Latest research in football - week 36 - 2014

#1 Effects of a Contrast Training Program Without External Load on Vertical Jump, Kicking Speed, Sprint, and Agility of Young Soccer Players
Reference: J Strength Cond Res 28(9): 2452–2460, 2014 doi: 10.1519/JSC.0000000000000452
Authors:  García-Pinillos F, Martínez-Amat A, Hita-Contreras F, Martínez-López E, Latorre-Román PA
Summary: The purpose of this study was to determine the effects of a 12-week contrast training (CT) program (isometric + plyometric), with no external loads, on the vertical jump, kicking speed, sprinting, and agility skills of young soccer players. Thirty young soccer players (age, 15.9 ± 1.43 years; weight, 65.4 ± 10.84 kg; height, 171.0 ± 0.06 cm) were randomized in a control group (n = 13) and an experimental group (n = 17). The CT program was included in the experimental group's training sessions, who undertook it twice a week as a part of their usual weekly training regime. This program included 3 exercises: 1 isometric and 2 plyometric, without external loads. These exercises progressed in volume throughout the training program. Performance in countermovement jump (CMJ), Balsom agility test (BAT), 5-, 10-, 20-, and 30-m sprint, and soccer kick were assessed before and after the training program. A 2-factor (group and time) analysis of variance revealed significant improvements (p < 0.001) in CMJ, BAT, and kicking speed in the experimental group players. Control group remained unchanged in these variables. Both groups significantly reduced sprint times over 5, 10, 20, and 30 m (p ≤ 0.05). A significant correlation (r = 0.492, p < 0.001) was revealed between ΔBAT and Δaverage kicking speed. Results suggest that a specific CT program without external loads is effective for improving soccer-specific skills such as vertical jump, sprint, agility, and kicking speed in young soccer players.


#2 Repeated Sprint Ability in Young Soccer Players at Different Game Stages
Reference: J Strength Cond Res 28(9): 2578–2584, doi: 10.1519/JSC.0000000000000383
Authors: Meckel Y, Einy A, Gottlieb R, Eliakim A
Summary: The purpose of this study was to determine the repeated sprint ability (RSA) of young (16.9 ± 0.5 years) soccer players at different game stages. Players performed repeated sprint test (RST) (12 × 20 m) after warm-up before a game, at half-time, and after a full soccer game, each on a different day, in a random order. The ideal (fastest) sprint time (IS) and total (accumulative) sprint time (TS) were significantly slower at the end of the game compared with those after the warm-up before the game (p < 0.01 for each). Differences between IS and TS after the warm-up before the game and at half-time, and between half-time and end of the game, were not statistically significant. There was no significant difference in the performance decrement during the RST after warm-up before the game, at half-time, or the end of the game. Significant negative correlation was found between predicted V[Combining Dot Above]O2 and the difference between TS after the warm-up before the game and the end of the game (r = −0.52), but not between predicted V[Combining Dot Above]O2 and the difference in any of the RST performance indices between warm-up before the game and half-time, or between half-time and the end of the game. The findings indicate a significant RSA reduction only at the end but not at the half-time of a soccer game. The results also suggest that the contribution of the aerobic system to soccer intensity maintenance is crucial, mainly during the final stages of the game.


#3 Soccer science and the bayes community: exploring the cognitive implications of modern scientific communication
Reference: Top Cogn Sci. 2010 Jan;2(1):53-72. doi: 10.1111/j.1756-8765.2009.01049.x. Epub 2009 Oct 14.
Authors: Shrager J, Billman D, Convertino G, Massar JP, Pirolli P.
Summary: Science is a form of distributed analysis involving both individual work that produces new knowledge and collaborative work to exchange information with the larger community. There are many particular ways in which individual and community can interact in science, and it is difficult to assess how efficient these are, and what the best way might be to support them. This paper reports on a series of experiments in this area and a prototype implementation using a research platform called CACHE. CACHE both supports experimentation with different structures of interaction between individual and community cognition and serves as a prototype for computational support for those structures. We particularly focus on CACHE-BC, the Bayes community version of CACHE, within which the community can break up analytical tasks into "mind-sized" units and use provenance tracking to keep track of the relationship between these units.


