Latest research in football - week 22 - 2023

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 Acute Rupture of the Plantar Fascia in a Soccer Player

Reference: Cureus. 2023 May 4;15(5):e38527. doi: 10.7759/cureus.38527. eCollection 2023 May.

Authors: Diogo Costa, Patrícia Cruz, Rui Brito, Pedro Cantista, Sérgio Rodrigues-Gomes

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Summary: Acute rupture of the plantar fascia is a rare but potentially debilitating injury in athletes, particularly those involved in running and jumping sports. Early recognition and prompt treatment are crucial for a successful recovery and return to play. Conservative treatment, including rest, immobilization, and physical therapy, may be effective in most cases, while surgical intervention may be required in those that are nonresponsive to conservative treatment. We report a case of plantar fascia rupture in a 22-year-old male semi-professional football player who presented with sudden severe pain in the sole of his right foot during a match, followed by a popping sensation and inability to weight bear. The athlete was healthy and had no history of previous injury in the right foot. MRI confirmed a complete rupture of the plantar fascia. The player was treated conservatively and underwent a rehabilitation program. The player returned to full competition after nine weeks, with no limitations.



#2 Creating an Optimal Learning Environment in the Operating Room: Lessons From the Soccer Field

Reference: J Surg Educ. 2023 Jun 3;S1931-7204(23)00161-7. doi: 10.1016/j.jsurg.2023.05.002.

Authors: Kathryn T Chen, Sharmila Dissanaike, Christian de Virgilio

Summary: For trainees, the operating room (OR) often represents an educational sanctuary, where for a few hours they can focus on their craft, rather than on phone calls, pages, and the never-ending task of electronic health record documentation. The OR provides a unique opportunity for unfettered one-on-one time with an attending surgeon at their side, where they can learn the art of surgery without interruption. It is vitally important to maximize learning in the OR, yet evidence suggests that it is not always an ideal educational environment. Considering the recent excitement over the World Cup soccer tournament (full disclosure: the senior author is an Argentine immigrant and soccer fan), in this article, we provide evidence-based ideas and suggestions on how to optimize learning in the OR using some analogies from the soccer field.



#3 Determining the capacity for effort and recovery of the elite soccer players specialized in different playing positions

Reference: PeerJ. 2023 May 29;11:e15477. doi: 10.7717/peerj.15477. eCollection 2023.

Authors: Liliana Mihailescu, Paul Bogdan Chiriac, Liviu Emanuel Mihailescu, Veaceslav Manolachi, Vladimir Potop

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Summary: The capacity for effort and recovery in performance sports can be increased by means of modern methodological strategies. This capacity to recover after intense matches and training helps to determine the performance in soccer. Using the Yumeiho technique will accelerate the exercise capacity recovery of the soccer players specialized in central zone positions. The research was conducted with the C.S. Internațional Bălești team, formed of 16 players, aged 19-37 years, divided into two groups: experimental group A, n = 8 with central area players and control group B, n = 8 with players from side zones. Measurement and assessment tests: determining lactic acid level (LAC) in blood; 60 m sprinting speed motor test (ST); anaerobic lactic exercise; Gacon Test for evaluating the aerobic power; VO2max test; Dorgo Test for determining the individual recovery capacity; Sleep Quality and Efficiency Index (PSQI) and sleep duration. Means used in the recovery strategy: easy running, static stretching, cryotherapy; Yumeiho therapy was applied only to group A to accelerate the recovery. The anaerobic lactic capacity was evaluated by 60 m sprint test at the beginning and the end of the research. The results highlight the increase of the sprinting speed by 0.08 s in group A (p < 0.001). The aerobic capacity evaluated by means of Gacon Test in both groups shows the value 23.7%, namely a well-prepared level (p < 0.001). VO2max value in the soccer players of group A shows 87.5% good aerobic power, while the players of group B have 50% good aerobic power (p < 0.001). The concentration of LAC after exercise has a higher value in group A (p > 0.05). The level of recovery after exercise is improved in both groups, with larger differences in group A (very good level, p < 0.001). The PSQI grew by 20.37% in group A and by 11% in group B. The sleep duration increased in both groups (p < 0.001). The results of the correlation analysis in the soccer players of group A highlight strong connections of 14.8% while in group B the value is 12.5%. The assessment of effort capacity in soccer players specialized in different playing positions at the beginning and the end of the research highlights the increase of the anaerobic lactic effort and aerobic effort. This assessment also shows the improvement of the individual recovery capacity. A higher PSQI and the increase of sleep duration in both groups, with greater differences of group A were found, which determined their level of capacity for effort and recovery. The use of the Yumeiho technique in the program of post-exercise recovery accelerates the aerobic and anaerobic lactic effort capacity of the soccer players specialized in the central zone positions. It positively influences exercise capacity recovery in general.



