Latest research in football - week 6 - 2022

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 Moving Toward a More Comprehensive Analysis of Acceleration Profiles in Elite Youth Football

Reference: Front Sports Act Living. 2022 Jan 4;3:802014.  doi: 10.3389/fspor.2021.802014. eCollection 2021.

Authors: Damian Kovacevic, George Elias, Susanne Ellens, Adam Cox, Fabio R Serpiello

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Summary: In football, having greater acceleration ability may decide the most important moments within matches. Up to now, commonly used acceleration variables have typically been investigated in isolation, with each variable suffering from unique limitations. Subsequently, any findings may provide a limited representation of what specific acceleration demands had actually occurred. Without gaining a comprehensive understanding of acceleration demands in football, it appears difficult to identify how to best monitor and maximize the long-term development of acceleration ability in footballers, all whilst doing so in a safe, sport-specific manner. Moving toward a more comprehensive analysis of acceleration profiles addresses this, as it can provide a more robust, informative understanding of the unique acceleration demands of competitive match-play. This perspective article aims to discuss the benefits of adopting a more comprehensive analysis of the acceleration demands during competitive matches for football players, by simultaneously analyzing high-intensity accelerations, repeated high acceleration ability (RHAA), and average acceleration. We discuss examples of the calculation and application of a more comprehensive acceleration profile at a team level throughout the course of an entire elite youth football season, as well as on an individual level. Monitoring acceleration profiles more comprehensively not only appears important from a training load/injury prevention perspective, but also, equips coaches and conditioning staff with the specific information necessary to develop and prescribe individualized, acceleration-emphasized training protocols that are replicable to the demands of match-play. Examples of such protocols are provided.



#2 The Importance of Selected Coordination Motor Skills for an Individual Football Player's Effectiveness in a Game

Reference: Int J Environ Res Public Health. 2022 Jan 10;19(2):728. doi: 10.3390/ijerph19020728.

Authors: Łukasz Bojkowski, Paweł Kalinowski, Robert Śliwowski, Maciej Tomczak

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Summary: The appropriate level of coordination motor skills (CMS) in a football player is one of the factors determining the effectiveness of their actions. Adaptability and complex reaction time are of particular importance in models of coordination requirements in football. The lead aim of this study is to determine the relationship between two selected coordination motor skills and the offensive, defensive and comprehensive effectiveness of an individual player's actions. The study was conducted on a group of 91 Polish male football players aged 20 to 31 years, all in the senior age category. The research tools included: a test assessing motor adaptation (research by dribbling the ball with the dominant leg), psychomotor test of complex reaction time (tested with an S-10.2 measuring device) and a test of the effectiveness of an individual player's actions (one-on-one simulation game). The conducted research indicated that adaptability and complex reaction time are both important abilities for success when attacking in an individual game, and in the assessment of a comprehensive index of individual competences in a one-on-one football game. However, the most significant factor influencing the effectiveness of a player's defensive action is solely the complex reaction time.



#3 Serum neurofilament light concentration does not increase following exposure to low velocity football heading

Reference: Sci Med Footb. 2021 Aug;5(3):188-194. doi: 10.1080/24733938.2020.1853210. Epub 2020 Dec 1.

Authors: Kieran Austin, Ben J Lee, Tessa R Flood, Jamie Toombs, Mina Borisova, Mike Lauder, Amanda Heslegrave, Henrik Zetterberg, Neal A Smith

Summary: The aim was to investigate if heading frequency and impact biomechanics in a single session influence the concentration of serum neurofilament light (NF-L), a sensitive biomarker for axonal damage, up to 7 days after heading incident at ball velocities reflecting basic training drills. Forty-four males were randomized into either control (n = 8), 10 header (n = 12), 20 header (n = 12) or 40 header (n = 12) groups. Linear and angular head accelerations were quantified during heading. Venous blood samples were taken at baseline, 6 h, 24 h and 7 days after heading. Serum NF-L was quantified using Quanterix NF-L assay kit on the Simoa HD-1 Platform. Serum NF-L did not alter over time (p = 0.44) and was not influenced by number of headers [p = 0.47; mean (95% CI) concentrations at baseline 6.00 pg · ml-1 (5.00-7.00 pg · ml-1); 6 h post 6.50 pg · ml-1 (5.70-7.29 pg · ml-1); 24 h post 6.07 pg · ml-1 (5.14-7.01 pg · ml-1); and 7 days post 6.46 pg · ml-1 (5.45-7.46 pg · ml-1)]. There was no relationship between percentage change in NF-L and summed session linear and angular head accelerations. In adult men, heading frequency or impact biomechanics did not affect NF-L response during a single session of headers at ball velocities reflective of basic training tasks.



