Latest research in football - week 2 - 2013

#1 Shoulder injuries in soccer players

Authors: Longo UG, Loppini M, Berton A, Martinelli N, Maffulli N, Denaro V.

Reference: Clin Cases Miner Bone Metab. 2012 Sep;9(3):138-41.

Summary: The purpose of this review was to report the epidemiological data on shoulder injuries in soccer players and to describe the common mechanisms of shoulder injuries in soccer. The authors stated that there are only few studies (!!!) focused on shoulder injuries in soccer players and therefore no definitive conclusions can be drawn. Further research is warranted to clarify the epidemiology, mechanisms and management of shoulder injuries in elite soccer players.

#2 Technical demands of soccer match-play in the English Championship

Authors: Russell M, Rees G, Kingsley M.

Reference: J Strength Cond Res. 2013 Jan 2.

Summary: The purpose of this study was to investigate the effect of match-play on the performance of technical actions in professional soccer players. An automatic notational analysis quantified the technical performance outfield players during the 2010/2011 English Championship season. The authors included players that played more than 10 games (n=10). Total possessions and number of ball distributions were lower in the second versus the first half of match-play (10 ± 7%, and 11 ± 8% respectively). Furthermore, analysis across 15-min intervals revealed reductions during the last 15-min of match-play in the total number of possessions (11.8 ± 1.9 vs. 9.5 ± 1.7) and distributions (in the initial 15 minutes 10.9 ± 2.3 minutes vs. the last 15 minutes 8.7 ± 2.1 minutes). Other variables such as the number of touches taken per possession, number of challenges, percentage of challenges won, length of forward distributions and percentage success of distributions were all similar between halves and across 15-min intervals. The data demonstrated that match-specific factors reduced total possessions and number of passes in the second half of match-play.

#3 Factors Influencing the Implementation of ACL Injury Prevention Strategies by Girls Soccer Coaches

Authors: Joy E, Taylor JR, Novak M, Chen M, Fink B, Porucznik C.

Reference: J Strength Cond Res. 2013 Jan 2. [Epub ahead of print]

Summary: The purpose of this study was to determine the rate of implementation of anterior cruciate ligament (ACL) and injury prevention programs (IPP), to identify factors that influence implementation, and to acquire information to assist in design dissemination and implementation strategies. The study utilized 756 female soccer players age 11 - 22 years in Utah and the data was gathered using a web-based survey, followed by a qualitative study in which "best practice coaches"-coaches who met criteria for successful implementation of ACL IPP-were interviewed via telephone. Only 19.8% (27/136) had implemented ACL IPP. The factors associated with successful implementation include length of coaching experience and presence of additional support staff such as a strength and conditioning coach or athletic trainer. Approximately 10% of the "Best practice coaches" unanimously agreed on the following three points: (1) ACL IPP had performance-enhancing benefits; (2) all coaches should receive an education on ACL injury prevention during licensure; and (3) dissemination and implementation will require soccer associations to enact policies that require injury prevention programs.

#4 Influence of mouthguards on the physical performance of soccer players

Authors: Queiróz AF, de Brito Jr RB, Ramacciato JC, Motta RH, Flório FM Reference: Dent Traumatol. 2013 Jan 10. [Epub ahead of print]

Summary: The aim was to evaluate the influence of different types of mouthguard (MG) on physical performance of female soccer players. Twenty-five female soccer players (aged 18-22) from 'Guarani Futebol Clube' participated in this study, which consisted of two physical tests and a questionnaire. Two tests were performed: agility test (shuttle run) and aerobic capacity and a Cooper test. The survey evaluated the perception of wearing mouthguards during the tests. Data analysis showed that a specific mouthguard (type III) presented better results in the VO2 and aerobic capacity tests (P < 0.05). The survey showed no difficulties experienced when wearing MGs during both physical tests. However, 100% of athletes affirmed that it was not possible to speak with MG type I, 80% (n = 20) with type II, and no athlete found difficulty in speaking when wearing MG type III. Distractions were reported by 35% (n = 6) only when athletes wore MG types I and II.