#4 Acute locomotor, heart rate and neuromuscular responses to added wearable resistance during soccer specific training

Reference: Sci Med Footb. 2023 Jun 5. doi: 10.1080/24733938.2023.2222100. Online ahead of print.

Authors: Matthew Brown, Mathieu Lacome, Cedric Leduc, Karim Hader, Gael Guilhem, Martin Buchheit

Summary: Investigate acute locomotor, internal (heart rate (HR) and ratings of perceived exertion (RPE)) and neuromuscular responses to using wearable resistance loading for soccer-specific training. Twenty-six footballers from a French 5th division team completed a 9-week parallel-group training intervention (intervention group: n = 14, control: n = 12). The intervention group trained with wearable resistance (200-g on each posterior, distal-calf) for full-training sessions on Day + 2, D + 4 and unloaded on D + 5. Between-group differences in locomotor (GPS) and internal load were analyzed for full-training sessions and game simulation drills. Neuromuscular status was evaluated using pre- and post-training box-to-box runs. Data were analyzed using linear mixed-modelling, effect size ± 90% confidence limits (ES ± 90%CL) and magnitude-based decisions. Full-training sessions: Relative to the control, the wearable resistance group showed greater total distance (ES [lower, upper limits]: 0.25 [0.06, 0.44]), sprint distance (0.27 [0.08, 0.46]) and mechanical work (0.32 [0.13, 0.51]). Small game simulation (<190 m2/player): wearable resistance group showed small decreases in mechanical work (0.45 [0.14, 0.76]) and moderately lower average HR (0.68 [0.02, 1.34]). Large game simulation (>190 m2/player): no meaningful between-group differences were observed for all variables. Training induced small to moderate neuromuscular fatigue increases during post-training compared to pre-training box-to-box runs for both groups (Wearable resistance:0.46 [0.31, 0.61], Control:0.73 [0.53, 0.93]). For full training, wearable resistance induced higher locomotor responses, without affecting internal responses. Locomotor and internal outputs varied in response to game simulation size. Football-specific training with wearable resistance did not impact neuromuscular status differently than unloaded training.



#5 Recovery of kicking kinematics and performance following repeated high-intensity running bouts in the heat: Can a rapid local cooling intervention help young soccer players?

Reference: J Sports Sci. 2023 Jun 6;1-11. doi: 10.1080/02640414.2023.2220194. Online ahead of print.

Authors: Luiz H Palucci Vieira, Christopher Carling, Carlos A Kalva-Filho, Felipe B Santinelli, Lorenzo A G Velluto, João Pedro da Silva, Filipe M Clemente, Eleftherios Kellis, Fabio A Barbieri

