a significantly (p < 0.05) lower injury burden (p < 0.001, relative risk = 5.05, 95% confidence interval = 3.27-7.79). This study demonstrated the beneficial effects of a 12-week maximal strength-training program on physical fitness attributes and injury burden in semi-professional soccer players.

Differences and relationship in functional movement screen (FMS™) scores and physical fitness in males and female semi-professional soccer players.

Soccer is the world's most popular sport for both men and women. Tests of athletic and functional performance are commonly used to assess physical ability and set performance goals. The Functional Movement Screen (FMS™) is a widely used seven-test battery developed by practitioners to provide interpretable measure of movement quality. The main objective of the present study was twofold, to analyze the relationship between FMS™ results from male and female soccer players and to compare their physical performance in different tests. A total of twenty-eight semi-professional soccer players: fourteen male (age: 21.29 ± 1.64 years; weight: 70.66 ± 5.29 kg; height: 171.86 ± 5.35 cm; BMI: 20.90 ± 2.22 kg/m2) and fourteen females (age: 20.64 ± 1.98 years; weight: 63.44 ± 5.83 kg; height: 166.21 ± 12.18 cm; BMI: 23.02 ± 2.50 kg/m2) were recruited for this study. A paired sample t-test was used for determining differences as a repeated measures analysis. All the participants conducted the following tests: The Functional Movement Test (FMS™), 10-m linear sprint, 5-0-5 COD Test and Yo-Yo Intermittent Recovery Test-Level 1 (YYIRT Level 1). A t-test with data from 505 COD (change of direction) test showed significant differences between groups, p = 0.001, d = 1.11, revealing faster times in male soccer players (2.50 ± 0.19) in respect with female soccer players (2.70 ± 0.17). Crucially, a t-test with data from FMS did not reveal significant differences between groups. Multiple regression for V02max revealed significant effects (r = 0.55, r2 = 0.30, adjusted r2 = 0.24, F = 5.21, p = 0.04 and standard error = 2.20). On the other hand, multiple regression for 10-m sprint showed significant effects (r = 0.58, r2 = 0.33, adjusted r2 = 0.28, F = 5.98, p = 0.03). The impact of these factors on the correlation between FMS™ scores and physical performance measures can vary among individuals. This study demonstrates the necessity of utilizing and applying multiple field-based tests to evaluate the movement and capabilities of physical performance in sports. Crucially, consider individual variations and factors such as training background, fitness level, and sport-specific demands when interpreting the relationship between the FMS™ and physical performance in both sexes.

Effects of 16-weeks of strength training on jump height and anthropometric variables in U19 semi-professional male soccer players

Purpose The aim of our study was to examine the effect of 16 weeks of strength training on anthropometric characteristics and jump height in semi-professional male players after a pre-season period. Methods A parallel two-group, longitudinal (pre, post) design was used with physical tests performed before (preintervention) and after (postintervention) the 16-week intervention period. The soccer players were assigned and matched into two groups, an experimental group (EG) and a control group (CG), based on the team of which they were a part. Results A two-way ANOVA was performed with group and time as factors. The results of a two-way ANOVA revealed no time×group interaction for body composition or jump height. Nevertheless, a paired measures t-test of weight, fat mass, lean mass, and countermovement jump (CMJ) test metrics (pre-post) and group (CG and EG) showed an improvement in all measures ( p &lt; 0.01). Discussion The 16-week intervention program resulted in an improvement in the EG both at the level of body composition and in CMJ performance. Conclusions Despite the benefits of the 16-week intervention program, a combination of training methods that includes power, agility-coordination, speed, and strength can enhance such improvements. It is important to take this strength-specific capacity into account in training, due to the importance outlined in the sport of soccer both for its transfer to both linear and COD sprints and specific strength skills and mainly to vertical jump.

Effects of Different Recovery Duration on External and Internal Load Measures during Bouts of Small-Sided Games.

The aim of this study was to analyse the effects of different recovery times between bouts of small-sided games (SSG) on external and internal load variables in semi-professional soccer players. Sixteen male semi-professional soccer players performed three 4 vs. 4 + goalkeeper SSG training sessions, each with different recovery bout duration: short (1 min) (SSG1), medium (2 min) (SSG2), and long (4 min) (SSG4). Time motion and neuromuscular measures were collected during all SSGs, in addition, the rating of perceived exertion (RPE) was determined at the end of the last bout of each SSG. Results showed a significant increase in the total number of accelerations (p = 0.016, ES = 0.97, large) and decelerations (p = 0.022, ES = 0.81, large) in SSG4 compared to SSG1. In terms of the internal load, SSG2 showed significantly higher RPE values (p = 0.011, ES = 1.00, large) in comparison with SSG1. If the sessions' focus is on neuromuscular training, longer recovery times between SSG bouts should be used. Conversely, if the aim is to reach a higher total and running distance at different intensities, a 2-min recovery period between bouts may be more appropriate.

