Latest research in football - week 18 - 2014

#1 Talent detection and development in soccer: a review
Reference: Journal of Sport and Health Research. 6(1):7-18. 2014.
Authors: Fernández-Rio J, Méndez-Giménez A.
Download link: http://www.journalshr.com/papers/Vol%206_N%201/V06_1_2.pdf
Summary: Soccer talent detection and development has become an extremely important issue for most clubs all over the world. The present article tries to review all published data in the period 1985-2012 related to these issues in order to gain a better understanding of the whole process of talent detection and development in soccer. A comprehensive search of computer databases (Ebsco, Medline/Pubmed, SportDiscus, Psychinfo, Teseo, InformaWorld, IngentaConnet, Ulrichs, Metapress, ScienceDirect, Doaj, Sage, Google Scholar, and Taylor & Francis) was conducted to identify relevant studies in English and Spanish on talent detection in soccer. Researchers seem to agree that physical, physiological, psychological, cognitive, and sociological factors are interconnected. Moreover, the amount of practice also plays an important role. Despite the traditional trend of selecting young players based on physical attributes and maturation, there is growing evidence that they should be selected based on several factors, like the ones previously mentioned, and others that include perceptual and tactical skills and abilities, and even genetics.


#2 Satisfaction and self-esteem in youth football players regarding teaching styles they receive of coaches from Cuidad del Carmen (Mexico)
Reference: Journal of Sport and Health Research. 6(1):63-74
Authors: Zurita Ortega F, Fernández Garcia  R, Cachón Zagalaz J, Ambris Sandoval J, Zaleta Morales L, Hernandez Gallardo D
Download link: http://www.journalshr.com/papers/Vol%206_N%201/V06_1_6.pdf
Summary: The relationship between education and training styles promoted by football coaches and the satisfaction variables (satisfaction and self-esteem) have been studied and analyzed from different perspectives, giving conflicting results due to methodological problems such as the non-use or non- homogeneous samples use specific tools for each sport. The aim of our study was to evaluate in a sample of 26 coaches and 277 soccer players in the Ciudad del Carmen (Mexico), more teaching styles used by football coaches, levels of satisfaction and self-esteem in three players Grassroots categories (children, cadet and youth) and the relationship between them. In addition to responding to the questionnaire of implicit theories also used the test of life satisfaction and self-esteem. Statistical analysis determined that teaching styles used are more interpretive and traditional type. The players tested showed high satisfaction with football and low self- esteem. Also found that teaching styles are distributed heterogeneously by category and further that the active teaching style generates little satisfaction in the players also found no relationship between type styles and self-esteem.


#3 Psychophysiological Stress in Under-17 Soccer Players
Reference: JEPonline 2014;17(2):67-80.
Authors: Santos PB, Kuczynski KM , Machado TA, Osiecki ACV, Stefanello JMF
Download link: http://www.asep.org/asep/asep/JEPonlineAPRIL2014_PriscillaSANTOS.pdf
Summary: Athletes experience a large number of stressors that can influence their sporting performance. Considering the increased participation of youth in elite sport, the purpose of this study was to examine the psychophysiological stress of soccer players. This study was conducted with a male team of base category soccer players. The Questionnaire Stress and Recovery for Athletes (RESTQ-76 Sport) was used to determine the current state of stress and recovery of athletes. The salivary cortisol (calculation of AUCg) was used to determine the physiological stress. Athletes showed low scores on stress scales and high scores on recovery scales in both training and competition situations (P≤0.05). Only the recovery scale showed a significant difference between the training situation and the game. The athletes demonstrated good recovery ability, since there were no extreme negative emotions suggestive of stress.


#4 Bridging the gap between empirical results, actual strategies, and developmental programs in soccer
Reference: Int J Sports Physiol Perform. 2014 May;9(3):540-3. doi: 10.1123/IJSPP.2014_0023.
Authors: Figueiredo AJ1, Gonçalves CE, Tessitore A.
Summary: Being one of the most prominent globalized sports, soccer played at club, national, and continental levels has a relevant societal role. At present, the specific competencies, interests, and languages of the different actors involved in the selection, development, and support of long-lasting careers of players might limit opportunities for potential talented players. Unless the cultural environment of soccer resolves the gaps between empirical results and actual soccer strategies, scientific discussion relating to the effectiveness of talent selection and development remains limited. This commentary is intended to highlight the need for developmental programs to prepare soccer personnel for a transdisciplinary dialogue, which could foster a future development of this sport. Finally, in considering the wide soccer-related employment opportunities at local, national, and international levels, the need for a clear qualification framework is crucial.


