Latest research in football - week 17 - 2015

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 Effects of Static and Dynamic Stretching on Injury Prevention in High School Soccer Athletes. A Randomized Trial
Reference: J Sport Rehabil. 2015 May 1. [Epub ahead of print]
Authors: Zakaria AA, Kiningham RB, Sen A.
Summary: The purpose of the study was to determine if there is any benefit to static stretching after performing a dynamic warm-up in the prevention of injury in high school soccer athletes. Twelve high schools with varsity and junior varsity boys soccer teams (twenty-four soccer teams) across the state of Michigan Participants: 499 student-athletes were enrolled and 465 student-athletes completed the study. One high school dropped out of the study in the first week leaving a total of twenty-two teams Interventions: Dynamic stretching protocol vs. Dynamic + Static stretching protocol. Lower extremity, core, or lower back injuries/team were used as outcome measures.
Twelve teams performed the dynamic stretching protocol and ten teams performed the dynamic + static stretching protocol. There were 17 injuries (1.42 injuries/team SD 1.49) among the teams that performed the dynamic stretching protocol and 20 injuries (2.0 injuries/team SD 1.24) among the teams that performed the dynamic +stretching protocol. There was no statistically significant difference in injuries between the two groups (p=0.33). There is no difference between dynamic stretching and dynamic + static stretching in the prevention of lower extremity, core and back injuries in high school male soccer athletes. Static stretching does not provide any added benefit to dynamic stretching in the prevention of injury in this population prior to exercise.

#2 Delayed presentation of compartment syndrome of the thigh secondary to quadriceps trauma and vascular injury in a soccer athlete
Reference: Int J Surg Case Rep. 2015 Apr 8;11:56-58. doi: 10.1016/j.ijscr.2015.04.003. [Epub ahead of print]
Authors: How MI, Lee PK, Wei TS, Chong CT
Summary: Compartment syndrome isolated to the anterior thigh is a rare complication of soccer injury. Previous reports in the English literature on sports trauma-related compartment syndrome of the thigh are vague in their description of the response of thigh musculature to blunt trauma, magnetic resonance imaging (MRI) findings of high-risk features of compartment syndrome, vascular injury in quadriceps trauma, and the role of vascular study in blunt thigh injury. We present herein the rare case of a 30-year-old man who developed thigh compartment syndrome 8 days after soccer injury due to severe edema of vastus intermedius and large thigh hematoma secondary to rupture of the profunda femoris vein. MRI revealed "blow-out" rupture of the vastus lateralis. Decompressive fasciotomy and vein repair performed with subsequent split-skin grafting of the wound defect resulted in a good functional outcome at 2-years follow-up. A high index of suspicion for compartment syndrome is needed in all severe quadriceps contusion. Vascular injury can cause thigh compartment syndrome in sports trauma. MRI findings of deep thigh muscle swelling and "blow-out" tear of the vastus lateralis are strongly suggestive of severe quadriceps injury, and may be a harbinger of delayed thigh compartment syndrome.

#3 Factors Affecting Match Running Performance of Elite Soccer Players: Shedding Some Light on the Complexity
Reference: Int J Sports Physiol Perform. 2015 May;10(4):516-519.
Authors: Paul DJ, Bradley PS, Nassis GP.
Summary: Time-motion analysis is a valuable data-collection technique used to quantify the match running performance of elite soccer players. However, interpreting the reductions in running performance in the second half or temporarily after the most intense period of games is highly complex, as it could be attributed to physical or mental fatigue, pacing strategies, contextual factors or a combination of mutually inclusive factors. Given that research in this domain typically uses a reductionist approach whereby match-running performance is examined in isolation without integrating other factors this ultimately leads to a 1-dimensional insight into match performance. Subsequently, a cohesive review of influencing factors does not yet exist. The aim of this commentary is to provide a detailed insight into the complexity of match running performance and the most influential factors.

