Latest research in football - week 33 - 2020

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 Nighttime Hypoglycemia in Children With Type 1 Diabetes After One Day of Football Tournament
Reference: Int J Sports Med. 2020 Jul 7. doi: 10.1055/a-1192-5992. Online ahead of print.
Authors: Mikołaj Kamiński, Andrzej Gawrecki, Aleksandra Araszkiewicz, Agnieszka Szadkowska, Bogda Skowrońska, Witold Stankiewicz, Arkadiusz Michalak, Aleksandra Cieluch, Katarzyna Dżygało, Sebastian Seget, Grzegorz Biegański, Anna Adamska, Katarzyna Ksiądz, Elektra Szymańska-Garbacz, Justyna Flotyńska, Dorota Zozulinska-Ziolkiewicz
Summary: The aim of the study was to investigate factors related to the occurrence of nighttime hypoglycemia after a football tournament in children with type 1 diabetes mellitus. The multicenter study (GoalDiab study) included 189 children and adolescents with type 1 diabetes mellitus, from 11 diabetes care centers in Poland. Hypoglycemia was defined according to the International Hypoglycemia Study Group Statement. We analyzed the data of 95 participants with completed protocols with regards to nighttime hypoglycemia (82% male), aged 11.6 (9.8-14.2) years, diabetes duration 5.0 (2.0-8.0) years. There were 47 episodes of nighttime Level 1 hypoglycemia (≤3.9 mmol/L). Occurrence of clinically important Level 2 hypoglycemia (<3.0 mmol/L) during a game period was positively associated with nighttime hypoglycemia (≤3.9 mmol/L) incident (Odds Ratio=10.7; 95% Confidence Interval: 1.1-100.2; p=0.04). Using Continuous Glucose Monitoring was negatively associated with the occurrence of nighttime hypoglycemia (≤3.9 mmol/L) compared with using glucose meters or Flash Glucose Monitoring (Odds Ratio=0.31; 95% Confidence Interval: 0.12-0.83; p=0.02). The occurrence of clinically important hypoglycemia related to physical activity is associated with the occurrence of hypoglycemia during the night. Continuous Glucose Monitoring is negatively associated with nighttime hypoglycemia after a day of competition.

#2 Feasibility and Safety of a Walking Football Program in Middle-Aged and Older Men With Type 2 Diabetes
Reference: Prog Cardiovasc Dis. 2020 Jul 4;S0033-0620(20)30137-7. doi: 10.1016/j.pcad.2020.06.014. Online ahead of print.
Authors: Ana Barbosa, João Brito, Júlio Costa, Pedro Figueiredo, André Seabra, Romeu Mendes
Summary: This study aimed to analyze the feasibility and safety of a community-based walking football program in middle-aged and older men with type 2 diabetes (T2D).  Thirty-one male (age, 64.4 ± 4.5 years old; glycated hemoglobin, 6.7 ± 1.0%; body mass index: 28.8 ± 3.3 kg/m2) patients with T2D were recruited from primary health care units in Porto, Portugal. The participants engaged in a 12-wk walking football program (three sessions per week of 60 min; consisting of strength and conditioning exercises, technical skills drills, and small-sided walking football games). Exercise intensity was planned to be gradual throughout the program in three 4-wk phases (phase I, light-intensity; phase II, moderate-intensity; phase III, vigorous-intensity) through the manipulation of game constraints, and monitored by OMNI scale and heart rate reserve (HRR). Sessions' enjoyment level, and exercise-related injuries and adverse events were recorded in all sessions.  The median (P25-P75) adherence to the program was 86.1% (77.8-97.2%). The median enjoyment levels reported by participants was 5 (4-5) points in phase I, 5 (5-5) points in phase II and 5 (5-5) points in phase III. Sessions' average subjective exercise intensity was 3.0 ± 0.6 points in OMNI scale in phase I, 3.5 ± 0.4 points in phase II, and 3.8 ± 0.4 points in phase III. Sessions' average HRR was 35.8 ± 6.7% in phase I, 41.6 ± 4.2% in phase II, and 37.3 ± 4.3% in phase III. Most participants attained vigorous-intensity peaks in all phases. Falls (n = 25) and musculoskeletal injuries (n = 8) were the most frequent adverse events. 31% of these events interfered with exercise participation, but no harm has resulted from it.  A community-based walking football program for T2D patients revealed high levels of adherence and enjoyment, and light-to-vigorous exercise intensity. The adverse events were according to the expected for the population and activity. Therefore, walking football seems to be feasible and safe exercise strategy, and therefore has the potential for large scale implementation for T2D control.

