Latest research in football - week 10 - 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 Thigh muscles injuries in professional soccer players: a one year longitudinal study
Authors: Corazza A, Orlandi D, Baldari A, Gatto P, Stellatelli M, Mazzola C, Galli R, Longo S, Sconfienza LM, Silvestri E.
Reference: Muscles Ligaments Tendons J. 2014 Feb 24;3(4):331-6. eCollection 2013.
Summary: Thigh muscles indirect injuries are common finding in soccer and represent a critical challenge for teams medical staffs. Indirect injuries are classified on the basis of their site and their clinical and radiological findings, but the assessment of a precise prognosis remains a crucial point. Both ultrasound (US) and magnetic resonance (MR) represent effective techniques not only to detect indirect injuries but also to accurately determine severity, location, and, consequently, the prognosis. In this setting, our aim is to review imaging findings of professional athletes muscle tears at three time points (3 days, 2 weeks, and 4 weeks after the time of injury) and, further, to investigate the correlation between tears extent and lay-off time of the athletes. Combined US-MR assessment could be helpful in the management of thigh muscles indirect injuries providing accurate information about the site, the extent, and the healing process.

#2 Reducing muscle injuries and reinjuries in one italian professional male soccer team
Authors: Melegati G, Tornese D, Gevi M, Trabattoni A, Pozzi G, Schonhuber H, Volpi P.
Reference: Muscles Ligaments Tendons J. 2014 Feb 24;3(4):324-30. eCollection 2013.
Summary: The incidence rate of muscle injuries and re-injuries in professional elite soccer players actually is very high and may interfere with the fate of a championship. The purpose of the study was to investigate the effect of a two-tiered injury prevention programme on first injury and re-injury incidence in top level male soccer players. Study design. Muscle injuries and re-injuries sustained by a group of 36 soccer player of an italian elite soccer team have been collected during 2010-2011 season. These data have been compared with those collected during the previous season in the same elite soccer team. A total of 64 injuries occurred, 36 (56%) of which during practice and 28 (44%) during matches. Muscle injuries accounted for 31.3% of the total (n=20), 70% (n=14) of which occurred during practice and 30% (n=6) during matches. Hamstring were the muscles most often injured (n=11) In all, 3 re-injuries occurred (15% of muscle injuries). No early re-injuries occurred. The incidence was 2.5 injuries/1000 hours and the burden was 37 days absence/1000 hours. Through the implementation of a group and personalized injury prevention program, we were able to reduce the total number of muscle injuries and days absent because of injury, in a team of elite soccer players, as compared to the previous season. Specifically, muscle injuries accounted for 31% of all injuries, as compared to 59% of all injuries sustained by the team during the previous season. The number of injuries/1000 hours of exposure was reduced by half (from 5.6 to 2.5) and the days absent/1000 hours fell from 106 to 37.

#3 Compression garments to prevent delayed onset muscle soreness in soccer players
Authors: Valle X, Til L, Drobnic F, Turmo A, Montoro JB, Valero O, Artells R.
Reference: Muscles Ligaments Tendons J. 2014 Feb 24;3(4):295-302. eCollection 2013.
Summary: The purpose of this study was to evaluate the use of a compression garment as DOMS prevention. This was accomplished by provoking a DOMS in 15 athletes, running on a treadmill at 73% of their maximal aerobic velocity, during 40 minutes with a 10% negative slope; wearing the compression garments on one thigh, protected thigh (PT), and not in the contralateral thigh, control thigh (CT). A clinical and MRI diagnosis of DOMS was performed. Biopsies in both vastus lateralis were done, and the amount and severity of the DOMS was estimated by measuring intracellular albumin, and lymphocytes CD3+ and neutrophils intra/interfibrilar infiltrates, 48h after the induced damaging exercise. There was less total injury in the PT than in the CT, a 26.7% average. These data indicate that this compression garment is an effective method to reduce the histological injury in DOMS.

