Latest research in football - week 11 Part 2 - 2014

Latest research in football

As previous literature updates, we have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.

Following studies were retrieved for this week:

#1 Evaluation of functional limitations in female soccer players and their relationship with sports level - a cross sectional study
Authors: Grygorowicz M1, Piontek T, Dudzinski W.
Reference: Br J Sports Med. 2014 Apr;48(7):603-4. doi: 10.1136/bjsports-2014-093494.118.
Summary: Little is known about the impact of functional muscle restrictions on the level of functional performance among female soccer players. The aim of this study was to analyze: a) abnormalities in the length of lower limb muscles, b) the correctness of movement patterns, and c) the impact of functional limitations of muscles on the correctness of fundamental movement patterns in a group of female soccer players, in relation to their skill level. 21 female soccer players from Polish Ekstraklasa (PE) and 22 players from the 1st Division (1D) participated in this study. All participants were tested for lower limb muscle length restrictions and level of fundamental movement skills (with the Fundamental Movement Screen(TM) test). Chi-square test was used for categorical unrelated variables. Differences between groups in absolute point values were analyzed using the non-parametric Mann-Whitney U test. Statistical significance was set at P<.05. Lower leg muscle length, FMS(TM) score were used as outcome measures. Significantly higher number of abnormal rectus femoris length in the 1D (P=.0433) and abnormal hamstring results (P=.0006) in the PE was observed. PE scored higher in the trunk rotational stability test (P=.0008), the 1D players scored higher in the deep squat (P=.0220), in-line lunge (P=.0042) and active straight leg raise (P=.0125) tests. The results suggest that there are different functional reasons affecting point values obtained in the FMS(TM) tests in both groups. The differences in the rectus femoris and hamstring muscle flexibility observed between female soccer players with different levels of training may result from a long-term impact of soccer training on the muscle-tendon system and articular structures. Different causes of abnormalities in fundamental movement patterns in both groups suggest the need for tailoring prevention programs to the level of sport skills represented by the players.

#2 Isokinetic relative strength profile of polish elite and sub-elite female and male soccer players - a cross sectional study
Authors: Grygorowicz M1, Hojszyk R, Piontek T, Dudzinski W.
Reference: Br J Sports Med. 2014 Apr;48(7):602-3. doi: 10.1136/bjsports-2014-093494.116.
Summary: However the isokinetic strength is well described in the literature, there is still little know about the relative isokinetic strength values in sub-elite and elite soccer players of both sexes. One has to remember that this value should be regarded as one of critical sport-return criteria in case of the injury. The purpose of this study was to describe distribution of isokinetic relative strength value in Polish elite female and male soccer players. We hypothesize that there will be no differences in relative isokinetic strength between players in different soccer level group. 41 young sub-elite (YSMS), 27 elite male (EMS) and 30 elite female soccer (EFS) players from Polish Ekstraklasa and Youth Division participated in this study. All soccer players performed concentric-concentric knee extension-flexion movements on Biodex System 3 Pro dynamometer at 60°/s of angular isokinetic velocity. Alignment axis of dynamometer rotation, thigh, hip and trunk stabilization as well as gravity correction and the range of motion was then set for each participant according to standard procedures. Values of relative isokinetic strength for were recorded. The one-way ANOVA with post hoc Tukey T test were used to assess differences between three groups. t-Test for two independent samples was used to analyze gender effects. Statistical significance was set at P<.05. Relative knee extensors and flexors isokinetic strength (Nm/kg) were used as strength measures. EFS had significantly higher results in isokinetic quadriceps and hamstring strength comparing to YSMS (2.64 vs. 2.31; P<.001 and 1.39 vs. 1.27; P=.0207, respectively) and significantly lower results comparing EMS group (2.64 vs. 3.11; P<.0001 and 1.39 vs. 1.78; P<.0001, respectively). However there were no differences between groups regarding sex (P=.8881 for extension and P=.0839 for flexion). Observed differences may be related to soccer skill level and not gender.

