Latest research in football - week 53 - 2019

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 Attitudes and behavior related to performance-enhancing substance use among elite Saudi football players
Reference: BMC Sports Sci Med Rehabil. 2019 Dec 5;11:35. doi: 10.1186/s13102-019-0149-1. eCollection 2019.
Authors: Al Ghobain M
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Summary: The purpose was to investigate the attitudes, beliefs and behavior related to performance enhancing substances (PES) use in elite Saudi football players. A cross-sectional survey was conducted. Using a systematic random sample of elite Saudi male football players, the standard World Anti-doping Agency (WADA) Social Science Research Package questionnaire was distributed to 408 players. The overall prevalence rate of PES use was 3.9%, with the overall prevalence rate of doping susceptibility 17.1%. PES use or doping susceptibility is strongly correlated but negatively associated with morality and cheating measures (p <  0.011, the estimate is - 0.139), threat or deterrence appraisal (p <  0.001, the estimate is - 0.301) and beliefs about the reference group's endorsement (p < 0.001, the estimate is - 0.213) but not with legitimacy perceptions (p = 0.513) and beliefs about the benefits of doping (p = 0.678). The strongest relationship was found between threat or deterrence appraisal (p < 0.001), and beliefs about the reference group's endorsement of PES use (p < 0.001). Morality and cheating measures, threat or deterrence appraisal and beliefs about the reference group's endorsement are the main predictors for PES use in Saudi Arabia.

#2 The Effect of 1600 μg Inhaled Salbutamol Administration on 30 m Sprint Performance Pre and Post a Yo-Yo Intermittent Running Test in Football Players
Reference: J Sports Sci Med. 2019 Nov 19;18(4):716-721. eCollection 2019 Dec.
Authors: Merlini M, Beato M, Marcora S, Dickinson J
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Summary: The purpose of the study was to investigate the effect of inhaling 1600 μg of salbutamol (SAL) on 30 m sprint before and after the Yo-Yo Intermittent Recovery test. In a randomised cross over single blind study 13 male non-asthmatic, football players volunteered (mean ± SD; age 18.1 ± 0.9 years; weight 69.5 ± 8.3 kg; height 1.78 ± 0.07 m). Participants completed two visits and were randomly assigned to either (SAL) or (PLA) treatment and performed a set of three sprints of 30 m before and after the Yo-Yo Intermittent Recovery Test (Yo-Yo IRT). Best sprint and mean sprint were analysed in addition to the distance covered during the Yo-Yo IRT; rating of perceived exertion and heart rate were collected at the end of each level completed. Repeated measures ANOVA were performed to investigate changes in performance between groups. Following the inhalation of supra-therapeutic salbutamol dose (1600 μg) neither 30 m sprint time (PLA 4.43 ± 0.14 s; SAL 4.44 ± 0.15 s, p = 0.76) nor distance covered in the Yo-Yo IRT test reported significant variation between PLA conditions (1660 ± 217 m) and SAL (1610 ± 229 m, p = 0.16). Moreover, lactate values, heart rate and RPE did not differ significantly between groups. The inhalation of 1600 μg salbutamol does not enhance 30 m sprint performance in non-fatigued and fatigue conditions. Our findings suggest when football players acutely inhale double the permitted dose of salbutamol, as indicated in the World Anti-Doping Agency List of Prohibited Substances and Methods, they will not experience improvements in sprint or endurance performance.

#3 The Physiological, Physical, and Biomechanical Demands of Walking Football: Implications for Exercise Prescription and Future Research in Older Adults
Reference: J Aging Phys Act. 2019 Dec 10:1-11. doi: 10.1123/japa.2019-0330. [Epub ahead of print]
Authors: Harper LD, Field A, Corr LD, Naughton RJ.
Summary: The aim of this investigation was to profile the physiological, physical, and biomechanical responses during walking football. A total of 17 male participants (aged 66 ± 6 years) participated. Heart rate; blood lactate; accelerometer variables (biomechanical load [PlayerLoad™], changes of direction); and rating of perceived exertion were measured. Participants mean percentage of maximum heart rate was 76 ± 6% during the sessions, with rating of perceived exertion across all sessions at 13 ± 2. Blood lactate increased by ∼157% from presession (1.24 ± 0.4 mmol/L) to postsession (3.19 ± 1.7 mmol/L; p ≤ .0005). PlayerLoad™ values of 353 ± 67 arbitrary units were observed, as well as ∼100 changes of direction per session. In conclusion, walking football is a moderate- to vigorous-intensity activity. The longitudinal health benefits of walking football remain to be elucidated, particularly on bone health, cardiovascular fitness, and social and mental well-being.

