Latest research in football - week 37 & 38 - 2013

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 The influence of coach reputation on the behavioral responses of male soccer players
Authors: Manley AJ, Greenlees IA, Smith MJ, Batten J, Birch PD.
Reference: Scand J Med Sci Sports. 2013 Sep 2. doi: 10.1111/sms.12108. [Epub ahead of print]
Summary: The present study examined the impact of reputation information on athletes' behavioral responses to coaches within a naturalistic, field-based setting. Using a between-group design, male soccer players (n = 35) were assigned to one of three experimental conditions (i.e., experienced reputation, inexperienced reputation, no reputation) prior to taking part in a coaching session delivered by an unknown coach. Participants' behaviors indicative of attention to coach instruction, effort and persistence, and willingness to participate in demonstrations were video recorded throughout the coaching session. Multivariate analyses of variance revealed that participants in the experienced reputation condition exhibited significantly greater attention to coach instruction, and greater effort and persistence during free practice than participants in the inexperienced reputation condition. Results related to participants' willingness to participate in demonstrations failed to yield any significant differences. The results provide further evidence to support the contention that athletes use reputation information as a basis for their initial expectancies of coaches, and such expectancies have the potential to influence athletes' behavior during coach-athlete interactions. The findings also indicate that expectancies based on positive information may be more powerful than negatively framed expectancies, and can be harnessed by coaches as a means of developing effective relationships with their athletes.

#2 Half-time and high-speed running in the second half of soccer
Authors: Mugglestone C, Morris JG, Saunders B, Sunderland C.
Reference: Int J Sports Med. 2013 Sep;34(9):847-8. doi: 10.1055/s-0033-1351318. Epub 2013 Sep 2.
Summary: This study investigated if the quantity of high-speed running (movements >15 km.h − 1) completed in the first 15 min of competitive football matches differed from that completed in the corresponding 15 min of the second half. 20 semi-professional soccer players (age 21.2±3.6 years, body mass 76.4±3.8 kg, height 1.89±0.05 m) participated in the study. 50 competitive soccer matches and 192 data files were analysed (4±2 files per match) using Global Positioning Satellite technology. Data were analysed using 2-way repeated measures ANOVA and Pearson correlations. No differences were found between the first 15 min of each half for the distance completed at high-speed (>15 km/h) or sprinting (>21 km/h), or in the number of sprints undertaken (p>0.05). However, total distance covered was shorter (1st half vs. 2nd half: 1 746±220 vs. 1 644±224 m; p<0.001) and mean speed lower (1st half vs. 2nd half: 7.0±0.9 vs. 6.6±0.9 km.h − 1; p<0.001) in the first 15 min of the second half compared to the first. The correlations between the duration of the half-time interval and the difference in the high-speed running or sprinting between first and second halves (0-15 min) were very small (r=0.08 [p=0.25] and r=0.04 [p=0.61] respectively). Therefore, this study did not find any difference between the amount of high-speed running and sprinting completed by semi-professional soccer players when the first 15 min of the first and second half of competitive matches were compared The maintenance of high-speed running and sprinting, as total distance and mean speed declined, may be a function of the pacing strategies adopted by players in competitive matches.

#3 High-Intensity Re-Warm-Ups Enhance Soccer Performance
Authors: Zois J, Bishop D, Fairweather I, Ball K, Aughey RJ
Reference: Int J Sports Med 2013; 34(09): 800-805

Summary: The effects of high-intensity, short-duration, re-warm-ups on team-sport-related performance were investigated. In a randomised, cross-over study, participants performed 2×26-min periods of an intermittent activity protocol (IAP) on a non-motorized treadmill, interspersed by 15-min of passive recovery (CON); 3-min small-sided game (SSG); or a 5RM leg-press. Measures included counter-movement jump, repeated-sprint, the Loughborough soccer passing test (LSPT), blood lactate concentration, heart-rate, and perceptual measures. Data were analyzed using effect size (90% confidence intervals), and percentage change; determining magnitudes of effects. A 5RM re-warm-up improved flight-time to contraction-time ratio when compared to SSG (9.8%, ES; 0.5±0.3) and CON (ES: 9.4%, 0.7±0.5) re-warm-ups, remaining higher following the second IAP (8.8%, ES; 0.5±0.3 and 10.2%, ES; 0.6±0.6, respectively). Relative-maximum rate-of-force development was greater in the 5RM condition following the second IAP compared to SSG (29.3%, ES; 0.7±0.5) and CON (16.2%, ES; 0.6±0.6). Repeated-sprint ability during the second IAP improved in the 5RM re-warm-up; peak velocity, mean velocity, and acceleration were 4, 3, and 18% greater, respectively. Within groups, the SSG re-warm-up improved LSPT performance post-intervention; 6.4% (ES: 0.6±0.8) and following the second IAP 6.2% (ES: 0.6±0.6), compared to pre-intervention. A 5RM leg-press re-warm-up improved physical performance, while a SSG re-warm-up enhanced skill execution following standardized intermittent exercise.


