Latest research in football - week 45 - 2014

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 An intensive winter fixture schedule induces a transient fall in salivary IgA in english premier league soccer players
Reference: Res Sports Med. 2014;22(4):346-54. doi: 10.1080/15438627.2014.944641.
Authors: Morgans R, Orme P, Anderson L, Drust B, Morton JP.
Summary: We examined the effects of an intensive fixture schedule on salivary IgA (SIgA) concentration in professional soccer players from the English Premier League. Salivary samples were obtained from 21 males who participated in seven games over a 30-day period during December 2013 and January 2014 (games 1-5 occurred in a 15-day period). Salivary-IgA decreased (P < 0.05) at 2 days post-game 3 (45 ± 9 μg mL(-1)), 4 (52 ± μg mL(-1)) and 5 (41 ± 10 μg mL(-1)) compared with game 1 (139 ± 25 μg mL(-1)). When the normal fixture schedule resumed (i.e. one game per week), SIgA returned towards baseline such that game 6 and 7 values were not different (P > 0.05) from game 1 (91 ± 18 and 99 ± 21 μg mL(-1), respectively). Data demonstrate for the first time that a congested winter fixture schedule induces detectable perturbations to mucosal immunity in professional soccer players.

#2 Match-play activity profile in professional soccer players during official games and the relationship between external and internal load
Reference: J Sports Med Phys Fitness. 2014 Oct 7. [Epub ahead of print]
Authors: Suarez-Arrones L, Torreño N, Requena B, Sáez de Villarreal E, Casamichana D, Barbero-Alvarez JC, Munguía-Izquierdo D.
Summary: The aim was to quantify for the first time the physical and physiological profile of professional soccer players in official games using GPS and heart rate response. Methods: Thirty professional soccer players were investigated during a half in competitive club level matches (n=348) using GPS devices. The relative total distance was 118.9±10.7 m∙min--1 and player's work--to--rest ratio was 2.1:1. Defenders covered the lowest total distance, while Second--Strikers (2ndS) and Wide--Midfielders (W--MD) traveled the greatest total distance. Defenders presented the lowest work--to--rest ratio values. Playing position also impacted on all sprinting performance results, except in average sprint distance and time of sprint. The number of sprints and repeated--sprint sequences recorded by the W--MD and Strikers (S) were significantly greater than any other group. The average Heart Rate (HR) recorded was 87.1%HRmax and the relationship between the external and internal load value (effindex) was 1.4 with significant differences in both between playing positions. W--MD recorded a significantly smaller average HR than any other group and Centre--Backs showed a significantly smaller effindex value than any other group. Conversely, W--MD showed a significantly greater effindex value than any other group, except the 2ndS. This study has verified a number of statistically significant differences between the different playing positions. Coaches should be focused on the specific physical and physiological requirements of the playing positions to optimize the training prescription in soccer. The relationships between external and internal load measures among position--specific indicates that players with less overall running performance during match--play were the worst in effindex.

#3 Mortality in international professional football (soccer): a descriptive study
Reference: J Sports Med Phys Fitness. 2014 Oct 7. [Epub ahead of print]
Authors: Gouttebarge V, Ooms W, Tummers T, Inklaar H.
Summary: The objective of this study was to describe the characteristics of mortalities from 2007 to 2013 in active (during career) and recently retired (post career) professional footballers. An observational prospective study was conducted. From 2007, the World Footballers' Union (FIFPro) and its related national footballers' unions (more than 70 countries distributed across all continents) collected descriptive data (football--related, cause…) on mortality of active (during career) and recently retired (post career before reaching 45 years of age) professional footballers by means of several official sources. A total of 214 deaths were recorded among active and recently retired professional footballers, leading to an overall mortality rate of 0.47 per 1,000 footballers per year. Of the 214 deaths, 183 were recorded among active players and 31 among recently retired players. Among the active players, 17% of the fatalities were related to football participation. Disease was the leading cause of death among professional footballers (55%), of which up to 33% accounted for suspected cardiac pathology. Accidents accounted for 25% of the overall deaths, and suicide for 11%. From 2007 to 2013, 214 deaths were recorded among active (during career) and recently retired (post career) professional footballers. Leading cause of death was disease (55%), one third of which were accounted for by suspected cardiac pathology, while accidents accounted for 25% of all deaths, and suicide for 11%. Attention to the predictive validity and application of heart--related pre--competition medical assessment should be given, and mental health support should be developed and implemented both during and after a professional football career to prevent potential suicidal behaviors.

