Latest research in football - week 36 - 2013

#1 Neuromuscular training to prevent knee injuries in adolescent female soccer players
Author: Wingfield K.
Reference: Clin J Sport Med. 2013 Sep;23(5):407-8. doi: 10.1097/01.jsm.0000433153.51313.6b.
Summary: The purpose was to evaluate the effectiveness of a neuromuscular warm-up program in preventing acute knee injury in adolescent female football (soccer) players. Cluster randomized (by team) controlled trial was chosen, stratified by geographical district. Sample size was calculated (n = 8118) with 80% power to show a reduction of 50% in an estimated 1.15% annual incidence of anterior cruciate ligament (ACL) injury at P ≤0.05.  Female under-14 to under-18 football clubs (ages 12-17 years) were recruited. Reasons for the exclusion of clubs were lack of response, <2 training sessions per week, and the current use of an injury prevention program. The clubs were randomized to a neuromuscular warm-up intervention (Knäkontroll, SISU Idrottsböcker, Sweden, 2005) or to a control group, who were instructed to continue with their usual training and playing practices. The neuromuscular training program included 6 exercises that focused on knee control and core stability (1- and 2-legged knee squats, a pelvic lift, the bench, the lunge, and jump/landing). The exercises were to be done twice per week and were to take about 15 minutes, after a brief running warm-up. They progressed through 4 levels of difficulty. The team coaches supervised the program after instruction from study therapists. The primary outcome was the rate of ACL injuries. Diagnosis was confirmed, as appropriate, by a physician and by magnetic resonance imaging. Secondary outcomes were the rates of serious knee injury and any acute knee injury, defined as those with sudden onset during play that led to a player being unable to participate in training or competition. Severe injuries were those that caused absences of >4 weeks. Two study therapists evaluated the injuries. The coaches recorded data, including when the intervention was performed, any injuries, individual playing times, and periods of absence. Assessment of the primary outcome was done by physicians blinded to group assignment. During 278 298 hours of play, 96 knee injuries occurred in 92 players (intervention group 48, control group 44). The rate did not differ between groups. Of the 21 ACL injuries, 7 occurred in the intervention group and 14 in the control group, giving a rate ratio (RR) of 0.36 (95% confidence interval [CI] 0.15-0.85; P = 0.02). Severe injuries (intervention group 26, control group 31) did not differ between groups. They included 22 collateral or capsular sprains, 21 ACL injuries, 7 patella dislocations or subluxations, 6 meniscal or chondral lesions, and 1 tibial plateau fracture. Compliant players (those who performed ≥1 exercise session per week; 1303 players) had a lower rate of ACL injury (RR, 0.17; 95% CI, 0.05-0.57), of severe knee injury (RR, 0.18; 95% CI, 0.07-0.45), and of any acute knee injury (RR, 0.53; 95% CI, 0.30-0.94) than the control group. A short weekly neuromuscular exercise program reduced the rate of ACL injuries among adolescent female football (soccer) players. Those who were compliant with the intervention had fewer severe knee injuries and fewer injuries overall.


#2 The Role and Development of Sprinting Speed in Soccer
Authors: Haugen T, Tønnessen E, Hisdal J, Seiler S.
Reference: Int J Sports Physiol Perform. 2013 Aug 27. [Epub ahead of print]
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 prior to 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 regimes similar to the progression model used in strength training and by world leading athletics practitioners, compared to the majority of guidelines that traditionally have been presented in research literature


#3 Match performance and physical capacity of players in the top three competitive standards of English professional soccer
Authors: Bradley PS, Carling C, Gomez Diaz A, Hood P, Barnes C, Ade J, Boddy M, Krustrup P, Mohr M.
Reference: Hum Mov Sci. 2013 Aug 23. pii: S0167-9457(13)00068-7. doi: 10.1016/j.humov.2013.06.002. Summary: The aim of this study was to compare the match performance and physical capacity of players in the top three competitive standards of English soccer. Match performance data were collected from players in the FA Premier League (n=190), Championship (n=155) and League 1 (n=366) using a multiple-camera system. In addition, a selection of players from the Premier League (n=56), Championship (n=61) and League 1 (n=32) performed the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2) to determine physical capacity. Players in League 1 and the Championship performed more (p<.01) high-intensity running than those in the Premier League (Effect Size [ES]: 0.4-1.0). Technical indicators such as pass completion, frequency of forward and total passes, balls received and average touches per possession were 4-39% higher (p<.01) in the Premier League compared to lower standards (ES: 0.3-0.6). Players also covered more (p<.05) high-intensity running when moving down (n=20) from the Premier League to the Championship (ES: 0.4) but not when players moved up (n=18) standards (ES: 0.2). Similar Yo-Yo IE2 test performances were observed in Premier League, Championship and League 1 players (ES: 0.2-0.3). Large magnitude relationships (p<.05) were observed between Yo-Yo IE2 test performances and the total and high-intensity running distance covered in both Championship (r=.56 and .64) and Premier League matches (r=.61 and .54). The data demonstrate that high-intensity running distance was greater in players at lower compared to higher competitive standards despite a similar physical capacity in a subsample of players in each standard. These findings could be associated with technical characteristics inherent to lower standards that require players to tax their physical capacity to a greater extent but additional research is still required to confirm these findings.


