Latest research in football - week 41 - 2014

#1 Influence of players' vocalisations on soccer referees' decisions
Reference: Eur J Sport Sci. 2014 Oct 2:1-5. [Epub ahead of print]
Authors: Lex H, Pizzera A, Kurtes M, Schack T.
Summary: The influence of a potentially fouled player's vocalisations on the referee's decisions was investigated. Experienced soccer referees watched video clips of real-match situations that were presented either without sound or with sound where a player's vocalisations were clearly audible and made judgements regarding fouls, direction of play and personal penalties. The results revealed that players' vocalisations had no impact on the foul decisions of the referees. However, once a referee made a foul decision, the player's vocalisations led to an increased number of personal penalties (increase in yellow cards) for the foul-causing player. In addition to crowd noise, a player's vocalisations during a foul are used as a proximal cue in the referee's decision-making process.


#2 Effects of shock-absorbing insoles during transition from natural grass to artificial turf in young soccer players a randomized controlled trial
Reference: J Am Podiatr Med Assoc. 2014 Sep;104(5):444-50. doi: 10.7547/0003-0538-104.5.444.
Authors: Kaalund S, Madeleine P.
Summary: Playing soccer on artificial turf can provoke pain in young players. Using shock-absorbing insoles (SAIs) can result in decreased pain perception. We sought to investigate the pain and comfort intensity experienced during the switch from natural grass to third-generation artificial turf and with the use of SAIs on artificial turf during training in young soccer players. Methods : In a prospective randomized controlled study, 75 players were included from the youth teams of U15, U17, and U19. Pain intensity and comfort were assessed after training on only grass turf for 3 months. Randomization stratified by team level and age was performed; the intervention group received SAIs, and the control group used their own insoles. Assessments were repeated after 3 weeks on artificial turf (baseline) and 3 more weeks (follow-up) on artificial turf with SAIs/usual insoles. Results : Pain intensity increased and comfort decreased significantly after 3 weeks of training on artificial grass compared with natural grass (P < .05). The addition of SAIs resulted in significantly reduced pain intensity compared with the usual insoles (P < .05). Conclusions : The switch to artificial turf is associated with less comfort and more pain during training in young soccer players. The use of SAIs led to lower pain intensity, highlighting a protective role of the insoles after 6 weeks of training on artificial turf.


#3 Splenic injury after blunt abdominal trauma during a soccer (football) game
Reference: Pediatr Emerg Care. 2014 Oct;30(10):725-9. doi: 10.1097/PEC.0000000000000236.
Authors: Padlipsky PS, Brindis S, Young KD.
Summary: The spleen is the most commonly injured abdominal organ in children who sustain blunt abdominal trauma, and pediatric splenic injury may result from minor mechanisms of injury, including sports participation. We present 2 cases of splenic injury in soccer goalies because of blunt abdominal trauma sustained during game play. Although abdominal organ injuries are uncommon in soccer, emergency medicine and primary care physicians must be aware of the possibility. A high index of suspicion and careful physical examination are key in making the diagnosis.


#4 Effects of vitamin C and exercise on lipid profile, platelet and erythrocyte indices in young soccer players
Reference: J Sports Med Phys Fitness. 2014 Oct;54(5):665-71.
Authors: Karakilcik AZ, Halat R, Zerin M, Celik H, Nazligul Y.
Summary: Exercise may increase production of reactive oxygen species (ROS) enhancing oxidative stress. Antioxidants can efficiently scavenge ROS before they initiate oxidative damage of biomolecules such as enzymes, nucleic acids, lipids and lipoproteins in the body. Vitamin C, an important antioxidant, may affect oxidative stress in living organism. Therefore, this study was carried out to investigate the effects of exercise and vitamin C on thiobarbituric acid-reactive substance (TBARS), lipid profile, erythrocyte and platelet indices in young soccer players. This investigation was carried out on twenty two male volunteer players in three groups. The first group was examined as a control. The second group was only exposed to exercise. The third group was exposed to exercise plus vitamin C (500 mg/day) administered per oral. The players were 23.50±0.59 year-old, 67.66±1.52 kg body weight and 1.74±0.03 m height. Blood samples were collected in vacutainer tubes for analysis of biochemical and hematological parameters. While the levels of high density lipoprotein-cholesterol (HDL-C) were significantly increased (P<0.05) with only exercise, the cholesterol and low density lipoprotein-cholesterol (LDL-C) were decreased (P<0.05 to P<0.01) with exercise and exercise plus vitamin C treatment. While TBARS levels were increased (P<0.05) with exercise training, it was decreased (P<0.05) with exercise plus vitamin C treatment. The platelet counts (PLT), mean platelet volume (MPV), plateletcrit (PCT) and red blood cell distribution width (RDW) were significantly decreased (P<0.05) with exercise plus vitamin C. There were significantly correlations (P<0.05 to P<0.01) between lipid values and erythrocyte and platelet indices. In light of these results, exercise may play a role in decreasing of LDL-C and in increasing of HDL-C. In addition, exercise plus vitamin C may diminish TBARS-levels and may affect the values of PLT, MPV, PCT and RDW in young soccer players.


