Latest research in football - week 28 - 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 Knee osteoarthritis in professional football is related to severe knee injury and knee surgery
Reference: Inj Epidemiol. 2018 Jun 18;5(1):26. doi: 10.1186/s40621-018-0157-8.
Authors: Gouttebarge V, Aoki H, Kerkhoffs GMMJ
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Summary: As a consequence of severe knee injuries, knee osteoarthritis (OA) seems prevalent in retired professional footballers. However, some epidemiological data remain missing, for instance whether knee OA is also prevalent in current professional footballers, whether knee OA is associated with knee injuries and surgeries, and whether knee OA leads to a lower level of functioning. Therefore, three research questions were answered: (i) what is the prevalence of knee osteoarthritis (OA) among current and retired professional footballers? (ii) is severe knee injury or knee surgery associated with knee OA among current and retired professional footballers? (iii) what are the consequences of knee OA on physical knee function among current and retired professional footballers? An observational study based on a cross-sectional design by means of questionnaires was conducted. Participants were current and retired professional footballers recruited by the World Players' Union (FIFPro). Information about severe knee injury and knee OA was gathered (medical record or team doctor), while physical knee function was assessed through a validated scale. A total of 1360 participants (964 current and 396 retired professional footballers) were enrolled in the study (response rate of 54%). Prevalence of knee OA was 13% among current players and 28% among retired players (p < 0.01), being higher among older players. Current and retired professional footballers were nearly twice as likely to suffer from knee OA by every additional severe knee injury and by every additional knee surgery (risk ratio: 1.72-1.96; p < 0.01). Current and retired professional footballers with knee OA reported a lower level of physical knee function than current and retired players without OA (p < 0.01), their physical knee function being also lower than reference values (adult population, young athletic population and amateur footballers). The prevalence of knee OA was higher among retired than among current professional footballers and reached up to 40%, leading to negative consequences for their physical knee function. Current and retired professional footballers were nearly twice as likely to suffer from knee OA by every additional severe knee injury and by every additional knee surgery incurred during their career. Management of knee OA should be prioritized among professional footballers, especially to prevent the worsening of the condition during their retirement years.

#2 Match Demands of National Collegiate Athletic Association Division I Men's Soccer
Reference: J Strength Cond Res. 2018 Jul 2. doi: 10.1519/JSC.0000000000002719. [Epub ahead of print]
Authors: Curtis RM, Huggins RA, Looney DP, West CA, Fortunati A, Fontaine GJ, Casa DJ
Summary: This study aimed to profile positional movement characteristics of National Collegiate Athletic Association (NCAA) Division I male soccer players. Eighteen Division I male soccer players were monitored using global positioning systems, inertial movement, and heart rate (HR) technology during 24 matches over a full competitive season (N = 235 observations). Positional groups were classified as either a forward (F), center midfield (CM), wide midfield (WM), or defender (D). Movement was profiled by locomotor (walking [0-7.19 km·h], jogging [7.20-14.39 km·h], running [14.40-21.59 km·h], and sprinting [>21.6 km·h]), and acceleration/deceleration characteristics (low intensity [0-1.99 m·s], moderate intensity [2-3.99 m·s], and high intensity [>4 m·s]). Players averaged distances of 9,367 ± 2,149 m per match at speeds of 91 ± 20 m·min and physiological intensities of 78 ± 8 %HRmax. Center midfields demonstrated the highest average speeds (97 ± 20 m·min) and covered the most distance (9,941 ± 2,140 m). Wide midfields accumulated the most sprint distance (391 ± 145 m) and high-intensity accelerations (129 ± 30 n)/decelerations (96 ± 24 n). Several practically meaningful differences exist between positions for internal and external load metrics. Match loads seen in NCAA Division I soccer vary from reports of professional soccer; however, the effects of match regulation, structure, and congestion, which are unique to NCAA soccer, require further investigation. Physical and physiological load monitoring of NCAA soccer may aid coaches and practitioners in the periodization of training programs leading up to and during a competitive soccer season. These data speak to the necessity for examining both internal and external loads by position.

