Latest research in football - week 12.5 - 2013

Latest research in football

As previous 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 Does playing experience improve coaching? An exploratory study of perceptual-cognitive skill in soccer coaches
Authors: Gründel A, Schorer J, Strauss B, Baker J.
Reference: Front Psychol. 2013;4:129. doi: 10.3389/fpsyg.2013.00129. Epub 2013 Mar 21.
Summary: In many sports, it is common for top coaching positions to be held by former players; however, despite the natural progression in many sports for skilled players to become high level coaches, we have little understanding of how playing may develop useful skills for coaching. In this study the authors considered perceptual-cognitive skill across groups of high and low-skilled soccer players and soccer coaches. A range of perceptual-cognitive variables was measured in an attempt to capture the diverse skills related to expertise in sport and coaching. Generally, results highlighted similarities between coaches and players on some tasks and differences on others.


#2 Home advantage in Australian soccer
Author: Goumas C.
Reference: J Sci Med Sport. 2013 Mar 18. pii: S1440-2440(13)00046-7. doi:10.1016/j.jsams.2013.02.014. [Epub ahead of print]
Summary: The purpose of this study was to quantify the magnitude of home advantage (HA) in Australian soccer and to investigate how home-team crowd support and away-team travel may contribute to that. The analyzed data were matches from the seasons (2005/06-2011/12) of the Australian A-League. Regression analysis was used to investigate the effect of crowd size and density, distance and direction travelled by away teams, and crossing time zones may have on HA. The results showed that in 58% of the points from competition was gained by home teams in the A-League. HA increased significantly with increasing number of time zones crossed by away teams. There was also a non-significant of HA with increasing crowd size but only up to about 20,000 persons. Crowd density, distance travelled and direction travelled were not independently associated with HA. The authors concluded that soccer competitions in the A-League where time zones are crossed, travel effects such as jet lag may play an even greater role in HA than home-team crowd support.


#3 EMG evaluation of hip adduction exercises for soccer players: Implications for exercise selection in prevention and treatment of groin injuries
Authors: Serner A, Jakobsen MD, Andersen LL, Hölmich P, Sundstrup E, Thorborg K.
Reference: Br J Sports Med. 2013 Mar 19. [Epub ahead of print]
Summary: The purpose of this study was to investigate muscle activity of adductor longus during six traditional and two new hip adduction exercises. Secondly, to analyse muscle activation of gluteals and abdominals in this movements. Data were obtained from 40 healthy male elite soccer players that participated >5 h a week in training. Muscle activity using surface electromyography (sEMG) was measured bilaterally for the adductor longus, gluteus medius, rectus abdominis and the external abdominal obliques during eight hip adduction strengthening exercises. The results show significant large differences (14% - 108%) in peak nEMG of the adductor longus between the exercises. Furthermore, there was a significant difference between legs in three of the eight exercises (35-48%). Generally, peak nEMG of the gluteals and the abdominals showed relatively low values results (5-48% nEMG). The authors concluded that specific hip adduction exercises can be graded by exercise intensity providing athletes and therapists with the knowledge to select appropriate exercises during different phases of prevention and treatment of groin injuries. The Copenhagen Adduction and the hip adduction with an elastic band are dynamic high-intensity exercises, which can easily be performed at any training facility and could therefore be relevant to include in future prevention and treatment programmes.

#4 Specificity of the copenhagen soccer test
Author: Vescovi JD.
Reference: Med Sci Sports Exerc. 2013 Apr;45(4):801. doi: 10.1249/MSS.0b013e31828216fd.
Summary: Unfortunately, there was no summary provided. However, we have contacted the authors and hopefully can add something later.