#4 Adductor tenotomy as a treatment for groin pain in professional soccer players
Authors: Mei-Dan O, Lopez V, Carmont MR, McConkey MO, Steinbacher G, Alvarez PD, Cugat RB.
Reference: Orthopedics. 2013 Sep 1;36(9):e1189-97. doi: 10.3928/01477447-20130821-23.
Summary: Chronic, exercise-related groin pain is a debilitating condition. Nonoperative treatment has limited efficacy, but surgical intervention on the adductor-abdomino complex may be used to alleviate symptoms and allow return to play (RTP). The purpose of this study was to report the outcome of adductor tenotomy and hernioplasty for professional soccer players with groin pain. Between 2000 and 2006, a total of 155 professional and recreational soccer players with recalcitrant groin pain (with or without lower abdominal pain) and resistance to conservative treatment were included in this retrospective analysis. Ninety-six patients were treated with adductor tenotomy and 59 patients were treated with combined adductor tenotomy and hernioplasty. No difference in pre- or postoperative parameters was detected between groups, apart from abdominal wall muscle defects revealed during ultrasound for patients in the combined group. The RTP time and subjective and objective outcome measures were compared. A combined score was developed to evaluate outcomes that consisted of overall satisfaction (50%), RTP time (15%), and Tegner scores (35%). Mean RTP was 11 weeks (range, 4-36 weeks). Postoperative Tegner score remained 8.2 (same as the preinjury Tegner score). Subjective outcome was rated 4.3 of 5. The combined score indicated 80% of good or excellent results for both groups. Surgical intervention allows RTP at the same level in professional soccer players following failure of nonoperative treatments. Athletes with adductor syndrome and accompanying sportsman's hernia may benefit from adductor tenotomy alone.

#5 Physical and Technical Comparisons between Various-Sided Games within Professional Soccer
Authors: Owen AL, Wong DP, Paul D, Dellal A.
Reference: Int J Sports Med. 2013 Sep 10. [Epub ahead of print]
Summary: This study compared the technical activity and physical movements of various-sided games within professional soccer. It also examined the test-retest reliability of sided games using various numbers of players. 10 elite male players from a Scottish Premier League performed small- (SSGs: 4 vs. 4), medium- (MSGs: 5 vs. 5 to 8 vs. 8) and large- (LSGs: 9 vs. 9 to 11 vs. 11) sided games each lasting for 3×5 min. Results show significant physical differences (p<0.05) between SSGs, MSGs and LSGs for most of the variables measured. It was shown that SSGs induce a significantly faster playing speed when compared to MSGs and LSGs (150.5 vs. 108.3 vs. 120.4 m.min-1, p<0.01) but significantly less (p<0.01) repeated high-intensity efforts (0.88 vs. 4.40 m), high-intensity running (7 vs. 39 m) and sprint distance (0 vs. 11 m) when compared to LSGs. Findings also revealed significant differences (p<0.05) between SSGs, MSGs and LSGs in technical demands (passes, dribbles, shots, headers). High levels of reproducibility (ICC=0.99) were yielded when using the same-sided games, pitch sizes and possession rules. This study provided information on different-sided games to facilitate its use as part of a periodised weekly structure.

#6 Sport Injuries Aligned to Peak Height Velocity in Talented Pubertal Soccer Players
Authors: van der Sluis A, Elferink-Gemser MT, Coelho-E-Silva MJ, Nijboer JA, Brink MS, Visscher C.
Reference: Int J Sports Med. 2013 Sep 10. [Epub ahead of print]
Summary: In young athletes, demands of sports are superimposed on normal growth and maturation. It has been suggested that this causes a temporarily increased vulnerability for injuries. We followed 26 talented soccer players (mean age 11.9±0.84 years) longitudinally for 3 years around their adolescent growth spurt, called Peak Height Velocity, to identify differences in number of traumatic and overuse injuries and days missed due to injuries. Peak Height Velocity was calculated according to the Maturity Offset Protocol. The number of injuries was calculated for each player per year. A repeated measurement analysis showed that athletes had significantly more traumatic injuries in the year of Peak Height Velocity (1.41) than in the year before Peak Height Velocity (0.81). A moderate effect size of 0.42 was found for the difference in number of overuse injuries per player per year before (0.81) and after Peak Height Velocity (1.41), respectively. Finally, a moderate effect size of 0.55 was found for difference between days missed due to injuries before (7.27 days per player per year) and during Peak Height Velocity (15.69 days per player per year). Adolescent growth spurt seems to result in increased vulnerability for traumatic injuries. Afterwards athletes seem to be susceptible to overuse injuries.

