Latest research in football - week 29 - 2016

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.

Following studies were retrieved for this week:

#1 Neck Pain in a Football Player
Reference: Phys Sportsmed. 1990 Mar;18(3):115-20. doi: 10.1080/00913847.1990.11709998.
Authors: McKeag DB, Cantu RC
Summary: The unavailability of a team physician for contact/collision sports such as football can sometimes mean that an injured player will continue in a game. By doing so, the player may risk greater, perhaps even permanent disabling injury.

#2 Lateral Knee Braces in Football: Do They Prevent Injury?
Reference: Phys Sportsmed. 1986 Jun;14(6):119-24. doi: 10.1080/00913847.1986.11709104.
Authors: Paulos LE, Drawbert JP, France P, Rosenberg TD
Summary: In brief: Lateral knee braces are being used in increasing numbers by football teams attempting to decrease the number of valgum knee injuries. There has been little proof to date that these braces are effective. In this paper we review the results of three recently presented clinical studies as well as an in-depth biomechanical study, all of which raise serious doubts about the efficacy of preventive knee braces that are currently available.

#3 Accumulated workloads and the acute:chronic workload ratio relate to injury risk in elite youth football players
Reference: Br J Sports Med. 2016 Jul 22. pii: bjsports-2015-095820. doi: 10.1136/bjsports-2015-095820. [Epub ahead of print]
Authors: Bowen L, Gross AS, Gimpel M, Li FX
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Summary: The purpose of this study was to investigate the relationship between physical workload and injury risk in elite youth football players. The workload data and injury incidence of 32 players were monitored throughout 2 seasons. Multiple regression was used to compare cumulative (1, 2, 3 and 4-weekly) loads and acute:chronic (A:C) workload ratios (acute workload divided by chronic workload) between injured and non-injured players for specific GPS and accelerometer-derived variables:total distance (TD), high-speed distance (HSD), accelerations (ACC) and total load. Workloads were classified into discrete ranges by z-scores and the relative risk was determined. A very high number of ACC (≥9254) over 3 weeks was associated with the highest significant overall (relative risk (RR)=3.84) and non-contact injury risk (RR=5.11). Non-contact injury risk was significantly increased when a high acute HSD was combined with low chronic HSD (RR=2.55), but not with high chronic HSD (RR=0.47). Contact injury risk was greatest when A:C TD and ACC ratios were very high (1.76 and 1.77, respectively) (RR=4.98). In general, higher accumulated and acute workloads were associated with a greater injury risk. However, progressive increases in chronic workload may develop the players' physical tolerance to higher acute loads and resilience to injury risk.

#4 Identification of genetic markers for skill and athleticism in sub-elite Australian football players: a pilot study
Reference: J Sports Med Phys Fitness. 2016 Jul 22. [Epub ahead of print]
Authors: Jacob Y, Cripps A, Evans T, Chivers PT, Joyce C, Anderton RS
Summary: Natural genetic variation contributes towards athletic performance in various strength/power and endurance based sports. To date, no studies have explored the genetic predisposition towards skill and athletic performance in Australian Football (AF) players. The present pilot study recruited 30 sub-elite AF players who completed tests of endurance, power and technical skill. Specific polymorphisms in nine genes were screened, and assessed for a possible association with athletic and skill traits. Statistical analysis using generalized linear models identified a number of polymorphisms predictive of endurance and technical skill. The angiotensin-converting enzyme (ACE), normally responsible for regulation of body fluid volume, was a significant factor in predicting 'all round' athletic performance and skill. Specifically, the deletion allele (DD) of ACE was identified as a predictor for AF power (p≤0.008), endurance (p=0.001) and skill assessments (p≤0.003). In addition, polymorphisms in the brain-derived neurotrophic factor, D2 dopamine receptor, and catechol-O-methyltransferase genes were also shown to contribute to kicking skill outcomes (p≤0.044). This is the first study to implicate the ACE deletion allele for a multi-dimensional sport in such a way. Further, the results from this study have identified several new candidate genes in predicting athletic and technical skill outcomes.

#5 European football: Goals change crowd air chemistry
Reference: Nature 535, 355 (21 July 2016) doi:10.1038/535355a
Authors: Christof Stönner C, Williams J
Link to read:

#6 Groin Pain and Muscular Imbalance of Quadriceps and Hamstrings in an Elite Soccer Player - A Case Study
Reference: Sportverletz Sportschaden. 2016 Aug;30(3):163-167. Epub 2016 Aug 4.
Authors: Ludwig O, Kelm J
Summary: Soccer and football players are exposed to a high risk of groin pain. In some cases, the pubic symphysis is the origin of the problems. This article presents a case report of a young elite soccer player who, over a period of two years, suffered from pain in the groin and symphysis area. The right leg was the kicking leg. Imaging techniques did not reveal pathological findings. Sports hernia, osteomyelitis, enthesopathy, adductor tendonitis, and muscle sprains, as well as rheumatic or urogenital disorders were excluded.A 3 D posture analysis was performed to examine the statics of the body and pelvis. The maximum isometric strength of the left and right leg adductors and abductors, as well as the knee flexors and extensors were measured.We found a muscular imbalance resulting from the type of sport the athlete engaged in with an unfavourable ratio between the right knee extensor and flexor muscles. Comparing sides, an imbalance was also identified between the right and left knee extensor. This imbalance resulted in a one-sided forward tilt of the right hemi-pelvis. This pelvic torsion may lead to an increase in shear forces in the pubic symphysis, which we suspected to be the reason for the recurring problems.After three months of specific training exercises, the pelvic position was harmonised and the muscular imbalances were significantly reduced. Even 6 months after completion of the specific training exercises, the player remained without complaints despite his unvaried soccer training intensity.Causal treatment of functional pain in the groin or symphysis area should take into account the ipsilateral and contralateral strength ratios of the knee extensors and flexors as well as the three-dimensional position of the pelvis.