Summary: The effects of a cooling strategy following repeated high-intensity running (RHIR) on soccer kicking performance in a hot environment (>30ºC) were investigated in youth soccer players. Fifteen academy under-17 players participated. In Experiment 1, players completed an all-out RHIR protocol (10×30 m, with 30s intervals). In Experiment 2 (cross-over design), participants performed this running protocol under two conditions: (1) following RHIR 5 minutes of cooling where ice packs were applied to the quadriceps/hamstrings, (2) a control condition involving passive resting. Perceptual measures [ratings of perceived exertion (RPE), pain and recovery], thigh temperature and kick-derived video three-dimensional kinematics (lower limb) and performance (ball speed and two-dimensional placement indices) were collected at baseline, post-exercise and intervention. In Experiment 1, RHIR led to small-to-large impairments (p < 0.03;d = -0.42--1.83) across perceptual, kinematic and performance measures. In experiment 2, RPE (p < 0.01; Kendall's W = 0.30) and mean radial error (p = 0.057; η2 = 0.234) increased only post-control. Significant small declines in ball speed were also observed post-control (p < 0.05; d = 0.35). Post-intervention foot centre-of-mass velocity was moderately faster in the cooling compared to control condition (p = 0.04; d = 0.60). In youth soccer players, a short cooling period was beneficial in counteracting declines in kicking performance, in particular ball placement, following intense running activity in the heat.



#6 Mixed Training Programs Applied to Young Soccer Players: Effects on Speed-Power Abilities

Reference: Int J Sports Med. 2023 Jun 6. doi: 10.1055/a-2106-8164. Online ahead of print.

Authors: Tomás T Freitas, Lucas A Pereira, Pedro E Alcaraz, Paulo H S M Azevedo, Vinicius Zanetti, Nuno B Pantarotto, Valter P Reis, Ian Jeffreys, Irineu Loturco

Summary: We compared the effects of two 4-week strength-power-speed training protocols on physical performance of young soccer players. Twenty-three highly-trained under-20 soccer players were randomly allocated to two mixed-training groups: 1) "traditional" (TRAD: n=11), comprising vertically-oriented strength-power exercises and linear sprints; or 2) "multidirectional" (MULTI: n=12), combining vertically- and horizontally-oriented strength-power exercises, linear sprints, and change-of-direction (COD) drills. Squat jump (SJ) and countermovement jump, 2) linear sprint, COD speed, and 3) jump-squat (JS) and hip-thrust (HT) power tests were performed pre- and post-training. Differences were determined using a two-way ANOVA with repeated measures and "target scores" were used to detect real changes in performance. No group-time interactions were found for any of the variables (p>0.05). Significant increases (p<0.05) in 20-m sprint velocity, JS- and HT-power were found in both groups, and in SJ in TRAD. Individual analyses revealed a greater number of meaningful changes in Zigzag velocity in MULTI while most players in TRAD displayed meaningful increases in SJ height. In conclusion, both training protocols resulted in similar adaptations but, at the individual level, it appears that MULTI protocol is superior to improve COD ability while TRAD should be preferred to maximize vertical jumping capabilities during short soccer pre-seasons.



#7 Cognitive Impairment and Self-Reported Dementia in UK Retired Professional Soccer Players: A Cross Sectional Comparative Study

Reference: Sports Med Open. 2023 Jun 8;9(1):43. doi: 10.1186/s40798-023-00588-2.

Authors: Tara-Mei Povall Macnab, Shima Espahbodi, Eef Hogervorst, Ahmed Thanoon, Gwen Sascha Fernandes, Bonnie Millar, Ashley Duncan, Maria Goodwin, Mark Batt, Colin W Fuller, Gordon Fuller, Eamonn Ferguson, Tobias Bast, Michael Doherty, Weiya Zhang

