Latest research in football - week 34 - 2018

#1 Changes in biomechanical knee injury risk factors across two collegiate soccer seasons using the 11+ prevention program
Reference: Scand J Med Sci Sports. 2018 Aug 17. doi: 10.1111/sms.13278. [Epub ahead of print]
Authors: Arundale AJH, Silvers-Granelli HJ, Marmon A, Zarzycki R, Dix C, Snyder-Mackler L
Summary: The 11+ injury prevention program effectively reduces injuries in high school aged female soccer player, but the mechanism of the 11+ is unknown, particularly whether it impacts biomechanical risk factors associated with knee injuries. The purpose was to report the changes in hip and knee biomechanics with use of the 11+ over two soccer seasons. Two collegiate women's soccer teams performed the 11+ for two soccer seasons. A control team was followed for one season. Athletes performed motion analysis of a drop vertical jump during preseason and postseason. Both groups had meaningful increases in peak knee abduction angle over the first season, and there were no meaningful changes in peak knee abduction moment over either season. The control group had bilateral decreases in knee flexion angle. The program did not seem to systematically impact biomechanical risk factors associated with knee injuries, with increase in peak knee abduction angle no bilateral changes in frontal or transverse hip motion. The 11+ may have mitigated clinically meaningful decreases in knee flexion, however as ACL injuries do not occur purely in the sagittal plane, it is unclear the impact of these changes. The results of this study indicate that the 11+ may require some modifications to impact landing biomechanics and potentially risky movement patterns, particularly when used in collegiate women over multiple seasons


#2 Timing Training in Female Soccer Players: Effects on Skilled Movement Performance and Brain Responses
Reference: Front Hum Neurosci. 2018 Aug 2;12:311. doi: 10.3389/fnhum.2018.00311. eCollection 2018.
Authors: Sommer M, Häger CK, Boraxbekk CJ, Rönnqvist L
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6082929/pdf/fnhum-12-00311.pdf
Summary: Although trainers and athletes consider "good timing skills" critical for optimal sport performance, little is known in regard to how sport-specific skills may benefit from timing training. Accordingly, this study investigated the effects of timing training on soccer skill performance and the associated changes in functional brain response in elite- and sub-elite female soccer players. Twenty-five players (mean age 19.5 years; active in the highest or second highest divisions in Sweden), were randomly assigned to either an experimental- or a control group. The experimental group (n = 12) was subjected to a 4-week program (12 sessions) of synchronized metronome training (SMT). We evaluated effects on accuracy and variability in a soccer cross-pass task. The associated brain response was captured by functional magnetic resonance imaging (fMRI) while watching videos with soccer-specific actions. SMT improved soccer cross-pass performance, with a significant increase in outcome accuracy, combined with a decrease in outcome variability. SMT further induced changes in the underlying brain response associated with observing a highly familiar soccer-specific action, denoted as decreased activation in the cerebellum post SMT. Finally, decreased cerebellar activation was associated with improved cross-pass performance and sensorimotor synchronization. These findings suggest a more efficient neural recruitment during action observation after SMT. To our knowledge, this is the first controlled study providing behavioral and neurophysiological evidence that timing training may positively influence soccer-skill, while strengthening the action-perception coupling via enhanced sensorimotor synchronization abilities, and thus influencing the underlying brain responses.


#3 Somatotype Hormone Levels and Physical Fitness in Elite Young Soccer Players over a Two-Year Monitoring Period
Reference: J Sports Sci Med. 2018 Aug 14;17(3):455-464. eCollection 2018 Sep.
Authors: Hammami MA, Ben Abderrahman A, Rhibi F, Nebigh A, Coppalle S, Ravé G, Tabka Z, Zouhal H
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6090385/pdf/jssm-17-455.pdf
Summary: The effect of two soccer-training seasons on the growth, development and somatotype hormone concentrations of elite youth soccer players were evaluated. Eighteen elite soccer players and 18 age-matched non-athletic control subjects participated in the study. Anthropometric-measurements, aerobic and anaerobic performance tests and serum concentrations of insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and growth hormone (GH) were assessed at 5 time points across two competitive seasons. Soccer players revealed higher GH, IGF-1 and IGFBP-3 than the control group across all-time points. Significant moderate correlations were observed only in soccer players between hormonal concentrations (IGF-1 and IGFBP-3) and the jumping tests (r = 0.45-0.48; p < 0.01). Somatotropic axis hormones, anthropometric and physical parameters increased to a greater degree with growth and soccer training combined compared to growth alone. Results from this investigation revealed that intense training did not impair growth or development in these young soccer players across 2-year period.