#4 Osteochondritis dissecans of the patella: a case-report in a juvenile football player

Reference: Sci Med Footb. 2021 Aug;5(3):250-253.  doi: 10.1080/24733938.2020.1846770. Epub 2020 Dec 14.

Authors: Patrícia Cruz, Filipe Bettencourt, Gonçalo Arneiro

Summary: Osteochondritis dissecans (OCD) lesions are a rare cause of joint pain. Most often they occur in the knee, but they can occur in elbow or ankle too. They have a predilection for the immature skeleton and are most commonly seen in male sex, athletically active young children and adolescents.Sport-specific risk factors by anatomic region include sports associated with high frequencies of knee or ankle injuries (e.g., football, basketball) and for the elbow, the overhead throwing athlete (e.g., baseball pitcher) or gymnast.In the knee, they are most commonly seen in the femoral condyles of the knee. OCD of the patella is a rare condition. There are a few reports of it.We present a case of 14-year-old-male patient, football player, with osteochondritis dissecans of the patella (OCP). The clinical presentation, radiographic and MRI findings, treatment and return to player are discussed.



#5 The effect of ball characteristics on head acceleration during purposeful heading in male and female youth football players

Reference: Sci Med Footb. 2021 Aug;5(3):195-203. doi: 10.1080/24733938.2021.1897657. Epub 2021 Apr 7.

Authors: Kerry Peek, Marnee McKay, Allan Fu, Tim Meyer, Vincent Oxenham, Carrie Esopenko, Jaclyn Caccese, Jordan Andersen

Summary: The objective of this cross-sectional study was to explore the effects of different ball types and characteristics on head acceleration during purposeful heading in youth football players. Experienced male and female players (n = 61) aged between 12-17 years completed heading trials with 4 different balls (Ball 1 mass 192 grams (g), pressure 5.0 pounds per square inch (psi); Ball 2 432 g, 5.0 psi; Ball 3 255 g, 5.0 psi; Ball 4 430 g, 10.5 psi) whilst wearing a head-mounted accelerometer and gyroscope. Balls 1, 2 and 4 were size 5 balls; Ball 3 was a size 4 ball. Multivariate analysis of variance and post-hoc univariate analyses revealed a statistically significant difference between ball type and head acceleration during heading for both linear acceleration (adjusted R2 = 0.68; F = 140.90; p = <0.001) and angular velocity (adjusted R2 = 0.28; F = 26.52; p = <0.001). Ball 1 (lightest size 5 ball) and Ball 3 (size 4 ball) demonstrated linear head accelerations up to 59% lower (p = <0.01) when compared with Ball 4 (size 5 regulated match ball). Head acceleration during purposeful heading is influenced by changes to ball pressure, ball size and/or ball mass. Changing ball characteristics, particularly in youth football training when heading is being taught, should be an easy strategy to implement.



#6 Heading incidence in boys' football over three seasons

Reference: Sci Med Footb. 2021 Aug;5(3):175-180. doi: 10.1080/24733938.2020.1849783. Epub 2020 Nov 18.