#5 Validity and reliability of the 45-15 test for aerobic fitness in young soccer players
Reference: Int J Sports Physiol Perform. 2014 May;9(3):525-31. doi: 10.1123/IJSPP.2012-0165.
Authors: Castagna C1, Iellamo F, Impellizzeri FM, Manzi V.
Summary: The aim of this study was to examine the reliability and validity of a popular field test for aerobic fitness used in soccer (45-15) in Italy. Alternating progressive 45-s runs with 15 s passive recovery until exhaustion, the test considers peak speed (PS) as a reflection of maximal aerobic speed (MAS). The validity and reliability of the 45-15 was assessed in 18 young male soccer players (age 16.7 ± 1.8 y, body mass 70 ± 7.45 kg, height 177 ± 0.5 cm, 55.62 ± 5.56 mL · kg1 · min1) submitted to laboratory testing for aerobic fitness and repeatedly to the 45-15. Results showed that 45-15 PS was significantly related to VO2max (r = .80, P < .001, 95%CI .47-.93) and MAS (r = .78, P = .001, 95%CI .43-.93). No significant bias between MAS 45-15 PS (P = .11) was found during the measurement-consistency study. Receiver-operating-characteristic (ROC) analysis showed that 45-15 PS was sensitive in detecting VO2max changes in subjects as revealed by area under the curve (.97; 95%CI .73-1). Players with peak 45-15 speed equal to or above 16.5 km/h (ie, ROC cutoff) may be considered to have good aerobic fitness. In light of this study's findings, the 45-15 test may be considered a reliable and valid test to evaluate meaningful information to direct generic aerobic training in soccer.


#6 VO2max Characteristics of Elite Female Soccer Players, 1989-2007
Reference: Int J Sports Physiol Perform. 2014 May;9(3):515-21. doi: 10.1123/IJSPP.2012-0150.
Authors: Haugen TA, Tønnessen E, Hem E, Leirstein S, Seiler S.
Summary: The purpose was to quantify VO2max among female competitive soccer players as a function of performance level, field position, and age. In addition, the evolution of VO2max among world-class players over an 18-y period was quantified. Female players (N = 199, 22 ± 4 y, 63 ± 6 kg, height 169 ± 6 cm), including an Olympic winning squad, were tested for VO2max at the Norwegian Olympic Training Center between 1989 and 2007. Results: National-team players had 5% higher VO2max than 1st-division players (P = .042, d = 0.4), 13% higher than 2nd-division players (P < .001, d = 1.2), and 9% higher than junior players (P = .005, d = 1.0). Midfielders had 8% higher VO2max than goalkeepers (P = .048, d = 1.1). No significant differences were observed across outfield players or different age categories. There was a trend toward lower relative VO2max across time epochs. This study demonstrated that VO2max varies across playing-standard level in women's soccer. No significant differences in VO2max were observed across outfield positions and age categories. Over time, there has been a slight negative development in VO2max among elite Norwegian soccer players.