#3 Angle-specific changes in eccentric hamstring torque and hamstring to quad ratio following simulated soccer
Authors: Cohen D, Zhao B, Okwera B, Martyn M, Delextrat A.
Reference: Br J Sports Med. 2014 Apr;48(7):580. doi: 10.1136/bjsports-2014-093494.54.
Summary: Soccer-specific fatigue decreases eccentric peak torque and the functional peak hamstring to quadriceps torque ratio (fHecc:Qcon), changes thought to increase the risk of hamstring strain (HS). Inadequate eccentric muscle strength specifically at long length may also be a risk factor for HS. The effect of simulated soccer on the hamstring eccentric torque-angle profile, or the hamstring:quad torque ratio at specific joint angles has not been reported. The purpose was to determine the effect of a simulated soccer on angle-specific eccentric hamstring torque and angle-specific. Hecc:Qcon (AS.Hecc:Qcon) across the range of motion. 9 male players semi-professional soccer players. Isokinetic concentric and eccentric knee flexion and concentric knee extension was evaluated in the dominant limb at 120°·s(-1) pre and post the Loughborough Intermittent Shuttle Test (LIST). Changes in eccentric hamstrings torque, concentric quadriceps torque and hamstring:quadriceps torque ratios at 9 joint angles (AS.Hecc:Qcon), angle of peak torque (APT), and fHecc:Qcon. The LIST resulted in significant decreases in eccentric hamstring torque at 60, 50 and 10 and a significant (21.8%) decrease in AS.Hecc:Qcon at 10 (P<.05). Eccentric hamstring APT increased significantly (P<.05) from 7.1to 18.8. Simulated soccer produces angle-specific changes in hamstring eccentric torque and in AS.Hecc:Qcon and a shift in the eccentric hamstring APT. Our findings suggest that a prevention programs should both increase fatigue resistance in the hamstrings and include exercises that specifically develop long-length eccentric hamstring strength. Further research is also needed to determine if the evaluation of angle-specific.Hecc:Qcon improves the predictive power of injury risk screening over assessment of the peak torque fHecc:Qcon alone.

#4 The change in lower limb kinematic and emg activity of sprinting after soccer-specific fatigue among female soccer players
Authors: Chan C, Yung Sh, Liu M, Chan K.
Reference: Br J Sports Med. 2014 Apr;48(7):578. doi: 10.1136/bjsports-2014-093494.50.
Summary: Hamstring strain during sprinting is one of the dominant injuries among soccer players, which constitutes 12-16% of all injury. Fatigue is claimed to alter the lower limb mechanism during sprinting, which trigger hamstring strain injury. The purpose of this study was to find out the changes in electromyography and kinematic profile of the lower limb muscles during sprinting after fatigue among female soccer players, hence, to suggest injury prevention strategies. It is hypothesized that the EMG activity of BF and ST decrease after fatigue. Kinematic and electromyographic analysis of sprinting before and after soccer-specific fatigue intervention were measured in an indoor setting. 9 semi-professional female soccer players were recruited from 1(st) division club teams. Each subject completed the SAFT90 soccer-specific fatigue protocol that simulates the movement pattern of soccer game. 20 metres sprint test were done on each subject before and after the SAFT90. EMG activity of biceps femoris (BF), semitendinosus (ST), rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) and lower limb kinematic in sagittal plane were measured between 10 m-20 m during the sprints. The sprint time across the pre-test and post-test increased. Significant reduction in stride length and maximum combined hip flexion and knee extension angle were observed in the post-test. The EMG amplitude of BF decreased by 14.3%, and the EMG amplitude of ST increased by 10% in late swing phase across pre-test and post-test. The reduction in maximum combined hip flexion and knee extension angle indicated that the length of hamstring muscle is shortened after fatigue. The alternation in muscle activation of ST and BF could be a mechanism to reduce the risk of muscle strain of BF during the late swing phase of sprinting after fatigue.