#4 Multi-directional sprints and small-sided games training effect on agility and change of direction abilities in youth soccer
Reference: J Strength Cond Res. 2014 Aug 21. [Epub ahead of print]
Authors: Chaouachi A, Chtara M, Hammami R, Chtara H, Turki O, Castagna C.
Summary: The aim of this study was to compare the training effects of a small-sided games (SSG) and a multi-directional sprints intervention on agility and change of direction (COD) ability in male youth-soccer. Thirty-six soccer players (age: 14.2±0.9 years; height: 167.2±5.7 cm; body mass: 54.1±6.3 kg, body fat: 12.5±2.2%) participated in a short-term (6 weeks) randomized parallel fully-controlled training study, with pre-to-post measurements. Players were randomly assigned to two experimental groups: training with pre-planned COD drills (CODG, n=12) or using SSGs (SSGG, n=12) and to a control group (CONG, n=12). Pre and post-training players completed a test battery involving linear sprinting (15 and 30-m sprint), COD sprinting (COD15m, Ball-15m, 10-8-8-10m, zigzag 20m), reactive-agility test (RAT, RAT-ball) and vertical and horizontal jumping (countermovement jump and 5-Jump respectively). A significant (p<0.05) group x time effect was detected for all variables in CODG and SSGG. Improvements in sprint, agility without ball, COD and jumping performances, were higher in CODG than in the other groups. The SSGG improved significantly more (p <0.05) than other groups in agility tests with the ball. The CONG showed significant improvements (p<0.05) on linear sprinting over distance longer than 10m and in all the agility and COD tests used in this study. It is concluded that in male young soccer-players agility can be improved either using purpose built SSG or pre-planned COD sprints. However the use of specifically designed SSG may provide superior results in match relevant variables


#5 Comment on 'Match Analysis of U9 and U10 English Premier League Academy Soccer Players using a Global Positioning System: Relevance for Talent Identification and Development'
Reference: J Strength Cond Res. 2014 Aug 21. [Epub ahead of print]
Authors: Carling C, Collins D.
Summary: We read with interest the recent article written by Goto, Morris & Nevill: 'Match Analysis of U9 and U10 English Premier League Academy Soccer Players using a Global Positioning System: Relevance for Talent Identification and Development'. In summary, the authors reported time motion analysis data from match-play showing that players who were retained by their Academy covered a significantly greater distance overall and in low-speed running in comparison to peers who were released. Consequently, the authors discussed their results in the context of talent identification and development processes. In light of their findings and discussion, it is of our opinion that further debate in the context of the current body of literature is necessary.


#6 Short-term power output and local muscular endurance of young male soccer players according to playing position
Reference: Coll Antropol. 2014 Jun;38(2):525-31.
Authors: Nikolaïdis PT
Summary: Although the contribution of anaerobic power in soccer performance is recognized and there is evidence that many anthropometric and physiological characteristics vary according to playing position, the association between playing position and short-term power output, and local muscular endurance is not well studied, especially in young players. Therefore, the aim of the present study is to examine whether this component of sport-related physical fitness of young soccer players varies according to playing position. Young male (N = 296; aged 10.94-21.00 y), classified in five two-year age-groups, and adults (N = 30; aged 21.12-31.59 y), all members of competitive soccer clubs, performed the 30-s Wingate anaerobic test against braking force 0.075 kg x kg(-1) of body mass. One-way analysis of variance (ANOVA) revealed significant differences between age groups with regard to peak power in absolute, P(peak) (F5,320 = 86.7, p < 0.001), and in relative to body mass values, rP(peak) (F5,320 = 43.27, p < 0.001), mean power in absolute, P(mean) (F5,313 = 108.97, p < 0.001), and in relative values, rP(mean) (F5,313 = 41.64, p < 0.001), while there was no difference with respect to fatigue index, FI (F5,312 = 1.09, p = 0.370). One-way analysis of covariance, considering age as covariate, did not reveal any significant differences among playing position groups with regard to P(peak) (F3,289 = 1.46, p = 0.226), rP(peak) (F3,289 = 0.87, p = 0.457) and P(mean) (F3,283 = 0.31, p = 0.817), while goalkeepers had lower rP(mean) than defenders, midfielders and forwards (F3,283 = 6.32, p < 0.001). One-way ANOVA revealed differences with regard to FI (F3,283 = 5.97, p < 0.001), according to which goalkeepers had higher values than defenders and midfielders. Compared with data from previous studies in general population, participants had superior short-term power output and local muscular endurance. Both these anaerobic parameters were in direct relationship with age (r = 0.64, p < 0.001, and r = 0.68, p < 0.001 respectively), even when the influence of body mass was partitioned out (r = 0.50, p < 0.001 in both cases). The comparison between playing positions revealed similar alactic anaerobic profile for all groups, and indicated local muscular endurance as the anaerobic parameter that discriminated goalkeepers from outfield players.