Latest research in football - week 2 - 2018

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 Impact of Sports-Related Subconcussive Injuries in Soccer Players
Reference: Semin Speech Lang. 2019 Feb;40(1):57-64. doi: 10.1055/s-0038-1676365. Epub 2019 Jan 7.
Authors: Díaz-Rodríguez YI, Salvatore AP
Summary: Sports-related subconcussive impacts to the head are receiving increased interest. Recent evidence indicates that subconcussive impacts will have greater relevance across time because of the number of repetitive impacts. Soccer players are at risk of receiving at least one impact during a soccer game. The authors review the cognitive-communication functioning following subconcussive head injuries in youth and recommendations for baseline assessments and cognitive-communication dysfunctions after subconcussive impacts in youth. The review is followed by a description and discussion of a study that assessed the cognitive-communicative dysfunction in young soccer players prior to and following a series of soccer matches and recommendations for monitoring recovery of cognitive-communication.

#2 Practical Torso Cooling During Soccer-Specific Exercise in the Heat
Reference: J Athl Train. 2018 Nov;53(11):1089-1097. doi: 10.4085/1062-6050-417-17. Epub 2019 Jan 7.
Authors: Parris K, Tyler CJ
Summary: Precooling and midevent cooling of the torso using cooling vests can improve exercise performance in the heat with or without physiological changes; however, the effects of such cooling during intermittent exercise in the heat are unknown. The objective of the study was to investigate the effects of torso cooling during intermittent exercise in the heat (35°C, 50% relative humdity) on sprint performance and the physiological and perceptual responses to the exercise. Ten non-heat-acclimated, male soccer players (age = 25 ± 2 years, height = 1.77 ± 0.06 m, mass = 72.9 ± 7.6 kg) participated in this study. Two 90-minute bouts of soccer-specific intermittent running in the heat: 1 trial with a cooling vest worn during the exercise and 1 trial without a cooling vest. Each trial comprised two 45-minute periods separated by approximately 15 minutes of seated rest in cool conditions (approximately 23°C, 50% relative humdity). Peak sprint speed, rectal temperature (Tr), mean-weighted skin temperature (Tsk), heart rate (HR), rating of perceived exertion (RPE), and thermal sensation (TS) were measured every 5 minutes. Peak sprint performance was largely unaffected by the cooling vest. The Tr, Tsk, HR, RPE, and TS were unaffected in the cooling-vest trial during the first 45 minutes, but Tr rose at a slower rate in the cooling-vest trial (0.026°C.min-1 ± 0.008°C.min-1) than in the no-vest trial (0.032°C.min-1 ± 0.009°C.min-1). During the second 45-minute period, Tr, Tr rate of rise, Tsk, RPE, and TS were lower in the cooling-vest trial (Hedges g range, 0.55-0.84), but mean HR was unaffected. Wearing a cooling vest during soccer-specific intermittent running in the heat reduced physiological and perceptual strain but did not increase peak sprint speed.

#3 Bone quality in young adults with intellectual disability involved in adapted competitive football
Reference: Eur J Sport Sci. 2019 Jan 9:1-10. doi: 10.1080/17461391.2018.1563633. [Epub ahead of print]
Authors: Lizondo V, Caplliure-Llopis J, Escrivá D, De La Rubia JE, Barrios C
Summary: The objective of this study was to analyse bone quality parameters of football players with intellectual disability (ID) participating in adapted competitive football. Sixty-seven male football players with ID were studied: 22 with Down syndrome (DS) and 45 without DS. The average age was 26 years (range: 16 ̶ 50 years). A group of 25 age-matched sedentary individuals with ID (11 DS and 14 non-DS) and another group of 20 healthy participants of the same age group not involved in competitive football were comparatively analysed. There were no differences in the bone quality parameters when the healthy sedentary individuals were compared with both the sedentary and the football players with ID. However, the speed of sound (SOS), T-score, and estimated bone mineral density (BMD) were of higher values in the football players with ID than in the sedentary ID group (p < 0.05). On comparing the football players with non-DS ID with the sedentary non-DS individuals, significant differences were noted in SOS (p < 0.01), T-scores (p < 0.01), and estimated BMD (p < 0.01). Four of the 45 non-DS (8.9%) and none of the football players with DS had T-scores less than -1.5. Two of the 14 sedentary non-DS participants (14.3%) had T-scores indicating osteoporosis. In summary, the ID population actively involved in football showed higher values of bone mass parameters than their sedentary ID and healthy peers. The participants with non-DS ID showed a higher prevalence of osteoporosis than the football players with DS. Participation in sports seems to prevent bone loss in individuals with ID.