#5 Role of Free Testosterone in Interpreting Physical Performance in Elite Young Brazilian Soccer Players

Authors: Moreira A, Mortatti AL, Aoki MS, Arruda A FS, de Freitas CG, Carling C.
Reference: Pediatr Exerc Sci. 2013 Mar 15. [Epub ahead of print]
Summary: This study investigated the contribution of salivary testosterone (sT) concentration, years from peak height velocity (YPHV) and height by body mass interaction on jumping performance (Countermovement jump; CMJ) and aerobic fitness (Yo-Yo intermittent endurance test, level 1) in young elite soccer players. Forty-five participants (age: 12.5 ± 0.5y; body mass: 48.6 ± 10.2kg, height: 155.7 ± 10.0cm) belonging to a top level Brazilian soccer club were evaluated at four time points across a single semester. None of the assessed players had reached PHV. The data from the four evaluations were averaged and multiple linear regression analysis conducted. For CMJ, the model explained 42.88% of the variance (R2 = 42.88; p < 0.000); sT concentration was the primary contributor (R2 = 32.84) and the YPHV contributed 9.95% of the variance. The model explained 28.50% (p < 0.000) of the variance in Yo-Yo. The sT was the primary and single significant contributor (R2 = 21.32). A significant difference was noted between high and low testosterone groups divided a posteriori to CMJ performance (t = 3.35; p = 0.001). These results suggest an important role for hormonal status in interpreting physical performance in pre-adolescent soccer players.


#6 A retrospective survey on injuries in Croatian football/soccer referees
Authors: Gabrilo G, Ostojic M, Idrizovic K, Novosel B, Sekulic D.
Reference: BMC Musculoskelet Disord. 2013 Mar 11;14:88. doi: 10.1186/1471-2474-14-88.
Summary: The purpose of the study was to investigate the frequency, type and consequences of match-related and fitness-testing related injuries among soccer referees of different competitive levels. 157 main referees and 185 assistant referees (comprised of International level (Union of European Football Associations-UEFA) referees; 1st, 2nd; or 3rd national level) participated in this study and completed a self-administered questionnaire retrospectively. The questionnaire included morphological/anthropometric data, refereeing variables, and musculoskeletal disorders together with the consequences. The results showed 29% of the main referees (MR) and 30% of the assistant referees (AR) had experienced an injury during the previous year, while 13% of the MRs, and 19% of the ARs suffered from an injury that occurred during fitness testing. An increase in injury severity was observed with an increase in level, however the UEFA referees were the least injured of all referees. The results showed a relatively high prevalence of injuries to the upper leg (i.e., quadriceps and hamstrings) during physical fitness testing for all but the UEFA referees. Game injuries showed ankles and lower legs were as the most commonly injured regions. The MRs primarily injured their ankles and the ARs experienced lower leg and lower back disorders. The overall injury rate was equal for both groups, with 5.29  and 4.58 injuries per 1000 hours of refereeing for MRs and ARs, respectively. The authors concluded that physical testing was classified as a injury risk for soccer referees in addition to the risk of injury during soccer games. Special attention should be given to lower leg injuries during games and upper leg injuries during physical fitness tests.


#7 High ambulatory blood pressure in male professional football players
Authors: Berge HM, Andersen TE, Solberg EE, Steine K.
Reference: Br J Sports Med. 2013 Mar 15. [Epub ahead of print]
Summary: The purpose was to identify ambulatory blood pressure (ABP) and examine recommended follow-up of high office blood pressure (OBP) in male professional football players and secondary study indicators of sympathetic activity. 594 screenings from 28 players were matched for age and ethnicity with players with optimal OBP (controls). High ABP was defined as a mean of ≥135/85 mm Hg during daytime and ≥120/75 mm Hg during night-time. High night-time ABP and lack of nocturnal dip (≤10% decline in average BP) were taken as indicators of increased sympathetic activity. A total of 56 players were included, from which 15 (58%) of the cases had sustained hypertension and 11 (42%) white coat hypertension. Among the controls, 17 (65%) had normotension and 9 (35%) masked hypertension. ABP during night-time was high in 23 (88%) of the cases and in 16 (64%) of the controls, and nocturnal dip was absent in 9 (35%) and 11 (42%), respectively. 10 (38%) of the cases had no follow-up of high OBP. The authors concluded that one-third of the players with optimal OBP had masked hypertension during daytime and more than half of all players had high ABP during night-time, which are novel findings in athletes. Together with the reduced nocturnal dip, this might indicate increased sympathetic activity. Follow-up of high OBP after preparticipation screening is random and should be organised.

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