Latest research in football - week 1 - 2014

#1 The Effect of NeuroMuscular Electrical Stimulation on Quadriceps Strength and Knee Function in Professional Soccer Players: Return to Sport after ACL Reconstruction
Authors: Taradaj J, Halski T, Kucharzewski M, Walewicz K, Smykla A, Ozon M, Slupska L, Dymarek R, Ptaszkowski K, Rajfur J, Pasternok M.
Reference: Biomed Res Int. 2013;2013:802534. doi: 10.1155/2013/802534. Epub 2013 Dec 5.
Download link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3870113/pdf/BMRI2013-802534.pdf
Summary: The aim of this study was to assess the clinical efficacy and safety of NMES program applied in male soccer players (after ACL reconstruction) on the quadriceps muscle. The 80 participants (NMES = 40, control = 40) received an exercise program, including three sessions weekly. The individuals in NMES group additionally received neuromuscular electrical stimulation procedures on both right and left quadriceps (biphasic symmetric rectangular pulses, frequency of impulses: 2500 Hz, and train of pulses frequency: 50 Hz) three times daily (3 hours of break between treatments), 3 days a week, for one month. The tensometry, muscle circumference, and goniometry pendulum test (follow-up after 1 and 3 months) were applied. The results of this study show that NMES (in presented parameters in experiment) is useful for strengthening the quadriceps muscle in soccer athletes. There is an evidence of the benefit of the NMES in restoring quadriceps muscle mass and strength of soccer players. In our study the neuromuscular electrical stimulation appeared to be safe for biomechanics of knee joint. The pathological changes in knee function were not observed. This trial is registered with Australian and New Zealand Clinical Trials Registry ACTRN12613001168741


#2 Brain regions concerned with the identification of deceptive soccer moves by higher-skilled and lower-skilled players
Authors: Wright MJ1, Bishop DT2, Jackson RC3, Abernethy B4.
Reference: Front Hum Neurosci. 2013 Dec 17;7:851. doi: 10.3389/fnhum.2013.00851.
Download link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3865769/pdf/fnhum-07-00851.pdf
Summary: Expert soccer players are able to utilize their opponents' early body kinematics to predict the direction in which the opponent will move. We have previously demonstrated enhanced fMRI activation in experts in the motor components of an action observation network (AON) during sports anticipation tasks. Soccer players often need to prevent opponents from successfully predicting their line of attack, and consequently may try to deceive them; for example, by performing a step-over. We examined how AON activations and expertise effects are modified by the presence of deception. Three groups of participants; higher-skilled males, lower-skilled males, and lower-skilled females, viewed video clips in point-light format, from a defender's perspective, of a player approaching and turning with the ball. The observer's task in the scanner was to determine whether the move was normal or deceptive (involving a step-over), while whole-brain functional images were acquired. In a second counterbalanced block with identical stimuli the task was to predict the direction of the ball. Activations of AON for identification of deception overlapped with activations from the direction identification task. Higher-skilled players showed significantly greater activation than lower-skilled players in a subset of AON areas; and lower-skilled males in turn showed greater activation than lower-skilled females, but females showed more activation in visual cortex. Activation was greater for deception identification than for direction identification in dorsolateral prefrontal cortex, medial frontal cortex, anterior insula, cingulate gyrus, and premotor cortex. Conversely, greater activation for direction than deception identification was found in anterior cingulate cortex and caudate nucleus. Results are consistent with the view that explicit identification of deceptive moves entails cognitive effort and also activates limbic structures associated with social cognition and affective responses.


#3 Descriptive epidemiology of injuries in a Brazilian premier league soccer team
Authors: de Freitas Guina Fachina RJ, Andrade Mdos S, Silva FR, Waszczuk-Junior S, Montagner PC, Borin JP, de Lira CA.
Reference: Open Access J Sports Med. 2013 Jun 27;4:171-4. doi: 10.2147/OAJSM.S44384.
Download link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3871049/pdf/oajsm-4-171.pdf
Summary: Soccer, which has a large number of participants, has a high injury incidence that causes both financial and time burdens. Therefore, knowledge about the epidemiology of soccer injuries could allow sports-medicine professionals, such as physicians and physiotherapists, to direct their work in specific preventive programs. Thus, our aim was to conduct an epidemiological survey of injuries sustained by professional soccer players from the same team who participated in the Brazilian championship premier league in 2009. To this end, we evaluated retrospectively player medical records from the team, which included name, date of birth, position, date of injury, mechanism of injury, and type of injury. In the period of study, 95 injuries were recorded: 42 (44.2%) were recorded during matches, and 53 (55.8%) during the training period. Injuries occurred more frequently in midfielders and strikers. All injuries happened in the lower limb, most of the injuries were muscular, and most occurred as the result of collisions with other athletes. In summary, this study demonstrates that there is a need for greater safety awareness in the training environment.