Authors: Kerry Peek, Tim Meyer, Florian Beaudouin, Marnee McKay

Summary: The purpose was to quantify the incidence and characteristics of purposeful headers and unintentional head impacts in football (soccer) in boys' football over three seasons. This retrospective longitudinal study analysed purposeful headers and unintentional head impacts collected over three seasons (under-10 to under-12) using match video analysis from boys' team in Australia. Total headers and head impacts, as well as incidence rate (IR) per 1000 match-hours for different match characteristics, were calculated. Total number of headers and heading IR increased significantly (r = 0.99) with age from under-10 (n = 29; IR: 483) to under-12 (n = 149; IR: 1515). All but three players (87%) were observed to head the ball at least once during a season (mean: 10, range 0-25) with the accumulative number of headers performed by out-field players over three seasons ranging from 6 to 40. Players in defensive positions (n = 121) headed the ball more frequently than midfielders (n = 83) or attackers (n = 53). Five (IR: 22) unintentional head impacts were observed, of which four required medical attention. Although the number of headers performed by young players in under-10 to under-12 age groups was low, the range of headers performed by individuals varied greatly. These results could be used to guide age-specific heading coaching practices.



#7 The variability of physical match demands in elite women's football

Reference: Sci Med Footb. 2022 Jan 21;1-7. doi: 10.1080/24733938.2022.2027999. Online ahead of print.

Authors: Ivan Baptista, Andreas K Winther, Dag Johansen, Morten B Randers, Sigurd Pedersen, Svein Arne Pettersen

Summary: Peak locomotor demands are considered as key metrics for conditioning drills prescription and training monitoring. However, research in female football has focused on absolute values when reporting match demands, leading to sparse information being provided regarding the degrees of variability of such metrics. Thus, the aims of this study were to investigate the sources of variability of match physical performance parameters in female football players and to provide a framework for the interpretation of meaningful changes between matches.54 female players from four top-level clubs were monitored during one season. GPS APEX (STATSports, Northern Ireland), with a sampling frequency of 10 Hz, were used in 60 official matches (n = 393) to determine the full-match and 1-min peak locomotor demands of total distance (TD), high-speed running distance (HSRD), sprint distance (SpD), accelerations and decelerations (Acc/Dec) and peak speed (Pspeed). For each variable, the between-team, between-match, between-position, between-player, and within-player variability was estimated using linear mixed-effect modelling.With exception to SpD (29.4 vs. 31.9%), all other metrics presented a higher observed match-to-match variability in the 1-min peaks than in the full-match (6.5 vs. 4.6%; 18.7% vs. 15.9%; 12.9 vs. 11.7%; for TD, HSRD and Acc/Dec, respectively). With the exception of SpD, higher changes in 1-min peaks than in full-match values are required to identify meaningful changes in each variable.Different sources of variability seem to impact differently the match physical performance of female football players. Furthermore, to identify meaningful changes, higher changes in 1-min peaks than in full-match values are required.



#8 The effect of stroboscopic vision on performance in a football specific assessment

Reference: Sci Med Footb. 2021 Nov;5(4):317-322. doi: 10.1080/24733938.2020.1862420. Epub 2020 Dec 20.

Authors: Adam Beavan, Lars Hanke, Jan Spielmann, Sabrina Skorski, Jan Mayer, Tim Meyer, Job Fransen

Summary: This study aimed to investigate how restricted visual feedback affects performance in a football-specific skills assessment that incorporates the coupling of football a-specific perceptual information with football-specific motor actions.  The Footbonaut is a 14x14m cage equipped with 8 ball dispensers and 64 targets measuring passing accuracy and time to complete each pass. Eighty-four amateur male participants (19.5 ± 5.4 years old; 13.1 ± 6.0 years experience) completed two sessions under two different visual conditions: stroboscopic and normal vision.  A linear regression revealed that performance under normal conditions was significantly associated (p < 0.001) with the performance decrement under stroboscopic vision conditions. Players were then subdivided into skilled (S; top 25%) and less-skilled (LS; bottom 25%) groups. Restricting visual feedback impacted the average time required to complete the passes in both S and LS groups equally (S: +0.18 s; LS: + 0.12 s; p = 0.385), yet S athletes' accuracy (-11.1%) was more heavily reduced under restricted visual conditions compared to their Normal condition; whereas the LS athletes' accuracy remained relatively unchanged (-1.9%).  Therefore, stroboscopic vision may be used to induce performance errors during practice to stimulate larger training effects, particularly in more skilled players.



#9 Mental stress reduces performance and changes musculoskeletal loading in football-related movements

Reference: Sci Med Footb. 2021 Nov;5(4):323-329. doi: 10.1080/24733938.2020.1860253. Epub 2020 Dec 14.