#7 Fast Response Training in Youth Soccer Players
Reference: Sportverletz Sportschaden. 2016 Aug;30(3):143-8. doi: 10.1055/s-0042-110250. Epub 2016 Aug 4.[Article in German]
Authors: Bartels T, Proeger S, Meyer D, Rabe J, Brehme K, Pyschik M, Delank KS, Fieseler G, Schulze S, Schwesig R
Summary: Injuries of the knee and ankle joint are a serious ongoing problem in soccer. Although there is a variety of prevention programmes, a significant reduction of severe knee injuries has not been observed. Therefore, current strategies for diagnostics and training need to be re-evaluated. Our study aimed to test a totally new intervention strategy (fast response training on the SpeedCourt). The efficiency of this method was evaluated with youth soccer athletes. 24 young male class A athletes (mean age 18.0 ± 0.7 years) of a local soccer team underwent SpeedCourt training for 7 weeks (1 training session per week = TS) during the regular season of competition. TS contained life-kinetic elements (time of exercise: 15 - 30 seconds, break: 2 minutes) and included a warm-up phase (15 minutes) and fast response training on the SpeedCourt (30 minutes). The players were tested on the SpeedCourt with different tests (Counter Movement Jump (CMJ), shuttle run, tapping, 10-second sprint) before and after the training programme. The univariate single-factor analysis of variance showed significant improvements in all test parameters (η(2)> 0.10). The range varied between η(2) = 0.106 (time of ground contact right leg) und η(2) = 0.730 (reaction time right leg). We did not find any relevant correlations between the tests and parameters. The number of injury-related accidents involving the lower extremities was reduced by about 50 % during defined periods of time. Our data revealed that training with fast responses at the SpeedCourt system clearly improved speed and speed strength performance of young soccer athletes, which is remarkable given the low intensity of influences (one TS per week). The increase in performance was accompanied by a significant reduction of the injury rate.

#8 SCAT3 assessment of non-head injured and head injured athletes competing in a large international youth soccer tournament
Reference: Appl Neuropsychol Child. 2016 Aug 2:1-5. [Epub ahead of print]
Authors: Gorman M, Hecht S, Samborski A, Lunos S, Elias S, Stovitz SD
Summary: To our knowledge, no study has evaluated Sideline Concussion Assessment Tool -3rd Edition (SCAT3) scores during competition in athletes who have not had a head injury. The purpose of our pilot study was to compare SCAT3 scores in non-injured (NI), injured (but not head injured) (I), and head injured (HI) youth soccer players during competition and to establish preliminary baseline data for non-head injured athletes in a competitive setting. The HI group demonstrated significantly more symptoms (M = 9.7, SE = 0.8) than the I and NI (3.3, SE = 1.2, and 3.2, SE = 0.7, respectively) groups. The HI group also demonstrated a significantly higher symptom severity score (25.3, SE = 2.8) than the I and NI groups (7.7, SE = 4.1, and 5.9, SE = 2.5, respectively). There were no statistically significant differences in mean total Standardized Assessment of Concussion (SAC) scores and mean subsection SAC scores between the groups. Clinicians should also be aware that non-injured in-competition athletes may report more symptoms on the SCAT3 than those evaluated in a non-competition setting.

#9 Torque-angle-velocity Relationships and Muscle Performance of Professional and Youth Soccer Players
Reference: Int J Sports Med. 2016 Aug 1. [Epub ahead of print]
Authors: Mazuquin BF, Dela Bela LF, Pelegrinelli AR, Dias JM, Carregaro RL, Moura FA, Selfe J, Richards J, Brown LE, Cardoso JR
Summary: Soccer matches consist of a variety of different activities, including repeated sprints. Time to attain velocity (TTAV), load range (LR) and the torque-angle-velocity relationship (TAV3D) represent an important measurement of muscle performance, however there are few related studies. The aim of this study was to compare these outcomes between soccer players of different age category. 17 professional (PRO) and 17 under-17 (U17) soccer players were assessed for concentric knee flexion/extension at 60, 120 and 300°/s. For the extensor muscles, differences were found in favor of the U17 group for TTAV and LR outcomes at 120°/s, however, the PRO group maintained higher torques in both movement directions in comparison to the U17 in TAV3D evaluation. These results suggest that muscle performance of the PRO group is more efficient than the U17 group.


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