Adolescent Male Soccer Players Research Articles

The Effects of Proprioceptive Training on Balance, Strength, Agility and Dribbling in Adolescent Male Soccer Players.

The aim of the study was to determine the effects of proprioceptive training (PT) on balance, strength, agility and dribbling in adolescent soccer players. In this research, we included an experimental (n = 48) and a control (n = 48) group (CG) with 14 years old players. The experimental group (EG) participated in an 8 week PT program, with four 30 min sessions per week. The experimental program included 12 bosu ball exercises to improve balance, stability and strength which were grouped into two subprograms: the first not using the soccer ball, the second subprogram using the soccer ball. The subprograms were implemented alternately during 16 proprioceptive training sessions, on two types of firm and foam surfaces. Pre- and post-tests included the static balance [Balance Error Scoring System (BESS)], vertical, horizontal, and lateral jumping, and the completion of agility (“arrowhead”) and dribbling (“short dribbling”) tests. Regarding the total BESS score, the CG has demonstrated progress between the pre- and the post-test, with 0.780 ± 0.895, fewer errors, while the EG had 5.828 ± 1.017 fewer errors. The difference between the two groups was of 5.148 fewer errors for the EG who had practiced the proposed program of proprioceptive training. The highest difference registered between the pre- and the post-test was at the test “single-leg forward jump with the right leg”, with a result of 1.083 ± 0.459 cm for the CG and of 3.916 ± 0. 761 cm for the EG. Through the analysis of average differences between the pre- and the post-tests, we observe that, regarding the “Agility right side test”, the EG has progressed with 0.382 s in comparison with the CG; regarding the “Agility left side test”, the EG has progressed with 0.233 s compared to the CG; regarding the “Agility right and left side test”, the EG has progressed with 0.196 s compared to the CG; in the “Short dribbling test”, the EG has progressed with 0.174 s compared to the CG. The highest progress was made at the “Agility right side test”, of 0.402 s for the EG, while the CG registered 0.120 s. Most of the results in all tests for both experimental groups show an effect size ranging from small to medium. The progress made by the experimental group in all tests was statistically significant, while in the control group the progress was mostly statistically insignificant for p < 0.05. The results suggest that a PT program performed at about 14 years of age could be successfully implemented in the training regime of soccer players to improve components of fitness along with dribbling skills. The results of the study revealed that sports training on the foam surfaces determined a superior progress of the development of proprioception compared to the increased training on the firm surfaces.

Gym Versus Home-Based Training During Transition Period in Adolescent Soccer Players: Effects on Physical Performance

Background: After the in-season period where trainings and games are consistant, players have the rest period, during which the volume and stress are reduced, which allows physical and mental recovery. Instead of having too much free time in transition period, the players should work on their fitness, in order to reduce the side effects of inactivity in transition period. The modern soccer demands the highest quality professional and scientific approach, especially with adolescents. Hence, the aim of this study was to determine gym versus home-based training during transition period in adolescent soccer players. Methods: The sample of participants was 34 adolescent male soccer players (16–18 years old). They were randomly allocated to experimental (GYM; N = 16) and control group (HOME; N = 18). The transition period itself lasted 3 weeks and it was separated by a weekly micro cycle, where players have done different activities each week. The procedures have included anthropometry (body height, mass and Body Mass Index), flexibility (sit and reach), vertical jump tests (countermovement jump, countermovement jump with arm swing and squat jump), running speed (sprint at 5 m, 10 m and 20 m) and agility (Illinois Agility Test). Kolmogorov-Smirnov test was used for distribution normality, while a repeated measurement (2 × Analysis of variance) was used to calculate the interactions, major effects for time (pretest vs. posttest) and group (GYM vs. HOME), with additional Cohen’s effect size. Results: The study results showed that physical performance variables, in both groups, were partially maintained, while in while running speed and agility showed small deterioration. Conclusions: It is crutial to carefully design the trainings and to work on the shortcomings of soccer players in transition period, because that is the only period when they can make up due to lack of time.

Low back pain prevalence and risk factors in Italian adolescent male soccer players: results from an online survey.