#5 Normative data for muscle flexibility in male soccer players
Authors: Bittencourt N1, Ocarino J, Sorrentino F, Jales F, Gabriel S, Mendonça L, Fonseca S.
Reference: Br J Sports Med. 2014 Apr;48(7):568-9. doi: 10.1136/bjsports-2014-093494.24.
Summary: Muscular tightness is frequently postulated as an intrinsic risk factor for a muscle injury in soccer. Further, hamstring, iliopsoas and quadriceps flexibility measurements are of clinical relevance for monitoring recovery after such injury. The modified Thomas test was used to measure flexibility for iliopsoas and quadriceps. The passive knee extension test was used to determine the hamstring flexibility. The ICC of these tests range from 0.97 to 0.99. All these measurements were performed at Sports Injuries Prevention and Rehabilitation Laboratory. 182 elite male soccer players participated in this study; the means for age were of 18.3±3.6 years, body mass of 73.3±8.5 kg and height of 1.78±10.6 m. Hamstring, iliopsoas and quadriceps flexibility was assessed as risk-factor. For the iliopsoas and quadriceps flexibility the means were -6.76°± 5.7 and 55.2°±8.35 in the dominant leg (DL) and -7.6°±5.1 and 53.1°±8.2 in the non-dominant leg (NDL), respectively. The hamstring means were 134°±8.5 in the DL and 134.7°±8.3 in the NDL. The DL were significantly less flexible than the NDL for iliopsoas (P<.0001) and for the quadriceps the NDL were less flexible (P<.0001).The study has provided normative data for a clinical test measuring flexibility of the hamstring, iliopsoas and quadriceps. The athletes had asymmetries between limbs for the MTT and had hamstring flexibility values similar to injured soccer players. Therefore, the flexibility assessment should be performed in preseason to guide preventive interventions and provide baseline values to rehabilitation parameters after a muscle strain.

#6 Lactate and Ventilatory Thresholds Reflect the Training Status of Professional Soccer Players Where Maximum Aerobic Power is Unchanged
Authors: Edwards AM1, Clark N2, Macfadyen AM1.
Reference: J Sports Sci Med. 2003 Mar 1;2(1):23-9. eCollection 2003.
Summary: The aim of this study was to investigate maximum aerobic power (VO2 max) and anaerobic threshold (AT) as determinants of training status among professional soccer players. Twelve professional 1st team British male soccer players (age: 26.2 ± 3.3 years, height: 1.77 ± 0.05 m, body mass: 79.3 ± 9.4 kg) agreed to participate in the study and provided informed consent. All subjects completed a combined test of anaerobic threshold (AT) and maximum aerobic power on two occasions: Test 1) following 5 weeks of low level activity at the end of the off-season and Test 2) immediately following conclusion of the competitive season. AT was assessed as both lactate threshold (LT) and ventilatory threshold (VT). There was no change in VO2 max between Test 1 and Test 2 (63.3 ± 5.8 ml·kg(-1)·min(-1) vs. 62.1 ± 4.9 ml·kg(-1)·min(-1) respectively), however, the duration of exercise tolerance (ET) at VO2 max was significantly extended from Test 1 to Test 2 (204 ± 54 vs. 228 ± 68 s respectively) (P<0.01). LT oxygen consumption was significantly improved in Test 2 versus Test 1 (P<0.01) VT was also improved (P<0.05). There was no significant difference in VO2 (ml·kg(-1)·min(-1)) corresponding to LT and VT. The results of this study show that VO2 max is a less sensitive indicator to changes in training status in professional soccer players than either LT or VT.

#7 Caffeine-containing energy drink improves physical performance in female soccer players
Authors: Lara B, Gonzalez-Millán C, Salinero JJ, Abian-Vicen J, Areces F, Barbero-Alvarez JC, Muñoz V, Portillo LJ, Gonzalez-Rave JM, Del Coso J.
Reference: Amino Acids. 2014 Mar 11. [Epub ahead of print]
Summary: There is little information about the effects of caffeine intake on female team-sport performance. The aim of this study was to investigate the effectiveness of a caffeine-containing energy drink to improve physical performance in female soccer players during a simulated game. A double-blind, placebo controlled and randomized experimental design was used in this investigation. In two different sessions, 18 women soccer players ingested 3 mg of caffeine/kg in the form of an energy drink or an identical drink with no caffeine content (placebo). After 60 min, they performed a countermovement jump (CMJ) and a 7 × 30 m sprint test followed by a simulated soccer match (2 × 40 min). Individual running distance and speed were measured using GPS devices. In comparison to the placebo drink, the ingestion of the caffeinated energy drink increased the CMJ height (26.6 ± 4.0 vs 27.4 ± 3.8 cm; P < 0.05) and the average peak running speed during the sprint test (24.2 ± 1.6 vs 24.5 ± 1.7 km/h; P < 0.05). During the simulated match, the energy drink increased the total running distance (6,631 ± 1,618 vs 7,087 ± 1,501 m; P < 0.05), the number of sprints bouts (16 ± 9 vs 21 ± 13; P < 0.05) and the running distance covered at >18 km/h (161 ± 99 vs 216 ± 103 m; P < 0.05). The ingestion of the energy drink did not affect the prevalence of negative side effects after the game. An energy drink with a dose equivalent to 3 mg of caffeine/kg might be an effective ergogenic aid to improve physical performance in female soccer players.