#7 Physiological response, time-motion characteristics, and reproducibility of various speed-endurance drills in elite youth soccer players: small-sided games versus generic running
Reference: Int J Sports Physiol Perform. 2014 May;9(3):471-9. doi: 10.1123/IJSPP.2013-0390.
Author: Ade JD, Harley JA, Bradley PS.
Summary: The purpose was to quantify the physiological responses, time-motion characteristics, and reproducibility of various speed-endurance-production (SEP) and speed-endurance-maintenance (SEM) drills. Sixteen elite male youth soccer players completed 4 drills: SEP 1 v 1 small-sided game (SSG), SEP running drill, SEM 2 v 2 SSG, and SEM running drill. Heart-rate response, blood lactate concentration, subjective rating of perceived exertion (RPE), and time-motion characteristics were recorded for each drill. The SEP and SEM running drills elicited greater (P < .05) heart-rate responses, blood lactate concentrations, and RPE than the respective SSGs (ES 1.1-1.4 and 1.0-3.2). Players covered less (P < .01) total distance and high-intensity distance in the SEP and SEM SSGs than in the respective running drills (ES 6.0-22.1 and 3.0-18.4). Greater distances (P < .01) were covered in high to maximum acceleration/deceleration bands during the SEP and SEM SSGs than the respective running drills (ES 2.6-4.6 and 2.3-4.8). The SEP SSG and generic running protocols produced greater (P < .05) blood lactate concentrations than the respective SEM protocols (ES 1.2-1.7). Small to moderate test-retest variability was observed for heart-rate response (CV 0.9-1.9%), RPE (CV 2.9-5.7%), and blood lactate concentration (CV 9.9-14.4%); moderate to large test-retest variability was observed for high-intensity-running parameters (CV > 11.3%) and the majority of accelerations/deceleration distances (CV > 9.8%) for each drill. The data demonstrate the potential to tax the anaerobic energy system to different extents using speed-endurance SSGs and that SSGs elicit greater acceleration/deceleration load than generic running drills.


#8 Integrating the internal and external training loads in soccer
Reference: Int J Sports Physiol Perform. 2014 May;9(3):457-62. doi: 10.1123/IJSPP.2012-0347.
Atuhors: Akubat I, Barrett S, Abt G.
Summary: This study aimed to assess the relationships of fitness in soccer players with a novel integration of internal and external training load (TL). Ten amateur soccer players performed a lactate threshold (LT) test followed by a soccer simulation (Ball-Sport Endurance and Sprint Test [BEAST90mod]). The results from the LT test were used to determine velocity at lactate threshold (vLT), velocity at onset of blood lactate accumulation (vOBLA), maximal oxygen uptake (VO2max), and the heart rate-blood lactate profile for calculation of internal TL (individualized training impulse, or iTRIMP). The total distance (TD) and high intensity distance (HID) covered during the BEAST90mod were measured using GPS technology that allowed measurement of performance and external TL. The internal TL was divided by the external TL to form TD:iTRIMP and HID:iTRIMP ratios. Correlation analyses assessed the relationships between fitness measures and the ratios to performance in the BEAST90mod. Results: vLT, vOBLA, and VO2max showed no significant relationship to TD or HID. HID:iTRIMP significantly correlated with vOBLA (r = .65, P = .04; large), and TD:iTRIMP showed a significant correlation with vLT (r = .69, P = .03; large). The results suggest that the integrated use of ratios may help in the assessment of fitness, as performance alone showed no significant relationships with fitness.


#9 The role and development of sprinting speed in soccer
Reference: Int J Sports Physiol Perform. 2014 May;9(3):432-41. doi: 10.1123/IJSPP.2013-0121.
Authors: Haugen TA1, Tønnessen E, Hisdal J, Seiler S.
Summary: The overall objective of this review was to investigate the role and development of sprinting speed in soccer. Time-motion analyses show that short sprints occur frequently during soccer games. Straight sprinting is the most frequent action before goals, both for the scoring and assisting player. Straight-line sprinting velocity (both acceleration and maximal sprinting speed), certain agility skills, and repeated-sprint ability are shown to distinguish groups from different performance levels. Professional players have become faster over time, indicating that sprinting skills are becoming more and more important in modern soccer. In research literature, the majority of soccer-related training interventions have provided positive effects on sprinting capabilities, leading to the assumption that all kinds of training can be performed with success. However, most successful intervention studies are time consuming and challenging to incorporate into the overall soccer training program. Even though the principle of specificity is clearly present, several questions remain regarding the optimal training methods within the larger context of the team-sport setting. Considering time-efficiency effects, soccer players may benefit more by performing sprint-training regimens similar to the progression model used in strength training and by world-leading athletics practitioners, compared with the majority of guidelines that traditionally have been presented in research literature.


