Thursday, September 13, 2012

Practical neuromuscular warm-up strategies applied consistently for long periods can reduce lower extremity injury incidence
Recent studies in football –Part II
Abstracts modified from PubMed

Eirale C, Farooq A, Smiley FA, Tol JL, Chalabi H. Epidemiology of football injuries in Asia: A prospective study in Qatar. J Sci Med Sport. 2012 Aug 1. [Epub ahead of print]

Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Qatar.
In a prospective cohort study, authors investigated the incidence, characteristics and patterns of football injuries at club level in Qatar. Data were prospectively collected from the first division football league clubs in Qatar, in accordance with the international consensus statement on football injury epidemiology. An injury was defined as any physical complaint sustained during football activity resulting in the inability to participate fully in the next training or match. Individual injuries and exposure of each player were recorded by the medical staff of each team over one season. A total of 217 injuries were recorded, with an injury rate during matches of 14.5/1000h (95% CI: 11.6-18.0) compared with 4.4/1000h during training sessions (95% CI: 3.7-5.2). More than one third of all injuries were muscle strains (36.4%). Hamstring strains (54.4% of all muscle strains) exhibited a higher incidence than all other injury types (p<0.001). The thigh was the most frequent injury location (41.9%, p<0.001). Reinjuries (15% of total injuries) were mainly comprised of muscle strains associated with a higher severity compared with new injuries.
CONCLUSIONS: Despite the different environmental, social and cultural setting, our findings are comparable with previous data from European club football, confirming the previous finding at national team level that there are no regional peculiarities of football injuries in this part of the Asiatic continent. The relatively high overuse injury incidence rate and the high recurrence rate for (severe) thigh muscle strains, especially during games, warrants prevention strategies.

Herman K, Barton C, Malliaras P, Morrissey D. The effectiveness of neuromuscular warm-up strategies, that require no additional equipment, for preventing lower limb injuries during sports participation: a systematic review. BMC Med. 2012 Jul 19;10:75.

Centre for Sports and Exercise Medicine, William Harvey Research Institute, Bart's and the London School of Medicine and Dentistry, Queen Mary University of London
Seven electronic databases were searched from inception to January 2012 for studies investigating neuromuscular warm-up strategies and injury prevention. The quality of each included study was evaluated using a modified version of the van Tulder scale. Data were extracted from each study and used to calculate the risk of injury following application of each evaluated strategy. Nine studies were identified including six randomized controlled trials (RCT) and three controlled clinical trials (CCT). Heterogeneity in study design and warm-up strategies prevented pooling of results. Two studies investigated male and female participants, while the remaining seven investigated women only. Risk Ratio (RR) statistics indicated 'The 11+' prevention strategy significantly reduces overall (RR 0.67, confidence interval (CI) 0.54 to 0.84) and overuse (RR 0.45, CI 0.28 to 0.71) lower limb injuries as well as knee (RR 0.48, CI 0.32 to 0.72) injuries among young amateur female footballers. The 'Knee Injury Prevention Program' (KIPP) significantly reduced the risk of noncontact lower limb (RR 0.5, CI 0.33 to 0.76) and overuse (RR 0.44, CI 0.22 to 0.86) injuries in young amateur female football and basketball players. The 'Prevent Injury and Enhance Performance' (PEP) strategy reduces the incidence of anterior cruciate ligament (ACL) injuries (RR 0.18, CI 0.08 to 0.42). The 'HarmoKnee' programme reduces the risk of knee injuries (RR 0.22, CI 0.06 to 0.76) in teenage female footballers. The 'Anterior Knee Pain Prevention Training Programme' (AKP PTP) significantly reduces the incidence of anterior knee pain (RR 0.27, CI 0.14 to 0.54) in military recruits.
CONCLUSIONS: Effective implementation of practical neuromuscular warm-up strategies can reduce lower extremity injury incidence in young, amateur, female athletes and male and female military recruits. This is typically a warm-up strategy that includes stretching, strengthening, balance exercises, sports-specific agility drills and landing techniques applied consistently for longer than three consecutive months.

Haugen TA, Tønnessen E, Seiler S. Anaerobic Performance Testing of Professional Soccer Players 1995-2010. Int J Sports Physiol Perform. 2012 Aug 6. [Epub ahead of print]

Norwegian Olympic Federation, Oslo, Norway.
The purpose of this investigation was to compare sprint and countermovement jump (CMJ) performance among competitive soccer players as a function of performance level, field position and age. In addition, we wanted to quantify the evolution of these physical characteristics among professional players over a 15 year period. 939 athletes (22.1 ±4.3 yr), including national team players, tested 40m sprint with electronic timing and CMJ on a force platform at the Norwegian Olympic Training Center between 1995 and 2010. National team and 1st division players were faster (p<0.05) than 2nd division (1.0-1.4 %), 3rd-5th division (3.0-3.8 %), junior national team (1.7-2.2 %) and junior players (2.8-3.7 %). Forwards were faster than defenders (1.4 %), midfielders (2.5 %) and goalkeepers (3.2 %) over 0-20m (p<0.001). Midfielders jumped ~2.0 cm lower than the other playing positions (p<0.05). Sprinting velocity peaked in the age range 20-28 yr and declined significantly thereafter (p<0.05). Players from time epoch 2006-2010 had 1-2 % faster 0-20m and peak velocity than players from the 1995-1999 and 2000-2005 epochs, whereas no differences in CMJ performance were observed.
CONCLUSIONS: This study provides effect magnitude estimates for the influence of performance level, position and age on sprint and CMJ performance in soccer. While CMJ performance has remained stable over the time, there has been a small but positive development in sprinting velocity among professional players.

