Junior Soccer Research Articles

Resting metabolic rate of Indian Junior Soccer players: Testing agreement between measured versus selected predictive equations.

Owing to a dearth of research related to Resting Metabolic Rate (RMR) among adolescent athletes in India, our study aimed to document RMR among junior soccer players (JSP) and to identify suitable RMR predictive models for JSP from nine existing equations. Forty Indian JSP (Boys = 21, Girls = 19) representing the under-12 and under-16 age categories were assessed for body composition (skinfold technique) and RMR (oxycon mobile). Two-way ANOVA and ANCOVA were used to examine the differences across age and sex. Bland-Altman plot was used to test agreement between measured vs. predicted RMR using the equations of Cunningham (, The American Journal of Clinical Nutrition, 33), Soares et al. (, European Journal of Clinical Nutrition, 47; 1998, British Journal of Nutrition, 79), Henry (, Public Health Nutrition, 8), and Patil and Bharadwaj (, Journal of Postgraduate Medicine, 59) for non-athletic populations and the equations of De Lorenzo et al. (, The Journal of Sports Medicine and Physical Fitness, 39), Wong et al. (, Singapore Medical Journal, 53), and ten Haaf & Weijs (, PloS One, 9) for adult athletes. RMR showed significant (P < .01) sex differences (Boys: 1343 ± 297.1; Girls: 1135 ± 116.7 kcal·day-1 ). While RMR values adjusted for fat-free mass (FFM) were similar across age and sex. The equation of Soares et al. (, British Journal of Nutrition, 79) for girls and Wong et al. (, Singapore Medical Journal, 53) for boys showed better RMR predictability. FFM explained variation in RMR across age and sex. The FFM-based Soares et al. (, British Journal of Nutrition, 79) equation for girls and body weight-based Wong et al. (, Singapore Medical Journal, 53) equation for boys are best suited for predicting RMR.

Effects of using mandatory technical exercises on the performance level of some individual and combined skills of junior soccer players

The aim of this research is to design a training program for compulsory technical training, 1- The impact of the proposed program on the performance of some of the skills of individual footballers. 2-The impact of the proposed program on the level of performance of some of the skills integrated with footballers.

Influence of Physical Maturity Status on Sprinting Speed Among Youth Soccer Players

McCunn, R, Weston, M, Hill, JKA, Johnston, RD, and Gibson, NV. Influence of physical maturity status on sprinting speed among youth soccer players. J Strength Cond Res 31(7): 1795-1801, 2017-The relative age effect is well documented with the maturation-selection hypothesis the most common explanation; however, conflicting evidence exists. We observed the birth date distribution within an elite junior soccer academy. The influence of physical maturity status on anthropometric variables and sprinting ability was also investigated. Annual fitness testing was conducted over an 8-year period with a total of 306 players (age: 12.5 ± 1.7 years [range: 9.7-16.6 years]; stature: 156.9 ± 12.9 cm; mass: 46.5 ± 12.5 kg) drawn from 6 age categories (under-11s to under-17s) who attended the same Scottish Premiership club academy. Measurements included mass, stature, maturity offset and 0-15 m sprint. Odds ratios revealed a clear bias toward recruitment of players born in quartile 1 compared with quartile 4. The overall effect (all squads combined) of birth quartile was very likely small for maturity offset (0.85 years; 90% confidence interval [CI], 0.44-1.26 years) and stature (6.2 cm; 90% CI, 2.8-9.6 cm), and likely small for mass (5.1 kg; 90% CI, 1.7-8.4 kg). The magnitude of the relationship between maturity offset and 15-m sprinting speed ranged from trivial for under-11s (r = 0.01; 90% CI, -0.14 to 0.16) to very likely large for under-15s (r = -0.62; -0.71 to -0.51). Making decisions about which players to retain and release should not be based on sprinting ability around the under-14 and under-15 age categories because any interindividual differences may be confounded by transient inequalities in maturity offset.

A Comparative Study on Kinematic Performance of Corner Kicks for Junior Soccer Players According to Ball Rotation towards Effective Areas in Front of the Goal

A Comparative Study on Kinematic Performance of Corner Kicks for Junior Soccer Players According to Ball Rotation towards Effective Areas in Front of the Goal

The Effects of Sleep Deprivation on Soccer Skills.