#4 Experiences Influencing Walking Football Initiation in 55- to 75-Year-Old Adults: A Qualitative Study
Reference: J Aging Phys Act. 2019 Dec 10:1-13. doi: 10.1123/japa.2019-0123. [Epub ahead of print]
Authors: Cholerton R, Breckon J, Butt J, Quirk H.
Summary: Adults aged 55 and older are least likely to play sport. Despite research suggesting this population experiences physical and psychological benefits when doing so, limited research focuses on older adult sport initiation, especially in "adapted sports" such as walking football. The aim of this study was to explore initiation experiences of walking football players between 55 and 75 years old. Semistructured interviews took place with 17 older adults playing walking football for 6 months minimum (Mage = 64). Inductive analysis revealed six higher order themes representing preinitiation influences. Eight further higher order themes were found, relating to positive and negative experiences during initiation. Fundamental influences preinitiation included previous sporting experiences and values and perceptions. Emergent positive experiences during initiation included mental development and social connections. Findings highlight important individual and social influences when initiating walking football, which should be considered when encouraging 55- to 75-year-old adults to play adapted sport. Policy and practice recommendations are discussed.

#5 The 11+ Kids warm-up programme to prevent injuries in young Iranian male high-level football (soccer) players: A cluster-randomised controlled trial
Reference: J Sci Med Sport. 2019 Dec 9. pii: S1440-2440(19)30140-9. doi: 10.1016/j.jsams.2019.12.001. [Epub ahead of print]
Authors: Zarei M, Abbasi H, Namazi P, Asgari M, Rommers N, Rössler R
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Summary: The purpose was to assess the effectiveness of the 11+ Kids warm-up programme regarding injury reduction in male high-level children's football players. Male youth football teams of Iran's high-level football schools were invited to participate. Inclusion criteria were: teams are competing in the highest league of their province; players are between 7 and 14 years old; regular training takes place at least twice per week. Teams were excluded if they used an injury prevention measure. Participating clubs were randomised to an intervention (INT, N = 20 teams) and a control group (CON, N = 22 teams), stratified by the number of teams and the age group. The groups were blinded against each other. The follow-up period was one season (9 months). INT replaced their warm-up by 11+ Kids. CON performed a standard warm-up programme. The primary outcome was the injury incidence density (injuries per 1000 h of football exposure), compared between groups by incidence rate ratios (RR). In total, 64,047 h of football exposure of 962 players (INT = 443 players, 31,934 h of football, CON = 519 players, 32,113 h of football) were recorded. During the study, 90 (INT = 30; CON = 60) injuries occurred. The overall injury incidence density in INT was reduced by 50% compared to CON (RR 0.50; 95%-CI 0.32, 0.78). No injuries occurred during the execution of the intervention exercises. The 11+ Kids reduces injuries in high-level children's football players, thus supporting player health and potentially performance and player development.

#6 Strategic rule breaking: Time wasting to win soccer games
Reference: PLoS One. 2019 Dec 18;14(12):e0224150. doi: 10.1371/journal.pone.0224150. eCollection 2019.
Authors: Greve HR, Rudi N, Walvekar A
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Summary: Rules regulate behavior, but in competitive contexts they also create incentives for rule-breaking because enforcement is imperfect. Sports is a prime example of this, and one that lends itself well to investigation because strategic rule-breaking is often measurable. Professional soccer is a highly competitive team sport with economic rewards for winning given to teams and players. It has a set of rules to ensure fair play, but the enforcement is incomplete, and hence can lead to strategic behavior. Using newly available data, we examine strategic time-wasting, a behavior that help teams win games, or tie games against superior opponents, but is contrary to the objective of game play as entertainment for the spectators. We demonstrate that strategic time-wasting is widespread and is done through delayed restart of the game after goalie capture of the ball, goal kick, throw-in, free kick, corner kick, and substitution. The strategic time-wasting has substantial magnitude, and models of the value per minute predict time-wasting well. Because this time-wasting is a result of incentives created by not stopping the game clock, we predict that a change to rules with stopped game clock when the play is stopped would make game play more time efficient.

