Latest research in football - week 27 - 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 Different Loading Schemes in Power Training During the Preseason Promote Similar Performance Improvements in Brazilian Elite Soccer Players
Authors: Loturco, I, Ugrinowitsch, C, Tricoli, V., Pivetti, B, Roschel, H.
Reference: J Strength Cond Res. 2013: 27(7): 1791-1797
Summary: Different loading schemes in power training during the preseason promote similar performance improvements in Brazilian elite soccer players. J Strength Cond Res 27(7): 1791–1797, 2013—The present study investigated the effects of 2 different power training loading schemes in Brazilian elite soccer players. Thirty-two players participated in the study. Maximum dynamic strength (1RM) was evaluated before (B), at midpoint (i.e., after 3 weeks; T1), and after 6 weeks (T2) of a preseason strength/power training. Muscle power, jumping, and sprinting performance were evaluated at B and T2. Players were randomly allocated to 1 of 2 training groups: velocity-based (VEL: n = 16; age, 19.18 ± 0.72 years; height, 173 ± 6 cm; body mass, 72.7 ± 5.8 kg) or intensity-based (INT: n = 16; age, 19.11 ± 0.7 years; height, 172 ± 4.5 cm; body mass, 71.8 ± 4.6 kg). After the individual determination of the optimal power load, both groups completed a 3-week traditional strength training period. Afterward, the VEL group performed 3 weeks of power-oriented training with increasing velocity and decreasing intensity (from 60 to 30% 1RM) throughout the training period, whereas the INT group increased the training intensity (from 30 to 60% 1RM) and thus decreased movement velocity throughout the power-oriented training period. Both groups used loads within ±15% (ranging from 30 to 60% 1RM) of the measured optimal power load (i.e., 45.2 ± 3.0% 1RM). Similar 1RM gains were observed in both groups at T1 (VEL: 9.2%; INT: 11.0%) and T2 (VEL: 19.8%; INT: 22.1%). The 2 groups also presented significant improvements (within-group comparisons) in all of the variables. However, no between-group differences were detected. Mean power in the back squat (VEL: 18.5%; INT: 20.4%) and mean propulsive power in the jump squat (VEL: 29.1%; INT: 31.0%) were similarly improved at T2. The 10-m sprint (VEL: −4.3%; INT: −1.6%), jump squat (VEL: 7.1%; INT: 4.5%), and countermovement jump (VEL: 6.7%; INT: 6.9%) were also improved in both groups at T2. Curiously, the 30-m sprint time (VEL: −0.8%; INT: −0.1%) did not significantly improve for both groups. In summary, our data suggest that male professional soccer players can achieve improvements in strength- and power-related abilities as a result of 6 weeks of power-oriented training during the preseason. Furthermore, similar performance improvements are observed when training intensity manipulation occurs around only a small range within the optimal power training load.

#2 Performance Effects of 6 Weeks of Aerobic Production Training in Junior Elite Soccer Players
Authors: Ingebrigtsen, J, Shalfawi, SAI, Tønnessen, E, Krustrup, P, and Holtermann, A
Reference: J Strength Cond Res. 2013: 27(7): 1861–1867.
Summary: This study investigates the performance effects of a 6-week biweekly anaerobic speed endurance production training among junior elite soccer players. Sixteen junior (age 16.9 ± 0.6 years) elite soccer players were tested in the Yo-Yo Intermittent Recovery test level 2 (IR2), 10-m and 35-m sprints, 7 × 35-m repeated-sprint ability (RSA) tests, countermovement jump and squat jump tests, and randomly assigned to either a control group (CG) performing their normal training schedule, which included 4 weekly soccer training sessions of approximately 90 minutes, or a training group performing anaerobic speed endurance production training twice weekly for 6 weeks in addition to their normal weekly schedule. We found that the intervention group significantly improved (p < 0.05) their performance in the Yo-Yo IR2 (63 ± 74 m) and 10-m sprint time (−0.06 ± 0.06 seconds). No significant performance changes were found in the CG. Between-group pretest to posttest differences were found for 10-m sprint times (p < 0.05). No significant changes were observed in the 35-m sprint times, RSA, or jump performances. These results indicate that short-term anaerobic production training is effective in improving acceleration and intermittent exercise performance among well-trained junior elite players