#4 Effects of acute l-carnitine supplementation on nitric oxide production and oxidative stress after exhaustive exercise in young soccer players
Reference: J Sports Med Phys Fitness. 2014 Oct 7. [Epub ahead of print]
Authors: Atalay Guzel N, Erikoglu Orer G, Bircan FS, Coskun Cevher S.
Summary: The aim of this study was to investigate the effect of acute Lcarnitine supplementation at two different doses on nitric oxide (NO) production and oxidative stress after exhaustive exercise. The subjects were 26 healthy males aged 1719 years. Subjects were randomly divided into two groups of 13 each and received 3 or 4 g Lcarnitine via a glass of fruit juice. After 1 h, the treadmill test was started at a speed of 8 km/h, afterwards increasing the speed 1 km/h every 3 min with a 1 min rest before every speed increase until exhaustion. Venous blood samples were collected again within 5 min following the exercise test. One week later, the test was repeated on the same athletes with placebo fluids. All subjects received a placebo via a glass of fruit juice. 1 h after the same exercise protocol mentioned above was performed and blood samples were drawn immediately. These plasma samples were used for measurement of nitrate nitrite (NOx), which are known to be the stable end products of NO, TBARs as a lipid peroxidation indicator and an antioxidant glutathione (GSH) levels. The results of this study have shown that Lcarnitine applied at a 3 g dose provides strong antioxidant action by increasing the GSH and NOx level and decreasing the TBARs level.

#5 Soccer-related Facial Trauma: Multicenter Experience in 2 Brazilian University Hospitals
Reference: Plast Reconstr Surg Glob Open. 2014 Jul 9;2(6):e168. doi: 10.1097/GOX.0000000000000129. eCollection 2014.
Authors: Goldenberg DC, Dini GM, Pereira MD, Gurgel A, Bastos EO, Nagarkar P, Gemperli R, Ferreira LM.
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Summary: Soccer is the most popular sport in Brazil and a high incidence of related trauma is reported. Maxillofacial trauma can be quite common, sometimes requiring prolonged hospitalization and invasive procedures. To characterize soccer-related facial fractures needing surgery in 2 major Brazilian Centers. A retrospective review of trauma medical records from the Plastic Surgery Divisions at the Universidade Federal de São Paulo-Escola Paulista de Medicina and the Hospital das Clinicas-Universidade de São Paulo was carried out to identify patients who underwent invasive surgical procedures due to acute soccer-related facial fractures. Data points reviewed included gender, date of injury, type of fracture, date of surgery, and procedure performed. A total of 45 patients (31 from Escola Paulista de Medicina and 14 from Universidade de São Paulo) underwent surgical procedures to address facial fractures between March 2000 and September 2013. Forty-four patients were men, and mean age was 28 years. The fracture patterns seen were nasal bones (16 patients, 35%), orbitozygomatic (16 patients, 35%), mandibular (7 patients, 16%), orbital (6 patients, 13%), frontal (1 patient, 2%), and naso-orbito-ethmoid (1 patient, 2%). Mechanisms of injury included collisions with another player (n = 39) and being struck by the ball (n = 6). Although it is less common than orthopedic injuries, soccer players do sustain maxillofacial trauma. Knowledge of its frequency is important to first responders, nurses, and physicians who have initial contact with patients. Missed diagnosis or delayed treatment can lead to facial deformities and functional problems in the physiological actions of breathing, vision, and chewing.

#6 Technical Performance Reduces during the Extra-Time Period of Professional Soccer Match-Play
Reference: PLoS One. 2014 Oct 24;9(10):e110995. doi: 10.1371/journal.pone.0110995. eCollection 2014.
Authors: Harper LD, West DJ, Stevenson E, Russell M.
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Summary: Despite the importance of extra-time in determining progression in specific soccer tournament matches, few studies have profiled the demands of 120-minutes of soccer match-play. With a specific focus on the extra-time period, and using a within-match approach, we examined the influence of prolonged durations of professional soccer match-play on markers of technical (i.e., skilled) performance. In 18 matches involving professional European teams played between 2010 and 2014, this retrospective study quantified the technical actions observed during eight 15-minute epochs (E1: 00∶00-14∶59 min, E2: 15∶00-29∶59 min, E3: 30∶00-44∶59 min, E4: 45∶00-59∶59 min, E5: 60∶00-74∶59 min, E6: 75∶00-89∶59 min, E7: 90∶00-104∶59 min, E8: 105∶00-119∶59 min). Analysis of players who completed the demands of the full 120 min of match-play revealed that the cumulative number of successful passes observed during E8 (61±23) was lower than E1-4 (E1: 88±23, P = 0.001; E2: 77±21, P = 0.005; E3: 79±18, P = 0.001; E4: 80±21, P = 0.001) and E7 (73±20, P = 0.002). Similarly, the total number of passes made in E8 (71±25) was reduced when compared to E1 (102±22, P = 0.001), E3 (91±19, P = 0.002), E4 (93±22, P≤0.0005) and E7 (84±20, P = 0.001). The cumulative number of successful dribbles reduced in E8 (9±4) when compared to E1 (14±4, P = 0.001) and E3 (12±4, P≤0.0005) and the total time the ball was in play was less in E8 (504±61 s) compared to E1 (598±70 s, P≤0.0005). These results demonstrate that match-specific factors reduced particular indices of technical performance in the second half of extra-time. Interventions that seek to maintain skilled performance throughout extra-time warrant further investigation.