#8 Do MRI and ultrasound of the anterior pelvis correlate with, or predict, young football players' clinical findings? A 4-year prospective study of elite academy soccer players
Authors: Robinson P, Grainger AJ, Hensor EM, Batt ME, O'Connor PJ.
Reference: Br J Sports Med. 2014 Mar 6. doi: 10.1136/bjsports-2013-092932. [Epub ahead of print]
Summary: The purpose was to prospectively follow a cohort of elite young male professional soccer players with sequential symptom questionnaires and imaging of the anterior pelvis to determine the prevalence and severity of imaging findings. 34 male athletes (mean age 16.5 years) underwent clinical examination, history/symptom questionnaire, ultrasound and 1.5 T MRI of the anterior pelvis. Athletes then underwent annual questionnaire and ultrasound with MRI also performed every 18 months. Two experienced radiologists scored ultrasound (consensus) and MRI (independently) for abnormality including pubic bone, capsule and tendon oedema and scores correlated with symptoms and presence or absence of previous injuries. Over 4 years the participants fell from 34 to 22 in number with no withdrawals due to groin injury. On study entry no athletes had undergone previous hip or pelvic surgery. On MRI pubic bone oedema, secondary cleft, capsule/tendon oedema and enhancement did not differ substantively between players with and without history of previous injury. κ Analysis for MRI scoring showed excellent agreement (0.84-0.96) for pubic bone marrow oedema, secondary cleft, capsule/tendon oedema and enhancement. On ultrasound inguinal wall motion and adductor tendinopathy did not differ substantively between players with and without history of previous injury. Stability of imaging assessments over time showed no consistent difference. Pubic bone marrow and parasymphyseal findings (cleft, capsule/tendon oedema) on MRI or inguinal canal ballooning on ultrasound were frequently found in asymptomatic athletes and did not predict injury or symptom development.

#9 The Effect of Short-Term Interval Training During the Competitive Season on Physical Fitness and Signs of Fatigue: A Cross-Over Trial in High-Level Youth Football Players
Authors: Faude O, Steffen A, Kellmann M, Meyer T.
Reference: Int J Sports Physiol Perform. 2014 Mar 11. [Epub ahead of print]
Summary: The purpose of the study was to analyze performance and fatigue effects of small-sided games (SSG) vs. high-intensity interval training (HIIT) performed during a 4 week in-season period in high-level youth football. Nineteen players from 4 youth teams (16.5 (SD 0.8) y, 1.79 (0.06) m, 70.7 (5.6) kg) of the two highest German divisions completed the study. Teams were randomly assigned to one of two training sequences (2 endurance sessions per week): One training group started with SSG, whereas the other group conducted HIIT during the first half of the competitive season. After the winter break, training programs were changed between groups. Before and after the training periods the following tests were completed: the Recovery-Stress Questionnaire for Athletes, creatine kinase and urea concentrations, vertical jump height (countermovement jump (CMJ), drop jump), straight sprint, agility, an incremental field test to determine the individual anaerobic threshold (IAT). Significant time effects were observed for IAT (+1.3%, ηp2=0.31), HRpeak (-1.8%, ηp2=0.45) and CMJ (-2.3%, ηp2=0.27) with no significant interaction between groups (p>0.30). Players with low baseline IAT values (+4.3%) showed greater improvements compared to players with high initial values (±0.0%). A significant decrease was found for Total Recovery (-5.0%, ηp2=0.29) and an increase for urea concentration (+9.2%, ηp2=0.44). Four weeks in-season endurance training can lead to relevant improvements in endurance capacity. The decreases in CMJ height and Total Recovery score together with the increase in urea concentration might be interpreted as early signs of fatigue. Thus, the danger of overtaxing the players should be considered.