#4 Effects of Spatiotemporal Constraints and Age on the Interactions of Soccer Players when Competing for Ball Possession
Reference: J Sports Sci Med. 2018 Aug 14;17(3):379-391. eCollection 2018 Sep.
Authors: Menuchi MRTP, Moro ARP, Ambrósio PE, Pariente CAB, Araújo D
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6090386/pdf/jssm-17-379.pdf
Summary: Although there are several descriptions of interpersonal coordination in soccer teams, little is known about how such coordination is influenced by space and time constraints. In this study, we analyzed variations in interpersonal coordination under different marking intensities and across different age groups. Marking intensity was manipulated by changing the players' game space and time of ball possession in a conditioned soccer game known as rondo. Five participants in each age category (U13, U15, U17, and U20) performed rondo tasks in four experimental conditions, in a total of 134 trials. The dependent variables considered were pass performance and eco-physical variables capturing the player-environment coupling, such as coupling of the marking between players. Our results demonstrate that in soccer: (1) markers and passers are tightly coupled; (2) the marker-passer coupling emerges from a flexible and adaptive exchange of passes; (3) the marker-passer coupling is stronger in markings of higher intensity and older age groups. Thus, the interactions between soccer players in marking can be analyzed as an emerging and self-organized process in the context of group performance.


#5 Behaviours of shooter and goalkeeper interact to determine the outcome of soccer penalties
Reference: Scand J Med Sci Sports. 2018 Aug 15. doi: 10.1111/sms.13276. [Epub ahead of print]
Authors: Hunter AH, Angilletta MJ Jr, Wilson RS
Summary: During a soccer penalty, the shooter's strategy and the goalkeeper's strategy interact to determine the outcome. However, most models of penalty success overlook its interactive nature. Here, we quantified aspects of shooter and goalkeeper strategies that interact to influence the outcome of soccer penalties - namely, how the speed of the shot affects the goalkeeper's leave-time or shot-blocking success, and the effectiveness of deceptive strategies. We competed 7 goalkeepers and 17 shooters in a series of penalty shootout competitions with a total of 1278 shot taken. Each player was free to use any strategy within the rules of a penalty shot and game-like pressure was created via monetary incentive for goal-scoring (or blocking). We found that faster shots lead to earlier leave-times and were less likely blocked by goalkeepers, and-unlike most previous studies-that deceptive shooting strategies did not decrease the likelihood goalkeepers moved in the correct direction. To help identify optimal strategies for shooter's and goalkeepers, we generated distributions and mathematical functions sport scientist can use to develop more comprehensive models of penalty success.


#6 Recreational soccer as sport medicine for middle-aged and older adults: a systematic review
Reference: BMJ Open Sport Exerc Med. 2018 Aug 9;4(1):e000336. doi: 10.1136/bmjsem-2017-000336. eCollection 2018.
Authors: Luo H, Newton RU, Ma'ayah F, Galvão DA, Taaffe DR
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089298/pdf/bmjsem-2017-000336.pdf
Summary: Strategies to prevent or attenuate the age-related decline in physical and physiological function and reduce chronic disease risk factors are of clinical importance. The objective was to examine the health benefits of recreational soccer in middle-aged and older adults. All available records up until 9 June 2017 in PubMed, Web of Science, SPORTDiscus, MEDLINE, Embase, CINAHL Plus, PsycINFO and Cochrane Library databases were utilize.  Eligibility criteria for selecting studies were: All randomised trials with or without a control group (randomised controlled trials or randomised uncontrolled trials) and non-randomised controlled trials that used recreational soccer, which includes small-sided soccer games, as the sole or principal intervention, and reported relevant effects in untrained/sedentary, healthy or unhealthy adults aged 40 years and above were included. Five trials described in 13 articles were included, which scored 6-9 out of 12 points on the modified Delphi quality rating scale. The duration was from 12 to 52 weeks, with various frequencies, volumes and game formats performed both outdoors and indoors with men and women. The trials indicate that recreational soccer may result in improvement in cardiovascular function, body composition and functional ability, although no significant changes were observed in postural balance. Recreational soccer should be considered an alternative exercise modality for untrained, healthy or unhealthy middle-aged and older adults of both sexes to maintain an active lifestyle and mitigate a wide array of physical and physiological age-related changes.