#3 A Teaching Games for Understanding Program to Deal With Reasons for Dropout in Under-11 Football
Reference: Res Q Exerc Sport. 2020 Jul 7;1-12. doi: 10.1080/02701367.2020.1759767. Online ahead of print.
Authors: Carmen Barquero-Ruiz, María T Morales-Belando, José L Arias-Estero
Summary: Young players report that they dropout of organized football due to excessive emphasis on technical execution, low success, and the lack of autonomy and motivation experienced by players during training sessions.  The purpose was to determine whether a TGfU intervention during a youth football program led players to improve in variables related to dropout. That means tactical-technical competence (decision-making, skill execution), success (successful game performance), autonomy (number of decisions made, player autonomy, number of game involvements, player participation), and motivation (enjoyment, intention to be physically active). Twenty under-11-players and two coaches were recruited from 17 clubs. A pretest-posttest design with a multi-method approach was used. Coaches were trained and mentored in TGfU. Data were collected using Game Performance Assessment Instrument, enjoyment and intention to be physically active scales, and two focus groups with the players and the coaches. Players improved in decision-making, skill execution, successful game performance, number of decisions made, number of game involvements, and intention to be physically active (p < .05). Participants attributed the results to the TGfU pedagogical features emphasized during the coaches' training and mentoring. Considering the reasons for dropout in football, in terms of excessive emphasis on technical execution, low success, and the lack of autonomy and motivation experienced by players, TGfU could be a useful pedagogical approach for teaching-learning organized youth football. The TGfU pedagogical features emphasized during coaches' training and mentoring could be crucial to obtain these results due to the fact that they were the sub-themes highlighted during the focus groups.

#4 Composite Indices of Femoral Neck Strength in Middle-Aged Inactive Subjects Vs Former Football Players
Reference: J Clin Densitom. 2020 Jun 12;S1094-6950(20)30093-7. doi: 10.1016/j.jocd.2020.06.002. Online ahead of print.
Authors: Boutros Finianos, Gautier Zunquin, El Hage Rawad
Summary: The purpose of this study was to compare composite indices of femoral neck strength ((compression strength index [CSI], bending strength index [BSI], and impact strength index [ISI]) in inactive middle-aged men (n = 20) and middle-aged former football players (n = 15). 35 middle-aged men participated in this study. Body composition and bone variables were evaluated by dual-energy X-ray absorptiometry. Composite indices of femoral neck strength (CSI, BSI, and ISI) were calculated. Handgrip strength, vertical jump, maximum power of the lower limbs (watts), horizontal jump, maximal half-squat strength, maximal bench-press strength, sprint performance (10 meters), and maximum oxygen consumption (VO2 max, ml/min/kg) were evaluated using validated tests. CSI, BSI, and ISI were significantly higher in football players compared to inactive men. Vertical jump, horizontal jump, maximal half-squat strength, VO2 max and sprint performance were significantly different between the 2 groups. CSI, BSI, and ISI remained significantly higher in football players compared to inactive men after adjusting for physical activity level. The current study suggests that former football practice is associated with higher composite indices of femoral neck strength in middle-aged men.