#4 Predictors of high intensity running capacity in collegiate women during a soccer game
Reference: J Strength Cond Res. 2013 Dec 27. [Epub ahead of print]
Authors: McCormack WP, Stout JR, Wells AJ, Gonzalez AM, Mangine GT, Fragala MS, Hoffman JR.
Summary: The purpose of this investigation was to determine which physiological assessments best predicted high intensity running performance during a women's collegiate soccer game. A secondary purpose was to examine the relationships among physiological performance measures including muscle architecture on soccer performance (distance covered, HIR, and sprints during the game) during a competitive collegiate women's soccer game. Ten National Collegiate Athletic Association (NCAA) Division I women soccer players performed physiological assessments within a two-week period prior to a competitive regulation soccer game performed during the spring season. Testing consisted of height, body mass, ultrasound measurement of dominant (DOMleg) and non-dominant leg (NDOMleg) vastus lateralis for muscle thickness (MT) and pennation angle (PA), VO2max, running economy, and Wingate anaerobic test (WAnT) for peak power (PP), mean power (MP), and fatigue rate (FR). During the game, distance run, high intensity running (HIR), and sprints were measured via a 10-Hz GPS system. Stepwise regression revealed that VO2max, dominant leg thickness, and dominant leg pennation angle were the strongest predictors of HIR distance during the game (R=0.989, SEE=115.5m, p=0.001). VO2max was significantly correlated with total distance run (r=0.831; p=0.003), HIR (r=0.755; p=0.012), WAnTPP (r=-0.737; p=0.015), WAnTPP[BULLET OPERATOR]kg (r=-0.706; p=0.022), and WAnTFR (r=-0.713; p=0.021). DOMlegMT was significantly correlated with WAnTFR (r=0.893; p=0.001). DOMlegPA was significantly correlated with WAnTFR (r=0.740; p=0.023). The NDOMlegPA was significantly correlated to peak running velocity (r=0.781; p=0.013) and WAnTMP[BULLET OPERATOR]kg (r=0.801; p=0.01). Results of this study indicate that VO2max and muscle architecture are important characteristics of NCAA Division I women soccer players and may predict HIR distance during a competitive contest.


#5 Comparison of dynamic balance in adolescent male soccer players from rwanda and the United States
Authors: Butler RJ, Queen RM1, Beckman B2, Kiesel KB, Plisky PJ.
Reference: Int J Sports Phys Ther. 2013 Dec;8(6):749-55.
Download link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3867068/pdf/ijspt-12-749.pdf
Summary: Dynamic balance is an important component of motor skill development. Poor dynamic balance has previously been associated with sport related injury. However, the vast majority of dynamic balance studies as they relate to sport injury have occurred in developed North American or European countries. Thus, the purpose of this study was to compare dynamic balance in adolescent male soccer players from Rwanda to a matched group from the United States. Twenty-six adolescent male soccer players from Rwanda and 26 age- and gender-matched control subjects from the United States were screened using the Lower Quarter Y Balance Test during their pre-participation physical. Reach asymmetry (cm) between limbs was examined for all reach directions. In addition, reach distance in each direction (normalized to limb length, %LL) and the composite reach score (also normalized to %LL) were examined. Dependent samples t-tests were performed with significant differences identified at p<0.05. Twenty-six male soccer players from Rwanda (R) were matched to twenty-six male soccer players from the United States (US). The Rwandan soccer players performed better in the anterior (R: 83.9 ± 3.2 %LL; US: 76.5 ± 6.6 %LL, p<0.01), posterolateral (R: 114.4 ± 8.3 %LL ; US: 106.5 ± 8.2 %LL, p<0.01) and composite (R: 105.6 ± 1.3 %LL; US: 97.8 ± 6.2 %LL, p<0.01) reach scores. No significant differences between groups were observed for reach asymmetry. Adolescent soccer players from Rwanda exhibit superior performance on a standardized dynamic balance test as comparison to similar athletes from the United States. The examination of movement abilities of athletes from countries of various origins may allow for a greater understanding of the range of true normative values for dynamic balance.