#4 Associations between poor oral health and reinjuries in male elite soccer players: a cross-sectional self-report study
Reference: BMC Sports Sci Med Rehabil. 2015 Apr 20;7:11. doi: 10.1186/s13102-015-0004-y. eCollection 2015.
Authors: Solleveld H, Goedhart A, Vanden Bossche L
Summary: Although it is well known that oral pathogens can enter the systemic circulation and cause disease, it is largely unknown if poor oral health increases the risk of sports injuries. The purpose of this study is to investigate the association between poor oral health and reinjuries in male elite soccer players, adjusted for psychosocial problems and player characteristics. 184 Players in premier league soccer clubs and 31 elite, junior soccer players in the Netherlands, Belgium and England, were enrolled in a retrospective cross-sectional study. The Sports Injury Risk Indicator, a self assessed questionnaire, was used to obtain information on reinjuries, age and player position, oral health and psychosocial problems. The number of different types of oral health problems was used as an indicator of poor oral health. (SumDental, range 0-2: 0 = no oral health problems, 1 = one type of oral health problem and 2 = two or more types of oral health problems). Multivariable logistic regression was used to investigate whether SumDental was associated with reinjuries, after adjustment for psychosocial problems and player characteristics. 37% of the players reported no oral health problems, 43% reported one type of oral health problem and 20% reported two or more types of oral health problems. After full adjustment for age, player position and psychosocial problems (i.e. injury anxiety, psychophysical stress, unhealthy eating habits and dissatisfaction with trainer/team), poor oral health (SumDental) was positively associated with all kind of reinjuries whether analyzed as a continuous variable or as a categorical variable. The fully adjusted odds ratios for SumDental analyzed as a continuous variable were: in relation to repeated exercise-associated muscle cramps: 1.82 (95% confidence interval (CI): 1.07, 3.12), in relation to muscle or tendon reinjury 1.57 (95% CI: 1.01, 2.45) and in relation to multiple types of reinjury 1.88 (95% CI: 1.19, 2.97). The results from this study justify a thorough examination of the effects of oral health problems on the injury risk of playing elite soccer.

#5 A multi-ingredient containing carbohydrate, proteins L-glutamine and L-carnitine attenuates fatigue perception with no effect on performance, muscle damage or immunity in soccer players
Reference: PLoS One. 2015 Apr 27;10(4):e0125188. doi: 10.1371/journal.pone.0125188. eCollection 2015.
Authors: Naclerio F, Larumbe-Zabala E, Cooper R, Allgrove J, Earnest CP
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Summary: We investigated the effects of ingesting a multi-ingredient (53g carbohydrate, 14.5g whey protein, 5g glutamine, 1.5g L-carnitine-L-tartrate) supplement, carbohydrate only, or placebo on intermittent performance, perception of fatigue, immunity, and functional and metabolic markers of recovery. Sixteen amateur soccer players ingested their respective treatments before, during and after performing a 90-min intermittent repeated sprint test. Primary outcomes included time for a 90-min intermittent repeated sprint test (IRS) followed by eleven 15 m sprints. Measurements included creatine kinase, myoglobin, interleukine-6, Neutrophil; Lymphocytes and Monocyte before (pre), immediately after (post), 1h and 24h after exercise testing period. Overall, time for the IRS and 15 m sprints was not different between treatments. However, the perception of fatigue was attenuated (P<0.001) for the multi-ingredient (15.9±1.4) vs. placebo (17.8±1.4) but not for the carbohydrate (17.0±1.9) condition. Several changes in immune/inflammatory indices were noted as creatine kinase peaked at 24h while Interleukin-6 and myoglobin increased both immediately after and at 1h compared with baseline (P<0.05) for all three conditions. However, Myoglobin (P<0.05) was lower 1h post-exercise for the multi-ingredient (241.8±142.6 ng·ml-1) and CHO (265.4±187.8 ng·ml-1) vs. placebo (518.6±255.2 ng·ml-1). Carbohydrate also elicited lower neutrophil concentrations vs. multi-ingredient (3.9±1.5 109/L vs. 4.9±1.8 109/L, P = 0.016) and a reduced (P<0.05) monocytes count (0.36±0.09 109/L) compared to both multi-ingredient (0.42±0.09 109/L) and placebo (0.42±0.12 109/L). In conclusion, multi-ingredient and carbohydrate supplements did not improve intermittent performance, inflammatory or immune function. However, both treatments did attenuate serum myoglobin, while only carbohydrate blunted post-exercise leukocytosis.