#4 Dual Kinect v2 system can capture lower limb kinematics reasonably well in a clinical setting: concurrent validity of a dual camera markerless motion capture system in professional football players
Reference: BMJ Open Sport Exerc Med. 2018 Dec 17;4(1):e000441. doi: 10.1136/bmjsem-2018-000441. eCollection 2018.
Authors: Kotsifaki A, Whiteley R, Hansen C
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Summary: The purpose was to determine whether a dual-camera markerless motion capture system can be used for lower limb kinematic evaluation in athletes in a preseason screening setting. Thirty-four (n=34) healthy athletes participated. Three dimensional lower limb kinematics during three functional tests: Single Leg Squat (SLS), Single Leg Jump, Modified Counter-movement Jump. The tests were simultaneously recorded using both a marker-based motion capture system and two Kinect v2 cameras using iPi Mocap Studio software. Excellent agreement between systems for the flexion/extension range of motion of the shin during all tests and for the thigh abduction/adduction during SLS were seen. For peak angles, results showed excellent agreement for knee flexion. Poor correlation was seen for the rotation movements. This study supports the use of dual Kinect v2 configuration with the iPi software as a valid tool for assessment of sagittal and frontal plane hip and knee kinematic parameters but not axial rotation in athletes.

#5 Don't Turn Blind! The Relationship Between Exploration Before Ball Possession and On-Ball Performance in Association Football
Reference: Front Psychol. 2018 Dec 10;9:2520. doi: 10.3389/fpsyg.2018.02520. eCollection 2018.
Authors: McGuckian TB, Cole MH, Jordet G, Chalkley D, Pepping GJ
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Summary: Visual exploratory action - scanning movements expressed through left and right rotation of the head - allows perception of a surrounding environment and supports prospective actions. In the dynamically changing football environment, the extent to which exploratory action benefits a player's subsequent performance with the ball is likely influenced by how and when the exploratory action occurs. Although few studies have examined the relationship between visual exploration and on-pitch football performance, it has been reported that a higher frequency of exploratory head movement up to 10-s before receiving the ball increases the likelihood of successful performance with the ball. This study investigated the relationship between head turn frequency and head turn excursion, and how and when exploratory head movement - within 10-s before ball possession - is related to performance with the ball in 11v11 match-play. Thirty-two semi-elite football players competed in 11v11 match-play. Head turn frequency and head turn excursion before ball possession were quantified with wearable inertial measurement units, and actions with the ball were coded via notational analysis. Odds ratio calculations were conducted to determine the associations between exploration variables and on-ball performance outcomes. A total of 783 actions with the ball were analyzed. Results revealed a strong relationship between head turn frequency and head turn excursion. Further, a higher than average head turn frequency and head turn excursion before receiving the ball resulted in a higher likelihood of turning with the ball, playing a pass in the attacking direction, and playing a pass to an area that is opposite to which it was received from. The strength of these outcomes varied for different time periods before receiving the ball. When players explored their environment with higher than average head turn frequency and excursion, they used more complex action opportunities afforded by the surrounding environment. Considerations for future research and practical implications are discussed.

