Latest research in football - week 39 - 2013

#1 Relationship between the relative age effect and anthropometry, maturity and performance in young soccer players
Authors: Gil SM, Badiola A, Bidaurrazaga-Letona I, Zabala-Lili J, Gravina L, Santos-Concejero J, Lekue JA, Granados C.
Reference: J Sports Sci. 2013 Sep 20. [Epub ahead of print]
Summary: The presence of the relative age effect (RAE) has been widely reported; however, its underlying causes have not yet been determined. With this in mind, the present study examined if anthropometry and performance were different amongst older and younger soccer players born in the same year. Eighty-eight young soccer players participated in the study (age 9.75 ± 0.30). Anthropometric measurements, physical tests (sprint, agility, endurance test, jump and hand dynamometry) and the estimation of the maturity status were carried out. Most players (65.9%) were born in the first half of the year. Older players were taller (P < 0.05), had longer legs (P < 0.01) and a larger fat-free mass (P < 0.05). Maturity offset was smaller in the older boys (P < 0.05); however, age at peak height velocity was similar. Older boys performed better in velocity and agility (P < 0.05) and particularly in the overall score of performance (P < 0.01). Stepwise regression analysis revealed that chronological age was the most important variable in the agility test and the overall score, after the skinfolds (negative effect). We report differences in anthropometry and physical performance amongst older and younger pre-pubertal soccer players. These differences may underlie the RAE


#2 Influence of a 2-year strength training programme on power performance in elite youth soccer players
Authors: Sander A, Keiner M, Wirth K, Schmidtbleicher D.
Reference: Eur J Sport Sci. 2013 Sep;13(5):445-51. doi: 10.1080/17461391.2012.742572. Epub 2012 Nov 13.
Summary: In soccer, strength, power and speed are very important because of the large number of power actions performed during the game. Therefore, the aim of this study was to examine the influence of periodised strength training for power performance more than 2 years. In this study, 134 elite youth soccer players were recruited from two youth training centres. The cohorts were arranged as follows: A (under 19 years), B (under 17 years) and C (under 15 years). The participants in each cohort were divided into two groups. One group (Strength training group [STG]) was subjected to regular soccer training in addition to strength training twice a week for 2 years. The other group (Control group [CG]) completed only the regular soccer training. The strength training was periodised with hypertrophy and intramuscular coordination blocks. For strength training, both the front squat and the back squat were performed once a week. The subjects were tested on the one-repetition maximum (1RM) of the front and back squat and a linear sprint over 30 m. There was significantly better performance from the STG on 1RM (p <0.001). In the sprint, the STG displayed significantly better improvements (p <0.05 to p <0.001) of up to 6%. The effects of strength training are reflected in the sprint performance. Therefore, it seems beneficial for youth to perform strength training to exploit the reserve capacity in sprint performances.


#3 SoccerStories: A Kick-off for Visual Soccer Analysis
Authors: Perin C, Vuillemot R, Fekete JD.
Reference: IEEE Trans Vis Comput Graph. 2013 Dec;19(12):2506-15. doi: 10.1109/TVCG.2013.192.
Summary: This article presents SoccerStories, a visualization interface to support analysts in exploring soccer data and communicating interesting insights. Currently, most analyses on such data relate to statistics on individual players or teams. However, soccer analysts we collaborated with consider that quantitative analysis alone does not convey the right picture of the game, as context, player positions and phases of player actions are the most relevant aspects. We designed SoccerStories to support the current practice of soccer analysts and to enrich it, both in the analysis and communication stages. Our system provides an overview+detail interface of game phases, and their aggregation into a series of connected visualizations, each visualization being tailored for actions such as a series of passes or a goal attempt. To evaluate our tool, we ran two qualitative user studies on recent games using SoccerStories with data from one of the world's leading live sports data providers. The first study resulted in a series of four articles on soccer tactics, by a tactics analyst, who said he would not have been able to write these otherwise. The second study consisted in an exploratory follow-up to investigate design alternatives for embedding soccer phases into word-sized graphics. For both experiments, we received a very enthusiastic feedback and participants consider further use of SoccerStories to enhance their current workflow