Many athletes sleep poorly due to stress, travel, and competition anxiety. In the present study, we investigated the effects of sleep deprivation on soccer skills (juggling, dribbling, ball control, continuous kicking, 20 and 40 m sprint, and 30 m sprint with changes of direction). In all, 19 male junior soccer players (14-19 years old) were recruited and participated in a cross-balanced experimental study comprising two conditions; habitual sleep and 24 hours sleep deprivation. In both conditions, testing took place between 8 a.m. and 10 a.m. Order of tests was counterbalanced. Each test was conducted once or twice in a sequence repeated three times. The results revealed a negative effect of sleep deprivation on the continuous kicking test. On one test, 30 meter sprint with directional changes, a significant condition × test repetition interaction was found, indicating a steeper learning curve in the sleep deprived condition from Test 1 to Test 2 and a steeper learning curve in the rested condition from Test 2 to Test 3. The results are discussed in terms of limitations and strengths, and recommendations for future studies are outlined.

Effects of a 10-Week Nordic Hamstring Exercise and Russian Belt Training on Posterior Lower-Limb Muscle Strength in Elite Junior Soccer Players.

Rey, E, Paz-Domínguez, Á, Porcel-Almendral, D, Paredes-Hernández, V, Barcala-Furelos, R, and Abelairas-Gómez, C. Effects of a 10-week Nordic hamstring exercise and Russian belt training on posterior lower-limb muscle strength in elite junior soccer players. J Strength Cond Res 31(5): 1198-1205, 2017-The purpose of this study was to assess the effect of 2 eccentric hamstring training exercises, Nordic hamstring exercise (NHE) and Russian belt (RB), on lower-limb strength and bilateral asymmetry using the single-leg hamstring bridge (SLHB) test. Forty-seven elite junior soccer players (age 17.7 ± 0.5 years, height 175.3 ± 3.6 cm, body mass 68.1 ± 7.4 kg) were randomized into 1 of 3 groups, the NHE group (n = 16), RB group (n = 15), or the control group (CG) (n = 16). The eccentric training intervention consisted of 27 supervised training sessions over 10 weeks. Within-group analysis showed significant improvements (p < 0.001) in right SLHB (+25.52% for NHE and +18.33% for RB) and left SLHB (+28.92% for NHE and +20.08% for RB) from pretest to posttest in NHE and RB. However, no significant pre-post changes were observed for the CG in any variable. In addition, a significant time effect (p = 0.028) was also observed for NHE in bilateral asymmetry decreasing from pre- to posttest. In the between-groups analysis, significant better results were found in right SLHB and left SLHB, in the NHE group and RB group in comparison with CG. However, there were no differences between the eccentric training groups (NHE vs. RB). The RB seems to be a viable alternative to the NHE to developing posterior lower-limb muscle strength based on SLHB.

High intrasexual competition is related to inflated height reports in male junior soccer players

Intrasexual competition refers to the rivalry between same-sex individuals over access to potential mates. Because in many animal species larger males are more likely to defeat smaller opponents over access to potential mates and additional resources, it has been suggested that intrasexual competition was a major driver in the emergence of male-biased sexual size dimorphism. In the same vein, human male height has been related to aggressive behavior, status and dominance. Given the value of body size in agonistic interactions, body inflation strategies are likely to have evolved in many animal species. In this study, we explored the relationship of the bias in reporting one's own height—a phenomenon reminiscent of animal self-inflation mechanisms—with intrasexual competition, and sociable and aggressive dominance, in the highly competitive context of Uruguayan pre-professional soccer. We also considered the bias in reporting additional operationalizations of body size, i.e., weight, and body mass index (BMI). We showed that intrasexual competition is positively correlated with height over-report. To the best of our knowledge, this study is the first to relate intrasexual competition and the bias in reporting one's own height, a putative indicator or power and status.

Relationship Between Morphological Characteristics and Match Performance in Junior Soccer Players

Soccer players are usually selected based on their anthropometry characteristics rather than their performances. Therefore, the purpose of this cross-sectional study was to examine the relationship between morphological and match performances among junior soccer players. Thirty seven junior soccer players were randomly selected using as stratification criteria age and playing role. Skinfolds (mm) were measured at six sites: triceps skinfold thickness, subscapular skinfold thickness, thigh skinfold thickness, calf skinfold thickness, supraspinal skinfold thickness and abdominal skinfold thickness. In addition, total distance covered during the match, as well as the distance traveled by walking, jogging, moderate and high intensity running and sprinting was determined. The total distance covered was associated with subscapular and abdominal skinfolds. In addition, the subscapular skinfolds were significantly related to high intensity running and sprinting. No other statistically significant correlations were found among other skinfold and performance parameters. The present study showed no significant relationships between morphological and match performances among junior soccer players. Our study supports the conclusions that beside the anthropometry advantage, psychological and soccer-specific skills should be also considered in the selection of soccer players.