Ingebrigtsen J, Bendiksen M, Randers MB, Castagna C, Krustrup P, Holtermann A. Yo-Yo IR2 testing of elite and sub-elite soccer players: Performance, heart rate response and correlations to other interval tests. J Sports Sci. 2012 Aug 6. [Epub ahead of print]

Centre of Practical Knowledge, Department of Sports , University of Nordland , Bodø , Norway.
This study examined performance, heart rate response and construct validity of the Yo-Yo IR2 test by testing 111 elite and 92 sub-elite soccer players from Norway and Denmark. VO(2)max, Yo-Yo IR1 and repeated sprint tests (RSA) (n = 51) and match-analyses (n = 39) were also performed. Yo-Yo IR2 and Yo-Yo IR1 performance was 41 and 25% better (P < 0.01) for elite than sub-elite players, respectively, and heart rate after 2 and 4 min of the Yo-Yo IR2 test was 20 and 15 bpm (9 and 6% HRmax), respectively, lower (P < 0.01) for elite players. RSA performance and VO(2)max was not different between competitive levels (P > 0.05). For top-teams, Yo-Yo IR2 performance (28%) and sprinting distance (25%) during match were greater (P < 0.05) than for bottom-teams. For elite and sub-elite players, Yo-Yo IR2 performance was correlated (P < 0.05) with Yo-Yo IR1 performance (r = 0.74 and 0.76) and mean RSA time (r = -0.74 and -0.34).
Conclusion: The Yo-Yo IR2 test has a high discriminant and concurrent validity, as it discriminates between players of different within- and between-league competitive levels and is correlated to other frequently used intermittent elite soccer tests.

Castellano J, Casamichana D, Dellal A. Influence of game format and number of players on heart rate responses and physical demands in small-sided soccer games. J Strength Cond Res. 2012 Jul 25. [Epub ahead of print]

Faculty of Physical Activity and Sport Sciences. University of the Basque Country, España, Olympique Lyonnais Football Club, Lyon, France, Santy Orthopedicae clinical, sport science and research department Lyon, France, & Tunisian Research Laboratory "Sport Performance Optimization", National Center of Medicine and Science in Sport, Tunisia
The aim of the study was to examine the extent to which changing the game format (possession play vs. regulation goals and goalkeepers vs. small goals only) and the number of players (3 vs. 3, 5 vs. 5 and 7 vs. 7) influenced the physiological and physical demands of small-sided soccer games (SSGs) in amateurs and semi-professional players. Fourteen semi-professional male soccer players were monitored with GPS and heart-rate devices. Heart rate, player-load, distance covered, running speed and the number of accelerations were recorded for nine different SSGs. The results show that changes both in game format and the number of players affect the players' physiological and physical demands. Possession play places greater physiological and physical demands on players, although reducing the number of players only increases the physiological load. In the 7 vs. 7 games, changing the game format did not alter the heart rate responses. Finally, in the possession play format, changing the number of players did not produce significant differences in heart rate responses, although physical demands did decrease in line with a reduction in the number of players.
Conclusions: These results should help coaches to understand how modifying different aspects of SSGs has a differential effect on the players' physiological and physical demands. Moreover, coaches in semi-professional and amateurs have now consistent information's to design and optimize their training time in mixing the technical, tactical and physical aspects.

Deprez D, Vaeyens R, Coutts AJ, Lenoir M, Philippaerts R. Relative Age Effect and Yo-Yo IR1 in Youth Soccer. Int J Sports Med. 2012 Jul 12. [Epub ahead of print]

Movement and Sports Sciences, Ghent University, Ghent, Belgium.
The aims of the study were to investigate the presence of a relative age effect and the influence of birth quarter on anthropometric characteristics, an estimation of biological maturity and performance in the Yo-Yo Intermittent Recovery Test level 1 in 606 elite, Flemish youth soccer players. The sample was divided into 5 chronological age groups (U10-U19), each subdivided into 4 birth quarters. Players had their APHV estimated and height, weight and Yo-Yo IR1 performance were assessed. Differences between quarters were investigated using uni- and multivariate analyses. Overall, significantly (P<0.001) more players were born in the first quarter (37.6%) compared to the last (13.2%). Further, no significant differences in anthropometric variables and Yo-Yo IR1 performance were found between the 4 birth quarters. However, there was a trend for players born in the first quarter being taller and heavier than players born in the fourth quarter. Players born in the last quarter tended to experience their peak in growth earlier, this may have enabled them to compete physically with their relatively older peers.
Conclusions: Our results indicated selection procedures which are focused on the formation of strong physical and physiological homogeneous groups. Relative age and individual biological maturation should be considered when selecting adolescent soccer players.

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