Daytime sleepiness in Chinese professional, semi professional and students soccer players in the Shanghai lockdown

PurposeApril-May 2021 Shanghai city was under strict lockdown. Soccer players suffered from the restrictions, being unable to train and have a social life. The aim of this study was to compare differences in daytime sleepiness between genders and qualification levels in a cohort university Chinese soccer player under 0 Covid policy restrictions in the urban area of Shanghai.Methods491 questionnaires of Epworth Sleepiness Scales (ESS) were compiled online by male and female Soccer Students (SS), Semi-Professional players (SP) and Professional Players (PP) during the ongoing restriction measures post Shanghai lockdown. ANOVA was performed for players levels and gender.ResultsSignificant differences were found between the 3 levels and between males and females. PP showed a very low score in the ESS (5,97) well below the threshold of 8 for daytime sleepiness, while SS and SP showed an ESS score above the threshold. Female showed higher scores in comparison to males. Differences between males and females reflect the confinement conditions in the ESS items, showing more difference in the item of ESS which are related with indoor situations.ConclusionsThis study shows the first data on sleepiness in Chinese soccer players of different level of qualification immediately post lockdown condition. Professional male’s players sleepiness was lower, than females, SS and SP after the exceptional lockdown measures. The reasons can reside in the more ordered lifestyle of PP in comparison to SS and SP, which mitigated the effects of the lockdown. Our results suggest that measures to improve sleep in females’ soccer player should be adopted if these exceptional conditions will happen again.

Differences Between U21 and U23 Semi-Professional Soccer Players in Perfectionism and Passion

Study purpose. The aim of this study is to analyse differences in perfectionism and passion and how these variables interact and might be expected to affect performance in U21 and U23 soccer players. Materials and methods. A total of 60 healthy semi-professional soccer players (age: 21.57±1.95 years; height: 179.76±5.79 cm) participated in the study. The participants were divided into two equal groups, one with those players younger than 21 years old and the other including players aged 21–23. This study was descriptive with a cross-sectional design and used the Frost Multidimensional Perfectionism Scale (FMPS) and Passion Scale questionnaires. Results. A paired-samples t-test was used for defining differences as a repeated measures analysis (U21 Group and U23 Group). Additionally, a t-test with data from the FMPS revealed significant differences in perfectionism global score, concern over mistakes, parental expectations, parental criticism, doubts about actions and organization. The participants were shown to be a heterogeneous group in both perfectionism and passion, with moderate perfectionistic characteristics, except for the personal standards subscale, in which the opposite trend was found. According to the outcomes obtained, the U21 group shows significant values in terms of the level of perfectionism. Conclusions. This research has highlighted the importance of addressing maladaptive perfectionism in interventions and support programs for athletes. Strategies such as promoting a growth mindset, encouraging self-compassion, and fostering a supportive and mastery-oriented environment have been suggested to help athletes manage perfectionistic tendencies and enhance their well-being and performance.

Clinical, Biomechanical, and Self-reported Health Status After ACL Reconstruction With Meniscal Repair in Soccer Players: Results at Minimum 1-Year Follow-up.

Performing meniscal repair with anterior cruciate ligament reconstruction (ACLR) has been shown to contribute to the long-term preservation of knee health and gait biomechanics. To evaluate the role of meniscal repair in the performance of semiprofessional soccer players who returned to sport after ACLR. Case series; Level of evidence, 4. This study included 51 male soccer players (mean ± SD age, 28.82 ± 5.33 years) who underwent ACLR at a single institution between July 2018 and July 2019. The players were divided into 3 groups according to surgery type: ACLR only (n = 30), ACLR with lateral meniscal repair (n = 9), and ACLR with medial meniscal repair (n = 12). Outcomes were evaluated through clinical examination, self-reported health questionnaires (Cincinnati Knee Rating System, Tegner activity score, Tegner Lysholm Knee Scoring Scale, Tampa Scale of Kinesiophobia, and ACL-Return to Sport After Injury), and biomechanical performance evaluations (balance, strength, coordination, and symmetry tests). Parametric and nonparametric tests were carried out for multiple comparisons. The mean ± SD follow-up time was 20.75 ± 9.38 months. Although no significant differences emerged in clinical and self-reported health status, almost all the physical parameters tested resulted in lower performance in players treated with ACLR and meniscal repair. Moreover, patients with ACLR with lateral meniscal repair reported higher pain and fear of reinjury, with lower outcomes in terms of strength, symmetry, and coordination as compared with the other 2 groups. Balance abilities were significantly affected in players who underwent meniscal repair as compared with those who underwent ACLR only. The findings showed that biomechanical performance measures and fear of reinjury were significantly worse in soccer players with associated meniscal repair at a minimum 1-year follow-up, especially in those with a lateral meniscal tear.