Authors: Simon Auer, Simone Kubowitsch, Franz Süß, Tobias Renkawitz, Werner Krutsch, Sebastian Dendorfer

Summary: Football players have a high risk of leg muscle injuries, especially when exposed to mental stress. Hence, this study investigated the musculoskeletal response of elite youth football players during highly dynamic movements under stress. The hypothesis is that mental stress reduces performance and changes the muscular forces exerted. Twelve elite youth football players were subjected to mental stress while performing sports-specific change-of-direction movements. A modified version of the d2 attention test was used as stressor. The kinetics are computed using inverse dynamics. Running times and exerted forces of injury-prone muscles were analysed. The stressor runs were rated more mentally demanding by the players (p = 0.006, rs = 0.37) with unchanged physical demand (p = 0.777, rs = 0.45). This resulted in 10% longer running times under stress (p < 0.001, d = -1.62). The musculoskeletal analysis revealed higher peak muscle forces under mental stress for some players but not for others. The study shows that motion capture combined with musculoskeletal computation is suitable to analyse the effects of stress on athletes in highly dynamic movements. For the first time in football medicine, our data quantifies an association between mental stress with reduced football players' performance and changes in muscle force.



#10 Resilience as a protective factor for well-being and emotional stability in elite-level football players during the first wave of the COVID-19 pandemic

Reference: Sci Med Footb. 2021 Nov;5(sup1):62-69. doi: 10.1080/24733938.2021.1959047. Epub 2021 Jul 31.

Authors: Esben Elholm Madsen, Peter Krustrup, Carsten Hvid Larsen, Anne-Marie Elbe, Johan Michael Wikman, Andreas Ivarsson, Franziska Lautenbach

Summary: In Denmark, the first COVID-19 pandemic lockdown resulted in a compact season finisher for elite footballers, potentially impacting their mental health. This study aimed to investigate the protective role of resilience and the impeding role of trait anxiety on elite footballers' level and variability of well-being and emotional stability. One hundred and twenty-five male elite-level players (Mage = 25.04 ± 4.82) completed baseline measures on trait anxiety and resilience. Additionally, well-being and positive and negative affect were assessed before games (n = 24) over 62 days. Separate two-level regression analysis using Bayesian statistics was conducted to test potential relationships.  Results show a credible positive relationship between the average level of well-being and within-person variability over time as well as the average level in positive affect. This indicates that resilience might be a protector for mental health. In addition, higher levels of trait anxiety (i.e., subscale concentration disruption) were associated with higher levels of negative affect and higher variability over time. This indicates that trait anxiety might facilitate negative affect. No other credible relationships were found.  High resilience and low trait anxiety are identified as relevant factors for mental health within elite footballers during COVID-19. Implications for practice are discussed.



#11 The psychological impact of COVID-19 infection on athletes: example of professional male football players

Reference: Sci Med Footb. 2021 Nov;5(sup1):53-61. doi: 10.1080/24733938.2021.1933156. Epub 2021 Jun 3.

Authors: Yavuz Lima, Nevzad Denerel, Nazli Deniz Öz, Seckin Senisik

Summary: The purpose of this study was to evaluate the psychological state of professional male football players who were infected by COVID-19. The Depression Anxiety Stress Scale 21 and Kessler Psychological Distress Scale were sent to players' smartphones by sharing a link to the questionnaire. A total of 523 professional football players aged between 18-38 years from 93 different sports clubs participated in the study. The players were divided into 2 groups according to Sars-COV-2 PCR test results. Depression, anxiety, stress, and psychological distress scores of football players who were infected by COVID-19 were higher compared to players who were not infected by COVID-19 (all p < 0.001). Depression, stress, and psychological distress scores were higher for football players with higher loss of income than players with lower loss of income (p = 0.017, p = 0.007, p = 0.005, respectively). There were significant differences in anxiety, depression, and psychological distress scores in favor of the 18-22-year age group (p = 0.002, p = 0.009, p = 0.004, respectively). COVID-19 infection negatively affects the psychological states of football players. The psychological states of professional football players who were infected by COVID-19 should be monitored closely and psychological support should be provided.