#4 Return to sport after anterior cruciate ligament reconstruction in professional soccer players
Authors: Zaffagnini S, Grassi A, Marcheggiani Muccioli GM, Tsapralis K, Ricci M, Bragonzoni L, Della Villa S, Marcacci M.
Reference: Knee. 2014 Feb 14. pii: S0968-0160(14)00016-7. doi: 10.1016/j.knee.2014.02.005. [Epub ahead of print]
Summary: The purpose was to investigate time to return to sport and rate of professional sport activity in a homogenous group of competitive soccer players 4years after anterior cruciate ligament (ACL) reconstruction and rehabilitation. Twenty-one male professional soccer players (mean age 22.9±5.4years) underwent non-anatomical double-bundle autologous hamstring ACL reconstruction and followed the same rehabilitative protocol. Clinical evaluation was performed preoperatively and at 3, 6 and 12-month follow-up. Data regarding return to train and official match, sport activity, complications and revision surgeries were collected at 4-year follow-up. Laxity test (KT-2000) and total KOOS mean score resulted in a significant improvement from the preoperative status to the 12-month follow-up (p<0.0001). The KOOS mean value showed a significant progressive improvement from the preoperative status to 6-month follow-up (p=0.0010) as well, while values collected at 6 and 12-month follow-up were comparable (p=0.2349). Returned to official matches 186±53days after surgery. After 12months, 95% came back to the same activity level performed before injury. Four years after ACL reconstruction, 15 patients (71%) were still playing competitive soccer. One patient (5%) underwent ACL failure and subsequent revision. The ACL reconstruction with the presented technique followed by patient-tailored rehabilitation, allowed 95% and 62% professional male soccer players to return to the same sport activity 1year and 4years after surgery respectively. However, 71% were still able to play competitive soccer at final follow-up. Clinical scores were restored after 6months. Level of evidence: IV, case series.

#5 Discrepancy between Exercise Performance, Body Composition, and Sex Steroid Response after a Six-Week Detraining Period in Professional Soccer Players
Authors: Koundourakis NE1, Androulakis NE2, Malliaraki N3, Tsatsanis C1, Venihaki M1, Margioris AN3.
Reference: PLoS One. 2014 Feb 19;9(2):e87803. doi: 10.1371/journal.pone.0087803. eCollection 2014.
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Summary: The aim of this study was to examine the effects of a six-week off-season detraining period on exercise performance, body composition, and on circulating sex steroid levels in soccer players. Fifty-five professional male soccer players, members of two Greek Superleague Teams (Team A, n = 23; Team B, n = 22), participated in the study. The first two weeks of the detraining period the players abstained from any physical activity. The following four weeks, players performed low-intensity (50%-60% of VO2max) aerobic running of 20 to 30 minutes duration three times per week. Exercise performance testing, anthropometry, and blood sampling were performed before and after the six-week experimental period. Our data showed that in both teams A and B the six-week detraining period resulted in significant reductions in maximal oxygen consumption (60,31±2,52 vs 57,67±2,54; p<0.001, and 60,47±4,13 vs 58,30±3,88; p<0.001 respectively), squat-jump (39,70±3,32 vs 37,30±3,08; p<0.001, and 41,05±3,34 vs 38,18±3,03; p<0.001 respectively), and countermovement-jump (41,04±3,99 vs 39,13±3,26; p<0.001 and 42,82±3,60 vs 40,09±2,79; p<0.001 respectively), and significant increases in 10-meters sprint (1,74±0,063 vs 1,79±0,064; p<0.001, and 1,73±0,065 vs 1,78±0,072; p<0.001 respectively), 20-meters sprint (3,02±0,05 vs 3,06±0,06; p<0.001, and 3,01±0,066 vs 3,06±0,063; p<0.001 respectively), body fat percentage (Team A; p<0.001, Team B; p<0.001), and body weight (Team A; p<0.001, Team B; p<0.001). Neither team displayed any significant changes in the resting concentrations of total-testosterone, free-testosterone, dehydroepiandrosterone-sulfate, Δ4-androstenedione, estradiol, luteinizing hormone, follicle-stimulating hormone, and prolactin. Furthermore, sex steroids levels did not correlate with exercise performance parameters. Our results suggest that the six-week detraining period resulted in a rapid loss of exercise performance adaptations and optimal body composition status, but did not affect sex steroid resting levels. The insignificant changes in sex steroid concentration indicate that these hormones were a non-contributing parameter for the observed negative effects of detraining on exercise performance and body composition.