The purpose of this retrospective survey was to analyze the prevalence of low back pain (LBP) among Italian adolescent soccer players, and to identify potential risk factors. Participants were requested to answer an online survey based on the standardized Nordic questionnaires for musculoskeletal symptoms. Data were obtained from 204 male soccer players aged 14-17 years competing at the national and regional level. More than half of the players had experienced LBP in their lives. One-way ANOVA revealed that the players with LBP were taller, heavier and with a higher BMI (all P values<0.00001). When considering the playing position, ANOVA revealed that 14-15 years-old strikers displayed higher LBP scores than all other roles (all P values<0.05). Accordingly, strikers were exposed to a higher risk of LBP than midfielders (RR=1.48; 95% CI: 1.10-2.01; P=0.01) and goalkeepers (RR=1.48; 95% CI: 1.02-2.971; P=0.04), but not defenders (RR=1.23; 95% CI: 0.93-1.63; P=0.15). Within the 14-15 age-class, strikers were, again, those most exposed to LBP risk (all P values<0.05). Anthropometric and soccer-related features should be monitored to ensure early identification of potential risk factors for LBP. This information should be considered along with the specific playing position as strikers emerged as the roles most exposed to LBP risk.

Can discreet performance banding, as compared to bio-banding, discriminate technical skills in male adolescent soccer players? A preliminary investigation

Maturation-related changes in body dimensions and performance can lead to physical mismatches and drop out from youth sport. Here, we propose a new method termed ‘discreet performance banding’ (DPB). We aimed to determine if dividing youths by actual physical performance of a discreet skill or ability (‘change or direction’ [COD] ability) could discriminate between the most and least skilled players better than a marker of implied performance, such as an assessment of biological maturation. 182 male academy Spanish soccer players (age: 13-18 years height: 143 to 188 cm; mass: 32.3 to 81.4 kg) were divided into maturation groups (Tanner stages 2 through 5) and COD groups (‘fast’, ‘intermediate’ and ‘slow’). Players’ skills (passing, shooting, ball control) were evaluated on a six-point scale with a value of ‘1’ considered ‘very bad’ and a value of ‘6’ as ‘very good’. When divided by maturity status, analyses revealed no significant differences between groups in soccer skill. However, when divided into COD groups, the analyses revealed significant differences between the fast and intermediate players ([p &lt; 0.001] favouring the fast group) and between the intermediate and slow players ([p &lt; 0.026] favouring the slow group). There was no significant difference in skill between the fast and slow groups, though the fast group demonstrated a higher skill level as indicated by a small effect size. Fast players were more skilful than both the intermediate and slower players, indicating that COD status can be a differentiating factor between players of different skill levels. DPB could be used to equalise competition in youth sport and to enhance the overall level of enjoyment that youths derive from engagement in sport.

Estimating somatic maturity in adolescent soccer players: Methodological comparisons

Purpose Monitoring maturation facilitates effective talent development. Various methods of maturity estimation exist with limited knowledge of concordance between methods. This study aims to establish agreement between methods of varied constructs to predict maturity status and compare concordance of methods to categorise players using established thresholds. Methods This study compared four maturity equations using anthropometrical data from 113 male adolescent soccer players (mean ±SD; age, 14.3 ± 1 years) from two academies. Conservative (±1 year) and less conservative (±0.5 years) circa-PHV thresholds were employed. Results Analysis indicates tight (±0.3 year) agreement between maturity offset methods (MO), but broader agreement between MO and predicted adult height methods (–1.5 to 1 year). However, Kappa Cohen k suggests moderate to substantial (44%–67%) and fair to moderate (31%–60%) concordance between methods when using the conservative and less conservative circa-PHV thresholds respectively. Conclusion Despite MO equation iterations claiming to reduce systematic error, they provide very similar estimations. Additionally, practitioners should not use maturity offset and predicted adult height methods interchangeably and are encouraged to apply either method consistently when looking to estimate maturity status or biologically calssify players.

Speed, Change of Direction Speed and Reactive Agility in Adolescent Soccer Players: Age Related Differences.

There are a plethora of studies investigating agility in soccer; however, studies have rarely presented the reaction time in differentiating age groups in adolescent soccer players. We investigated age differences in reactive agility, speed, and change of direction speed (CODs), in a group of highly trained adolescent soccer players. A total of 75 adolescent male soccer players (aged 14–19 years) were recruited. The players were grouped based on their age to under 15 (U15; n = 27), under 17 (U17; n = 25), and under 19 (U19; n = 23) players. Players were tested for 5 m, 10 m, and 20 m sprint, CODs speed test, Illinois test, and reactive agility test (total and reaction time). Only the reactive agility test with a live tester (RAT live) and RAT live reaction time (RAT live RT) distinguished U19 from both groups, U17 (RAT live, p < 0.01; RAT RT live, p < 0.01) and U15 (RAT live, p < 0.01; RAT RT live, p < 0.01). Groups did not have different times for 5 m sprint, RAT light and RAT RT light, F = 0.472, 2.691, 1.023, respectively, p > 0.05. Moreover, a significantly slower average performance of sprint 20, CODs left and right, and Illinois was also observed in U15 as compared to U17 and U19 (p < 0.05). We can conclude that results in agility tests that include live testers can be a significant factor that differentiates between adolescent soccer players considering their age.