#12 Exploring sports nutritionists' and players' perspectives of nutrition practice within English professional football during the COVID-19 pandemic

Reference: Sci Med Footb. 2021 Nov;5(sup1):32-37. doi: 10.1080/24733938.2021.1984559. Epub 2021 Sep 27.

Authors: Jennie L Carter, Adam L Kelly, Rachel A Williams, Tom J Ford, Matthew Cole

Summary: The outbreak of the COVID-19 pandemic, and the subsequent suspension of all football-related activity, caused significant disruption to the daily habits of professional football players and support staff. Even when the most severe restrictions were lifted, strict control measures remained in place which likely continued to impact upon nutrition support and intake of players. Thus, this study aimed to understand how restrictions impacted upon nutrition support within professional football, as well as identify how these experiences could inform future practice. Interviews were conducted with twelve sports nutritionists and twelve male professional football players to explore their perspectives of nutrition provision during the COVID-19 pandemic. Thematic analysis indicated three common outcomes: (a) Sub-optimal Nutrition Provision; (b) Reduction in Time with or Access to Players, and; (c) Adaption of Nutrition Practice and/or Dietary Habits. In sum, football clubs should consider the immediate and short-term impact of COVID-19 restrictive measures as players' transition back to normality. Specifically, clubs should provide sports nutritionists with greater capacity to control the nutrition provision, including portion size and food quality. Looking ahead, sports nutritionists are encouraged to reflect upon the novel opportunities that have emerged and consider how these may enhance long-term practice.



#13 Reference values for performance test outcomes relevant to English female soccer players

Reference: Sci Med Footb. 2022 Jan 31. doi: 10.1080/24733938.2022.2037156. Online ahead of print.

Authors: Naomi Datson, Matthew Weston, Barry Drust, Greg Atkinson, Lorenzo Lolli, Warren Gregson

Summary: The purpose of this study was to present reference standards for physical performance test outcomes relevant to elite female soccer players. We analysed mixed-longitudinal data (n = 1715 observations) from a sample of 479 elite youth and senior players as part of the English Football Association's national development programme (age range: 12.7 to 36.0 years). Semi-parametric generalized additive models for location, scale and shape (GAMLSS) estimated age-related reference centiles for 5-m sprinting, 30-m sprinting, countermovement jump (CMJ) height, and Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance. The estimated reference centiles indicated that the median of the distribution of physical performance test scores varied non-linearly with advancing chronological age, improving until around 25 years for each performance variable. These are the first reference ranges for performance test outcomes in elite English female soccer players. These data can assist practitioners when interpreting physical test performance outcomes to track an individual's progress over time and support decision making regarding player recruitment and development.



#14 Apophysitis Among Male Youth Soccer Players at an Elite Soccer Academy Over 7 Seasons

Reference: Orthop J Sports Med. 2022 Jan 20;10(1):23259671211065063. doi: 10.1177/23259671211065063. eCollection 2022 Jan.

Authors: Mindaugas Gudelis, Luis Til Perez, Javier Trujillano Cabello, Daniel Medina Leal, Mauricio Monaco, Dai Sugimoto

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Summary: Apophyseal injuries are common in children and adolescent athletes. These injuries are believed to be caused by repetitive overloading, which can create inflammatory and degenerative conditions in growing bone prominences. However, their prevalence, diagnosis, and treatment in young soccer players have been understudied. The purpose was to evaluate characteristics of apophyseal injuries in adolescent athletes at an elite soccer academy. All apophyseal injuries between July 2008 and June 2015 were evaluated. For each injury, the authors recorded the type and location, age of the player, injury date, imaging modalities, and time absent from training/competition. Over the 7 seasons of this study, 210 apophyseal injuries were documented, including 172 simple apophyseal injuries and 38 apophyseal avulsion fractures. The rate of apophyseal injuries was 0.35 per 1000 hours of training exposure. A total of 196 (93.3%) cases were primary injuries, and the rest (6.7%) were reinjuries. Ultrasonography was the most commonly used imaging modality for diagnosis (172 cases; 81.9%). The most common location of apophyseal injuries was the anterior inferior iliac spine (AIIS). Return to sport was faster in athletes with apophyseal injury at the ischiopubic ramus, those with simple apophyseal injuries, and younger athletes. The most common location for apophyseal injury among soccer players was the AIIS. Return to training and competition differed according to injury location, type of apophyseal injury, and age.



