Latest research in football - week 15 - 2013

Latest research of the week

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 Validity of a Complex Soccer-Specific Field Test and a Non-Specific Sprint Test-Assessments for Test and Match Performance
Authors: Schwesig R, Hartmann M, Leuchte S, Fischer D, Kuß O.
Reference: Sportverletz Sportschaden. 2013 Apr 11. [Epub ahead of print] [Article in German]
Summary: The purpose of this study was to assess the validity of a soccer-specific complexity test (FBKT) and a repeated non-specific sprint test (ST) based on three gold standards: match performance, coach ranking, and league affiliation. A German fourth league soccer team (n = 14) was assessed using FBKT and ST in the pre-season for the second half of the 2010/2011 season. Afterwards, their performance in 17 matches was evaluated using video analysis in order to compare them with the test parameters (e. g., pass/assist ratio, goals, duelling behaviour). Eighteen months later, the league affiliation of all players was identified and the coach evaluated the tested players. With regard to match performance, playing time was proved to be the most suitable parameter for validating the test performance (FBKT, ST). The total and minimum times of ST were the most powerful parameters in relation to playing time and explained 50 % and 46 % of the variance, respectively. Concerning the FBKT, the parameters "sum of all linear sprints" (24 %) and "total time of all activity series with penalty time in round two" (22 %) explained the highest amount of variance. Coach ranking generated significant odds ratios for the minimum time of ST (OR = 6.5; p = 0.037), and total time of speed dribbling of the FBKT (OR = 1.3; p = 0.036) based on a proportional-odds model. With regard to league affiliation, significant odds ratios occurred with the following parameters: minimum time of ST (OR = 15.8; p = 0.007); total time of ST (OR = 3.28; p = 0.011); and, total time of speed dribbling for the FBKT (OR = 1.3; p = 0.044). The authors concluded that the larger logical validity of soccer-specific complex tests does not necessarily translate to a larger construct validity, as compared to non-specific tests. However, their value is not limited to performance evaluation. The FBKT provides valuable information concerning training process control. It is possible that its low validity is caused by the poor performance of the players in soccer-specific consequences of actions (centres, goals) due to the restricted differentiation of players.

#2 Short-Term Training Effects of Vertically and Horizontally Oriented Exercises on Neuromuscular Performance in Professional Soccer Players
Authors: Los Arcos A, Yanci J, Mendiguchia J, Salinero JJ, Brughelli M, Castagna C.
Reference: Int J Sports Physiol Perform. 2013 Apr 9. [Epub ahead of print]
Summary: The purpose of this study was to compare the effects of two strength and conditioning programs involving either purely vertically oriented or combining vertically and horizontally oriented exercises on soccer relevant performance variables (i.e. acceleration, jumping ability, peak power, and endurance). Twenty-two professional male soccer players were randomly assigned to two training groups: vertical strength (VS, N=11) and vertical and horizontal strength (VHS, N=11). Players trained 2 times per week during the pre-season (5 weeks) and 3 weeks of the competitive season. The effect of the training protocols was assessed using double and single leg vertical countermovement jumps (i.e. CMJ, CMJ-SL respectively), half-squat peak power (PP), sprint performance over 5 and 15 m and blood lactate concentration at selected running speeds. The results indicated that both groups obtained significant improvements in PP and small practical improvements in 5 m and 15 m sprint time. The CMJ performance showed a small improvement (P<.05, ES= 0.34) only in the VHS group. Sub maximal aerobic-fitness changes were similar in both groups. The authors concluded that this study provided a small amount of practical evidence for the consideration of pre-season training protocols that combine exercises for vertical and horizontal axis strength development in professional male soccer players. Further studies using more aggressive training protocols involving horizontally-oriented conditioning exercises are warranted.

#3 Does Soccer Practice Influence Compressive Strength, Bending Strength, and Impact Strength Indices of the Femoral Neck in Young Men?
Authors: El Hage R, Zakhem E, Zunquin G, Theunynck D, Moussa E, Maalouf G.
Reference: J Clin Densitom. 2013 Apr 5. pii: S1094-6950(13)00047-4. doi: 10.1016/j.jocd.2013.03.010. [Epub ahead of print]
Summary: unfortunately none summary given

#4 Effect of wearing mouthguards on the physical performance of soccer and futsal players: a randomized cross-over study
Authors: Collares K, Correa MB, Silva IC, Hallal PC, Demarco FF.
Reference: Dent Traumatol. 2013 Apr 8. doi: 10.1111/edt.12040. [Epub ahead of print]
Summary: The purpose of this study was to assess the influence of custom-fit mouthguards on the aerobic performance of soccer and futsal players under 17 (U-17). Forty players from 3 Brazilian clubs participated in the study. The athletes' aerobic performance was assessed through the 20-meter shuttle-run test. All athletes performed two tests with and without mouthguard. Two outcome variables were analyzed: (i) the total distance covered in the test (meters) and (ii) the maximum oxygen uptake (VO2 max). A questionnaire assessing the level of acceptance of mouthguards considering different parameters was administered to the athletes before the delivery of the mouthguards and after 2 weeks of use. The questionnaire used a visual analogue scale (VAS). Paired t-test was used to compare the results obtained from the shuttle-run tests and the questionnaires. Results indicated that the mouthguards did not influence the aerobic performance of the players, considering both the total distance covered in the tests and the VO2 max. Stability was the parameter with the highest acceptance. Levels of acceptance regarding breathing and communication increased after mouthguards usage. Communication had the lowest level of acceptance considering all parameters assessed. Only 10% of the players reported receiving recommendations to use mouthguards while playing football or futsal. None of the participants reported having used mouthguards before. The authors concluded that the use of custom-fit mouthguards does not affect the aerobic performance of soccer and futsal U-17 players. Future studies should focus on the development of appliances with maximum protection and minimum influence on communication.

The Training Manager -