Summary: Previous studies based on death certificates have found professional soccer players were more likely to die with neurodegenerative diseases, including dementia. Therefore, this study aimed to investigate whether retired professional male soccer players would perform worse on cognitive tests and be more likely to self-report dementia diagnosis than general population control men. A cross-sectional comparative study was conducted between August 2020 and October 2021 in the United Kingdom (UK). Professional soccer players were recruited through different soccer clubs in England, and general population control men were recruited from the East Midlands in the UK. We obtained self-reported postal questionnaire data on dementia and other neurodegenerative diseases, comorbidities and risk factors from 468 soccer players and 619 general population controls. Of these, 326 soccer players and 395 general population controls underwent telephone assessment for cognitive function. Retired soccer players were approximately twice as likely to score below established dementia screening cut-off scores on the Hopkins Verbal Learning Test (OR 2.06, 95%CI 1.11-3.83) and Verbal Fluency (OR 1.78, 95% CI 1.18-2.68), but not the Test Your Memory, modified Telephone Interview for Cognitive Status, and Instrumental Activities of Daily Living. Analyses were adjusted for age, education, hearing loss, body mass index, stroke, circulatory problems in the legs and concussion. While retired soccer players were younger, had fewer cardiovascular diseases and other morbidities and reported healthier lifestyles, 2.8% of retired soccer players reported medically diagnosed dementia and other neurodegenerative disease compared to 0.9% of controls (OR = 3.46, 95% CI 1.25-9.63) after adjustment for age and possible confounders. UK male retired soccer players had a higher risk of performing below established cut-off scores of dementia screening tests and were more likely to self-report medically diagnosed dementia and neurodegenerative diseases, despite having better overall physical health and fewer dementia risk factors. Further study is needed to determine specific soccer-related risk factors.



#8 The Association of Age and Sex With Joint Angles and Coordination During Unanticipated Cutting in Soccer Players

Reference: Motor Control. 2023 Jun 8;1-18. doi: 10.1123/mc.2022-0130. Online ahead of print.

Authors: Shawn M Robbins, Yuri Lopes Lima, Harry Brown, Moreno Morelli, David J Pearsall, Marco Bühler, Anouk Lamontagne

Summary: Deficits in movement patterns during cutting while running might place soccer players at risk of injury. The objective was to compare joint angles and intersegment coordination between sexes and ages during an unanticipated side-step cutting task in soccer players. This cross-sectional study recruited 11 male (four adolescents and seven adults) and 10 female (six adolescents and four adults) soccer players. Three-dimensional motion capture was used to measure lower-extremity joint and segment angles as participants performed an unanticipated cutting task. Hierarchical linear models examined relationships between joint angle characteristics with age and sex. Continuous relative phase was used to quantify intersegment coordination amplitude and variability. These values were compared between age and sex groups using analysis of covariance. Adult males had greater hip flexion angle excursions than adolescent males, while adult females had smaller excursions than adolescent females (p = .011). Females had smaller changes in hip flexion angles (p = .045), greater hip adduction angles (p = .043), and greater ankle eversion angles (p = .009) than males. Adolescents had greater hip internal rotation (p = .044) and knee flexion (p = .033) angles than adults, but smaller changes in knee flexion angles at precontact compared with stance/foot off (p < .001). For intersegment coordination, females were more out-of-phase than males in the foot/shank segment in the sagittal plane. There were no differences in intersegment coordination variability between groups. Differences in joint motion during an unanticipated cutting task were present between age groups and sexes. Injury prevention programs or training programs may be able target specific deficits to lower injury risk and improve performance.



#9 Positional Differences in Absolute vs. Relative Training Loads in Elite Academy Soccer Players

Reference: J Sports Sci Med. 2023 Jun 1;22(2):317-328. doi: 10.52082/jssm.2023.317. eCollection 2023 Jun.