#7 "Soccer or emergency?" Sporting event can lead to a decreased attendance in the pediatric emergency department
Reference: Minerva Pediatr. 2014 Dec;66(6):559-62.
Authors: Fabre A, Mancini J, Boutin A, Bremond V.
Summary: Sporting events have been seen to be related to a decline in adult male visits in emergency departments. Studies about the influence of sporting events on pediatric emergency attendance are scarce and non-conclusive. In our institution there is a widely shared popular belief of the local pediatric emergency medical staff that there is a decrease in the attendance when the local soccer team (Olympique de Marseille) is playing. We have collected data on attendance and orientation (medical or surgery) in the pediatric emergency unit (35,000 annual admission) for the Wednesdays, Saturdays and Sundays between July 1, 2008 and May 31, 2012 compassing 4 soccer seasons. We have also collected the date and the localization (at home or abroad) of all the games played by the city's soccer team for the four seasons. The study included 512 days (171 Saturdays and Sundays and 170 Wednesdays), 173 were match days and 339 were control days. After adjusting for day, month, and years, there was a 3.5% decrease of attendance during game days (P=0.007), which was higher for days of away games (4.7% decrease, P=0.012). For matches played at 9 p.m. for a 4 hour period (allowing for 1 hour before and 1 hour after the matches) the decrease was that of 8% (P=0.05) mostly for medicine admission. We observed that sporting events as soccer games can have a effect on the attendance rate in a children's emergency department. The underlying reason for this difference is not well understood.

#8 Are the Yo-Yo intermittent recovery test levels 1 and 2 both useful? Reliability, responsiveness and interchangeability in young soccer players
Reference: J Sports Sci. 2014 Oct 21:1-8. [Epub ahead of print]
Authors: Fanchini M, Castagna C, Coutts AJ, Schena F, McCall A, Impellizzeri FM.
Summary: The aim of this study was to compare the reliability, internal responsiveness and interchangeability of the Yo-Yo intermittent recovery test level 1 (YY1), level 2 (YY2) and submaximal YY1 (YY1-sub). Twenty-four young soccer players (age 17 ± 1 years; height 177 ± 7 cm; body mass 68 ± 6 kg) completed each test five times within pre- and in-season; distances covered and heart rates (HRs) were measured. Reliability was expressed as typical error of measurement (TEM) and intraclass correlation coefficient (ICC). Internal responsiveness was determined as effect size (ES) and signal-to-noise ratio (ESTEM). Interchangeability was determined with correlation between training-induced changes. The TEM and ICC for distances in the YY1 and YY2 and for HR in YY1-sub were 7.3% and 0.78, 7.1% and 0.93 and 2.2% and 0.78, respectively. The ESs and ESTEMs were 0.9 and 1.9 for YY1, 0.4 and 1.2 for YY2 and -0.3 and -0.3 for YY1-sub. Correlations between YY1 vs. YY2 and YY1-sub were 0.56 to 0.84 and -0.36 to -0.81, respectively. Correlations between change scores in YY1 vs. YY2 were 0.29 and -0.21 vs. YY1-sub. Peak HR was higher in YY1 vs. YY2. The YY1 and YY2 showed similar reliability; however, they were not interchangeable. The YY1 was more responsive to training compared to YY2 and YY1-sub.

#9 Three-dimensional kinematic differences between the preferred and non-preferred limbs during maximal instep soccer kicking
Reference: J Sports Sci. 2014 Oct 21:1-10. [Epub ahead of print]
Authors: Sinclair J, Fewtrell D, Taylor PJ, Atkins S, Bottoms L, Hobbs SJ.
Summary: The current investigation aimed to determine whether there are differences in ball velocity and 3D kinematics when performing maximal kicks with the dominant and non-dominant limbs. Seventeen male academy soccer players performed maximal speed place kicks with their dominant and the non-dominant limbs. The 3D kinematics of the lower extremities were obtained using a 10-camera motion capture system operating at 500 Hz. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes and then contrasted using paired t-tests. Significantly higher ball velocities were obtained with the dominant limb. Foot linear velocity and knee extension velocity at ball contact were also found to be significantly greater in the dominant limb. That reduced ball velocities were observed between kicking limbs highlights the potential performance detriments that may occur when kicking with the non-dominant limb; thus, it is recommended that additional bilateral training be undertaken in order to attenuate this and improve overall kicking performance.

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