Improvement of Physical Performance Following a 6 Week Change-of-Direction Training Program in Elite Youth Soccer Players of Different Maturity Levels.

Background: Change-of-direction (CoD) is a necessary physical ability of a field sport and may vary in youth players according to their maturation status.Objectives: The aim of this study is: to compare the effectiveness of a 6-week CoD training intervention on dynamic balance (CS-YBT), horizontal jump (5JT), speed (10 and 30-m linear sprint times), CoD with (15 m-CoD + B) and without (15 m-CoD) the ball, in youth male soccer players at different levels of maturity [pre- and post-peak height velocity (PHV)].Materials and Methods: Thirty elite male youth soccer players aged 10–17 years from the Tunisian first division participated in this study. The players were divided into pre- (G1, n = 15) and post-PHV (G2, n = 15) groups. Both groups completed a similar 6-week training program with two sessions per week of four CoD exercises. All players completed the following tests before and after intervention: CS-YBT; 5 JT; 10, 30, and 15 m-CoD; and 15 m-CoD + B, and data were analyzed using ANCOVA.Results: All 30 players completed the study according to the study design and methodology. Adherence rate was 100% across all groups, and no training or test-related injuries were reported. Pre-PHV and post-PHV groups showed significant amelioration post-intervention for all dependent variables (after test > before test; p < 0.01, d = 0.09–1.51). ANOVA revealed a significant group × time interaction only for CS-YBT (F = 4.45; p < 0.04; η2 = 0.14), 5JT (F = 6.39; p < 0.02; η2 = 0.18), and 15 m-CoD (F = 7.88; p < 0.01; η2 = 0.22). CS-YBT, 5JT, and 15 m-CoD improved significantly in the post-PHV group (+ 4.56%, effect size = 1.51; + 4.51%, effect size = 1.05; and -3.08%, effect size = 0.51, respectively), more than the pre-PHV group (+ 2.77%, effect size = 0.85; + 2.91%, effect size = 0.54; and -1.56%, effect size = 0.20, respectively).Conclusion: The CoD training program improved balance, horizontal jump, and CoD without the ball in male preadolescent and adolescent soccer players, and this improvement was greater in the post-PHV players. The maturity status of the athletes should be considered when programming CoD training for soccer players.

Association of Sex With Adolescent Soccer Concussion Incidence and Characteristics

Because of the negative consequences of concussion, considerable research efforts have been directed toward understanding the risk factors for sport-related concussion (SRC) and its outcomes to better inform strategies for risk reduction. Girls are suggested to have an increased risk of concussion, warranting exploration into sex-dependent variations in concussion presentation and management, with the potential that this information might inform sex-specific rules directed toward risk reduction within sports. To compare sex-associated differences in epidemiology and concussion management in adolescent soccer players within a prospective, longitudinal high school injury surveillance project. This prospective, longitudinal cohort study assessed male and female soccer athletes from all high schools in the Michigan High School Athletic Association (MHSAA) during academic years 2016-2017 to 2018-2019. Sport-related concussion captured in the MHSAA Head Injury Reporting System. Outcomes included details regarding each documented SRC event, including injury mechanism, immediate management, and return-to-play time. Multiple comparisons were made between male and female athletes regarding SRC risk, mechanism, short-term management, and outcomes. A total of 43 741 male and 39 637 female soccer athletes participated in MHSAA soccer during the 3 consecutive academic years of study (2016-2017: n = 751 schools; 2017-2018: n = 750 schools; and 2018-2019: n = 747 schools). During the 3 years of surveillance, 1507 of the 83 378 soccer athletes (1.8%) were reported to have SRC during soccer participation, including 557 boys (37.0%) and 950 girls (63.0%). Documented SRC risk in female soccer participants was greater than in male soccer participants (risk ratio, 1.88; 95% CI, 1.69-2.09; P < .001). Male soccer athletes most often sustained SRC from contact with another player (48.4%), whereas SRCs in female soccer players recorded in the Head Injury Reporting System were most often from nonplayer contact events (41.9%; P < .001). Adolescent male soccer players with a documented SRC were more likely to be removed from play on the day of injury (odds ratio, 1.54; 95% CI, 1.15-2.06; P = .004). Although the overall median time to return to play was 11 days (interquartile range [IQR], 7-15 days), male athletes typically returned 2 days earlier than female athletes (median, 10 [IQR, 7-14] days vs 12 [IQR, 7-16] days; Peto test P < .001). In this cohort study, sex-associated differences were revealed among adolescent soccer athletes in SRC risk, mechanism of injury, immediate management, and outcomes in injuries documented in a statewide injury reporting system. Thus, consideration might be given to sex-specific approaches to participation and concussion management in the sport.