#5 Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players: A Preliminary Study
Reference: Front Physiol. 2020 Jun 24;11:608. doi: 10.3389/fphys.2020.00608. eCollection 2020.
Authors: Hamid Arazi, Abbas Asadi, Farhood Khalkhali, Daniel Boullosa, Anthony C Hackney, Urs Granacher, Hassane Zouhal
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Summary: This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.

#6 Comment on: "Changes in Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match by a NonInvasive MuscleSound ® Technology. A Cross Sectional Pilot Study
Reference: Nutrients 2020, 12(4), 971"
Authors: Niels Ørtenblad, Joachim Nielsen, Kasper D Gejl, Harry E Routledge, James P Morton, Graeme L Close, David C Niemann, Julia L Bone, Louise M Burke
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#7 Reply to Comment on: "Changes in Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match by a Non-Invasive MuscleSound ® Technology. A Cross Sectional Pilot Study
Reference: Nutrients. 2020 Jul 12;12(7):E2066. doi: 10.3390/nu12072066.
Authors: Iñigo San-Millán, John C Hill, Julio Calleja-González
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#8 Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players
Reference: Int J Sport Nutr Exerc Metab. 2020 Jul 15;1-8. doi: 10.1123/ijsnem.2020-0031. Online ahead of print.
Authors: Rodrigo Dos Santos Guimarães, Alcides Correa de Morais Junior, Raquel Machado Schincaglia, Bryan Saunders, Gustavo Duarte Pimentel, João Felipe Mota
Summary: Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1 years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90 min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. -0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. -1.45 ± 0.31 mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41 s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64 W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51 cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11 cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.

#9 Effects of 6 Weeks Direct Instruction and Teaching Games for Understanding Programs on Physical Activity and Tactical Behaviour in U-12 Soccer Players
Reference: Int J Environ Res Public Health. 2020 Jul 12;17(14):E5008. doi: 10.3390/ijerph17145008.
Authors: Juan Vicente Sierra-Ríos, Filipe Manuel Clemente, Ezequiel Rey, Sixto González-Víllora
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Summary: The purpose of this study was to compare the effects of 6 weeks direct instruction and teaching games for understanding (TGfU) programs on the decision-making and execution (post-interventions), as well, as on the physical activity (PA) levels during sessions. Thirty under-12 football players participated in this study (age: 10.3 ± 0.45 years) and were randomly assigned to TGfU (n = 15) or direct instruction (n = 15) group. Two sessions/week were implemented. Results revealed that TGfU promoted higher levels (p = 0.043; d = 2.99) of light PA (28.96%) compared with direct instruction (27.55%). Non-significant higher sedentary PA levels (p = 0.073; d = 2.62) were found in the control group (35.48%). In terms of tactical principles, conservation of the ball increased the percentage of moderate to vigorous physical activity in TGfU (43.60%) compared with direct instruction (38.05%). According to the Game Performance Evaluation Tool (GPET), significant improvements (p = 0.018, d = 3.78) of the attacking player with the ball in the percentage of change between groups in the unsuccessful execution in TGfU (% = -62.2) were observed compared with direct instruction (% = 14.2). TGfU seems to be more appropriate than direct instruction to increase the light PA levels during sessions while no significant differences were found between programs in moderate and vigorous intensities. Regarding the effects of programs in decisions, greater improvements in decisions with the ball were found in TGFU compared to DI.