#3 Use of platelet rich plasma in an isolated complete medial collateral ligament lesion in a professional football (soccer) player: a case report
Authors: Eirale C, Mauri E, Hamilton B.
Reference: Asian J Sports Med. 2013 Jun;4(2):158-62. Epub 2012 Dec 15.
Summary: Platelet-rich plasma (PRP) is derived from centrifuging whole blood to obtain a high platelet concentration containing numerous growth factors. Despite its widespread use, there is still a lack of high-level evidence regarding randomized clinical trials assessing the efficacy of PRP in treating ligament injuries. Although there is research showing an improvement in the early stages of healing in the animal model of acute medial collateral ligament (MCL) injury of the knee, there is no strong evidence to support the efficacy of PRP injections for treating MCL lesions in humans. In this report, we present a case of an elite football player, treated with multiple PRP local injections followed by rehabilitation, for a high grade MCL lesion of the knee. He was able to resume training at day 18, painfree, with full range of motion and the ability to complete a functional test based on all sport specific movements. He played matches at 25 days with no residual symptoms or functional deficit. There were no further complaints or recurrences at the 16 months follow up. On the basis of this report, we can assume that the treatment of high grade acute MCL lesions of the knee with PRP is a promising therapeutic option to be further explored with good quality Randomized Controlled Trials (RCTs).

#4 Match Analysis of U9 and U10 English Premier League Academy Soccer Players using a Global Positioning System: Relevance for Talent Identification and Development
Authors: Goto H, Morris JG, Nevill ME.
Reference: J Strength Cond Res. 2013 Jun 24. [Epub ahead of print]
Summary: The purpose of this study was to examine the match activity profile of U9 and U10 elite soccer players and to establish if there were any differences between players who were subsequently retained or released by their clubs. Such information should prove valuable in the design of training programs for these very young players and in the talent identification and development process. A Global Positioning System was used to analyze 2-4 inter-academy 6-a-side matches of English Premier League Academy players (U9: N = 22 and U10: N = 12) who trained three times a week (4.5 h) . Speed zones were created based on 5 and 10 m sprint times and an independent sample t-test was employed for a statistical analysis.Both squads covered ∼4000 m in total or ∼4700 m·h during a match (NS between squads), with the U10s tending to cover a greater distance at moderate (p = 0.10) and high speeds (p = 0.08) than the U9s. Retained group covered a greater distance than released group (retained vs. released: 4478 ± 513 m vs. 4091 ± 462 m, p < 0.05) during a match and covered a greater distance during low speed running in absolute (1226 ± 259 m vs. 1005 ± 221 m, p < 0.05) and relative (1325 ± 235 m[BULLET OPERATOR]h vs. 1132 ± 210 m[BULLET OPERATOR]h, p < 0.05) terms.Thus, U9 and U10 players cover over 4000 m in match play and those players who are retained by academies cover a greater distance in total and at low speeds (2.1-3.1 m·s). This information may support the preparation of squad training programs and the talent identification and development process

#5 The expertise reversal effect for sequential presentation in dynamic soccer visualizations
Authors: Khacharem A, Zoudji B, Kalyuga S, Ripoll H.
Reference: J Sport Exerc Psychol. 2013 Jun;35(3):260-9.
Summary: Cognitive load perspective was used as a theoretical framework to investigate effects of expertise and type of presentation of interacting elements of information in learning from dynamic visualizations. Soccer players (N = 48) were required to complete a recall reconstruction test and to rate their invested mental effort after studying a concurrent or sequential presentation of the elements of play. The results provided evidence for an expertise reversal effect. For novice players, the sequential presentation produced better learning outcomes. In contrast, expert players performed better after studying the concurrent presentation. The findings suggest that the effectiveness of different visual presentation formats depend on levels of learner expertise.


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