Is Increased Kicking Leg Iliopsoas Muscle Tightness a Predictive Factor for Developing Spondylolysis in Adolescent Male Soccer Players?

To identify predictive risk factors of lumbar stress (LS) fracture developing from an asymptomatic stress reaction of the pedicle among adolescent male soccer players. Prospective cohort study. Amateur Japanese adolescent male soccer team. Japanese adolescent male soccer players (n = 195) aged 12 to 13 years. Height, body weight, body mass index, muscle tightness of both lower extremities (iliopsoas, hamstrings, and quadriceps), lumbar bone mineral content, developmental age, and lumbar lordosis angle were measured as baseline measurements. Players who were diagnosed with an asymptomatic stress reaction of the lumbar spine pedicle at baseline were followed; extension-based lumbar pain was defined 1 year after the baseline. The players were assigned to the LS fracture or control (CON) group at follow-up. At baseline, 40 boys were diagnosed with an asymptomatic stress reaction of the lumbar spine pedicle. The difference in muscle tightness between the kicking leg and supporting leg was significantly different (P = 0.012) between the LS (n = 16) and CON (n = 22) groups. Increase in iliopsoas muscle tightness in the kicking leg was a predictive risk factor of developing extension-based lumbar pain after adjusting for developmental age and body mass index (odds ratio, 1.54; 95% confidence interval, 1.05-2.27). Development of extension-based lumbar pain from an asymptomatic stress reaction of the pedicle among adolescent male soccer players was associated with increased iliopsoas muscle tightness of the kicking leg relative to that of the supporting leg.

Relationship between biological age, body dimensions and cardiorespiratory performance in young soccer players

Background: During adolescence, performance in competitive sport is influenced not only by the levels of physical activity, but also by the biological state and body dimensions. Objective: The purpose of our study was to compare cardiorespiratory performance between groups with different biological age in male adolescent soccer players. Methods: Eighty-eight young soccer players (age = 15.9 &#177; 0.5 years, body height = 176.1 &#177; 5.6 cm, body weight = 65.4 &#177; 7.2 kg) performed a vita-maxima protocol on a treadmill. Starting speed was 6 km/h and inclination 1.4%, which were increased linearly every minute, to 11 km/h and to 3.5% respectively (first 5 minutes). Then we increased inclination by 2% every minute until exhaustion. The effect of the biological age on functional indices was examined based on two grouping methods. First, the participants were classified into sub-groups by their morphological (or developmental) age, which is an expression of biological age and evaluates the developmental state of specific body dimensions (body height, body weight, shoulder width, lower arm girth, and hand circumference). Then, from anthropometric and body composition measures three clusters were created, according to the participants' developmental state. For both grouping methods, the groups were: late-maturing, average-maturing, early-maturing. Results: Based on the morphological age grouping method, biologically more advanced athletes achieved greater cardiorespiratory performance (late-maturing: 337 &#177; 33 W, average maturing: 363 &#177; 48 W, early maturing: 386 &#177; 43 W) with higher oxygen uptake (late-maturing: 3529 &#177; 336 ml/min, average-maturing: 3798 &#177; 436 ml/min, early-maturing: 3983 &#177; 541 ml/min) and oxygen pulse (late-maturing: 18.1 &#177; 1.8 ml/beat, average-maturing: 19.6 &#177; 2.5 ml/beat, early-maturing: 20.8 &#177; 2.8 ml/beat). There were no differences in time spent on the treadmill, maximal lactic acid levels, relative power, maximal heart rate, respiratory rate, tidal volume, relative maximal oxygen uptake, maximal ventilation. There were significant differences in weight, plastic index and muscle mass between all the three groups. Differences in cardiorespiratory indices between groups of different maturity status were larger when we grouped the athletes based on cluster analysis compared to the morphological age-based grouping method. Conclusions: During growth and maturation Body dimensions and body (and muscle) mass significantly affect maximal oxygen uptake in young athletes. The inclusion of body composition components in addition to body dimensions increases the explanatory power of biological age on cardiorespiratory performance.