#7 Application of the Copenhagen Soccer Test in high-level women players - locomotor activities, physiological response and sprint performance
Authors: Bendiksen M, Pettersen SA, Ingebrigtsen J, Randers MB, Brito J, Mohr M, Bangsbo J, Krustrup P.
Reference: Hum Mov Sci. 2013 Sep 6. pii: S0167-9457(13)00087-0. doi: 10.1016/j.humov.2013.07.011. [Epub ahead of print]
Summary: We evaluated the physiological response, sprint performance and technical ability in various phases of the Copenhagen Soccer Test for Women (CSTw) and investigated whether the locomotor activities of the CSTw were comparable to competitive match-play (CM). Physiological measurements and physical/technical assessments were performed during CSTw for eleven Norwegian high-level women soccer players. The activity pattern during CSTw and CM was monitored using the ZXY tracking system. No differences were observed between CSTw and CM with regards to total distance covered (10093±94 and 9674±191m), high intensity running (1278±67 and 1193±115m) or sprinting (422±55 and 372±46m) (p>.05). During CSTw, average HR was 85±2%HRmax with 35±2% playing time >90%HRmax. Blood lactate increased (p<.05) from 1.4±0.3mM at rest to an average of 4.7±0.5mM during CSTw, with no changes during the test. Blood glucose was 5.4±0.3mM at rest and remained unaltered during CSTw. Sprint performance (2×20m) decreased (p<.05) by 3% during CSTw (8.19±0.06-8.47±0.10s). In conclusion, the locomotor activities during CSTw were comparable to that of high-level competitive match-play. The physiological demands of the CSTw were high, with no changes in heart rate, blood lactate or technical performance during the test, but a lowered sprint performance towards the end of the test.

#8 Activity profiles of professional soccer, rugby league and Australian football match play
Authors: Varley MC, Gabbett T, Aughey RJ.
Reference: J Sports Sci. 2013 Sep 9. [Epub ahead of print]
Summary: We compared the match activity profiles of elite footballers from Australian football (AF), rugby league (RL) and soccer (SOC), using identical movement definitions. Ninety-four elite footballers from AF, RL or SOC clubs in Australia participated in this study. Movement data were collected using a 5-Hz global positioning system from matches during the 2008-2011 competitive seasons, including measures of velocity, distance, acceleration and bouts of repeat sprints (RS). Australian footballers covered the greatest relative running distances (129 ± 17 m/min) compared to RL (97 ± 16 m/min) and SOC (104 ± 10 m/min) (effect size [ES]; 1.0-2.8). The relative distance covered (4.92 ± 2.10 m/min vs. 5.42 ± 2.49 m/min; 0.74 ± 0.78 m/min vs. 0.97 ± 0.80 m/min) and the number of high-velocity running (0.4 ± 0.2 no/min vs. 0.4 ± 0.2 no/min) and sprint (0.06 ± 0.06 no/min vs. 0.08 ± 0.07 no/min) efforts between RL and SOC players were similar (ES; 0.1-0.3). Rugby league players undertook the highest relative number of accelerations (1.10 ± 0.56 no/min). RS bouts were uncommon for all codes. RL and SOC players perform less running than AF players, possibly due to limited open space as a consequence of field size and code specific rules. While training in football should be code specific, there may be some transference of conditioning drills across codes.

#9 An investigation of the effect of athletes' age on the coaching behaviours of professional top-level youth soccer coaches
Authors: Partington M, Cushion C, Harvey S.
Reference: J Sports Sci. 2013 Sep 9. [Epub ahead of print]
Summary:  The aim of the study was to investigate the behaviours, cognitive processes and practice activities of 12 English youth professional soccer coaches across 6 different age groups. Systematic observation data were collected using a modified version of the Coach Analysis and Intervention System which provided a detailed analysis of coaching behaviours performed during practice. Interpretive interviews were then triangulated with the behavioural data to identify the cognitive processes underlying the behaviours performed. The behavioural results showed that the coaches of the younger age groups used more instruction and the coaches of the older age groups used more divergent questioning and significantly more total feedback and punitive behaviours. The coaches of the younger age groups used more training form activities than the coaches of the older age groups who used more playing form activities. However, the interviews revealed that instead of the age of athletes' directly affecting the cognitive process of coaches it was in fact the coaches underlying beliefs about coaching, their previous experiences and perceived pressures from the context that determined the behaviours performed.