#5 Physical fitness is inversely related with body mass index and body fat percentage in soccer players aged 16-18 years

Authors: Nikolaïdis PT.

Reference: Med Pregl. 2012 Nov-Dec;65(11-12):470-5.

Summary: The purpose of this study were to examine (a) the prevalence of overweight/obesity in youth soccer players aged 16-18 years, (b) the relationship between body mass index and body fat percentage in youth soccer players aged 16-18 years, and (c) the association between body mass index, body fat and physical fitness in soccer players aged 16-18 years. One-hundred and nine soccer competitive soccer players (17.0 +/- 0.5 years) were examined for physical and physiological characteristics. Based on international body mass index cut-off points, 18.3% (n=20) of participants were classified as overweight. Additionally, the body mass index was highly correlated with body fat percentage (r=0.70) and the body fat percentage was in inverse relationship with aerobic power (r=-0.21). maximal anaerobic power (r=-0.20) and local muscular endurance (r=-0.39), while corresponding values of body mass index were non-significant (r=-0.05, r=0.03, r=-0.12, respectively). Furthermore, body fat percentage and body mass index were inversely related with fatigue index of Wingate anaerobic test (r=-0.26; r=-0.29, respectively). Due to the correlations, the authors suggested the usage of body mass index and body fat percentage in adolescent soccer players. These findings confirmed previous observations on general population. The population in this study showed similar prevalence of overweight compared with a general population. Therefore, sport participation cannot guarantee physiological body mass and body composition, and it is necessary to prescribe exercise targeting body mass and fat control.

#6 The effects of one-half of a soccer match on the postural stability and functional capacity of the lower limbs in young soccer players

Authors: Yamada RK, Arliani GG, Almeida GP, Venturine AM, Santos CV, Astur DC, Cohen M.

Reference: Clinics (Sao Paulo). 2012 Dec;67(12):1361-4.

Summary: The purpose of this study was to analyze the effects of one-half of a soccer match on the functional capacity and stability of the lower limbs in young soccer players. Twenty-seven soccer players were evaluated with regards to their functional capacity of the lower limbs using the hop test protocol and their level of postural stability using the Biodex Stability System before and after 45 minutes of game time. A significant decrease in overall stability index (OSI) and the anterior-posterior stability index (APSI) was reported after the match. The pre- vs. post-game comparison of the single and triple hop tests showed a significant higher functional capacity in the dominant limb compared to the non dominant limb. The authors concluded that there is a decrease in the stability of the lower limbs in young soccer players after a 45 minutes soccer match.

#7 Validity and Reliability of the 45-15 Test for Aerobic Fitness in Young Soccer Players

Authors: Castagna C, Iellamo F, Impellizzeri FM, Manzi V.

Reference: Int J Sports Physiol Perform. 2013 Jan 4.

Summary: The purpose of this study was to examine the reliability and validity of a the 45-15 field-test for aerobic fitness in soccer. The tests consisted of alternating progressive 45-seconds runs with 15-seconds passive recovery until exhaustion. The test considered peak speed (PS) as reflection of maximal aerobic-speed (MAS). In order to test the validity and reliability, 18 young male soccer players (age 16.7±1.8 years; body-mass 70±7.45 kg, height 177±0.5 cm, 55.62±5.56 ml/kg/min) were tested for aerobic fitness (in a laboratory setting) and repeatedly to 45-15. Results showed that 45-15 PS was significantly related to VO2max (r=0.80) and MAS (r=0.78). There was no significant bias between the MAS 45-15 PS (p=0.11) achieved 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 size. Players with peak 45-15 speed equal or above 16.5 km•h-1 may be considered as possessing good aerobic-fitness. As a conclusion, the 45-15 test may be considered as a reliable and valid test to evaluate meaningful information to direct generic aerobic training in soccer.