Characteristics of select and non-select U15 male soccer players.

Baseline characteristics of 31 healthy male U15 soccer players who were classified as select or non-select at the end of the season were compared. Players were 14.4 ± 0.54 years (13.6–15.3 years) at baseline; characteristics included body size, proportions and composition, estimated maturity status, several functional capacities, and coach classifications of potential in the sport. Decisions regarding selection or non-selection were made about two months after baseline. Select and non-select U15 soccer players differed significantly in estimated maturity status, body size, proportions and estimated muscle mass, functional tests related to speed, power and strength, and coach evaluation of potential, specifically tactical skills on offense and skills associated with creativity and decision making. When age and biological maturity status were statistically controlled, select and non-select players differed significantly only on the vertical jump, grip strength, and coach ratings of tactical skills on offense and of creativity and decision making. Results of stepwise discriminant analysis highlighted the importance of coach evaluation of tactical skills associated with offense, and of power and strength in distinguishing select from non-select players. The results highlight the advantages of advanced biological maturity status among adolescent male soccer players and also the importance of coach perceptions of talent. The latter implies a need for further study of the basis of coach perceptions, specifically how they are influenced by and perhaps interact with player characteristics at different ages, and how the perceptions influence playing time and player behaviors and interactions.

The Effect of Different Attentional Focus on the Penalty Kicking Performance of Adolescent Male Soccer Players in Different Levels

The Effect of Different Attentional Focus on the Penalty Kicking Performance of Adolescent Male Soccer Players in Different Levels

Coronary artery z score values in adolescent elite male soccer players.

With the increased training loads at very early ages in European elite youth soccer, there is an interest to analyse coronary artery remodelling due to high-intensity exercise. Prospective echocardiographic study in 259 adolescent elite male soccer players and 48 matched controls. The mean age was 12.7 ± 0.63 years in soccer players and 12.6 ± 0.7 years in controls (p > 0.05). Soccer players had significant greater indexed left ventricular mass (93 ± 13 g/m2 versus 79 ± 12 g/m2, p = 0.001). Both coronary arteries origin could be identified in every participant. In soccer players, the mean diameter of the left main coronary artery was 3.67 mm (SD ± 0.59) and 2.61 mm (SD ± 0.48) for right main coronary artery. Controls showed smaller mean luminal diameter (left main coronary artery, p = 0.01; right main coronary artery, p = 0.025). In soccer players, a total of 91% (n = 196) and in controls a total of 94% (n = 45) showed left main coronary artery z scores within the normal range: -2.0 to 2.0. In right main coronary artery, a pattern of z score values distribution was comparable (soccer players 94%, n = 202 vs. controls 84%, n = 40). A subgroup of soccer players had supernormal z score values (>2.0 to 2.5) for left main coronary artery (9%, n = 19, p = 0.01) and right main coronary artery (6%, n = 10, p = 0.025), respectively. Elite soccer training in early adolescence may be a stimulus strong enough to develop increased coronary arteries diameters. In soccer players, a coronary artery z score >2.0-2.5 might reflect a physiologic response induced by multiannual high-intensity training.

The Main and Interactive Effects of Biological Maturity and Relative Age on Physical Performance in Elite Youth Soccer Players

The main and interactive effect of biological maturity and relative age upon physical performance in adolescent male soccer players was considered. Consistent with previous research, it was hypothesised that participants of greater maturity or born earlier in the selection year would perform better in terms of physical performance tests. This cross-sectional study consisted of 84 male participants aged between 11.3 and 16.2 years from a professional soccer academy in the English Premier League. Date of birth, height, weight, and parental height were collected. Sprint, change of direction, countermovement jump, and reactive strength index were considered for physical performance. Relative age was based on the birth quarter for the selection year. Maturity status was based upon the percentage of predicted adult height attained. Linear regression models highlighted that maturation was associated with performance on all but one of the physical performance tests, the reactive strength index. In contrast, relative age only served as a significant predictor of performance on the countermovement jump. This study indicated that physical performance (in the tests studied) seems to be related to the biological maturity status of a player but not their relative age. This finding is important because it suggests that early-maturing players perform better in the majority of physical performance tests, and the commonly held belief that relative age effect influences performance may be overstated.