Authors: Tom Douchet, Christos Paizis, Hugo Roche, Nicolas Babault

Summary: Weekly training loads are typically reported using absolute values and are not individualized according to competition positional demands (relative values). The aim of this study was to evaluate absolute and relative training loads and compare across playing positions during a full in-season in an elite soccer academy. 24 elite academy soccer players, categorized into five positions (CD: central defender [n = 4]; FB: full back [n = 5]; CM: central midfielder [n = 6]; WM: wide midfielder [n = 5]; FW: forward [n = 4]), were monitored using a global positioning system. Absolute training load was calculated using the total distance, the distance at moderate-speed ([15-20[ km·h-1), high-speed ([20-25[ km·h-1), sprint (> 25 km·h-1), the total number of accelerations (> 3 m·s-2) and decelerations (< -3 m·s-2). Relative training load was calculated by dividing absolute training loads by mean values from the competitive matches. Training loads were determined daily according to their distance from match day (MD). One-way ANOVAs were performed to evaluate differences between playing positions. Absolute moderate-speed distance was greater for WM compared to CD (p = 0.015, and p = 0.017), while the opposite was shown for relative values (p = 0.014, and p < 0.001) on MD-4 and MD-3, respectively. The absolute moderate-speed distance was not different between CD, FB, CM, and FW, whereas relative values were greater for CD on MD+2 and MD-4 (p < 0.05). FB and WM performed greater absolute high-speed distance than CD on MD-4 and MD-3 (p < 0.05) while no difference was highlighted for relative values.Our results demonstrated that in the present academy players, training load for CD was underestimated using absolute training loads for moderate and high-speed distances. In contrast, relative training loads highlighted WM as an underloaded position. Therefore, relative training loads are recommended as they contextualize training loads according to competitive demands and favor training individualization.



#10 Effectiveness of Vertical versus Horizontal Plyometric Training on Stretch-Shortening Cycle Performance Enhancement in Adolescent Soccer Players

Reference: Healthcare (Basel). 2023 Jun 1;11(11):1615. doi: 10.3390/healthcare11111615.

Authors: Cem Kurt, Umut Canli, Sadullah Erdal Erdaş, Luca Poli, Roberto Carvutto, Stefania Cataldi, Francesco Fischetti, Gianpiero Greco

Summary: Plyometric exercise is a major tool for improving explosive actions. This study aimed to compare the efficacy of a vertical and horizontal plyometric training program on stretch-shortening performance variables in adolescent soccer players. Thirty-two male soccer players (aged 12.09 ± 0.89 years, with soccer experience 5.37 ± 1.58 years) were divided into horizontal plyometric, vertical plyometric, or control groups. The horizontal and vertical plyometric groups participated in a 6-week training program that was performed twice per week, with a 48-h interval, in conjunction with regular soccer training. The control group participated only in regular soccer training. Vertical jump height, reactive strength index, leg stiffness, ground contact time, standing long jump distance, agility, and 10 and 20 m sprint performances were tested as stretch-shortening performance variables of the participants. Stretch-shortening performance variables were assessed before and after completion of the training program. The results showed that either horizontal or vertical plyometric training had no effect on VJH, RSI, GCT, or Kleg performance (F = 2.14, 1.32, 0.66, 1.03; p > 0.05). Furthermore, there was no effect on SLJ, 10 m sprint, 20 m sprint, or agility performance (F = 2.06, 0.14, 0.06, 0.27; p > 0.05). A 6-week horizontal or vertical plyometric intervention was found to be insufficient to elicit stretch-shortening performance enhancement in adolescent male soccer players. Although there was no performance change in any group, it was observed that the players enjoyed plyometric training. Therefore, coaches could safely use plyometric exercises to design enjoyable training programs.



#11 Rehabilitation of a lateral ankle reconstruction in a male professional football player - A narrative case report

Reference: Phys Ther Sport. 2023 Jun 1;62:32-38. doi: 10.1016/j.ptsp.2023.05.004. Online ahead of print.

Authors: Isaac Leckie, Luke Thomas, Richard Weiler

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Summary: Lateral ankle sprains involving the ATFL and CFL are common injuries in football with a high recurrence rate. There is a lack of research to guide post-operative rehabilitation of football players following lateral ligament ankle reconstructive surgery. This narrative case report discusses the management of a lateral ligament reconstruction in a male professional football player. A 25-year-old professional footballer underwent a lateral ankle reconstruction following recurrent lateral ankle sprains leading to an unstable ankle. Following 11-weeks of rehabilitation the player was cleared to return to full-contact training. The player competed in his first competitive match 13-weeks post-injury and completed a 6-month full-training block, without episodes of pain or instability. This case report illustrates the rehabilitation process of a football player following a lateral ankle ligament reconstruction within a timeframe expected in elite sport.