#6 Use of viscosupplementation for the recovery of active football players complaining of knee pain
Reference: Open Access J Sports Med. 2018 Dec 24;10:11-15. doi: 10.2147/OAJSM.S164693. eCollection 2019.
Authors: Migliore A, Giannini S, Bizzi E, Massafra U, Cassol M, Abilius MJM, Boni G
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Summary: The aim of this study is to investigate the effect of intra-articular hyaluronic acid administration in active football players complaining of knee pain after sports activity. Efficacy and safety profiles of intra-articular hyaluronic acid and time needed for football players to recover and restart sports activity were examined. Clinical data of active football players reporting knee pain after sports activity were included in this retrospective study. All patients who received an intra-articular injection at time 0 and after 2 weeks were included in the study. Patients underwent laboratory examination, knee X-ray, ultrasound, and clinical examination before receiving the intra-articular injection. Effusions or cysts were drained before injections. Lequesne index score, pain visual analog scale (VAS) score, and patient's global assessment score were recorded at time 0 (day of the first injection), 1 and 2 days after the first injection, at 2 weeks (day of the second injection), and at follow-up visits. Only data from patients completing the follow-up were analyzed. Data from 17 patients were analyzed: 16 males and one female, of which three were professional players (two males and one female) and 14 were nonprofessional players. The mean age of patients was 39.8±11.8 years. Two patients (one male and one female) showed joint effusion. Two patients reported relevant joint pain after injection that regressed without any medication. At the first week, all parameters examined indicated improvement that was maintained until the end of follow-up. One day after the first and second injection, patients reported a slight increase in pain VAS score, which was not statistically significant, and the pain resolved after 1 day. All patients successfully restarted playing after the first injection within 3.1±2.0 days and kept playing after the second injection following our indication (1 day of break). The use of a medium-molecular weight hyaluronic acid in football players affected by knee osteoarthritis seems efficacious and safe and resulted, in our experience, a stable improvement of symptoms; moreover, it allowed a rapid restart of sports activity. Larger studies on larger populations are needed to confirm these findings.

#7 The value of tibial mounted inertial measurement units to quantify running kinetics in elite football (soccer) players. A reliability and agreement study using a research orientated and a clinically orientated system
Reference: J Electromyogr Kinesiol. 2019 Jan 7;44:156-164. doi: 10.1016/j.jelekin.2019.01.001. [Epub ahead of print]
Authors: Hughes T, Jones RK, Starbuck C, Sergeant JC, Callaghan MJ
Summary: In elite football, measurement of running kinetics with inertial measurement units (IMUs) may be useful as a component of periodic health examination (PHE). This study determined the reliability of, and agreement between a research orientated IMU and clinically orientated IMU system for initial peak acceleration (IPA) and IPA symmetry index (SI) measurement during running in elite footballers. On consecutive days, 16 participants performed treadmill running at 14kmph and 18kmph. Both IMUs measured IPA and IPA SI concurrently. All measurements had good or excellent within-session reliability (intraclass correlation coefficient (ICC2,1) range = 0.79-0.96, IPA standard error of measurement (SEM) range = 0.19-0.62 g, IPA SI SEM range = 2.50-8.05%). Only the research orientated IMU demonstrated acceptable minimal detectable changes (MDCs) for IPA at 14kmph (range = 7.46-9.80%) and IPA SI at both speeds (range = 6.92-9.21%). Considering both systems, between-session IPA reliability ranged from fair to good (ICC2,1 range = 0.63-0.87, SEM range = 0.51-1.10 g) and poor to fair for IPA SI (ICC2,1 range = 0.32-0.65, SEM range = 8.07-11.18%). All MDCs were >10%. For IPA and SI, the 95% levels of agreement indicated poor between system agreement. Therefore, the use of IMUs to evaluate treadmill running kinetics cannot be recommended in this population as a PHE test to identify prognostic factors for injuries or for rehabilitation purposes.

#8 Premenstrual Syndrome, Inflammatory Status, and Mood States in Soccer Players
Reference: Neuroimmunomodulation. 2019 Jan 17:1-6. doi: 10.1159/000494559. [Epub ahead of print]
Authors: Foster R, Vaisberg M, Bachi ALL, Dos Santos JMB, de Paula Vieira R, Luna-Junior LA, Araújo MP, Parmigiano TR, Borges F, Di-Bella ZIKJ
Summary: The aim was to evaluate the relationship between the inflammatory profile and mood states in the different phases of the menstrual cycle in soccer players with and without premenstrual syndrome (PMS). Data on the menstrual cycle and mood states were collected using the Daily Symptom Report and the Brunel Mood Scale. Cytokine and stress hormone concentrations were measured in urine by flow cytometry before and after a game in the luteal phase and in the follicular phase of one menstrual cycle. In all, 59.6% of the athletes had PMS. The PMS group showed higher concentrations of interleukin (IL)-1β, IL-6, and IL-8 than the athletes without PMS. After the game, IL-6 decreased in the follicular phase and the luteal phase. The tumor necrosis factor-α levels were higher in the group without PMS during the post-game follicular phase than before the game. In the PMS group, tension was higher in the follicular phase before the game and depression was higher in the pre-game luteal phase than in the group without PMS. The PMS group also presented a negative correlation between depression and IL-10 levels in the pre-game follicular phase. Finally, in the pre-game luteal phase were found positive correlations between growth hormone and IL-10. PMS influences the inflammatory condition related to mood states and stress hormones in female soccer players.

