Динамика сезонных изменений сывороточной концентрации 25(ОН)D у юных футболистов

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Hospital de Clínicas de Porto Alegre Research and Event Incentive Fund (FIPE-HCPA) Introduction Black athletes may present some peculiarities in the resting 12-lead electrocardiogram, such as T-wave inversion (TWI) confined to V1-V4 preceded by ST-segment and J-point elevation (‘domed’ ST-elevation and TWI in V1-V4), the so-called Afro-Caribbean pattern, a benign variant of the athlete's heart according to the "2017 International criteria for electrocardiographic interpretation in athletes". However, the prevalence of these findings in young Afro-Brazilian (AB) soccer players is unknown. Purpose To compare the prevalence of ‘domed’ ST-elevation and TWI in V1-V4 among young AB soccer players with Ghanaians black soccer players. Methods We sought to do this analysis visually, as the data from AB soccer players were as raw data; and those from Ghana’s were else aggregated. A forest plot with the point estimate and confidence intervals at 95% was built and, whenever any region from the lower limit up to the upper limit of the confidence interval of a given variable interpolate to the other, no differences could be claimed. The forest plot was built at R v. 4.1.2 using the package "metafor". Results Data from 517 young AB soccer players (mean age: 20 years) and 159 young black soccer players from Ghana (mean age: 19 years) were evaluated and compared. The average height and weight were similar (177.2 cm and 70.7 kg for AB, and 175.2 cm and 68.4kg for Ghanaians players). Ghanaians had a significant higher prevalence of ‘domed’ ST-elevation and TWI in V1-V4 than AB (16.7%; 95% CI, 13.1 to 25.8 versus 2.1%; 95% CI, 1.2 to 3.9, respectively). Conclusion To the best of our knowledge, this is the first study to describe the low prevalence of the ‘domed’ ST-elevation combined with TWI in V1-V4 in young AB soccer players. Interestingly, when compared to Ghanaians young soccer players (all of them black African individuals), AB athletes presented a significant lower frequency of this finding (16.7% versus 2.1%). Finally, we hypothesize that ‘domed’ ST-elevation and TWI in V1-V4 seen in African athletes appears to become less prevalent in the generations after the time of migration from Africa to Brazil. Whether this is due to environmental or genetic changes, further studies should clarify.

ObjectivesTo investigate hip pain, hip range of motion and the presence and size of cam morphology among young soccer players and skiers. DesignCross-sectional study. MethodsThe hip joints of young male soccer players and male and female skiers were examined clinically for hip range of motion (ROM) and with MRI (the presence of cam morphology). All participants answered questions about hip pain, debut age for training/competing and training frequency. ResultsClinical examinations were performed on 135 athletes (60 male soccer players, 40 male skiers and 35 female skiers), of which 93 athletes had additional MRIs. Mean age was 17.7 (SD 1.2) years. Cam morphology (α-angle ≥60°) was significantly less present in female skiers (3%) compared with male skiers (38%, p ​< ​0.001) and male soccer players (33%, p ​= ​0.03). The soccer players had significantly reduced internal and external hip rotation and self-reported hip pain, compared with the skiers. Female skiers had significantly greater hip ROM, compared with both male skiers and soccer players. A low positive correlation was found between cam morphology and hip pain in male skiers (r ​= ​0.42; p ​= ​0.014). ConclusionsFemale skiers had a lower prevalence of cam morphology compared with the male groups while no difference was found between the male skiers and soccer players. Young male soccer players had significantly reduced internal and external hip rotation and a lower grade of self-reported hip pain compared with male and female skiers.

The ability to maintain a stable single-leg balance stance during a fast change of direction movement is a fundamental aspect both for improving sport-specific skills and for prevention strategies. The aim of this cross-sectional study was to investigate the associations between multidirectional speed performance (MDS), dynamic balance performance (DBP), and chronological age in young and uninjured soccer players. In addition, it was examined whether chronological age and balance can predict variance in speed performance. One-hundred forty-six young male soccer players (age range 11–19) performed the y-balance test (YBT) and the lower extremity functional test (LEFT). Descriptive statistics, Pearson correlation, and multiple regression analysis were executed. The analyses were carried out on the further variables: for the DBP, the YBT composite score % (CS dominant leg/CS non-dominant leg) and limb symmetry index % (LSI) were used; for the MDS, the LEFT time in seconds (s) was used. Findings revealed LEFT scores to have a significant association with chronological age (p = 0.000), CS dominant (p = 0.019) and LSI (p = 0.044) of the YBT. In addition, CS dominant and chronological age explained the variance of the LEFT by 44%, regardless of LSI. To conclude, MDS revealed a strong association with DBP of the dominant side but a small association with LSI. In addition, a small association was found between quick LEFT times and older players. Finally, MDS variance can be predicted from DBP of the dominant side and chronological age in young soccer players. The tests used in this study could be useful screening tools for the detection of performance deficits, the implementation of prevention training programs, and the optimization of selection strategies in soccer academies.