#10 Heading in football, long-term cognitive decline and dementia: evidence from screening retired professional footballers
Authors: Vann Jones SA, Breakey RW, Evans PJ.
Reference: Br J Sports Med. 2013 Sep 11. doi: 10.1136/bjsports-2013-092758. [Epub ahead of print]
Summary: Heading impairs cognition in the short and medium-terms; however, little is known about the long-term consequences. This study aimed to investigate the hypothesis that chronic low-level head trauma is associated with persistent cognitive decline. All members of Former Player Associations (FPAs) from four professional football clubs in the UK were contacted to participate in the study. Participants were required to complete a self-assessed test of cognition, the Test Your Memory questionnaire. Further information was collected from respondents in order to analyse the potential effect of a number of variables on cognition. 10 of 92 respondents (10.87%) screened positive for possible mild cognitive impairment (MCI) or dementia. There was no association between low-risk and high-risk playing positions (HR = 0.40, p = 0.456) or length of playing career (HR = 1.051 95% CI 0.879 to 1.257, p = 0.586) and a positive screening result. Age was a risk factor (HR = 1.137 per additional year, 95% CI 1.030 to 1.255, p < 0.05), although this was not significantly different from the population prevalence across age groups. These results suggest that once a player ends their playing career, their risk of harm falls in line with the population, suggesting either that changes are reversible or that heading may not be as harmful as commonly thought. Future longitudinal studies of large numbers of professional football players are needed to support the findings from this study.

#11 Alcohol Marketing in Televised English Professional Football: A Frequency Analysis
Authors: Graham A, Adams J.
Reference: Alcohol Alcohol. 2013 Sep 10. [Epub ahead of print]
Summary: The aim of the study was to explore the frequency of alcohol marketing (both formal commercials and otherwise) in televised top-class English professional football matches. A purposive sample of six broadcasts (total = 1101 min) of televised top-class English club football matches were identified and recorded in full. A customized coding framework was used to identify and categorize all verbal and visual alcohol references in non-commercial broadcasting. The number and the duration of all formal alcohol commercials were also noted. A mean of 111 visual references and 2 verbal references to alcohol per hour of broadcast were identified. Nearly all visual references were to beer products and were primarily simple logos or branding. The majority of verbal alcohol references were related to title-sponsorship of competitions. A total of 17 formal alcohol commercials were identified, accounting for <1% of total broadcast time. Visual alcohol references in televised top-class English football matches are common with an average of nearly two per minute. Verbal references are rare and formal alcohol commercials account for <1% of broadcast time. Restriction of all alcohol sports sponsorship, as seen for tobacco, may be justified.

#12 Effect of player position on movement behaviour, physical and physiological performances during an 11-a-side football game
Authors: Gonçalves BV, Figueira BE, Maçãs V, Sampaio J.
Reference: J Sports Sci. 2013 Sep 9. [Epub ahead of print]
Summary: The aim of this study was to identify differences in time-motion, modified training impulse, body load and movement behavior between defenders, midfielders and forwards, during an 11-a-side simulated football game. Twenty elite youth male footballers from the same squad participated in this study (age: 18.1 ± 0.7 years old, body mass: 70.5 ± 4.3 kg, height: 1.8 ± 0.3 m and playing experience: 9.4 ± 1.3 years). All data were collected using GPS units (SPI-Pro, GPSports, Canberra, Australia). The movement behaviour was measured with kinematic data, used to calculate position-specific centroids (defenders, midfielders and forwards), and processed with non-linear statistical procedures (approximate entropy normalised and relative phase). There were significant effects and interactions in all variables across the players' positions. The results showed that displacements of all players (defenders, midfielders and forwards) were nearer and more coordinated with their own position-specific centroids than with the other centroids. However, this coupling effect was stronger in midfield players and weaker in forwards. All players' dynamical positioning showed more irregularity when related to the forwards' centroid, as a consequence of their need to be less predictable when playing. The time-motion and physiological variables showed lower activity in forward players. Adding together, the results may contribute to a better understanding of players' specific performances and football complexity.

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