#6 A Cam Deformity Is Gradually Acquired During Skeletal Maturation in Adolescent and Young Male Soccer Players: A Prospective Study With Minimum 2-Year Follow-up
Authors: Agricola R1, Heijboer MP, Ginai AZ, Roels P, Zadpoor AA, Verhaar JA, Weinans H, Waarsing JH.
Reference: Am J Sports Med. 2014 Feb 28. [Epub ahead of print]
Summary: A cam deformity is a major risk factor for hip osteoarthritis, and its formation is thought to be influenced by high-impact sporting activities during growth. The purpose of the study was to (1) prospectively study whether a cam deformity can evolve over time in adolescents and whether its formation only occurs during skeletal maturation and (2) examine whether clinical or radiographic features can predict the formation of a cam deformity. Preprofessional soccer players (N = 63; mean age, 14.43 years; range, 12-19 years) participated both at baseline and follow-up (mean follow-up, 2.4 ± 0.06 years). At both time points, standardized anteroposterior and frog-leg lateral radiographs were obtained. For each hip, the α angle was measured, and the anterosuperior head-neck junction was classified by a 3-point visual system as normal, flattened, or having a prominence. Differences between baseline and follow-up values for the α angle and the prevalence of each visual hip classification were calculated. Additionally, the amount of internal hip rotation, growth plate extension into the neck, and neck shaft angle were determined. Overall, there was a significant increase in the prevalence of a cam deformity during follow-up. In boys aged 12 and 13 years at baseline, the prevalence of a flattened head-neck junction increased significantly during follow-up (13.6% to 50.0%; P = .002). In all hips with an open growth plate at baseline, the prevalence of a prominence increased from 2.1% to 17.7% (P = .002). After closure of the proximal femoral growth plate, there was no significant increase in the prevalence or increase in severity of a cam deformity. The α angle increased significantly from 59.4° at baseline to 61.3° at follow-up (P = .018). The amount of growth plate extension was significantly associated with the α angle and hip classification (P = .001). A small neck shaft angle and limited internal rotation were associated with cam deformities and could also significantly predict the formation of cam deformities (α angle >60°) at follow-up. In youth soccer players, cam deformities gradually develop during skeletal maturation and are probably stable from the time of growth plate closure. The formation of a cam deformity might be prevented by adjusting athletic activities during a small period of skeletal growth, which will have a major effect on the prevalence of hip osteoarthritis.

#7 The perceptions of professional soccer players on the risk of injury from competition and training on natural grass and 3rd generation artificial turf
Authors: Poulos CC, Gallucci J Jr, Gage WH, Baker J, Buitrago S, Macpherson AK.
Reference: BMC Sports Sci Med Rehabil. 2014 Mar 1;6(1):11. [Epub ahead of print]
Summary: The purpose of this study was to describe professional soccer players' perceptions towards injuries, physical recovery and the effect of surface related factors on injury resulting from soccer participation on 3rd generation artificial turf (FT) compared to natural grass (NG). Information was collected through a questionnaire that was completed by 99 professional soccer players from 6 teams competing in Major League Soccer (MLS) during the 2011 season. The majority (93% and 95%) of the players reported that playing surface type and quality influenced the risk of sustaining an injury. Players believed that playing and training on FT increased the risk of sustaining a non-contact injury as opposed to a contact injury. The players identified three surface related risk factors on FT, which they related to injuries and greater recovery times: 1) Greater surface stiffness 2) Greater surface friction 3) Larger metabolic cost to playing on artificial grounds. Overall, 94% of the players chose FT as the surface most likely to increase the risk of sustaining an injury. Players believe that the risk of injury differs according to surface type, and that FT is associated with an increased risk of non-contact injury. Future studies should be designed prospectively to systematically track the perceptions of groups of professional players training and competing on FT and NG.

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