Introduction: In youth soccer, for examining injury prevention and exercise performance, most of the interventional studies concerning corrective postural asymmetries have applied general intervention programs, ignoring the specific individual corrective needs of each youth player separately. The aim, therefore, of the present study was to examine the effect of 8 weeks of an individualized corrective exercise intervention program on musculoskeletal asymmetries in young soccer players. Materials and Methods: Eighty young male soccer players (age: 14.4 ± 1.2 years; body height: 166.3 ± 9.6 cm; body mass: 59.1 ± 11.5 kg) participated in the current laboratory-based study. A battery of postural and musculoskeletal asymmetry evaluations were initially performed. After the completion of the initial assessment, each player was provided with an individual musculoskeletal asymmetry corrective exercise intervention program which lasted for 8-weeks, with the aim of restoring muscular asymmetries. Following the application of the intervention program, a re-evaluation of their musculoskeletal asymmetries was performed. Results: There was a significant improvement in the primary angle of trunk rotation (r = −0.56, p &lt; 0.001), hamstring flexibility (right: r = −0.55, p &lt; 0.001; left: r = −0.48, p &lt; 0.001), hip external rotation (right: r = −0.46, p &lt; 0.001; left: r = −0.26, p = 0.020), hip internal rotation (right: r = −0.26, p = 0.021; left: r = −0.35, p = 0.002), the opened-eyes Stork Test (right: r = −0.33, p = 0.003: left: r = −0.33, p = 0.003), the closed-eyes Stork Test (right: r = −0.39, p &lt; 0.001; left: r = −0.43, p &lt; 0.001), the Thomas test [right: (χ2(3) = 52.281, p = 0.001, γ^ = −0.751; left: (χ2(3) = 45.832, p = 0.001, γ^ = −0.696)] and of ankle prone passive dorsiflexion (flexed knees) (χ2(2) = 13.019, p = 0.005, V = 0.285). Conclusions: An 8-week individual corrective intervention exercise program may improve postural and musculoskeletal asymmetry status in young male soccer players.

The aim of the study was to assess the effects of multidirectional plyometric training (MPT) on vertical jump height, change of direction performance (CODP), and dynamic postural control (DPC) in young soccer players. Twenty-eight young male soccer players were randomly assigned to an experimental group (EG, n = 14; age: 11.8 ± 0.4 years) and a control group (CG, n = 14; age: 11.6 ± 0.5 years). The EG introduced 8-week MPT, two days per week into their in-season training, while CG continued training without change. Measurements of vertical jump height, CODP, and DPC were completed at the beginning and end of the 8-week MPT. A significant group × time interaction was observed for Squat-Jump (p < 0.05), for Counter-Movement Jump (p < 0.05), and for CODP test (p < 0.05). In addition, a significant group × time interaction was observed for DPC in seven axes for the dominant- (anterior, lateral, postero-lateral, posterior, postero-medial, medial, and antero-medial; p < 0.05 for all) and in seven axes for the non-dominant- (anterior, antero-lateral, lateral, posterior, postero-medial, medial and antero-medial; p < 0.05 for all) legs. The rest of the axes of both legs did not show any significant group × time interaction (p > 0.05). In conclusion, incorporating MPT into the in-season regimen of young male soccer players improved performance of various indices related to soccer activity (i.e., vertical jump height, CODP, and DPC). MPT has the potential to be appealing to coaches, as it requires little time while yielding valuable results in the physical preparation of young soccer players.