#10 Functional and rtd h/q ratio in 11-16-year old male football players
Authors: Schuth G, Péter A, Hegyi A, Tihanyi J.
Reference: Br J Sports Med. 2014 Apr;48(7):659. doi: 10.1136/bjsports-2014-093494.265.
Summary: The strength profile of the hamstrings is reported to be important to prevent strain and anterior cruciate ligament (ACL) injuries. There is little information about the functional state of muscles around the knee in young soccer players. The purpose was to determine the differences in the characteristics of knee extensors and flexors in 11-16-year old, male soccer players. 60 randomly selected young male soccer players (11-16 years) - without lower extremity injury history - were assigned into 6 age groups: under 11, 12, 13, 14, 15 and U16 (10 players/group). The peak torque of isometric hamstring (ICH) and quadriceps (ICQ) (70° of knee flexion), eccentric hamstring (ECH) and concentric quadriceps (CCQ) (60°/s, 10-90° knee flexion range of movement) for both lower extremities were measured on an isokinetic dynamometer (Multicont II). Hecc/Qcc and rate of torque development (RTD) H/Q ratio were calculated 50 ms after the onset of the contraction (RTD H/Q50). ICH and ICQ significantly differed (P<.05) between U11 and U14 for both legs. There were no significant differences in ICH and in ECH between U13-U16 in the dominant leg, similarly between U14-U16 in the non-dominant leg (P>.05). Hecc/Qcc was significantly higher in the U11 group than in the U16 group (P<.05) in the dominant leg. There were no differences in RTD H/Q50 across age groups for both legs (P>.05). As eccentric and isometric hamstring peak torques did not differ between U14-U16, hamstring-emphasized strength training is advisable. RTD H/Q50 may have clinical relevance, as most ACL injuries occur 17-50 ms after initial contact. It did not differ between age groups, so the effects of intervention programs should be tested aiming to increase the RTD of the hamstrings.

#11 The efficacy of comprehensive warm-up program in male adolescent football players
Authors: Saho Y, Haruyasu K, Nakahori C, Matsuda T, Nakajo S, Shimada M, Kobayashi T, Fukubayashi T.
Reference: Br J Sports Med. 2014 Apr;48(7):655-6. doi: 10.1136/bjsports-2014-093494.256.
Summary: FIFA 11+ program has been shown to reduce injury risk in female football players but has not been evaluated in an Asian male adolescent players. The purpose was to investigate the effects of the FIFA 11 + on injury risk in a Japanese male adolescent football players. 6 Japanese U-18 (age: 16-18) and U-15 (age: 13-15) football teams followed for three seasons (2010, 2011 and 2012). The 2010 season, players completed the usual warm-up as control group, whereas the 2011 and 2011 players performed the FIFA 11+ throughout the entire season as intervention group. A total 986 male athletes (age: 12-18 years) participated in this study.  FIFA 11+program was conducted twice a week or more in entire season in 2010 and 2011. Injury rate during football (match and training), match and training were reported as the number of injuries per 1000 player-hours. The injury rate during football, match, and training in the control season were 4.0, 8.9, and 3.4 injuries per 1000 player-hours and 2.0, 4.4, and 1.5 injuries per 1000 player-hours in the intervention season. The intervention season had reductions in relative risk (RR) of game of 29% (RR=0.71, 95% confidence interval (CI)=0.664 -0.747), of match of 46% (RR=0.54, 95% CI=0.477-0.611), and of training of 28% (RR=0.72, 95% CI=0.674-0.768). The injury rate of lower extremity was reduced significantly in intervention season compared with control season. The FIFA 11+ program reduced overall injury risk and lower extremity injury risk in a Japanese male adolescent football players.