#7 Effects of short-term in-season break detraining on repeated-sprint ability and intermittent endurance according to initial performance of soccer player
Reference: PLoS One. 2018 Aug 15;13(8):e0201111. doi: 10.1371/journal.pone.0201111. eCollection 2018.
Authors: Rodríguez-Fernández A, Sánchez-Sánchez J, Ramirez-Campillo R, Rodríguez-Marroyo JA, Villa Vicente JG, Nakamura FY
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0201111&type=printable
Summary: The objective was to better understand the detraining effects in soccer, the purpose of the study was to analyse if performance level of soccer players modulate repeated-sprint ability (RSA) and intermittent endurance changes during 2-weeks of detraining (i.e., in-season break). Seventeen professional and sixteen young elite soccer players of two different teams performed, before and after 2-weeks of detraining, the RSA test and the Yo-Yo Intermittent Recovery Test, level 1 (YYIR1). Before detraining, professional players perform better (p < 0.05) RSA best time (RSAbest) than young players. A decrease (p < 0.05) in RSAbest, RSA total time (RSAtotal) and mean time (RSAmean) performance was observed in both teams, without changes in RSA fatigue index (Sdec). No significant changes in distance covered during YYIR1 was observed in any team. Before detraining, faster players from both teams (FG) (following the median split technique, soccer players with RSAbest ≤ 3.95 s) performed better (p < 0.01) in RSAtotal, RSAmean and RSAbest, but worse (p < 0.01) in Sdec. Although FG and the slower players (SG, RSAbest > 3.95 s) showed a worse (p < 0.05) RSAtotal, RSAbest and RSAmean performance after detraining (ES = 1.5, 1.4 and 2.9; ES = 0.6, 1.2 and 0.6; for FG and SG, respectively), the deterioration was greater in the FG for RSAbest (p < 0.05) and RSAtotal (ES = 1.46). After detraining, FG improved (p < 0.05) Sdec performance. In conclusion, a 2-week in-season break (detraining) period induced a worse RSA, with no effect on intermittent endurance in professional and elite young soccer players, with greater detrimental effects on RSAtotal and RSAbest in FG. In addition, Sdec does not seem to be sensitive to changes in RSA after a 2-week in-season break.


#8 Enhancing motor learning of young soccer players through preventing an internal focus of attention: The effect of shoes colour
Reference: PLoS One. 2018 Aug 15;13(8):e0200689. doi: 10.1371/journal.pone.0200689. eCollection 2018.
Authors: De Giorgio A, Sellami M, Kuvacic G, Lawrence G, Padulo J, Mingardi M, Mainolfi L
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0200689&type=printable
Summary: The purpose of this research was to assess how the motor learning skills in 7-years old soccer players can be improved by preventing an internal focus of attention via the use coloured shoes. We painted the classic black soccer shoes in six areas corresponding to six regions of the foot with which it is possible to interact with the ball. Thirty-four 7-years-old soccer players were randomized to two groups (Coloured n = 17 and Black, n = 17) to perform four basic football manoeuvres/tasks: reception (RECP), passing (PASS), ball management (MAGT), and shooting (SHOT). We found highly significant differences (P<0.001) in all four performance tests: mean(sd) RECP: 0.82(0.07) vs. 0.45(0.12); PASS: 0.85(0.07) vs. 0.47(0.09); MAGT: 0.91(0.09); SHOT: 1.00(1.00) vs. 0.44(0.16). Colored shoes appear to draw children's attention away from body centered cues without explicit verbal communications. We propose that this cognitive adaptation enhanced the technical gesture by preventing the negative processes associated with action constraining when adopting an internal focus attention (perhaps by allowing the foot to adapt to surfaces and movements more naturally than conditions that promote a focus on the body movement). Consequently, this type of coloured footwear could be used during childhood to allow children to enhance the performance of basic football exercises through preventing action constraining and promoting intuitive (non-body centered) action knowledge.