Introduction College soccer is a major priority for the Chinese sports department. Among the most relevant issues is the search for solutions to prevent sports injuries among young college soccer players in the development process. Objective Investigate the causes and characteristics of sports injuries among young college soccer players, aiming to develop scientific measures for prevention and control. Methods A total of 304 young people from primary and secondary schools in one city were selected as volunteers for the research, and the causes and characteristics of sports injuries among these players were analyzed using questionnaires, interviews with experts, and statistical-mathematical analysis. Results According to the characteristics of injury factors of soccer players at different learning stages, a good job should be done on preventing sports injuries of physiological, psychological, technological, training, and other aspects, to reduce the risk of sports injuries in young soccer players. Conclusion Fully understanding sports injury risk prevention, timely summarizing the experience and learnings, and doing a good job in sports injury prevention from the aspects of physiology, psychology, technology, training, and other aspects according to the characteristics of injury factors of soccer players at different school stages are desirable practices to reduce the risk of sports injury and improve the quality of school soccer training and competition for young college soccer players. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

There is a lack of studies concerning hydration status of young athletes exercising in the heat. To assess preexercise hydration status in young soccer players during a summer sports camp and to evaluate body- water balance after soccer training sessions. Initial hydration status was assessed in 107 young male soccer players (age 11-16 yr) during the 2nd day of the camp. Seventy-two athletes agreed to be monitored during 2 more training sessions (3rd and 5th days of the camp) to calculate dehydration via changes in body weight, while water drinking was allowed ad libitum. Hydration status was assessed via urine specific gravity (USG), urine color, and changes in total body weight. Mean environmental temperature and humidity were 27.2 ± 2 °C and 57% ± 9%, respectively. According to USG values, 95 of 107 of the players were hypohydrated (USG ≥ 1.020) before practice. The prevalence of dehydration observed was maintained on both days, with 95.8% and 97.2% of the players being dehydrated after the training sessions on the 3rd and 5th days, respectively. Despite fluid availability, 54 of the 66 (81.8%) dehydrated players reduced their body weight (-0.35 ± 0.04 kg) as a response to training, while 74.6% (47 out of the 63) further reduced their body weight (-0.22 ± 0.03 kg) after training on the 5th day. Approximately 90% of the young soccer players who began exercising under warm weather conditions were hypohydrated, while drinking ad libitum during practice did not prevent further dehydration in already dehydrated players.

The purpose of this investigation was to clarify the differences in the musculoskeletal profiles between the dominant leg (DL) and nondominant leg (NDL) of Japanese soccer players. This study included 227 young elite soccer players (121 males and 106 females with mean ages of 19.0 and 17.5 years, respectively). Anthropometric measurements were obtained. In addition, joint range of motion measurements was performed for internal rotation of the hip, ankle dorsiflexion, and knee extension. Muscle flexibility tests were performed on the iliopsoas, quadriceps femoris, hamstring, gastrocnemius, and soleus muscles. Moreover, isometric knee extension, flexion strength, and isometric hip abduction strength were measured. Single-leg balance tests were also performed. As a result, in male soccer players, DL's knee flexor strength and hip abductor strength were significantly stronger than in the NDL. In female soccer players, knee extension and knee flexion strength of the DL were significantly stronger than the NDL. In male soccer players, the hamstring-quadriceps ratio of the DL was significantly greater than NDL. DL demonstrated a significantly lesser center of pressure excursion in the single-leg balance test in male and female soccer players. In both male and female soccer players, the quadriceps muscle of DL was significantly more flexible than those of the NDL. There was no difference in the internal rotation angle of the hip joint between the DL and NDL in male soccer players. In contrast, the internal rotation angle of the DL was significantly (1.6°) greater than NDL in female soccer players. For some anthropometric measurements, muscle flexibility tests and joint range of motion measurements, the difference between the DL and NDL was significant but not large enough to be clinically relevant. In conclusion, the present study showed musculoskeletal asymmetry between the DL and NDL in young male and female soccer players.

This study aimed to clarify potential gender differences across a comprehensive set of anthropometric and musculoskeletal characteristics within a young soccer player population. This study included 227 (121 males and 106 females with mean ages of 19.0 and 17.5 years, respectively) young elite soccer players. Anthropometric measurements were obtained. In addition, general joint laxity tests assessing the wrist, elbow, shoulder, trunk, hip, knee, and ankle were performed. Muscle flexibility tests were performed on the iliopsoas, quadriceps femoris, hamstring, gastrocnemius, and soleus muscles. Moreover, isometric knee extension and flexion strength and isometric hip abduction strength were measured. Single- and double-leg balance tests were also performed. Male soccer players were taller, heavier, and had lower fat mass and percent body fat, and greater skeletal muscle mass and body minerals than female soccer players. Female soccer players had significantly greater laxity in all tests for general joint laxity. Female soccer players demonstrated significantly better hamstring and soleus flexibility than male soccer players but worse iliopsoas flexibility. Consequently, no significant differences were noticed in the quadriceps and gastrocnemius muscles between the male and female soccer players. However, female soccer players demonstrated significantly weaker knee extension and flexion and hip abduction. The hamstring- quadriceps ratio was significantly lower in female soccer players. Although no significant difference exists in the center of pressure excursion in the double-leg balance test between male and female soccer players, female soccer players displayed a significantly lower center of pressure excursion in the single-leg balance test. Young male and female soccer players demonstrate significantly different anthropometric and musculoskeletal profiles.