#10 Evaluation of the match performances of substitution players in elite soccer
Reference: Int J Sports Physiol Perform. 2014 May;9(3):415-24. doi: 10.1123/IJSPP.2013-0304.
Authors: Bradley PS1, Lago-Peñas C, Rey E.
Summary: The purpose was to evaluate match performances of substitute players using different research designs. Methods: English Premier League matches were analyzed using a multiple-camera system. Two research designs were adopted: an independent-measures analysis comparing the match-performance characteristics of players completing the entire match (n = 810) vs substitutes (n = 286) and the players they replaced (n = 286) and a repeated-measures analysis comparing the same players completing full matches vs those in which they were introduced as a substitute (n = 94). Most substitutions (P < .05) occurred at halftime and between the 60- to 85-min vs all first-half periods and the remaining second-half periods (effect size [ES]: 0.85-1.21). These substitutions become more (P < .01) offensive (eg, more attacking positions were introduced) in relation to the positions introduced as the half progressed (ES: 0.93-1.37). Independent-measures analysis indicated that high-intensity running was greater (P < .01) in substitutes compared with players who either completed the entire match or were replaced (ES: 0.28-0.67), but no differences were evident for pass-completion rates (ES: 0.01-0.02). Repeated-measures analysis highlighted that players covered more (P < .01) high-intensity running when they were introduced as substitutes compared with the equivalent period of the second- but not the first-half period (ES: 0.21-0.47). Both research designs indicated that attackers covered more (P < .05) high-intensity running than peers or their own performances when completing the entire match (ES: 0.45-0.71). Substitutes cover greater high-intensity-running distance; this was particularly evident in attackers, but pass-completion rates did not differ for any position. This information could be beneficial to coaches regarding optimizing the match running performances of their players, but much more work needs to be undertaken to investigate the overall impact of substitutes (physical, technical indicators, and contribution to key moments of matches).


#11  Anticipatory postural adjustments during cutting manoeuvres in football and their consequences for knee injury risk
Reference: J Sports Sci. 2014 Apr 17:1-8. [Epub ahead of print]
Authors: Mornieux G1, Gehring D, Fürst P, Gollhofer A.
Summary: Anticipatory postural adjustments (APAs), i.e. preparatory positioning of the head, the trunk and the foot, are essential to initiate cutting manoeuvres during football games. The aim of the present study was to determine how APA strategies during cutting manoeuvres are influenced by a reduction of the time available to prepare the movement. Thirteen football players performed different cutting tasks, with directions of cutting either known prior to the task or indicated by a light signal occurring 850, 600 or 500 ms before ground contact. With less time available to prepare the cutting manoeuvre, the head was less orientated towards the cutting direction (P = 0.033) and the trunk was even more rotated in the opposite direction (P = 0.002), while the foot placement was not significantly influenced. Moreover, the induced higher lateral trunk flexion correlated with the increased knee abduction moment (r = 0.41; P = 0.009). Increasing lateral trunk flexion is the main strategy used to successfully perform a cutting manoeuvre when less time is available to prepare the movement. However, higher lateral trunk flexion was associated with an increased knee abduction moment and therefore an increased knee injury risk. Reducing lateral trunk flexion during cutting manoeuvres should be part of training programs seeking the optimisation of APAs.


#12 Analysis of football game-related statistics using multivariate techniques
Reference: J Sports Sci. 2014 Apr 17:1-7. [Epub ahead of print]
Authors: Moura FA, Martins LE, Cunha SA.
Summary: The purpose of this study was to explore football game-related statistics during a competition, using principal component and cluster analyses to determine if it is possible to distinguish the winning teams from the drawing and losing ones. We collected the game-related statistics of the group phase matches of the 2006 World Cup and organised them into a matrix. The principal components of the covariance matrix were calculated. The scores of the first and second components were used to represent the new data, and cluster analysis was applied to separate the elements in two groups (G1 and G2). To analyse the degree of separation between the groups, we calculated the Silhouette Coefficient for each group. Finally, we checked if the winning teams were classified into the same group. The Silhouette Coefficients found for G1 and G2 were 0.54 and 0.55, respectively. Results showed that 70.3% of the winning teams were classified into the same group (G1). Similarly, 67.8% of the drawing and losing teams were classified in G2. This study presented a different way to analyse game-related statistics that allowed the multivariate differences to be shown between successful and unsuccessful teams.