#6 Acute hamstring injury in football players: Association between anatomical location and extent of injury-A large single-center MRI report
Reference: J Sci Med Sport. 2015 Apr 15. pii: S1440-2440(15)00087-0. doi: 10.1016/j.jsams.2015.04.005. [Epub ahead of print]
Authors: Crema MD, Guermazi A, Tol JL, Niu J, Hamilton B, Roemer FW
Summary: The purpose of the study was to describe in detail the anatomic distribution of acute hamstring injuries in football players, and to assess the relationship between location and extent of edema and tears, all based on findings from MRI. We included 275 consecutive male football players who had sustained acute hamstring injuries and had positive findings on MRI. For each subject, lesions were recorded at specific locations of the hamstring muscles, which were divided into proximal or distal: free tendon, myotendinous junction, muscle belly, and myofascial junction locations. For each lesion, we assessed the largest cross-sectional area of edema and/or tears. We calculated the prevalence of injuries by location. The relationships between locations and extent of edema and tears were assessed using a one-sample t-test, with significance set at p<0.05. The long head of biceps femoris (LHBF) was most commonly affected (56.5%). Overall, injuries were most common in the myotendinous junction and in proximal locations. The proximal myotendinous junction was associated with a greater extent of edema in the LHBF and semitendinosus (ST) muscles (p<0.05). Proximal locations in the LHBF had larger edema than distal locations (p<0.05). Distal locations in the ST muscle had larger tears than proximal locations (p<0.05). The proximal myotendinous junction (LHBF and ST muscles) and proximal locations (LHBF muscle) are more commonly affected and are associated with a greater extent of edema in acute hamstring muscle injury. Distal locations (ST muscle), however, seem to be more commonly associated with larger tears.

#7 Non-operative management of a complete anterior cruciate ligament injury in an English Premier League football player with return to play in less than 8 weeks: applying common sense in the absence of evidence
Reference: BMJ Case Rep. 2015 Apr 26;2015. pii: bcr2014208012. doi: 10.1136/bcr-2014-208012.
Authors: Weiler R, Monte-Colombo M, Mitchell A, Haddad F
Summary: This case report illustrates and discusses the non-operative management of a complete anterior cruciate ligament (ACL) injury in an English Premier League football player, his return to play within 8 weeks and problem-free follow-up at 18 months post injury. When non-operative verses surgical ACL reconstruction is considered there are many fundamental gaps in our knowledge and currently, at elite level, there are no cases in cutting sports within the literature to guide these decisions. When the norm is for all professional footballers to be recommended surgery, it will be very challenging when circumstances and patient autonomy dictate a conservative approach, where prognosis, end points and risk are unclear and assumed to be high. This case challenges current dogma and provides a starting point for much needed debate about best practice, treatment options, research direction and not just at the elite level of sport.

#8 Strength training in soccer with a specific focus on highly trained players
Reference: Sports Medicine – Open, (2016) 2:1, DOI 10.1186/s40798-015-0006-z
Authors: Silva JR, Nassis GP, Rebelo A

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Summary: Data concerning the physical demands of soccer (e.g., activity pattern) suggest that a high level of performance requires well-developed neuromuscular function (NF). Proficient NF may be relevant to maintain and/or increase players’ short- (intense periods of soccer-specific activity; accelerations, decelerations, and sprinting) and long-term performance during a match and throughout the season. This review examines the extent to which distinct modes of strength training improve soccer
players’ performance, as well as the effects of concurrent strength and endurance training on the physical capacity of players. A selection of studies was performed in two screening phases. The first phase consisted of identifying articles through a systematic search using relevant databases, including the US National Library of Medicine (PubMed), MEDLINE, and SportDiscus. Several permutations of keywords were utilized (e.g., soccer; strength; power; muscle function), along with the additional scanning of the reference lists of relevant manuscripts.
Given the wide range of this review, additional researchers were included. The second phase involved applying six selection criteria to the articles.

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