Bidaurrazaga-Letona, I, Lekue, JA, Amado, M, and Gil, SM. Progression in youth soccer: Selection and identification in youth soccer players aged 13-15 years. J Strength Cond Res 33(9): 2548-2558, 2019-The aim of this study was to identify the factors that are important for the identification and selection of young soccer players. Ninety-four adolescent soccer players from the under-13 (U13; age = 12.3 ± 0.3 years; n = 50) and under-15 (U15; age = 14.0 ± 0.2 years; n = 44) categories belonging to a professional club participated in the study. Anthropometric measurements, physical tests (sprint, agility, endurance and jump), and maturity status (age at peak height velocity) were recorded over 4 seasons. Comparisons were performed among new players joining the club (Enter players, n = 15), players progressing to the next age category (Club players, n = 54), and players leaving the club (Deselected players, n = 25). A 2-way repeated measures analysis of variance (ANOVA) was performed to determine if significant differences existed between groups and testing time. Better physical performance and improvements observed during the season in performance were found to be one of the main factors for U13 players to continue in the club (p < 0.05-0.001). In the U15 group, although body size, maturation and physical performance appeared to be the most important characteristics for being identified to play in the club (p < 0.05), Club players demonstrated better improvements during the season (p < 0.05). Overall, these results indicate that the identification or promotion of players by coaches depends on indicators which are age-dependent. Therefore, this study has shown that the talent identification program was more a selection process than a promotion process, selecting and identifying a posteriori rather than a priori.

Five-week sensory motor training program improves functional performance and postural control in young male soccer players – A blind randomized clinical trial

ABSTRACTYoung soccer players often use one particular dominant leg (DL) to perform dynamic movements which require strength, resulting in leg asymmetry. The aim of this study was to compare, in young soccer players, the effect of using DL and non-dominant leg (NDL) on time performance of two change of direction (COD) manoeuvres in several angles of COD. Seventy-three young male soccer players (mean ± SD, age: 16.1 ± 1.8 year) participated in this study. Players performed 10-m sprints, either in a straight line or with a COD (5 m straight ahead and a turn of 45°, 90°, 135° and 180° to the opposite side of the DL or NDL). Testing for COD speed was conducted over two different manoeuvres: (1) sidestepping and (2) bypass. Maximal isometric voluntary contraction of the knee extensors/flexors and hip abductors/adductors was also measured using a handheld dynamometer. For sidestepping, COD performance with use of the DL was significantly better compared to the NDL (P < 0.05) in all angles of COD. However, bypass COD performance through use of the DL was better compared to the NDL only when turning at 135°. Additionally, strength of the knee extensors/flexors and hip abductors of the DL was significantly (P < 0.05) greater than the NDL. The use of the DL allows better COD performance than the NDL when sidestepping manoeuvre is used. However, the DL allows better COD performance than the NDL only at 135° with the use of the bypass manoeuvre. Furthermore, the greater strength of the DL compared to the NDL may contribute to COD performance difference between legs.

BackgroundThe rate of torque development (RTD) has been associated with sports performance and can be improved during the biological maturation process of young soccer players. The aim of this study was to compare the effects of maturity status on the knee extensors’ RTD of soccer players after appropriate normalization.MethodsTwenty-seven young male soccer players aged 13–18 years old were allocated into two groups: pubescent (PUB, n = 11) and postpubescent (POSP, n = 16). RTD was obtained by performing a maximum voluntary isometric contraction at six different knee joint angles (30º, 45º, 60º, 75º, 90º, and 105º). Anthropometric (height and body mass) and muscle architecture variables (muscle thickness, muscle volume, fascicle length, pennation angle, and cross-section area) were evaluated as body size descriptors and used to identify the best way for appropriate normalization of RTD data.ResultsMuscle architecture variables showed no correlations with RTD (p > 0.05), while body mass showed a positive correlation (0.405 < r < 0.680; p < 0.05). Maturity status showed positive effects on absolute late RTD values (N·m·s−1) obtained at four different angles (60º, 75º, 90º, and 105º). However, maturity status showed no effects on RTD values after normalization by body mass (N·m·s−1·kg−1).ConclusionsMaturity status showed no positive effects on RTD values after appropriate normalization by body mass in young soccer players.