A Comparative Study on Kinematic Performance of Corner Kicks for Junior Soccer Players According to Ball Rotation towards Effective Areas in Front of the Goal

In this study the research aim was to compare differences among kinematic properties such as displacement and linear velocities and angles and angular velocities during performing corner kicks for Junior Soccer players with techniques of ball rotation towards the goal in the close post area and to the contrary of the goal in the rear area at the moment of launching the ball. The study was carried out on (3) Junior players from Al-Sharkia Sporting Club under (18) years who were the best in playing corner kicks according to the test of corner kicks performance precision to specific areas in front of the goal with the right foot. (10) Trials were shot with video for each technique. To measure the precision of corner kicks according to ball rotation towards the goal technique the researcher depended on the test of the precision of passing the corner kick in front of the goal. Kinematic parameters were determined by using Simi Motion Program for motor analysis designed to track and to analyze the motion. Results indicated that there are significant differences in Displacements and linear (horizontal, cross and vertical) velocities of some body parts and the ball during performing corner kicks for the close post and beyond area according to ball rotation technique at the moment of launching the ball, and there are significant differences in Angles and angular velocities of body parts during performing corner kicks for the close post and beyond area according to ball rotation technique at the moment of launching the ball

RELIABILITY OF PHOTOGRAPHIC POSTURAL ASSESSMENT IN MALE ELITE JUNIOR SOCCER PLAYERS (UNDER 16, 17 & 19)

BackgroundJunior soccer players aged 16 to 19 years old competing on high level already present with postural deviations which are associated with an increased injury risk due to mechanical overloading...

SIDE- AND AGE-SPECIFIC POSTURAL ADAPTATIONS OF MALE ELITE JUNIOR SOCCER PLAYERS (UNDER 16, 17 & 19)

BackgroundPlaying soccer at professional level may induce functional and structural adaptations of the neuro-musculoskeletal system based on soccer specific movement coordination due to continuous asymmetrical loadings. This may predispose young...

Difference in training load and technical actions during small-sided games in junior and senior soccer players

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Langendam L, Linden C, Clemente F. Difference in training load and technical actions during small-sided games in junior and senior soccer players. Human Movement Special Issues. 2017:146-156. doi:10.5114/hm.2017.73623. APA Langendam, L., Linden, C., & Clemente, F. (2017). Difference in training load and technical actions during small-sided games in junior and senior soccer players. Human Movement Special Issues, 146-156. https://doi.org/10.5114/hm.2017.73623 Chicago Langendam, Lianne, Cornelis M. I. (Niels) van der Linden, and Filipe Manuel Clemente. 2017. "Difference in training load and technical actions during small-sided games in junior and senior soccer players". Human Movement Special Issues: 146-156. doi:10.5114/hm.2017.73623. Harvard Langendam, L., Linden, C., and Clemente, F. (2017). Difference in training load and technical actions during small-sided games in junior and senior soccer players. Human Movement Special Issues, pp.146-156. https://doi.org/10.5114/hm.2017.73623 MLA Langendam, Lianne et al. "Difference in training load and technical actions during small-sided games in junior and senior soccer players." Human Movement Special Issues, 2017, pp. 146-156. doi:10.5114/hm.2017.73623. Vancouver Langendam L, Linden C, Clemente F. Difference in training load and technical actions during small-sided games in junior and senior soccer players. Human Movement Special Issues. 2017:146-156. doi:10.5114/hm.2017.73623.

Junior soccer players biological maturity and final height prediction in Japan (2007–2012)

Junior soccer players biological maturity and final height prediction in Japan (2007–2012)

Iron, Hematological Parameters and Blood Plasma Lipid Profile in Vitamin D Supplemented and Non-Supplemented Young Soccer Players Subjected to High-Intensity Interval Training.