#15 Depression in Collegiate Runners and Soccer Players: Relationships with Serum 25-Hydroxyvitamin D, Ferritin, and Fractures

Reference: Int J Exerc Sci. 2021 Sep 1;14(5):1099-1111. eCollection 2021.

Authors: Devin Tomlinson, Evan Eschker, Jade Callan, Tamara Hewbutler

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Summary: The main purpose of this study was to evaluate relationships between depression versus serum 25-hydroxyvitamin D (vitamin D), serum ferritin (ferritin), and fractures across a competitive season. The authors conducted a prospective observational study (both pre- and post-season testing) on 51 collegiate soccer and cross-country athletes from a Midwest University. Our main outcome measure was depression, measured using the Center for Epidemiological Studies Depression Scale (CES-D). A CES-D score ≥ 16 represented the threshold value for clinical depression. Secondary outcome variables included vitamin D, ferritin, and fractures. Two athletes (3.9%; one female) pre-season while seven athletes (13.7%; five females) post-season demonstrated clinically relevant depression (CES-D score ≥ 16). Depression scores increased from pre- to post-season (6.0 to 8.9; p = 0.009; effect size = 0.53; n = 51). A medium effect noted for depressed athletes vs. non-depressed athletes (n = 7; post-season) to have lower pre-season serum vitamin D (38.4 vs. 50.2 ng/ml; p = 0.15; effect size = 0.68) with a small overall correlation effect (r = -0.08; p = 0.58). A medium correlation effect was noted between post-season ferritin vs. depression scores (r = -0.45; p = 0.01) in the female cohort only. Six athletes (11.8%) sustained fractures and had lower depression scores vs. non-injured athletes (4 vs. 10; p = 0.04; effect size = 1.08) post-season. Depression scores increased over a competitive season, especially in females. Small correlation effects were observed between depression and vitamin D. A medium correlation effect was noted between depression and low ferritin levels, in female athletes only. A large effect was noted between athletes sustaining fractures during the season and depression, post-season, with injured athletes being less depressed than non-injured athletes.



#16 No independent or synergistic effects of carbohydrate-caffeine mouth rinse on repeated sprint performance during simulated soccer match play in male recreational soccer players

Reference: Sci Med Footb. 2022 Jan 31;1-9. doi: 10.1080/24733938.2021.2021277. Online ahead of print.

Authors: Lewis A Gough, Mark Faghy, Neil Clarke, Adam L Kelly, Matthew Cole, Wee Lun Foo

Summary: The study examined the synergistic and independent effects of carbohydrate-caffeine mouth rinse on repeated sprint performance during simulated soccer match play. Nine male soccer players (21 ± 3 years, 1.75 ± 0.05 m, 68.0 ± 9.0 kg) completed four trials with either 6 mg·kg-1 caffeine + 10% maltodextrin (CHO+CAFMR), 6 mg·kg-1 caffeine (CAFMR), 10% maltodextrin (CHOMR), water (PLA) in a block randomised, double-blinded, counterbalanced and crossover manner separated by minimum 96 h. All solutions were taste-matched and a carbohydrate-rich meal (2 g·kg-1body mass) was provided 2 h before each trial. Each trial consisted of a 90-min soccer-specific aerobic field test (SAFT90) and two bouts of repeated sprint ability tests (RSAT; 6 × 6 s sprints with 24 s recovery) completed at 0 min and 75th min of SAFT90. A 25 ml solution of either CHO+CAFMR, CAFMR, CHOMR or PLA was rinsed immediately before the second RSAT (75 min). Mean power output, peak power output (PPO) or fatigue index (FI) was not impacted by any treatment during the 75th min RAST (p > 0.05). These results suggest that carbohydrate and/or caffeine mouth rinses do not have an ergogenic effect during simulated soccer exercise after a high carbohydrate meal.



#17 Use of GPS to measure external load and estimate the incidence of muscle injuries in men's football: A novel descriptive study

Reference: PLoS One. 2022 Feb 4;17(2):e0263494. doi: 10.1371/journal.pone.0263494. eCollection 2022.