#5 Modifications of biochemical parameters related to protein metabolism and renal function in male soccer players after a match
Reference: J Sports Med Phys Fitness. 2014 Oct;54(5):658-64.
Authors: Colombini A, Machado M, Lombardi G, Lanteri P, Banfi G.
Summary: The impact of a soccer match on parameters related to protein catabolism and renal function was evaluated in male players. Blood was collected before and immediately after a 90 minutes soccer match from 19 athletes of two first division teams in Brazil. Red blood cells (RBC), hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC), ammonia, uric acid, urea and creatinine were analyzed. The modification of plasma volume was calculated, and biochemical values were corrected for this change. Urea/creatinine ratio and equations to estimate the glomerular filtration rate (eGFR) were used to assess kidney function. Plasma volume decreased from pre- to post-match. Post-match values higher than the pre-match ones were observed for RBC, Hb and Ht, as a consequence of plasma volume decrease. An increase in ammonia and creatinine concentrations post-match in comparison with pre-match values was registered, without changes in uric acid and urea levels. A reduction in urea/creatinine ratio and in eGFR was observed post-match, suggesting a decrease of renal function. A soccer match induced alterations in parameters linked to renal function and protein metabolism in male athletes. Particular attention should be paid in the monitoring of the ammonia concentration as an indicator of metabolic activity and energy requirement during prolonged exercise.


#6 Uncommon external abdominal oblique muscle strain in a professional soccer player: a case report
Reference: BMC Res Notes. 2014 Oct 1;7(1):684. [Epub ahead of print]
Authors: Dauty M, Menu P, Dubois C.
Download link: http://www.biomedcentral.com/content/pdf/1756-0500-7-684.pdf
Summary: This is the first report of external abdominal oblique muscle injury occurring in a professional soccer player. A 28-year-old Caucasian professional soccer player presented after experiencing a popping sensation associated with strong parietal pain localized between the left 11th and 12th ribs. Ultrasound examination revealed a collection of fluid under the 11th rib, suggesting injury of the left external oblique muscle. Platelet-rich plasma treatment was administered and the soccer player returned to competition on the 21st day after treatment. This rare injury results from a sudden intrinsic eccentric contraction of the internal oblique muscle while in a stretched position. Ultrasound can help to confirm the diagnosis and to monitor clinical follow-up. Platelet-rich plasma treatment could aid recovery in high-level athletes.


#7 Effect of soccer shoe upper on ball behaviour in curve kicks
Reference: Sci Rep. 2014 Aug 14;4:6067. doi: 10.1038/srep06067.
Authors: Ishii H, Sakurai Y, Maruyama T
Download link: http://www.nature.com/srep/2014/140814/srep06067/pdf/srep06067.pdf
Summary: New soccer shoes have been developed by considering various concepts related to kicking, such as curving a soccer ball. However, the effects of shoes on ball behaviour remain unclear. In this study, by using a finite element simulation, we investigated the factors that affect ball behaviour immediately after impact in a curve kick. Five experienced male university soccer players performed one curve kick. We developed a finite element model of the foot and ball and evaluated the validity of the model by comparing the finite element results for the ball behaviour immediately after impact with the experimental results. The launch angle, ball velocity, and ball rotation in the finite element analysis were all in general agreement with the experimental results. Using the validated finite element model, we simulated the ball behaviour. The simulation results indicated that the larger the foot velocity immediately before impact, the larger the ball velocity and ball rotation. Furthermore, the Young's modulus of the shoe upper and the coefficient of friction between the shoe upper and the ball had little effect on the launch angle, ball velocity, and ball rotation. The results of this study suggest that the shoe upper does not significantly influence ball behaviour.