Energy Requirements of Male Academy Soccer Players from the English Premier League.

This study aimed to inform the energy requirements of highly trained adolescent soccer players. Total energy expenditure (TEE) was quantified in academy soccer players from the English Premier League (EPL). Twenty-four male adolescent soccer players from an EPL academy (under (U) 12/13 (U12/13), n = 8; U15, n = 8; U18, n = 8) were assessed for baseline maturity (maturity offset), body composition (dual-energy x-ray absorptiometry), and resting metabolic rate (indirect calorimetry). Subsequently, TEE, energy intake (EI) and physical loading patterns were assessed over a 14-d in-season period using doubly labeled water, the remote food photographic method, and global positioning system technology, respectively. U18 players presented with greater resting metabolic rate (2236 ± 93 kcal·d) and TEE (3586 ± 487 kcal·d; range, 2542-5172 kcal·d) than did both U15 (2023 ± 162 and 3029 ± 262 kcal·d, respectively; TEE range, 2738-3726 kcal·d) and U12/13 players (1892 ± 211 and 2859 ± 265 kcal·d, respectively; TEE range, 2275-3903 kcal·d; all, P < 0.01), although no difference in TEE was apparent between the U12/13 and U15 age groups. Fat-free mass was significantly different between all comparisons in a hierarchal manner (U18: 57.2 ± 6.1 kg > U15: 42.9 ± 5.8 kg > U12/13: 31.1 ± 3.5 kg; all, P < 0.01). Within age groups, no differences were apparent between EI and TEE (U12/13: -29 ± 277 kcal·d, P = 0.78; U15: -134 ± 327 kcal·d, P = 0.28; U18: -243 ± 724 kcal·d, P = 0.37), whereas U18 players (3180 ± 279 kcal·d) reported higher EI than did both U15 (2821 ± 338 kcal·d; P = 0.05) and U12/13 players (2659 ± 187 kcal·d; P < 0.01). The TEE of male academy soccer players progressively increase as players progress through the academy age groups. In some individuals (evident in all age groups), TEE was greater than that previously observed in adult EPL soccer players.

Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players.

Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. -0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. -1.45 ± 0.31mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.

The kick motion analysis of adolescent male soccer players with Osgood-Schlatter disease

Objectives:Osgood-Schlatter disease (OSD) is an injury during adolescence, in which inflammation occurs in the epiphyseal cartilage of the tibial tubercle by repeated traction of patellar tendon. OSD is associated with more in sports that involve jumping, kicking, and running, such as soccer. However, whether the kick motion of adolescent soccer players is related to onset of OSD remains unclear. The purpose of this study was to clarify the characteristics of kick motion in adolescent soccer players who developed OSD prospectively, using three-dimensional motion analysis system.Methods:A total of 29 Japanese adolescent male soccer players who were 12 years old (Hight 153.1 ± 6.9cm, Bodyweight 42.8 ± 7.0kg) joining the same soccer team were followed over a half year period. The team is a town recreation league team. At the baseline, all players went through the medical examination, ultrasonography of tibial tubercle and measurement of real-time kick motion using a three-dimensional motion analysis system (Qualisys track manager, Qualisys AB., Sweden). The three-dimensional angle of the lumbar spine, pelvis, hips, knees, ankles of both legs, the position of supporting leg and center of mass (COM) were calculated by 65 spherical markers on each anatomical landmark. COM was adjusted dividing by height. The ball speed, kicking time, angular velocity and angular acceleration were also calculated. The data of each phase was collected for the following eight events: foot contact, toe off, maximum hip extension, maximum knee flexion, ball impact, maximum hip flexion of kicking leg, and foot contact, maximum knee flexion of supporting leg. Phase duration was calculated as a percentage of the kick motion. The muscle tightness test of bilateral lower limbs (Iliopsoas, Hamstrings, Quadriceps, Gastrocnemius, Soleus muscle) were measured at the baseline and the follow-up. The participants were followed six months later, and OSD was diagnosed by tenderness and ultrasonography findings of the tibial tubercle and were divided into two groups: presence of OSD on supporting leg; OSD and absence of OSD; CON. All the factors calculated by the kick motion analysis at the baseline and the development of muscle tightness of bilateral lower limbs between OSD and CON were compared by using the unpaired t-test. Players who were diagnosed as OSD at the baseline (n=6) were excluded from the analysis.Results:There were 10 players of OSD and 13 players of CON. The growth of height, muscle tightness, ball speed, kicking time, phase duration in OSD were not different from CON. The sagittal translation of COM in OSD was significantly smaller than CON(p<0.05) before the ball impact phase. The knee angular acceleration of supporting leg was significantly larger in OSD(p<0.05) between the phase supporting leg lands and the flexion angle of its knee reaches the peak before the ball impact. The lateral bending angle of the pelvis toward the supporting leg in OSD was significantly smaller(p<0.05), and the maximum hip extension angle of kicking leg, lumbar rotation angle, kicking leg’s knee angular velocity and acceleration at the ball impact were smaller in OSD(p<0.1).Conclusion:The kick motion with small translation of COM before ball impact was associated to onset of OSD. OSD also showed smaller range of motion in proximal joints to the knees compared with CON. The large knee angular acceleration of supporting leg towards maximum knee flexion was found in OSD, which may increase the traction of quadriceps muscle to the tibial tubercle.Figure 1.