Authors: Marc Guitart, Martí Casals, David Casamichana, Jordi Cortés, Francesc Xavier Valle, Alan McCall, Francesc Cos, Gil Rodas

Summary: Measurement of external load in players provides objective information to optimise the weekly balance between training and recovery to improve performance and prevent injuries. Our aim was to evaluate the incidence of sports-related muscle injuries of the lower limb in relation to external load, measured by global positioning system (GPS), in football players. A descriptive study was carried out. Data were collected from 71 professional male football players (30 professionals and 41 youth players) from an elite football club competing in the Spanish and European League in the 2017-2018 season. As external load variables, we measured High Metabolic Load Distance (HMLD), High Speed Running (HSR), Player Load (PL), and Total Distance (TD) through GPS. Injury rate (IR) was calculated both in relation to such GPS load metrics and to load exposure time. We considered categories (youth and professional), playing positions (centre back, full back, midfielder, and forward), and training day with respect to match-day (-4MD, -3MD, -2MD, -1MD, MD, +1MD, +2MD). The GPS load metrics HMLD, HSR, PL, and TD showed very similar patterns across categories and positions, but varied according to training session or MD. The highest loads were observed on MD and three days prior to the match (-3MD). Similarly, the overall IR, both calculated per load exposure time and per GPS load metrics, was highest on MD and -3MD. Again, no differences were observed between youth and professional players. Midfielders demonstrated the highest IR in all metrics, followed by the forwards. In conclusion, this study suggests that external load and incidence of muscle injuries are directly proportional. Therefore, the measurement of more external load variables other than load exposure time, such as the GPS metrics HMLD, HSR, PL, and TD may help to describe the pattern and magnitude of injuries. Future studies based on ours may help to further improve the understanding of the incidence of muscle injuries on the basis of external loads measurements in different football teams.



#18 Assessment of changes in blood lactate levels in children and adolescents with type 1 diabetes during a football tournament (GoalDiab Study)

Reference: Pediatr Endocrinol Diabetes Metab. 2021;27(4):237-244. doi: 10.5114/pedm.2021.109272.

Authors: Justyna Flotyńska, Andrzej Gawrecki, Aleksandra Araszkiewicz, Mikołaj Parchimowicz, Marcin Michalski, Olga Różańska, Marta Stopczyńska-Szymecka, Mikołaj Kamiński, Aleksandra Cieluch, Grzegorz Biegański, Arkadiusz Michalak, Katarzyna Domaszewska, Dorota Zozulińska-Ziółkiewicz

Summary: Monitoring physical activity is a very important issue, especially in type 1 diabetes. One of the parameters assessing the intensity of exercise is the concentration of lactate in the blood. Aim of the study We assessed the intensity of PE and changes in lactate levels in children and adolescents with type 1 diabetes (T1D) during a football tournament. We enrolled 141 participants, the results of 70 of whom were analyzed, playing in two age categories: 10-13 and 14-17 years. Lactate levels were measured in the capillary blood before and after matches. Blood lactate of 4 mmol/l (Onset Blood Lactate Accumulation OBLA) was used as parameter indicating the prevalence of anaerobic metabolic changes. The median lactate level was 1.8 mmol/l before and 4.4 mmol/l after matches (p < 0.001). The increase in lactate levels was higher in the older age category (4.3 vs. 1.8, p = 0.001) and was independent on gender (3.2 vs. 2.1, p = 0.597), personal insulin pump vs insulin pen use (3.0 vs. 1.5, p = 0.145) or training in a sports club (1.4 vs. 3.0, p = 0.084). A positive correlation was noted between increased lactate levels and age (Rs = 0.253, p = 0.034). 61% of the participants exceeded lactate levels ≥ 4 mmol/l. In univariate logistic regression analysis age was a significantly associated with lactate level ≥ 4 mmol/l [OR = 1.45 (1.08-1.95)] independent of HbA1c, gender, treatment method and training in a sports club. PE intensity levels during football matches were found to be mixed aerobic-anaerobic. Increases in lactate levels were greater in the older subjects independently on the assessed factors.


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