#5 The role of specialisation in the promotion of young football talents: A person-oriented study
Authors: Zibung M, Conzelmann A.
Reference: Eur J Sport Sci. 2013 Sep;13(5):452-60. doi: 10.1080/17461391.2012.749947. Epub 2012 Dec 20.
Summary: This paper investigates the controversial question whether it is more effective to promote specialisation in a specific sport at the beginning of a career or whether to encourage a broad range of sports when promoting competitive sports talents in order for them to achieve a high level of performance in adulthood. The issue of promoting talents depends on human developmental processes and therefore raises developmental scientific questions. Based on recent, dynamic-interactionist concepts of development, we assume a person-oriented approach focussing on the person as a whole rather than individual features. Theoretical considerations lead to four interacting factors being summarised to form a subsystem: childhood training. The relative weights of these factors lead to patterns. By relating these to a performance criterion at the age of peak performance, particularly promising developmental patterns may be identified. One hundred fifty-nine former Swiss football talents were retrospectively interviewed about their career and the data analysed using the LICUR method. Two early career patterns were identified as having a favourable influence on adult performance. Both are characterised by an above-average amount of in-club training. One pattern also exhibits an above-average amount of informal football played outside the club, the other above-average scores for activity in other sports. Hence, comprehensive training and practice inside and outside the club form the basis for subsequent football expertise


#6 Reducing Resistance Training Volume during Ramadan Improves Muscle Strength and Power in Football Players
Authors: Rebaï H, Chtourou H, Zarrouk N, Harzallah A, Kanoun I, Dogui M, Souissi N, Tabka Z.
Reference: Int J Sports Med. 2013 Sep 18. [Epub ahead of print]
Summary: We aimed to examine the effect of maintaining or reducing resistance training volume during Ramadan-intermittent-fasting (RIF) on short-term maximal performances. 20 footballers (age: 18.4±0.8 years; body-mass: 72.4±4.1 kg; height: 183.4±4.6 cm) were matched and randomly assigned to a normal-training-group (G1) or a tapering-group (G2). They were tested for muscular strength (maximal-voluntary-contraction) and power (squat-jump and counter-movement-jump) 1 month before RIF (T0), 1 week before RIF (T1), after 2 weeks of fasting (T2) and at the end of RIF (T3). From T1 to T2, subjects performed a whole-body resistance training program (8-repetitions×4-sets with 4-min recovery in-between). During RIF, G1 maintained the same training program, while G2 performed a period of reduced training volume (3 sets/exercise; - 22%). Muscle strength and power increased significantly from T0 to T1, from T0 to T2 and from T0 to T3 in G1 and G2 and from T1 to T2 and from T1 to T3 only in G2 (p<0.05). Performance was higher in G2 than G1 during T2 (p<0.01). Moreover, the ∆-change of performance between T0 and T2 and T3 was significantly higher in G2 than G1 (p<0.05). For young soccer players, a tapering period characterized by a reduced training volume during RIF may lead to significant improvement in muscle strength and power


#7 What do community football players think about different exercise-training programmes? Implications for the delivery of lower limb injury prevention programmes
Authors: Finch CF, Doyle TL, Dempsey AR, Elliott BC, Twomey DM, White PE, Diamantopoulou K, Young W, Lloyd DG
Reference: Br J Sports Med. 2013 Sep 18. doi: 10.1136/bjsports-2013-092816. [Epub ahead of print]
Summary: Players are the targeted end-users and beneficiaries of exercise-training programmes implemented during coach-led training sessions, and the success of programmes depends upon their active participation. Two variants of an exercise-training programme were incorporated into the regular training schedules of 40 community Australian Football teams, over two seasons. One variant replicated common training practices, while the second was an evidence-based programme to alter biomechanical and neuromuscular factors related to risk of knee injuries. This paper describes the structure of the implemented programmes and compares players' end-of-season views about the programme variants. This study was nested within a larger group-clustered randomised controlled trial of the effectiveness of two exercise-training programmes (control and neuromuscular control (NMC)) for preventing knee injuries. A post-season self-report survey, derived from Health Belief Model constructs, included questions to obtain players' views about the benefits and physical challenges of the programme in which they participated. Compared with control players, those who participated in the NMC programme found it to be less physically challenging but more enjoyable and potentially of more benefit. Suggestions from players about potential improvements to the training programme and its future implementation included reducing duration, increasing range of drills/exercises and promoting its injury prevention and other benefits to players. Players provide valuable feedback about the content and focus of implemented exercise-training programmes, that will directly inform the delivery of similar, or more successful, programmes in the future.