Basic Cognitive Abilities Relevant to Male Adolescents' Soccer Performance.

While there is a theoretical and empirical consensus that specific cognitive abilities gained through deliberate sports practice influence sports performance, it is less clear whether basic cognitive abilities that are not specifically related to sports practice are relevant to sports performance. Accordingly, this research examined the roles of basic concentration and visuospatial ability in adolescent soccer performance. Participants were 46 adolescent male soccer players (Mage = 16.15 years, standard deviation = 1.13) who averaged 7.21 years (standard deviation = 2.2) of prior soccer training. We measured participant's basic cognitive abilities with the Corsi block and the concentration grid tasks, and we measured their soccer performance through five soccer skills. Concentration had no predictive role in elements of soccer performance, but visuospatial ability was significantly related to tactical abilities, technical skills, mental toughness, and situational awareness and thus, to overall soccer performance. These findings provided support for the importance of visuospatial ability but not concentration (as measured by the concentration grid) in young males' soccer performance.

The Importance of Reactive Agility Tests in Differentiating Adolescent Soccer Players

The ability to differentiate the elite from nonelite athletes is not clearly defined. We investigated level differences in speed, change of direction speed (CODS), and reactive agility in a group of trained adolescent soccer players. A total of 75 adolescent male soccer players (aged 14–19 years) were recruited. The players were grouped based on the level of play to elite, sub-elite, and amateur players. Players were tested for 5-, 10- and 20-m sprints, CODS, and reactive agility tests (RAT). Elite players had faster reaction movement time during RAT with live opponent stimuli (p ≤ 0.01) compared to sub-elite and amateur players. Moreover, elite players showed a faster time during light stimuli (p ≤ 0.01) but only compared to amateur players. The times for 5-m and 10-m sprint groups did not differ (p > 0.05). The results demonstrated that the skilled players (elite and sub-elite) performed better in reactive agility tests, speed, and COD speed compared to amateur players. Additionally, we can conclude that total and reaction time in the agility test with live opponent stimuli can be a significant factor that differentiates between adolescent soccer players considering their level.

Risk Factors in Elite, Adolescent Male Soccer Players: Prospective Study.

Purpose. To find risk factors for soccer-related musculoskeletal injuries among elite, adolescent male soccer players. Methods. Prior to the season, various physical, clinical, and functional measurements were taken. One season was used as an injury surveillance period. Then, after the season, measures of potential risk factors were compared between (1) those players who sustained musculoskeletal injuries and (2) those who remained injury free. Results. Among 61 players, 37.7% (23/61) sustained soccer-related musculoskeletal injuries. After adjusting for covariates in a logistic regression model, presence of previous hip and low back injury (adjusted odds ratio [aOR] = 8.93, P = .046) and Functional Movement Screen (FMS) scores (aOR = 1.92, P = .022) were independently associated with musculoskeletal injures. Conclusion. Elite, adolescent male soccer players with a history of hip and back injury are at greater risk of sustaining a soccer-related musculoskeletal injury. In addition, our study indicated greater risk of sustaining a future soccer-related injury as FMS scores increase.