#3 Promoting additional activity in youth soccer: a half-longitudinal study on the influence of autonomy-supportive coaching and basic psychological need satisfaction
Reference: J Sports Sci. 2018 Jul 5:1-9. doi: 10.1080/02640414.2018.1495394. [Epub ahead of print]
Authors: Gjesdal S, Wold B, Ommundsen Y
Summary: This study investigated the relationships between perceptions of coach autonomy support, basic psychological need satisfaction and the frequency at which youth soccer players engage in additional soccer activity outside of team sessions. We employed structural equation modelling to test a two-wave (T1 and T2) half-longitudinal study to see if basic psychological need satisfaction mediated the relationship between coach autonomy support and additional soccer activity across a competitive season. The sample consisted of 527 youth soccer players, aged 10-15 years. Results revealed moderate to strong temporal stability for autonomy, competence, relatedness and frequency of additional soccer activity. Furthermore, no support is offered for mediation as T1 coach autonomy support was not related to any of the three basic needs at T2 when accounting for their T1 levels. However, a positive relationship between T1 autonomy and T2 additional soccer activity emerged. This suggests that those who experience high levels of autonomy in the team setting at the start of the season report an increased frequency of additional activity at the end of the season. Results are discussed in light of the Self-Determination Theory and the Trans-Contextual Model.

#4 The effect of two different speed endurance training protocols on a multiple shuttle run performance in young elite male soccer players
Reference: Res Sports Med. 2018 Jul 4:1-14. doi: 10.1080/15438627.2018.1492402. [Epub ahead of print]
Authors: Vitale JA, Povia V, Vitale ND, Bassani T, Lombardi G, Giacomelli L, Banfi G, La Torre A
Summary: There is not enough evidence on the impact of different speed endurance training regimes on footballers' ability to perform multiple shuttle run performance. This study examined the effect of 4 weeks of speed endurance maintenance (SEM) and speed endurance production (SEP) training on the 5-meter multiple shuttle run test (5-m MST) performance in young elite soccer players. A parallel two-groups, longitudinal design was used. Fifteen players were divided to either SEM (8 repetitions of 20-s all-out sprint interspersed with 40 s of recovery) or SEP (8 repetitions of 20-s all-out bout interspersed with 120 s of recovery) training group. SEM improved the ability to tolerate fatigue and maintained the performance development during the 5-m MST while SEP increased only the 1st sprint showing, simultaneously, an increased fatigue index and performance decrement. The selection of which training regimes to prioritize should be based on the players' characteristics and individual game requirements Abbreviations: SEP: Speed Endurance Production; SEM: Speed Endurance Maintenance; PRE: Baseline; POST: End of experimental protocol; 5-m MST: 5-meters Multiple Shuttle Run Test; TD: Total Distance; FI: Fatigue Index; MSTdec: Percentage Decrement Score; BMI: Body Mass Index.

#5 Recreational soccer practice among adults, in Brazilian capitals, 2011-2015
Reference: Epidemiol Serv Saude. 2018 Jul 2;27(2):e2017284. doi: 10.5123/S1679-49742018000200013. [Article in English, Portuguese; Abstract available in Portuguese from the publisher]
Authors: Lima DF, Piovani VGS, Lima LA
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Summary: The aim of the study was to describe the profile of recreational adult soccer players who lived in the Brazilian capitals in the period from 2011 to 2015. A sample of adults were interviewed by the Surveillance System for Risk and Protective Factors for Chronic Diseases by Telephone Survey - VIGITEL (2011 to 2015). 11.812 adults (11.375 men and 437 women) pointed to soccer as their main leisure physical exercise, with higher prevalence in the North region (32%) and lower in the South region (10%) of the country; the average reduction of soccer players 3.4% for every 5 years over age (95%CI 2.9;4.1); from 2011 to 2015, there was decrease in the number of soccer players, -1.4% per year (95%CI -0,7;2,2). Tthe practice of soccer was predominantly male, presented an inverse relationship with the increase of age, more prevalent in the Northern region and less prevalent in the Southern region.

#6 Left ventricular function during exercise in trained pre-adolescent soccer players
Reference: Scand J Med Sci Sports. 2018 Jul 3. doi: 10.1111/sms.13258. [Epub ahead of print]
Authors: Unnithan VB, Rowland TW, George K, Lord R, Oxborough D
Summary: It is unclear, what the underlying cardiovascular mechanisms are that give rise to the high level of aerobic fitness seen in youth soccer players. The aim of the study was to evaluate global and regional markers of systolic and diastolic function in a group of pre-adolescent soccer players during an incremental exercise test. Twenty-two, male soccer players (SP) from two professional soccer clubs (age: 12.0 ± 0.3 years) volunteered for the study. Fifteen recreationally active boys (CON), of similar age (age: 11.7 ± 0.2 years) were also recruited. All boys underwent a cycle ergometer test to exhaustion. Cardiac dimensions were determined using M-mode echocardiography. During submaximal and maximal exercise, continuous-wave Doppler ultrasound techniques were used to derive stroke volume (SVIndex). Tissue-Doppler imaging was used to quantify systolic (S'adj) and diastolic function (E; E'adj and E/E') at rest and both submaximal and maximal exercise intensities. Speckle tracking echocardiography was used to determine peak longitudinal ε at submaximal exercise intensities. SP demonstrated significantly (P ≤ 0.05) greater peak VO2 values than CON (SP: 48.0 ± 5.0 vs CON: 40.1 ± 7.5 mL·kg-1 ·min-1 ). Allometrically scaled to body surface area left ventricular end-diastolic volume (LVEDV) was larger (P ≤ 0.05) in the SP (51.3 ± 9.0) compared to CON (44.6 ± 5.8 mL·BSA1.5 ). At the same relative, submaximal exercise intensities, the SP demonstrated greater SVIndex, cardiac output (QIndex) and E. No differences were noted for peak longitudinal ε during submaximal exercise. Factors that augment pre-load and LV volume appear to determine the superior aerobic fitness seen in the soccer players.