#12 Lower extremity injuries among nigerian male youth football players
Authors: Owoeye O, Akinbo S, Olawale O, Tella B.
Reference: Br J Sports Med. 2014 Apr;48(7):649. doi: 10.1136/bjsports-2014-093494.237.
Summary: Football (soccer) is the leading sport for participation among Nigerian youths. Studies on youth football injuries and their risk factors in Nigeria are lacking. The purpose was to assess the risk and pattern of lower extremity (LE) injuries in Nigerian male youth football players. The study involved 706 players (aged 17.67±1.11 years [14-19 years]) from 36 teams in the Premier League and League I of a Nigerian youth football league. A structured questionnaire based on the FIFA Medical and Research Centre consensus for studies relating to football injuries was administered to players at a pre-season screening programme. Information collected from the players included occurrence of time-loss LE injuries in the past 1 year, injury type, location, severity and exposure type. Furthermore, descriptive data on potential risk factors such as age, level and position of play, leg dominance and total number of matches played were documented. A total of 227 players sustained 307 time-loss LE injuries (range, 1-6 injuries) with an overall 1-year prevalence rate of 32.5%; equivalent to 1.4 injuries per player per year. There was no significant difference in injury prevalence between the Premier League and Division I players (P=.659). Injuries sustained were mostly located on the ankle (45.6%) and the knee joints (27.8%). Moderate injuries (48.5%) were mostly reported and more injuries were sustained during matches than training (P<.001). Exposure to high frequency of matches (>50 matches per year) (OR=2.49, P=.002) was significantly associated with injury occurrence. There is a high risk of moderate and severe LE injuries among Nigerian male youth footballers, however, pattern of injuries are mostly consistent with literatures on football injuries. This study suggests the need for injury prevention and rehabilitation interventions for players.

#13 Risk factors for lower extremity injuries in elite female football players
Authors: Nilstad A1, Andersen T, Bahr R, Holme I, Steffen K.
Reference: Br J Sports Med. 2014 Apr;48(7):645. doi: 10.1136/bjsports-2014-093494.225.
Summary: The incidence of lower extremity injuries in female football players is high, but their risk factors are poorly understood. The purpose was to investigate risk factors for lower extremity injuries in elite female football players. Norwegian elite female football players were used in this study. Baseline screening tests were conducted prior to the 2009 competitive football season and included tests assessing maximal lower extremity strength, balance, knee valgus angles in a drop jump landing, knee joint laxity, generalized joint laxity and foot pronation. We also included a questionnaire to collect information on demographic data, elite level experience and injury history. Time-loss injuries and exposure in training and match were recorded prospectively during the subsequent football season using weekly text messaging. Players reporting an injury were contacted to collect data regarding injury circumstances. Univariate and multivariate regression analyses were used to calculate odds ratios (OR) and 95% confidence intervals (CI) for one standard deviation change. New lower extremity injuries were recorded. In total, 173 players provided complete screening tests and registrations of injuries and exposure throughout the season. A total of 171 injuries in 107 players (62%) were recorded. Multivariate analyses showed that greater BMI (OR 1.51, CI 1.21-1.90, P=.001) was the only factor significantly associated with new lower extremity injuries. Greater BMI was associated with new thigh injuries (OR 1.51, CI 1.08-2.11, P=.01), lower knee valgus angles in a drop jump landing was associated with ankle injuries (OR 0.64, CI 0.41-1.00, P=.04) and a previous knee injury with lower leg and foot injuries (OR 3.57, CI 1.27-9.99, P=.02), whereas neither of the factors investigated influenced the risk of knee injuries. Greater BMI was associated with lower extremity injuries in elite female football players.

#14 The uefa injury study: 11-year data concerning 346 mcl injuries in professional football
Reference: Br J Sports Med. 2014 Apr;48(7):629. doi: 10.1136/bjsports-2014-093494.188.
Authors: Lundblad M, Waldén M, Magnusson H, Hägglund M, Karlsson J, Ekstrand J.
Summary: Medial collateral ligament (MCL) injury of the knee is scarcely investigated in football.
The purpose was to investigate the rate and circumstances of MCL injuries and their development over the past decade. 27 professional football teams were followed between 2001/02 and 2011/12. Individual player exposure and time loss injuries were recorded. Seasonal trend, expressed as the average annual percentage of change, was analysed using linear regression with log-transformed injury rates as the dependent variable. A 2-year moving average approach, by summarising two consecutive seasons, was also used to smooth out large seasonal variations. Injury circumstances such as player contact and foul play was also studied. Injury rate was defined as the number of injuries per 1000 player hours. 346 MCL injuries occurred during the study period, being the most common knee injury constituting 4% of all injuries. The MCL injury rate was 0.33 per 1000 hours, and a time trend analysis indicated a significant average annual decrease of approximately seven per-cent over the study period (P=.023). Almost 70% of all MCL injuries were contact-related, and no difference in lay-off times between contact (median=16, Q1=8, Q3=29) and non-contact (median=16, Q1=7, Q3=30) injuries was detected (P=.741). A higher percentage of foul play injuries were found in MCL contact injuries compared with other contact injuries during match play (24% vs. 18%, P=.015). MCL injury is still the most frequent knee injury in professional football, but the rate has decreased significantly during the 11-year study period. MCL injuries are commonly caused by contact situations and foul play.