#12 How much does it cost to implement a community-based walking football programme for patients with type 2 diabetes?

Reference: BMJ Open Sport Exerc Med. 2023 Jun 7;9(2):e001549. doi: 10.1136/bmjsem-2023-001549. eCollection 2023.

Authors: Ana Barbosa, João Brito, Pedro Figueiredo, André Seabra, Ding Ding, Romeu Mendes

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Summary: The current study analysed the implementation costs of a community-based walking football exercise programme for patients with type 2 diabetes. The direct costs of a community-based walking football programme for middle-aged and older male patients with type 2 diabetes, designed and tested in Porto (Portugal), were calculated from the payer's perspective. One season of this programme consists of three sessions per week (60 min per session) for nine months (October to June). Cost calculations were based on two groups of 20 patients and included the sports infrastructure and equipment, human resources, pre-exercise clinical evaluation, medical equipment, technical training and other consumable costs. An economic depreciation of 1 year using the linear method for sports and electronic materials was considered. Cost analysis dated December 2021 and is expressed in international dollars ($).This programme was estimated to have a total implementation cost of $22 923.07; $2547.01/month; $573.08/patient; $106.13/session; $63.68/patient/month and $5.31/patient/session. A community-based walking football programme for patients with type 2 diabetes is affordable and can be scaled up by local communities to promote physical activity and manage type 2 diabetes with the involvement of multiple stakeholders such as the football clubs, municipalities and primary healthcare units.



#13 Football players' strength training method using image processing based on machine learning

Reference: PLoS One. 2023 Jun 16;18(6):e0287433. doi: 10.1371/journal.pone.0287433. eCollection 2023.

Authors: Xiaoxiang Cao, Xiaodong Zhao, Huan Tang, Nianchun Fan, Fateh Zereg

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Summary: This work addresses the declining physical fitness levels observed in both football players and the general population. The objective is to investigate the impact of functional strength training on the physical capabilities of football players and to develop a machine learning-based approach for posture recognition. A total of 116 adolescents aged 8 to 13 participating in football training are randomly assigned to either an experimental group (n = 60) or a control group (n = 56). Both groups underwent 24 training sessions, with the experimental group engaging in 15-20 minutes of functional strength training after each session. Machine learning techniques, specifically the backpropagation neural network (BPNN) in deep learning, are utilized to analyze the kicking actions of football players. Movement speed, sensitivity, and strength are employed as input vectors for the BPNN to compare the images of players' movements, while the similarity between the kicking actions and standard movements served as the output result to enhance training efficiency. The experimental group's kicking scores are compared to their pre-experiment scores, demonstrating a statistically significant improvement. Moreover, statistically significant differences are observed in the 5*25m shuttle running, throwing, and set kicking between the control and experimental groups. These findings highlight the significant enhancement in strength and sensitivity achieved through functional strength training in football players. The results contribute to the development of training programs for football players and the overall improvement of training efficiency.



#14 The side hop test: Validity, reliability, and quality aspects in relation to sex, age and anterior cruciate ligament reconstruction, in soccer players

Reference: Phys Ther Sport. 2023 Jun 3;62:39-45. doi: 10.1016/j.ptsp.2023.05.008. Online ahead of print.