#7 Hidden dynamics of soccer leagues: The predictive 'power' of partial standings
Reference: PLoS One. 2019 Dec 18;14(12):e0225696. doi: 10.1371/journal.pone.0225696. eCollection 2019.
Authors: Beggs CB, Bond AJ, Emmonds S, Jones B
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Summary: Soccer leagues reflect the partial standings of the teams involved after each round of competition. However, the ability of partial league standings to predict end-of-season position has largely been ignored. Here we analyze historical partial standings from English soccer to understand the mathematics underpinning league performance and evaluate the predictive 'power' of partial standings. Match data (1995-2017) from the four senior English leagues was analyzed, together with random match scores generated for hypothetical leagues of equivalent size. For each season the partial standings were computed and Kendall's normalized tau-distance and Spearman r-values determined. Best-fit power-law and logarithmic functions were applied to the respective tau-distance and Spearman curves, with the 'goodness-of-fit' assessed using the R2 value. The predictive ability of the partial standings was evaluated by computing the transition probabilities between the standings at rounds 10, 20 and 30 and the final end-of-season standings for the 22 seasons. The impact of reordering match fixtures was also evaluated. All four English leagues behaved similarly, irrespective of the teams involved, with the tau-distance conforming closely to a power law (R2>0.80) and the Spearman r-value obeying a logarithmic function (R2>0.87). The randomized leagues also conformed to a power-law, but had a different shape. In the English leagues, team position relative to end-of-season standing became 'fixed' much earlier in the season than was the case with the randomized leagues. In the Premier League, 76.9% of the variance in the final standings was explained by round-10, 87.0% by round-20, and 93.9% by round-30. Reordering of match fixtures appeared to alter the shape of the tau-distance curves. All soccer leagues appear to conform to mathematical laws, which constrain the league standings as the season progresses. This means that partial standings can be used to predict end-of-season league position with reasonable accuracy.

#8 Positive fantasies and negative emotions in soccer fans
Reference: Cogn Emot. 2019 Dec 17:1-12. doi: 10.1080/02699931.2019.1703649. [Epub ahead of print]
Authors: Sevincer AT, Wagner G, Oettingen G
Summary: Positive thinking is often assumed to foster effort and success. Research has shown, however, that positive thinking in the form of fantasies about achieving an idealised future predicts less (not more) effort and success and more (not less) depressive symptoms over time. This relationship was mediated by people having invested little effort and achieved little success. Here, we ask a different question. We investigate the emotional consequences of positive fantasies about futures that people cannot act on. Specifically, we analyse these consequences when the future fantasies fail to come true (one's favourite soccer team loses). Study 1 provided correlational evidence. The more positively soccer fans fantasised about their favourite team winning an upcoming match, the stronger were their negative emotions when their team lost. That is, the more sad, disappointed, and frustrated they felt. Study 2 provided experimental evidence. Soccer fans who were led to fantasise positively about their team winning an upcoming match reported feeling stronger negative emotions after their team lost than those who were led to fantasise negatively. Positive fantasies were not related to how positive participants felt after their team won (joy, happiness, relief). We discuss theoretical and applied implications for emotion regulation in everyday life.

#9 Half Soccer Season Induced Physical Conditioning Adaptations in Elite Youth Players
Reference: Int J Sports Med. 2019 Dec 16. doi: 10.1055/a-1014-2809. [Epub ahead of print]
Authors: Arregui-Martin MA, Garcia-Tabar I, Gorostiaga EM
Summary: This study aimed to investigate training-induced fitness changes and their relationship with training-competition load during half a soccer season (18 wks). Training load [heart rate (HR) and ratings of perceived exertion (RPE)] and match time were monitored, including 108 training (3 223 individuals) and 23 match sessions, in 38 youth elite male soccer players. Fitness variables were assessed before and after the study. Yo-Yo intermittent recovery test 1 (Yo-Yo IRT1) improved (P<0.001; 90%CI: 418-632 m; ES: 2.14). Anthropometrical, jump, sprint, and change-of-direction measures remained unchanged. Jump test correlated with sprint (r=0.74; P<0.001; SEE=3.38 m·s-1) and Yo-Yo IRT1 (r=-0.58; P=0.005; SEE=4.11 m) tests. Initial sum of 6 skinfolds was associated with changes in this same measure (r=-0.51; P<0.001; SEE=21%). Initial Yo-Yo IRT1 results were related to changes in Yo-Yo IRT1 (r=-0.84; P<0.001; SEE=10%) and match time played (r=0.44; P=0.033; SEE=445 m). Mean RPE records were related to training spent within 75-90% maximal HR (r=0.54; P<0.001; SEE=4%). The half-season was beneficial for endurance running performance but not for lower-limb strength-velocity production capacity. The more aerobically deconditioned players played fewer minutes of match, although they showed the greatest improvements in endurance performance. Non-soccer-specific, scientifically based, and individualized fitness programs in addition to soccer-specific training are recommended.