Background The intermittent fasting period of Ramadan is associated with reductions in training volumes and intensities to maintain physical fitness levels and reduce injury occurrence. Accordingly, it might be beneficial to include neuromuscular training (NMT) applied during Ramadan to avoid detraining and promote injury prevention in soccer players. This study aimed to analyze NMT effects on physical fitness and injury prevention during the Ramadan fasting period in young soccer players. Methods Forty young highly-trained male soccer players (U17/U19) were randomly assigned to a NMT (n = 20) or a traditional soccer-specific training group (TT, n = 20). NMT was conducted during Ramadan, lasted four weeks, and included two weekly sessions with exercises to promote muscle strength, power (plyometrics), speed, balance. TT contents were similar to the training period before Ramadan and comprised two weekly sessions including endurance and sprint-based exercises. The training volume was similar between groups. Body composition (body fat), linear sprint (5-m, 10-m, 30-m sprint), and change-of-direction (CoD) speed (T-test with and without ball), muscle power (squat [SJ], countermovement jump [CMJ]), peak isokinetic torque of the knee flexors, extensors, and soccer-specific performance (Loughborough soccer passing test [LSPT], Yoyo intermittent test level 1 [YYIRT L1], repeated-shuttle-sprint ability test [RSSA]) were determined before and after the Ramadan period. The overall injury rate per 1000 h of exposure (training, match) was carried out during and after the four-week Ramadan period and until the end of the soccer season (overall 8 weeks). Results No significant between group baseline differences were noted. Group-by-time interactions were significant for most assessed variables (0.001 &lt; p &lt; 0.004, 0.22 &lt; d &lt; 0.76) in favor of NMT. Variations in body mass, body fat, and BMI determined by post-hoc tests indicated significant decreases in NMT but not TT (0.026 &lt; p &lt; 0.047, 0.65 &lt; d &lt; 0.73). Moreover, post-hoc tests showed that NMT provided linear and COD speed improvements, enhanced muscle power (SJ, CMJ) and improved soccer-specific performance (p &lt; 0.001, 0.71 &lt; d &lt; 2.53). Additionally, post-hoc tests revealed significant isokinetic strength increases in favor of NMT for all peak torque variables (0.015 &lt; p &lt; 0.049, 0.64 &lt; d &lt; 0.81). The overall injury rate was significantly lower in NMT (8.00/1000 h exposure) compared to TT (13.33/1000 h exposure) (p = 0.049; d = 0.66). Conclusions Findings suggest that a four-week NMT conducted during Ramadan fasting helped to maintain or even improve measures of physical fitness including isokinetic strength. In addition, significant NMT-related reductions in injury occurrence were noted in highly-trained young male soccer players.

The present-day conservative treatment algorithms of Osgood-Shlatter Disease (OSD) are often inadequate for young athletes because they require extremity immobilization and avoidance of sports, and hence the longer duration of rehabilitation. Therefore, the development of safe and efficacious treatment protocols for young athletes is of great practical importance. The aim of the study was to assess the efficacy and safety of the conservative treatment of Osgood-Schlatter disease in young professional soccer players. Medical records of young soccer players from two different Russian soccer-academies from the period January 2016-July 2019 were analyzed in a retrospective cohort study. Trauma records of young soccer players aged 11-15years were included in the analysis. Statistical analysis was performed using IBM SPSS Statistics software, 23.0. Descriptive statistics tools were applied for the analysis. A total of 280 soccer players were included in the study. The aged ranged between 11 and 15years. Ten percent of players (n = 28, mean age 12.9 ± 1.3) were diagnosed with OSD during the observation period. The mean OSD treatment duration was 27.3± 13.9days. Bilateral symptoms were observed in 42.9% of cases, and unilateral symptoms in 57.1%. In 53.6% of players, the first manifestation of OSD symptoms was observed during wintertime. All players were training on artificial turf playing fields. Conservative treatment without immobilization was applied to all patients. It included kinesiotherapy for quadriceps muscle lengthening and physiotherapy as well as gradual increase of physical activity. A total of 35.7% of players reported having discomfort upon resuming regular training, which caused some restrictions in exercise. However, the symptoms resolved spontaneously with time. Surgical treatment or complete avoidance of exercise was not used in any of the patients. High incidence of OSD was revealed among young soccer players of the leading Russian soccer academies. The OSD most commonly occurred during wintertime. Conservative treatment of OSD-i.e., physiotherapy and kinesiotherapy-enabled disease-free resuming of sports activity for the majority of patients.