Authors: Anne Fältström, Martin Hägglund, Henrik Hedevik, Hanna Lindblom, Joanna Kvist

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Summary: To study the side hop test regarding validity, reliability, and quality in relation to sex, age and ACL-reconstruction in soccer players. 117 females with a primary ACL-reconstruction, and 119 females, 46 males (age 16-26 years), 49 girls and 66 boys (age 13-16 years) without injury participated in this study. For convergent validity, one physiotherapist analysed side hops live and later on video. One physiotherapist and two physiotherapy students analysed side hops from 92 players for interrater reliability (video). For intrarater reliability, side hops from 35 players were analysed twice (video). Quality aspects (flaws), i.e. number of times the hopping limb touched the strips, the non-hopping limb touched the floor, and double hops/foot turns with the hopping limb, were registered (video). Convergent validity was excellent; the intraclass correlation coefficient (ICC) was 0.93-1.0. All reliability measures were excellent (ICC 0.92-1.0). Adult male players had fewest and girls had most flaws, especially double hops/foot turns with the hopping limb, compared with all other players (mean, 11-12 vs 1-6, η2 = 0.18, large effect size). No differences were reported between knee-healthy and ACL-reconstructed females. The side hop test is valid and reliable. Quality aspects differ between sexes and ages.



#15 Energy expenditure during training and official league match in professional female soccer players - a pilot study

Reference: Rocz Panstw Zakl Hig. 2023;74(2):143-150. doi: 10.32394/rpzh.2023.0253.

Authors: Hubert Dobrowolski, Dariusz Włodarek

Summary: The most important component of a well-balanced diet is the proper energetic value. However, adequate estimation of the body's energy needs is difficult for professional athletes, including soccer players. There is little research showing energy expenditure during training and lack of studies on the energy expenditure of professional female soccer players during a match. The aim of our study was to estimate energy expenditure during training and official league match in female soccer players and comparing it. Seven Polish professionally practicing soccer females (23.4±6,6 years old; 63.5±7.8 kg; 168.5±5.8 cm; 46±4.4 kg fat-free mass) participated in the study. The participants had their height and body mass measured. Energy expenditure during activities was measured by means of a SenseWear Pro3 Armband device. Body composition was assessed with Akern BIA 101 Anniversary Sport Edition device. Statistically higher energy expenditure was achieved in the study group during the match hour (452±55 kcal/hour) compared to the training hour (353±28 kcal/ hour) as well as in the case of energy expenditure per hour of activity per kg of fat-free mass (match: 9.94±1.75 kcal/kg fat-free mass/hour; training: 7.71±0.8 kcal/kg fat-free mass/hour). During one hour of training, more time was spent on sedentary, light, and moderate activities, but the difference was statistically significant only for light activities. More time during the match hour than during the training hour was spent on vigorous and very vigorous activities. In conclusion, the energy expenditure of the players during the match was greater than in the case of the planned intensive training, which was caused by the timeshare of more intense physical activities and going a longer distance during match.



#16 Single leg drop jump is affected by physical capacities in male soccer players following ACL reconstruction

Reference: Sci Med Footb. 2023 Jun 14. doi: 10.1080/24733938.2023.2225481. Online ahead of print.

Authors: Luca Maestroni, Anthony Turner, Konstantinos Papadopoulos, Jason Pedley, Vasileios Sideris, Paul Read

Summary: Single leg drop jump (SLDJ) assessment is commonly used during the later stages of rehabilitation to identify residual deficits in reactive strength but the effects of physical capacity on kinetic and kinematic variables in male soccer players following ACL reconstruction remains unknown. Isokinetic knee extension strength, kinematics from an inertial measurement unit 3D system and SLDJ performance variables and mechanics derived from a force plate were measured in 64 professional soccer players (24.7 ± 3.4 years) prior to return to sport (RTS). SLDJ between-limb differences were measured (part 1) and players were divided into tertiles based on isokinetic knee extension strength (weak, moderate and strong) and reactive strength index (RSI) (low, medium and high) (part 2). Moderate to large significant differences between the ACL reconstructed and uninjured limb in SLDJ performance (d = 0.92- 1.05), kinetic (d = 0.62- 0.71) and kinematic variables (d = 0.56) were evident. Stronger athletes jumped higher (p = 0.002; d = 0.85), produced greater concentric (p = 0.001; d = 0.85) and eccentric power (p = 0.002; d = 0.84). Similar findings were present for RSI, but the effects were larger (d = 1.52- 3.84). Weaker players, and in particular those who had lower RSI, displayed landing mechanics indicative of a 'stiff' knee movement strategy. SLDJ performance, kinetic and kinematic differences were identified between-limbs in soccer players at the end of their rehabilitation following ACL reconstruction. Players with lower knee extension strength and RSI displayed reduced performance and kinetic strategies associated with increased injury risk.