#10 Oculomotor Control in Amputee Soccer Players
Reference: Adapt Phys Activ Q. 2019 Dec 14:1-15. doi: 10.1123/apaq.2019-0028. [Epub ahead of print]
Authors: Jedziniak W, Lesiakowski P, Zwierko T
Summary: The authors investigated the dynamics of saccadic parameters during a stationary oculomotor target task in amputee soccer players (n = 16), able-bodied soccer players (n = 16), and nonathletic control subjects (n = 16). Eye movements during the visual-search tasks were recorded binocularly using a mobile eye-tracking system, and the gaze parameters were analyzed (fixation duration, saccade duration, saccade amplitude, saccade average acceleration, saccade peak deceleration, saccade average velocity, and ocular mobility index). The average saccade acceleration in the amputee soccer players was significantly lower than in the able-bodied players (p = .021). Other saccade characteristics in disabled athletes were comparable to those of the able-bodied groups. Moreover, the able-bodied soccer players presented faster saccadic parameters than nonathletes in terms of saccade acceleration (p = .002), deceleration (p = .015), and velocity (p = .009). The modification of oculomotor functions may result from extensive practice and participation in ball games. The authors' hypothesis that oculomotor functions in amputee soccer players may be impaired was not fully confirmed.

#11 Prevalence and severity of groin problems in Spanish football: A prospective study beyond the time-loss approach
Reference: Scand J Med Sci Sports. 2019 Dec 17. doi: 10.1111/sms.13615. [Epub ahead of print]
Authors: Esteve E, Clausen MB, Rathleff MS, Vicens-Bordas J, Casals M, Palahí-Alcàcer A, Hölmich P, Thorborg K
Summary: The time-loss definition of injury is commonly adopted in epidemiological groin-injury studies in football, with a significant risk of underestimating the impact of these injuries. This study investigated the extent of groin problems, beyond the time-loss approach, over a full Spanish football season. Players from 17 amateur male teams were followed over 39 consecutive weeks. Groin-injury time loss and self-reported groin pain, irrespective of time loss, were combined to calculate the average weekly prevalence of all groin problems with or without time loss. A subscale measuring hip- and groin-related sporting function from the Copenhagen Hip And Groin Outcome Score questionnaire (HAGOS, Sport/Rec) was registered every 4 weeks. In total, 407 players participated in the study. The average (range) weekly prevalence of all groin problems was 11.7% (7.2-20.8%); 1.3% with time loss (0.0-3.2%) and 10.4% without time loss (6.3-17.6%). Players with groin problems reported lower scores (mean difference) on the HAGOS, Sport/Rec subscale compared to players without (-19.5 (95% CI: -20.7 - -18.4), while there was no difference between players reporting groin problems with and without time loss (4.0 (95% CI: -1.1 - 9.1). The traditional time-loss measure only captured 10% of all groin problems. Hip- and groin-related sporting function was not different between players reporting groin problems with or without time loss, suggesting the reason for continuing to play is not only related to the severity of symptoms. These findings question the judicious use of the time-loss approach in overuse conditions, such as groin pain in footballers.

#12 Electrocardiographic and Echocardiographic Findings in Elite Ghanaian Male Soccer Players
Reference: Clin J Sport Med. 2019 Dec 24. doi: 10.1097/JSM.0000000000000801. [Epub ahead of print]
Authors: Pambo P, Adu-Adadey M, Agbodzakey H, Scharhag J
Summary: The purpose was to analyze the athlete's heart of adult and adolescent elite male soccer players by electrocardiography (ECG) and echocardiography (ECHO) and to describe typical ECG and ECHO findings in this cohort (West African elite soccer players). A cross-sectional study of ECGs and ECHOs conducted as part of precompetition medical assessment for national male soccer teams preparing for various Fédération Internationale de Football Association (FIFA) tournaments in 2016 and 2017. One hundred fifty-nine players playing for the National male soccer teams preparing for tournaments in 2016 and 2017 participated in this study. Number of athletes with abnormal ECGs and ECHO findings were used as main outcome measures. Twenty-three percent of the players had abnormal ECGs. Nine percent of the participants had T-wave inversions in lateral leads (V5-V6). Sokolow-Lyon criteria for left ventricular hypertrophy were present in 64% of participants. Thirty-six (23%) players had left ventricular wall thickness (LVWT) ≥13 mm, with no player exceeding 16 mm. Four percent of players had left ventricular cavity dimension greater than 60 mm. Relative wall thickness >0.42 was present in 44% of the players. Uncommon ECG changes seem to be more common in elite Ghanaian soccer players compared with previously reported results for Caucasians and even mixed populations of black athletes. Although ST elevation, T-wave inversions, and LVWT up to 15 mm are common, ST depression, deep T-waves in lateral leads, and LVWT ≥16 mm always warrant further clinical and scientific investigations.

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