Vitamin D deficiency has been associated with increased risk for cardiovascular disease and anemia. Vitamin D-related changes in lipid profile have been studied extensively but the relationship between vitamin D and lipid metabolism is not completely understood. As both vitamin D and intermittent training may potentially affect iron and lipid metabolism, the aim of the study was to evaluate whether a daily supplementation of vitamin D can modulate the response of hematological and lipid parameters to high-intensity interval training (HIIT) in soccer players. Thirty-six young elite junior soccer players were included in the placebo-controlled, double-blind study. Participants were non-randomly allocated into either a supplemented group (SG, n=20, HIIT and 5,000 IU of vitamin D daily) or placebo group (PG, n=16, HIIT and sunflower oil). Hematological parameters were ascertained before and after the 8-wk training. The change score (post- and pre-training difference) was calculated for each individual and the mean change score (MCS) was compared between SG and PG using the t test and analysis of covariance. There were no differences between SG and PG at baseline. The red and white cell count, hemoglobin, hematocrit, MCHC, ferritin, and HDL-cholesterol changed significantly over the 8-wk HIIT. However, no significant differences in MCS were observed between SG and PG for any variable. A daily vitamin D supplement did not have any impact on alteration in hematological or lipid parameters in young soccer players in the course of high-intensity interval training.

Instrument of Sources of Sport-Confidence for Junior Soccer Player

Instrument of Sources of Sport-Confidence for Junior Soccer Player

Effects of an In-season Plyometric Training Program on Repeated Change of Direction and Sprint Performance in the Junior Soccer Player

Hammami, M, Negra, Y, Aouadi, R, Shephard, RJ, and Chelly, MS. Effects of an in-season plyometric training program on repeated change of direction and sprint performance in the junior soccer player. J Strength Cond Res 30(12): 3312-3320, 2016-We aimed to determine the gains in explosive movements of male junior soccer players induced by incorporating an 8-week plyometric training program (PTP) into a standard soccer conditioning regimen 5 months after the beginning of the competitive season. Our hypothesis was that PTP would enhance explosive movements, and thus sprint running, repeated shuttle sprint ability (RSSA), agility and the ability to make repeated changes of direction (RCOD). A group of junior soccer players were randomly divided into 2 groups: an experimental group (E, n = 15, age 15.7 ± 0.2 years) and a control group (C, n = 13, age 15.8 ± 0.2 years). The participants in E and C performed training exercises and matches together, but for an 8-week period in the latter part of the season, the experimental group replaced a part of the normal regimen (the tactical session) by a biweekly course of PTP (hurdle and drop jumps). Two familiarization sessions were held 2 weeks before definitive testing. The ability of the players was assessed by 3 agility tests (a sprint test with 180° turns, a 9-3-6-3-9 m sprint with backward and forward running, and a four 5-m sprint test with turns); 2 repeated sprint tests (RSSA and RCOD); and running times over 5-, 10-, 20-, 30-, and 40-m distances. Participants in E showed gains relative to C in sprint times (p ≤ 0.05 for 5, 10, and 20 m), and 2 of 3 the RCOD parameters (RCOD best, p ≤ 0.001; RCOD total, p ≤ 0.05). However, with the pattern of plyometric training that we adopted, and perhaps because participants were in good initial physical condition, the agility and RSSA test scores remained unchanged. Nevertheless, we conclude that our PTP can be commended to junior soccer players as a means of improving important components of their physical performance.

The Challenge of Evaluating the Intensity of Short Actions in Soccer: A New Methodological Approach Using Percentage Acceleration.

PurposeThere are several approaches to quantifying physical load in team sports using positional data. Distances in different speed zones are most commonly used. Recent studies have used acceleration data in addition in order to take short intense actions into account. However, the fact that acceleration decreases with increasing initial running speed is ignored and therefore introduces a bias. The aim of our study was to develop a new methodological approach that removes this bias. For this purpose, percentage acceleration was calculated as the ratio of the maximal acceleration of the action (amax,action) and the maximal voluntary acceleration (amax) that can be achieved for a particular initial running speed (percentage acceleration [%] = amax,action / amax * 100).MethodsTo define amax, seventy-two highly trained junior male soccer players (17.1 ± 0.6 years) completed maximal sprints from standing and three different constant initial running speeds (vinit; trotting: ~6.0 km·h–1; jogging: ~10.8 km·h–1; running: ~15.0 km·h–1).ResultsThe amax was 6.01 ± 0.55 from a standing start, 4.33 ± 0.40 from trotting, 3.20 ± 0.49 from jogging and 2.29 ± 0.34 m·s–2 from running. The amax correlated significantly with vinit (r = –0.98) and the linear regression equation of highly-trained junior soccer players was: amax = –0.23 * vinit + 5.99.ConclusionUsing linear regression analysis, we propose to classify high-intensity actions as accelerations >75% of the amax, corresponding to acceleration values for our population of >4.51 initiated from standing, >3.25 from trotting, >2.40 from jogging, and >1.72 m·s–2 from running. The use of percentage acceleration avoids the bias of underestimating actions with high and overestimating actions with low initial running speed. Furthermore, percentage acceleration allows determining individual intensity thresholds that are specific for one population or one single player.