#9 Electromyographic analysis of hip adductor muscles in soccer instep and side-foot kicking
Reference: Sports Biomech. 2018 Aug 13:1-12. doi: 10.1080/14763141.2018.1499800. [Epub ahead of print]
Authors: Watanabe K, Nunome H, Inoue K, Iga T, Akima H
Summary: A possible link between soccer-specific injuries, such as groin pain and the action of hip adductor muscles has been suggested. This study aimed to investigate neuromuscular activation of the adductor magnus (AM) and longus (AL) muscles during instep and side-foot soccer kicks. Eight university soccer players performed the two types of kick at 50%, 75% and 100% of the maximal ball speed. Surface electromyography (EMG) was recorded from the AM, AL, vastus lateralis (VL) and biceps femoris (BF) muscles of both kicking and supporting legs and the kicking motions were three-dimensionally captured. In the kicking leg, an increase in surface EMG with an increase in ball speed during instep kicking was noted in the AM muscle (p < 0.016), but not in AL, VL or BF muscles (p > 0.016). In the supporting leg, surface EMG of both AM and AL muscles was significantly increased with an increase in the ball speed before ball impact during both instep and side-foot kicks (p < 0.016). These results suggest that hip adductor muscles markedly contribute to either the kicking or supporting leg to emphasise the action of soccer kicks.


#10 Meniscal fixation is a successful treatment for hypermobile lateral meniscus in soccer players
Reference: Knee Surg Sports Traumatol Arthrosc. 2018 Aug 11. doi: 10.1007/s00167-018-5080-6. [Epub ahead of print]
Authors: Steinbacher G, Alentorn-Geli E, Alvarado-Calderón M, Barastegui D, Álvarez-Díaz P, Cugat R
Summary: The purpose was to report the outcomes (subjective function, return to play, complications and reoperations) of arthroscopic all-inside meniscal fixation in a large sample of soccer players with hypermobile lateral meniscus. Between 2010 and 2015, 55 patients undergoing surgical treatment for hypermobile lateral meniscus at Mutualidad Catalana de Futbolistas (Barcelona, Spain) were identified. Patients with open physes, associated injuries, discoid meniscus, or clinical follow-up less than 6 months were excluded. Once identified, all patients were contacted over the phone to collect cross-sectional data on International Knee Documentation Committee (IKDC) score, postoperative Tegner score, and postoperative visual analogue scale (VAS) for pain. In addition, complications and reoperations were retrospectively collected. Forty-six cases (in 45 patients) with a mean (SD) age of 26.3 (9.5) years and mean (SD; range) follow-up of 43 (19.5; 8-73) months were included. The pre- and post-operative median (range) Tegner score was 9 (6-9) and 8 (0-9), respectively. Compared to the preoperative period, the postoperative Tegner score was equal in 27/46 (59%) cases and lower in 16/46 (35%) cases (3 missing values). Return to play was possible in 38/46 (82%) cases, from which 27/46 (59%) corresponded to the same pre-injury activity level. Postoperatively, the median (range) VAS for pain was 1 (0-9), and the mean (SD) subjective IKDC was 86.2 (16.7). Three of the 46 cases (6.5%) required a reoperation because of pain in one patient (meniscal suture failure) and meniscal tear in two patients. All-inside meniscal fixation is a successful treatment for hypermobile lateral meniscus, which allows acceptable return to play and good function in soccer players at a low reoperation rate. However, according to the present cross-sectional case series, players should be advised that return to the same pre-injury activity level is achieved in only 27 of 46 (59%) of the cases. Surgeons facing with the difficult problem of hypermobile lateral meniscus in soccer players should consider meniscus fixation as an easy and successful option.


#11 Attitudes and Experiences of Men with Prostate Cancer on Risk in the Context of Injuries Related to Community-based Football - A Qualitative Study
Reference: J Aging Phys Act. 2018 Aug 17:1-24. doi: 10.1123/japa.2018-0089. [Epub ahead of print]
Authors: Rørth M, Tjørnhøj-Thomsen T, Cormie P, Oliffe JL, Midtgaard J
Summary: While football training may be a potent strategy for health promotion in older men, the considerable risk of injuries may constitute a barrier for referral of clinical populations. The current study explored the attitudes of men with prostate cancer on risk in the context of injuries related to participating in a community-based football program. Four videotaped focus group interviews, and three individual in-depth telephone interviews were carried out with men with prostate cancer (n=35; mean age 68.8). Thematic networks technique was used to derive the global theme Injury-induced reinforced masculinity comprising five sub-themes: "Part of the game", "A good story to tell", "Like boys again", "An old, carefree body", and "Camaraderie". Collectively, these themes explained how football injuries may reflect masculine ideals in some men with prostate cancer. The study indicates that injuries are largely acceptable to men with prostate cancer, especially those in search of a means for expressing their masculinity.