#9 Nutrition-Related Considerations in Soccer: A Review
Reference: Am J Orthop (Belle Mead NJ). 2018 Dec;47(12). doi: 10.12788/ajo.2018.0100.
Authors: Keen R
Summary: Soccer is the world's most popular sport. As the sport has grown, so have the physical demands and the search for ways to edge out the competition with the use of sports science and nutrition. The demands, which include intense training, ≥90 minutes matches, congested fixtures, and travel, lead to increased energy and nutrient requirements, stress on the body, and risk of impaired sleep cycles. Identifying key areas to enhance a player's performance is an ongoing effort because of individual differences. Moreover, new information is being discovered via research, and advancing technology to measure performance is always evolving. This article focuses on the core nutrition principles known to lay the foundation for a better soccer player. These principles are obvious for some; however, nutrition and hydration are often undervalued, leaving the individual player with the responsibility to eat right. This review addresses the most applicable nutrition-related recommendations for soccer players.

#10 Limb Differences in Unipedal Balance Performance in Young Male Soccer Players with Different Ages
Reference: Sports (Basel). 2019 Jan 11;7(1). pii: E20. doi: 10.3390/sports7010020.
Authors: Muehlbauer T, Schwiertz G, Brueckner D, Kiss R, Panzer S
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Summary: In soccer, the dominant leg is frequently used for passing and kicking while standing on the non-dominant leg. Consequently, postural control in the standing leg might be superior compared to the kicking leg and is further enhanced with increasing age (i.e., level of playing experience). Unfortunately, leg differences in postural control are associated with an increased risk of injuries. Thus, we examined differences between limbs in unipedal balance performance in young soccer players at different ages. Performance in the Lower Quarter Y Balance Test (YBT-LQ) of the dominant and non-dominant leg and anthropometry was assessed in 76 young male soccer players (under-13 years [U13]: n = 19, U15: n = 14, U17: n = 21, U19: n = 22). Maximal reach distances (% leg length) and the composite scores were used for further analyses. Statistical analyses yielded no statistically significant main effects of leg or significant Leg × Age interactions, irrespective of the measure investigated. However, limb differences in the anterior reach direction were above the proposed cut-off value of >4 cm, which is indicative of increased injury risk. Further, statistically significant main effects of age were found for all investigated parameters, indicating larger reach distances in older (U19) compared to younger (U13) players (except for U15 players). Although reach differences between legs were non-significant, the value in the anterior reach direction was higher than the cut-off value of >4 cm in all age groups. This is indicative of an increased injury risk, and thus injury prevention programs should be part of the training of young soccer players.

#11 Recruiting Older Men to Walking Football: A Pilot Feasibility Study
Reference: Explore (NY). 2018 Dec 11. pii: S1550-8307(18)30194-0. doi: 10.1016/j.explore.2018.12.001. [Epub ahead of print]
Authors: McEwan G, Buchan D, Cowan D, Arthur R, Sanderson M, Macrae E
Summary: Walking football (soccer) has recently emerged as a physical activity option targeted at older males to enhance health and wellbeing. This pilot study aimed to examine the feasibility of recruiting and retaining males aged 50 years and over to an 8-week walking football programme in a professional football club. Participants were recruited via social media and assigned to an intervention group or a wait-list control group. The intervention group engaged in 1 h of walking football a week led by a community coach from the professional football club, followed by an optional social session in the club facility. Physiological and psychological outcome measures were obtained onsite at the football club facility (aiding compliance and retention) at baseline and following 8-weeks, from both groups. Semi-structured interviews were conducted after the 8-week programme and 1 year later, to explore motivations for engagement and the social impact. The opportunity to engage in football and the link to a professional football club were key attractions. All participants recruited were overweight, sedentary, exhibited blood pressures outside normal ranges, and all but two were hypertensive. Adherence to the programme was 90% over 8 weeks, and of the participants who were contacted after one year, all (n = 6) had maintained engagement in walking football. Walking football is therefore a feasible, cost-effective method of recruiting and retaining males aged 50 years and over to a physical activity programme, though attrition is to be expected.

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