#4 Voice use in professional soccer management
Authors: O'Neill J, McMenamin R.
Reference: Logoped Phoniatr Vocol. 2013 Aug 23. [Epub ahead of print]
Summary: Vocal load related to heavy voice use in particular professions increases the risk of occupational voice disorders. Research on professional voice use has primarily focused on educators, singers, and call-centre advisors. This paper describes the daily experiences of professional soccer managers' occupational voice use through qualitative methods. Four global themes were identified: 1) voice uses, 2) factors affecting voice change, 3) impact of voice use, and 4) the importance of voice in soccer management. All describe the nature of soccer managers' vocal demands. Risk factors for voice disorders include intense and prolonged voice use in environments with adverse acoustic properties for speakers and poor phonation methods. Research on vocal behaviours and early prevention programmes for this population group is warranted.


#5 Yo-Yo intermittent recovery test performances within an entire football league during a full season
Authors: Mohr M, Krustrup P.
Reference: J Sports Sci. 2013 Aug 28. [Epub ahead of print]
Summary: The study examined Yo-Yo intermittent recovery level 2 (YYIR2) and submaximal YYIR1 test performances in 172 male semi-professional football players (age; 25.8 ± 4.1 years) representing all teams in a top league at pre-season, start-season, mid-season and end-season. YYIR2 performance was 847 ± 227 m (±SD) at pre-season and rose (P < 0.05) by 128 ± 113 m to 975 ± 205 m at start of season and further (P < 0.05) by 59 ± 102 m to 1034 ± 211 m at mid-season. Submaximal YYIR1 HR was 90.9 ± 4.2% HRmax at pre-season, which was higher (P < 0.05) than at start, mid and end of season (87.0 ± 3.9, 85.9 ± 4.1 and 87.0 ± 3.7% HRmax, respectively). Peak YYIR2 performance and minimum YYIR1 HR were 1068 ± 193 m and 85.1 ± 3.8% HRmax, respectively, with ∼50% of the players peaking at mid-season. Top-teams and middle-teams had higher (P < 0.05) peak YYIR2 scores (1094 ± 205 and 1121 ± 152 m, respectively) than bottom-teams (992 ± 185 m). YYIR2 performance was 16% higher (P < 0.05) and YYIR1 HR was 1.4% HRmax lower (P < 0.05) for regular players than non-regular players at pre-season and remained lower (P < 0.05) throughout the season. Central defenders had poorer (P < 0.05) YYIR performances compared to other positional roles. In conclusion, YYIR performances are highly variable within a football league over a season and are influenced by league ranking, regularity of competitive play and playing position.


#6 Science and football: evaluating the influence of science on performance
Authors: J Sports Sci. 2013 Sep;31(13):1377-82. doi: 10.1080/02640414.2013.828544.
Reference: Drust B, Green M.
Summary: The scientific study of football has its origins in the early research completed in the 1970's. Since these early efforts the available scientific knowledge base related to football has developed substantially. The ability of this scientific information to influence practice in the day-to-day activity of football organisations, especially elite teams, has been largely taken for granted. The close examination of this impact can lead to more uncertainty regarding the usefulness of the scientific data to the sport. Few articles are available that have attempted to critique the link between science and football practice. As such, the aims of this article are 2-fold; (i) to examine the historical background to "science and football" and to analyse the influence of sports science research on the current practice of coaches and practitioners within the sport and (ii) to identify potential ways to increase the influence of scientific research on practice in the "real world"