#15 Implementation of a neuromuscular training programme in female adolescent football: 3-year follow-up study after an rct
Authors: Lindblom H, Waldén M, Carlfjord S, Hägglund M.
Reference: Br J Sports Med. 2014 Apr;48(7):627-8. doi: 10.1136/bjsports-2014-093494.183.
Summary: Neuromuscular training (NMT) has been shown to reduce injury rates in highly structured clinical trials. There is, however, a paucity of studies that evaluate implementation of NMT programmes in sports. The purpose was to evaluate the spread and implementation of a NMT programme in female adolescent football three years after a randomised controlled trial (RCT). Cross-sectional study using web-based questionnaires, based on the RE-AIM SSM (Reach, Effectiveness, Adoption, Implementation and Maintenance Sports Setting Matrix) framework. Representatives for the Swedish Football Association (FA) and eight district FAs that participated in an RCT in 2009, all coaches (n=303) who participated in the RCT and all currently (season 2012) active coaches for female adolescent teams (n=496) within the same districts were contacted. The response rates were 100% (Swedish and district FAs), 57% (RCT coaches, n=173) and 36% (current coaches, n=179), respectively. Reach, perceived effectiveness, adoption, implementation and maintenance of the NMT programme were recorded. The reach of the programme was high, 99% of RCT coaches (control group) and 91% of current coaches were familiar with it, and the programme was generally positively perceived. The adoption rate (usage) among current coaches was 74%. Regarding implementation, 75-77% of coaches reported programme modifications. Usage of the programme was fairly well maintained over time among RCT coaches. Formal or informal policies regarding the programme's implementation existed in the Swedish FA and in two district FAs. Among current coaches 87% reported no club routines for programme use. Reach and adoption of the NMT programme was high among coaches. However, the follow-up also identified low programme fidelity and lack of formal policies for its implementation and use in clubs and district FAs.

#16 A novel mobile device based hamstring strength test result can predict isokinetic hamstring strength in professional football players: a study of reliability and validity
Authors: Lee J, Yan S, Chan H, Yau Q, Shyung P, Chan K.
Reference: Br J Sports Med. 2014 Apr;48(7):623-4. doi: 10.1136/bjsports-2014-093494.172.
Summary: Isokinetic hamstring strength test is considered as a golden standard for identifying players with increased risk of hamstring strain injuries. However, those testing protocols were time consuming and inconvenient. The aim of this study is to examine the reliability and validity of a novel mobile device based hamstring strength test in soccer players. It is hypothesized that a greater forward flexion angle is associated a greater isokinetic hamstring strength. 30 first team players were recruited from professional football clubs. In the CUHK hamstring strength test (CUHK test), a smartphone was attached on subject's lower back. Subjects were instructed to lower the upper body from a kneeling position until the point he cannot sustain. Trunk forward flexion angle and angular velocity were recorded by the device. In the isokinetic hamstring strength test, it examined subjects' concentric and eccentric hamstring peak torque. Pearson Correlation, linear regression and intra-class correlation coefficient (ICC) were used to examine the validity and reliability. Result shown that the reliability was good, R=0.845. The CUHK strength test result was highly correlated with isokinetic hamstring peak torque at ecc. 30 degree/second, con. 60 degree/second, con. 240 degree/second respectively, i.e. R=0.81, 0.73 and 0.66. Linear regression analysis shown that the CUHK test was the best to predict isokinetic eccentric hamstring performance at 30 degree/second, R(2)=0.81, P<.001). CUHK hamstring strength test is a reliable and valid tool to examine athletes' hamstring muscle performance. Clinician and sports coaches may adopt this test for screening and monitoring athletes or patients during rehabilitation or preseason period. Individualized rehabilitation or strength training recommendation could be made based on the test result.


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