#10 Adductor Muscles Strength and Strength Asymmetry as Risk Factors for Groin Injuries among Professional Soccer Players: A Prospective Study
Reference: Int J Environ Res Public Health. 2020 Jul 9;17(14):E4946. doi: 10.3390/ijerph17144946.
Authors: Goran Markovic, Nejc Šarabon, Jelena Pausic , Vedran Hadžić
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Summary: The aim of this study was to prospectively examine the association between isometric hip adductor strength and between-limb strength asymmetry to groin injuries in male professional soccer players. Isometric hip adductor strength and between-limb strength asymmetry of 45 professional outfield soccer players from three First Division teams were tested during the 2017/2018 preseason. Players were then monitored throughout the 2017/2018 season for groin injuries. Ten groin injuries were recorded. When compared with uninjured players, players who sustained groin injury had significantly lower strength of respective muscle groups and significantly higher between-limb strength asymmetries (all p < 0.05; ES = 1.16 and 0.88; mean % difference = 26% and 51%). Isometric hip adductor strength had a significant inverse relationship with the incidence of occurring groin injuries (p = 0.016). No significant relationship between hip adductor strength asymmetry and the incidence of future groin injury was observed (p = 0.09). Finally, players' age and previous groin injury were not significantly associated with the incidence of future groin injuries (all p > 0.05). These results generally suggest that isometric adductor strength is a significant predictor of future groin injuries in men's professional football; however, due to the relatively low sample size, further studies are required.

#11 Injuries on the Youth Soccer (Football) Field: Do Additional Referees Reduce Risk? Randomized Crossover Trial
Reference: J Pediatr Psychol. 2020 Jul 11;jsaa050. doi: 10.1093/jpepsy/jsaa050. Online ahead of print.
Authors: David C Schwebel, D Leann Long, Leslie A McClure
Summary: Youth soccer injury can be prevented through various means, but few studies consider the role of referees. Following previous research suggesting children take fewer risks when supervised intensely, this randomized crossover trial evaluated whether risky play and injuries decrease under supervision from three referees instead of one referee. Youth soccer clubs serving a metropolitan U.S. area participated. Boys' and girls' clubs at under age 10 (U10) and under age 11 (U11) levels were randomly assigned such that when the same clubs played each other twice in the same season, they played once with one referee and once with three referees. A total of 98 games were videotaped and subsequently coded to obtain four outcomes: collisions between players, aggressive fouls (involving physical player-to-player contact) called by the referee(s) on the field, aggressive fouls judged by trained coders, and injuries requiring adult attention or play stoppage. Poisson mixed model results suggest players in the 98 games committed fewer aggressive fouls, as identified independently by referees (rate ratio [RR] 0.58; 95% confidence interval [CI] 0.35-0.96) and by researchers (RR 0.67; 95% CI 0.50-0.90), when there were three referees versus one referee. Collisions (RR 0.98; 95% CI 0.86-1.12) and injury rates (RR 1.15; 95% CI 0.60-2.19) were similar across conditions. When the same youth soccer clubs played with three referees rather than one, they committed fewer aggressive fouls. More intense supervision created better rule adherence. Injury rates were unchanged with increased supervision. Results raise questions concerning whether financial investment in additional referees on youth soccer fields yields safety benefits.

#12 'When you have the adrenalin pumping, it kind of flushes out any negative emotions': a qualitative exploration of the benefits of playing football for people with mental health difficulties
Reference: J Ment Health. 2020 Jul 17;1-8. doi: 10.1080/09638237.2020.1793119. Online ahead of print.
Authors: Mark Llewellyn, Alecia L Cousins, Philip John Tyson
Summary: Physical activity is a factor by which mental health can be improved. However, the association between mental health and physical exercise, in a "team-based sport" setting within the community, remains unclear. The current paper aims to provide an evaluation of a football programme, implemented by Time to Change Wales, funded by the Welsh Government, to improve mental health. Participants attended weekly 90-120 minute football sessions, held in local community venues across Wales, UK, with no requirement on the number of sessions that participants had to attend. A qualitative method was employed to explore the experiences of those who took part. Individuals who participated in the programme reported psychosocial and physical benefits, such as improved physical and mental health, improved social confidence and having a sense of purpose added to their day-to-day living. Factors affecting participation were also identified within the data, such as environmental barriers. The findings provide both support and contextual extension to previous research in this area; demonstrating the positive effects of sport-based therapy for those with mental health difficulties. Implications and conclusions should be used to inform future research into developing community sport-based programmes to improve mental health.

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