Effect of the pitch size and presence of goalkeepers on the work load of players during small-sided soccer games

Small-sided games (SSGs) are spontaneous forms of specific training where exercise intensity can be manipulated by modifying external factors. To ensure suitable usage of small-sided games in practice, we have to know which variables can influence internal responses and external loads. The aim of the present study was to determine the influence of presence of a goalkeeper and the pitch size on internal responses and the external load during five-a-side soccer games. Twenty nine junior soccer players (age: 18.11 ± 1.31 years; body mass index: 21.04 ± 2.58 kg·m-2; peak heart rate: 199.53 ± 7.51 beats·min–1) participated in the study. The heart rate, distance covered and the rate of perceived exertion were monitored. We found significantly higher average heart rates of players in 5v5 SSGs without goalkeepers than with them on a small pitch. Analysis showed significant differences in the time spent in 65-85% of the peak heart rate zone and ˂65% of the peak heart rate zone on the small pitch. Furthermore, we found significantly higher distance covered by players during five-a-side games with goalkeepers than without them played on the small pitch. Our results indicate that the pitch size is a very important variable that influences the work load of players. The inclusion of the goalkeeper decreases the work load of the player on a small pitch (28 × 20 m; 560 m2), but not on a medium or large pitch.

Balance Maintenance in the Upright Body Position: Analysis of Autocorrelation.

The present research aimed to analyze values of the autocorrelation function measured for different time values of ground reaction forces during stable upright standing. It was hypothesized that if recording of force in time depended on the quality and way of regulating force by the central nervous system (as a regulator), then the application of autocorrelation for time series in the analysis of force changes in time function would allow to determine regulator properties and its functioning. The study was performed on 82 subjects (students, athletes, senior and junior soccer players and subjects who suffered from lower limb injuries). The research was conducted with the use of two Kistler force plates and was based on measurements of ground reaction forces taken during a 15 s period of standing upright while relaxed. The results of the autocorrelation function were statistically analyzed. The research revealed a significant correlation between a derivative extreme and velocity of reaching the extreme by the autocorrelation function, described as gradient strength. Low correlation values (all statistically significant) were observed between time of the autocorrelation curve passing through 0 axis and time of reaching the first peak by the said function. Parameters computed on the basis of the autocorrelation function are a reliable means to evaluate the process of flow of stimuli in the nervous system. Significant correlations observed between the parameters of the autocorrelation function indicate that individual parameters provide similar properties of the central nervous system.

Effect of Kinetic Resistance Training and Technique on Special Strength Level and Effective Kinematic Variables in Instep Kick for Soccer Juniors

Background: Training with resistance is considered the essential and complementary part of players' preparation period during training season through developing different aspects. Objective : This study aims to investigate the Effect of Kinetic resistance training and technique on special power level and effective kinematic variables in instep kick for soccer juniors. Methodology : 20 junior soccer players (age: 17.54 ±0.5 years, body mass: 69.05 kg, height: 170 cm, training age=7.7 years) participated in this study were randomly assigned into two groups experimental (n=10) trained with kinetic resistance training program and technique and control (n=10) trained with traditional soccer training program only where, the experimental approach was used. Results : The kinetic resistance trainings and technique positively affected the special power level, kicking accuracy and time and effective kinematic variables in instep kick. Conclusion : The researcher recommended that coaches should give attention to special strength developing and to be an essential part of the training program through kinetic resistance trainings and technique. Also coaches should depend on the kinematic variables affecting performance for detecting the improvement level in performance as a result of kinetic resistance trainings and technique. Keywords : kinetic resistance, technique, special strength, kinematic, Instep Kick