#8 Plantar fascia rupture in a professional soccer player
Reference: J Med Invest. 2014;61(3-4):413-6.
Authors: Suzue N, Iwame T, Kato K, Takao S, Tateishi T, Takeda Y, Hamada D, Goto T, Takata Y, Matsuura T, Sairyo K.
Download link: https://www.jstage.jst.go.jp/article/jmi/61/3.4/61_413/_pdf
Summary: We report the case of a 29-year-old male professional soccer player who presented with symptoms of plantar fasciitis. His symptoms occurred with no remarkable triggers and gradually worsened despite conservative treatments including taping, use of insoles, and physical therapy. Local corticosteroid injection was given twice as a further intervention, but his plantar fascia partially ruptured 49 days after the second injection. He was treated conservatively with platelet-rich plasma, and magnetic resonance imaging showed regenerative change of the ruptured fascia. Five months after the rupture, he returned to his original level of training. If professional athletes find it difficult to refrain from athletic activity, as in the present case, the risk of rupture due to corticosteroid injection should not be overlooked.


#9 Prevalence of childhood and adolescent soccer-related overuse injuries
Reference: J Med Invest. 2014;61(3-4):369-73.
Authors: Suzue N, Matsuura T, Iwame T, Hamada D, Goto T, Takata Y, Iwase T, Sairyo K.
Download link: https://www.jstage.jst.go.jp/article/jmi/61/3.4/61_369/_pdf
Summary: To investigate the prevalence of osteochondrosis in children and adolescent soccer players. A questionnaire was distributed to players of all 113 junior soccer teams participating in a regional summer championship in August 2012 inquiring about pain in the body during or after training or a match. Physical examination of the lumbar spine or legs was recommended to players who complained of pain on the questionnaire, and for those who had positive findings on the physical examination, radiographic or ultrasonic examination at our hospital was recommended. Questionnaires were collected from 1162 players of 97 teams, and 547 players (47.1%) complained of pain in the lumbar spine or legs. Physical examination was performed on 494 players, 394 of whom were referred for physical examination (79.8%). Of these 494 players, 20 (4.0%) had positive lumbar spine findings, 26 (5.3%) had hip findings, 198 (40.1%) had knee findings, 117 (23.7%) had ankle findings, 226 (45.7%) had heel findings, and 90 had findings in other parts of foot (18.2%). Radiographic or ultrasonic examination was performed in 106 (26.9%) players at our hospital and 80 (75.5%) players were diagnosed with osteochondrosis. Sever's disease was diagnosed in 49 players, Osgood-Schlatter disease in 13, bipartite patella was in 12, Sinding-Larsen-Johansson disease in 10, osteochondritis dissecans of the distal femur in 1, and spondylolysis in 3. The majority of players who had experienced pain and were found to have osteochondrosis had severe injuries such as osteochondritis dissecans or lumbar spondylolysis. We suggest many of the players involved in this study receive further radiographic or ultrasonic examination.


#10 Return to play after all-inside meniscal repair in competitive football players: a minimum 5-year follow-up
Reference: Knee Surg Sports Traumatol Arthrosc. 2014 Sep 27. [Epub ahead of print]
Authors: Alvarez-Diaz P, Alentorn-Geli E, Llobet F, Granados N, Steinbacher G, Cugat R.
Summary: The purpose of this study was to report the mid-to-long-term return to sports after all-inside meniscal repair in competitive football players. All football players undergoing all-inside meniscal repair with a minimum Tegner activity score of 9 and minimum follow-up of 5 years were eligible for inclusion. Patients were excluded if: (a) they had ipsilateral or contralateral: meniscectomy, posterior cruciate ligament tear, multi-ligament knee injuries, osteotomies, or meniscal transplant (b) they had meniscal tears in the anterior horn, and (c) they had bucket-handle tears. All patients included were contacted by phone and asked for current sport status or Tegner score. Preoperative Tegner scores were collected from the medical charts. All patients (n = 29) were men with a median (range) age of 27 (18-37) years and a follow-up of 6 (5-8) years. All meniscal injuries were complete and longitudinal tears. The median preinjury Tegner activity score was 9 (range 9-10). Two patients required revision arthroscopy (6.7 %) with partial meniscectomy before being able to return to competitive football due to suture failure. Twenty-six patients (89.6 %) returned to the same level of competition after recovering from surgery. At the last follow-up, 13 patients (45 %) were able to continue playing football at any level, and 8 (28 %) of them were able to return to the same pre-injury competitive level. The main reasons for the decreased level of activity (from competitive to recreational) or to give up football were job-related or changes in their personal life situation, but were not related to knee or meniscal disorders. Fourteen patients underwent meniscal repair alone, whereas 15 patients had an associated ACL reconstruction procedure. There were no significant differences in the collected variables between both subgroups. All-inside meniscal repair allows for excellent results with regard to return-to-play rates in competitive football. However, only half of the patients are still playing football in the mid-to-long-term follow-up, although reasons to give up football are not related to knee or meniscal disorders.