#7 Operative Outcomes of Grade 3 Turf Toe Injuries in Competitive Football Players
Reference: Foot Ankle Int. 2018 Jun 1:1071100718775967. doi: 10.1177/1071100718775967. [Epub ahead of print]
Authors: Smith K, Waldrop N
Summary: Turf toe is a term used to describe a hyperextension injury to the first metatarsophalangeal joint. Although the vast majority of turf toe injuries can be treated successfully without operative intervention, there are instances where surgery is required to allow the athlete to return to play. Although there is a plethora of literature on turf toe injuries and nonoperative management, there are currently few reports on operative outcomes in athletes. We obtained all cases of turf toe repair according to the ICD-10 procedural code. The inclusion criteria included: age greater than 16, turf toe injury requiring operative management and at least a varsity level high school football player. The charts were reviewed for age, BMI, level of competition, injury mechanism, football position, setting of injury and playing surface. In addition, we recorded the specifics of the operative procedure, a listing of all injured structures, the implants used and the great toe range of motion at final follow-up visit. The AOFAS Hallux score and VAS was used postoperatively as our outcome measures. Our patient population included 15 patients. The average follow-up time was 27.5 months. The average patient was 19.3 years old with a body mass index of 32.3. The average playing time missed was 16.5 weeks. The average dorsiflexion range of motion at the final follow-up was 42.3 degrees. At final follow-up, the average AOFAS Hallux score was 91.3. The average VAS pain score was 0.7 at rest and 0.8 with physical activity. Complete turf toe injuries are often debilitating and may require operative management to restore a pain-free, stable, and functional forefoot. This study represents the largest cohort of operatively treated grade 3 turf toe injuries in the literature and demonstrates that good clinical outcomes were achieved with operative repair.

#8 Load distribution on the foot and lofstrand crutches of amputee football players
Reference: Gait Posture. 2018 Jun 9;64:169-173. doi: 10.1016/j.gaitpost.2018.06.008. [Epub ahead of print]
Authors: Tatar Y, Gercek N, Ramazanoglu N, Gulmez I, Uzun S, Sanli G, Karagozoglu C, Cotuk HB
Summary: Amputee football is a worldwide popular sport with positive physical and psychological effects on the disabled. Amputee players use their hands dominantly for locomotion. However, the effect of using upper extremity which is not accommodated to loading is not very well known. The objective of this study was to determine the load distribution of amputee football players during walking, running and kicking the ball. This study was conducted with 15 certified amputee football players (age 24.5 ± 5.8 years, body weight 62.3 ± 10.9 kg, height 171.6 ± 7.7 cm). The loads on their non-amputated lower extremity were measured with F-Scan mobile system sensors inserted in their shoes, and the loads on their upper extremities were measured with F-Grip system sensors affixed to the gloves. The participants were asked to walk, run and kick the ball using Lofstrand Crutches. The maximum loading on the upper extremities during walking, running and kicking the ball varied between 111% and 175% of the body weight. While loading during walking and running was similar, the loading on the upper extremity during kicking the ball exceeded that of walking by 58.1% and running by 47.4%. The maximum loading on the non-amputated lower extremity varied between 134% and 196% of the body weight. Loading during running was 46.2% higher than that of walking. The loading on the foot during kicking the ball was 45.7% higher than that of walking. The loading on the foot during running and kicking were similar. Walking-running-kicking the ball with LC resulted in unusual loading particularly on the upper extremity. During running, the increased loading was transferred to the foot rather than the hands. During kicking, the loading increased extremely and was mainly transferred to the hands. The frequent repetition of kicking during the game may therefore increase the incidence of upper extremity injuries.

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