#8 The relative age effect in the German Football TID Programme: Biases in motor performance diagnostics and effects on single motor abilities and skills in groups of selected players
Authors: Votteler A, Höner O.
Reference: Eur J Sport Sci. 2013 Sep 19. [Epub ahead of print]
Summary: This study examined the disturbing effects of relative age on the talent identification process in the talent development programme of the German Football Association. The bias in the selection rate was examined via the extent of relative age effects. The bias in motor performance diagnostics was analysed by comparing the motor performance of selected players with normal motor development. The mechanisms underlying the relative age biases in motor performance were examined by modelling the direct and indirect effects of relative age on single motor performance tests for sprint, running agility, dribbling and ball passing and control. Data from 10,130 selected football players from the U12 to U15 age groups were collected in autumn 2010. The birth distribution differed significantly from the reference population with approximately 61% of the players born in the first half of the year. The selection probability was approximately two times higher for players born in the first quarter of the year than for players born in the last quarter. Revised motor performance diagnostics showed better results on average for relatively younger players. Path analysis revealed significant direct and indirect relative age effects for physiologically demanding tests and almost no effects for technically demanding tests. Large sample sizes allowed high resolution in relative age with additional informational content and multivariate modelling of the complex relationships among relative age, physical development and motor performance. The results are discussed on how relative age affects the effectiveness and fairness of talent identification and development processes


#9 The impact of the achievement motive on athletic performance in adolescent football players
Authors: Zuber C, Conzelmann A.
Reference: Eur J Sport Sci. 2013 Sep 17. [Epub ahead of print]
Summary: Researchers largely agree that there is a positive relationship between achievement motivation and athletic performance, which is why the achievement motive is viewed as a potential criterion for talent. However, the underlying mechanism behind this relationship remains unclear. In talent and performance models, main effect, mediator and moderator models have been suggested. A longitudinal study was carried out among 140 13-year-old football talents, using structural equation modelling to determine which model best explains how hope for success (HS) and fear of failure (FF), which are the aspects of the achievement motive, motor skills and abilities that affect performance. Over a period of half a year, HS can to some extent explain athletic performance, but this relationship is not mediated by the volume of training, sport-specific skills or abilities, nor is the achievement motive a moderating variable. Contrary to expectations, FF does not explain any part of performance. Aside from HS, however, motor abilities and in particular skills also predict a significant part of performance. The study confirms the widespread assumption that the development of athletic performance in football depends on multiple factors, and in particular that HS is worth watching in the medium term as a predictor of talent.


#10 Quality of life and energy expenditure in transplant recipient football players
Authors: Totti V, Zancanaro M, Trerotola M, Nanni Costa A, Antonetti T, Anedda A, Roi GS.
Reference: Transplant Proc. 2013 Sep;45(7):2758-60. doi: 10.1016/j.transproceed.2013.07.027.
Summary: Football (soccer) is a highly motivating leisure activity with important potential as a health-promoting activity also for transplant recipients. The aim of this study was to assess the "on the field" energy expenditure during football games and the quality of life of transplant recipients practicing football. Twenty-two recipients of kidney (n = 11), bone marrow (n = 7), liver (n = 3) or corneal (n = 1) transplantations had an overall mean age of 37 ± 9 years, body mass index of 23.5 ± 2.4 kg/m(2), and time after transplantation of 9.3 ± 6.4 years. They were compared with 25 healthy football players of mean age 41 ± 10 years and body mass index of 26.3 ± 3.9 kg/m(2). There were no significant differences between transplant recipients and controls regarding mean energy expenditure (393 ± 113 vs 392 ± 132 kcal/h) number of steps (3.978 ± 1.317 vs 3.933 ± 1.563) during, and capillary blood lactate concentrations (4.8 ± 0.9 vs 5.2 ± 1.3 mmol/L) after the matches. The SF-36 questionnaire administered before the matches showed transplant recipient players to score significantly worse in the scales of general (P < .05) and mental health (P < .01). This study indicated that transplant recipients involved in football matches attained a level of energy expenditure and a quality of life consistent with a healthy lifestyle. Football has the potential to be implemented as a permanent health-promoting activity also for transplant recipients.