What happens in the prefrontal cortex? Cognitive processing of novel and familiar stimuli in soccer: An exploratory fNIRS study

ABSTRACT The importance of both general and sport-specific perceptual-cognitive abilities in soccer players has been investigated in several studies. Although these perceptual-cognitive skills could contribute significantly to soccer players’ expertise, the underlying cortical mechanisms have not been clarified yet. Examining activity changes in the prefrontal cortex under different cognitive demands may help to better understand the underlying mechanisms of sports expertise. The aim of this study was to analyse the prefrontal activity of soccer experts during general and sport-specific cognitive tasks. For this purpose, 39 semi-professional soccer players performed four perceptual-cognitive tests, two of which assessed general cognition, the other two assessed sport-specific cognition. Since soccer is a movement-intensive sport, two tests were performed in motion. While performing cognitive tests, prefrontal activity was recorded using functional near-infrared spectroscopy (fNIRS) (NIRSport, NIRx Medical Technologies, USA). Differences of prefrontal activity in general and sport-specific cognitive tasks were analysed using paired t-tests. The results showed significant increases in prefrontal activity during general cognitive tests (novel stimuli) compared to sport-specific tests (familiar stimuli). The comparatively lower prefrontal activity change during sport-specific cognition might be due to learned automatisms of experts in this field. These results seem in line with previous findings on novel and automated cognition, “repetition suppression theory” and “neural efficiency theory”. Furthermore, the different cortical processes could be caused by altered prefrontal structures of experts and might represent a decisive factor for expertise in team sports. However, further research is needed to clarify the prefrontal involvement on expertise in general and sport-specific cognition.

축구선수의 은퇴인식 및 은퇴준비의 심층 분석

Objectives In this study, we will analyze in-depth the retirement awareness and retirement preparation of soccer players to explore what they perceive and recognize retirement awareness and retirement preparation as and what are the constituent factors.&#x0D; Methods To this end, this study adopted an open questionnaire and a focus group interview method. The open questionnaire surveyed 259 university, professional, and semi-professional soccer players, and the data collected through this were analyzed inductive content. Since then, in order to secure integrity, validity, and identity, a focus group interview (FGI) was conducted with 7 soccer players to understand in-depth the retirement awareness and retirement preparation of soccer players.&#x0D; Results As a result of the inductive content analysis of the open-ended questionnaire on the retirement awareness of soccer players, 647 detailed original data were derived, and 9 subcategories and 5 upper categories were derived. The five upper categories were derived as “Psychological conflict”, “Fear of the future”, “Challenge”, “Bittersweet”, and “Others”. From the results of the FGI analysis, actual and in-depth interview data on the retirement awareness of soccer players were derived. As a result of the open-ended question analysis on soccer players' retirement preparation, 607 detailed original data, 10 subcategories, and 7 upper categories were derived. The 7 derived categories were “Leader Preparation”, “Economic Preparation”, “Intellectual Competency Preparation”, “Interpersonal Relationship”, “Career Search”, “Focus on the present”, and “Others”.&#x0D; Conclusions The results of this study will be able to provide empirical data on soccer players' positive perception of retirement and efficient preparation, and ultimately lead soccer players' future happy lives and suggest a direction for soccer player welfare. In order to build a better retirement environment for players, it seems that members in the soccer environment must take the lead in creating it.

Effects of horizontal compared to vertical-based plyometric jump training on semi-professional soccer player's performance

This study aimed to compare the effects of horizontal (HJ) and vertical (VJ)-based plyometric jump training on male semi-professional soccer player's performance (e.g., change-of-direction speed [5-0-5 test]; 10-m, 20-m, and 30-m linear sprint speed). A parallel-study design was conducted. Participants were organized into HJ (n = 10) or VJ (n = 9) during 12 weeks. Measures of athletic performance were obtained in four phases: (i) before and (ii) end of the pre-season, (iii) during (weeks 7th), and (iv) after the intervention. The within-group analysis revealed that both HJ and VJ improved change of direction ({x}^{2} = 27.783; p < 0.001 ({x}^{2} = 21.635; p < 0.001),), 10-m linear sprint time ({x}^{2} = 28.576; p < 0.001), 20-m linear sprint time ({x}^{2} = 28.969, p < 0.001), and 30-m linear sprint time ({x}^{2} = 26.143; p < 0.001). Similarly, the VJ-group also imposed significant changes on 5-0-5 time, 10-m linear sprint time ({x}^{2} = 25.787; p < 0.001), 20-m linear sprint time ({x}^{2} = 24.333, p < 0.001), and 30-m linear sprint time ({x}^{2} = 22.919; p < 0.001). Between-group analysis revealed no significant differences in any of the assessment moments. HJ and VJ plyometric jump training are effective for improving the change-of-direction and a linear sprint of semi-professional players with no difference between types of intervention.