#17 Genomic Epidemiology of a Severe Acute Respiratory Syndrome Coronavirus 2 Outbreak in a US Major League Soccer Club: Was It Travel Related?

Reference: Open Forum Infect Dis. 2023 May 5;10(6):ofad235. doi: 10.1093/ofid/ofad235. eCollection 2023 Jun.

Authors: Ludy R Carmola, Jacquelyn Turcinovic, Garrison Draper, David Webner, Margot Putukian, Holly Silvers-Granelli, Andrei Bombin, Bradley A Connor, Kristina M Angelo, Phyllis Kozarsky, Michael Libman, Ralph Huits, Davidson H Hamer, Jessica K Fairley, John H Connor, Anne Piantadosi, Daniel L Bourque

Summary: Professional soccer athletes are at risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). United States Major League Soccer (MLS) uses protocol-based SARS-CoV-2 testing for identification of individuals with coronavirus disease 2019. Per MLS protocol, fully vaccinated players underwent SARS-CoV-2 real-time polymerase chain reaction testing weekly; unvaccinated players were tested every other day. Demographic and epidemiologic data were collected from individuals who tested positive, and contact tracing was performed. Whole genome sequencing (WGS) was performed on positive specimens, and phylogenetic analyses were used to identify potential transmission patterns. In the fall of 2021, all 30 players from 1 MLS team underwent SARS-CoV-2 testing per protocol; 27 (90%) were vaccinated. One player who had recently traveled to Africa tested positive for SARS-CoV-2; within the following 2 weeks, 10 additional players and 1 staff member tested positive. WGS yielded full genome sequences for 10 samples, including 1 from the traveler. The traveler's sample was Delta sublineage AY.36 and was closely related to a sequence from Africa. Nine samples yielded other Delta sublineages including AY.4 (n = 7), AY.39 (n = 1), and B.1.617.2 (n = 1). The 7 AY.4 sequences clustered together; suggesting a common source of infection. Transmission from a family member visiting from England to an MLS player was identified as the potential index case. The other 2 AY.4 sequences differed from this group by 1-3 nucleotides, as did a partial genome sequence from an additional team member. WGS is a useful tool for understanding SARS-CoV-2 transmission dynamics in professional sports teams.



#18 Affective Responses Mediate the Body Language of Penalty Taker - Decision-Making Relationship from Soccer Goalkeepers

Reference: Res Q Exerc Sport. 2023 Jun 16;1-8. doi: 10.1080/02701367.2023.2189466. Online ahead of print.

Authors: Raphael Laurin, Julien Pellet

Summary: Previous studies have shown that penalty-takers' body language affects the impressions that goalkeepers form about them and their anticipation performance. This research aimed to replicate these results and test the mediating effect of threat/challenge responses on the relationship between impression formation and the quality of goalkeeper decision-making. We report 2 experiments. The first showed that participants (goalkeepers) form more positive impressions and have a lower expectation of success from dominant penalty-takers than submissive penalty-takers, and the second showed under pressure conditions that goalkeepers' decision-making was significantly less accurate against dominant players than against submissive players. In addition, we found that the more goalkeepers perceived the penalty-taker as competent, the more threatened they felt; conversely, the less they perceived the penalty-taker as competent, the more challenged they felt. Finally, our analysis showed that participants' cognitive appraisal (challenge vs. threat) influenced the quality of their decision-making and played a partial mediating role in the relationship between impression formation and decision-making.


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