Latest research in football - week 9 - 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 Is there a relationship between lower-extremity injuries and foot postures in professional football players? A prospective cohort study

Reference: Sci Med Footb. 2022 Feb;6(1):49-59. doi: 10.1080/24733938.2020.1870711. Epub 2021 Apr 8.

Authors: Afsaneh Safar Cherati, Salman Khalifeh Soltani, Navid Moghadam, Bahar Hassanmirzaei, Zohreh Haratian, Shayesteh Khalifeh Soltani, Meisam Rezaei

Summary: Lower extremity injuries are an ongoing concern for professional football players. This study aims to evaluate the relationship between foot posture and lower extremity injuries in professional football players. In this prospective cohort study, 420 male players of the Iran Premium football league were evaluated during the 2015-2016 season. The players were assessed for their foot types based on optical and static foot scans and foot posture index (FPI). The trained club physicians recorded all injuries during the season. The analyzed data of 244 players showed the highest rate of lower extremity injury in hamstrings, ankle, and groin, respectively. These injuries led to 46% of time loss. The probability of hamstrings injuries was higher among pronated players based on static, optic, FPI, and visual examination, 2.1, 1.8, 1.8, and 2.3, respectively. Medial Collateral Ligament (MCL) injuries were associated with subtalar joint abnormality defined by visual observation. An increased relative risk of leading-to-absence injuries among the flat foot group was significant based on optic scanning, FPI, and visual observation. Abnormal foot postures in professional football players may increase the risk of hamstring and MCL injuries and time loss due to lower extremity injuries.



#2 The Irish Football Player Pathway: Examining Stakeholder Coherence Throughout and Across the Player Development System

Reference: Front Sports Act Living. 2022 Feb 14;4:834633. doi: 10.3389/fspor.2022.834633. eCollection 2022.

Authors: Liam Sweeney, Áine MacNamara, Dan Horan

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Summary: Maximizing the efficiency of the player development system is a strategic priority for any professional football club or association. However, the successful development of a young footballer is largely dependent upon the roles and relationships of the different stakeholders invested in the developmental process. This study examined the level of horizontal (i.e., extent to which stakeholders across a pathway stage work with players in an agreed fashion to optimize their experience) and vertical (i.e., extent to which multiple stages of the pathway are coordinated and build chronologically from previous involvement toward long-term needs) stakeholder coherence throughout the Irish football player pathway following a restructuring of development policies and the implementation of a nationwide academy system between 2016 and 2020 under the Football Association of Ireland's (FAI) Player Development Plan. As a second aim, we explored each of the key stakeholders' alignment to academic talent development principles in order to provide practical recommendations for future player and coach development policies. Accordingly, a series of interviews were conducted with 31 key stakeholders currently engaged in the player pathway. These key stakeholders consisted of parents, coaches and members of the FAI as the National Governing Body for football in Ireland. Data were analyzed using Reflexive Thematic Analysis, with findings highlighting a lack of stakeholder coherence across the pathway, both vertically and horizontally. Stakeholders displayed inconsistency in their understanding of the purpose of the player pathway and its long-term strategic aims, as well as demonstrating poor and incohesive relationships with each of the different stakeholders. Moreover, talent development principles between the different stakeholders appeared well-understood overall, although the practical implementation of several of these principles in applied practice did not appear to exist. Results highlight the need for organizational intervention and structural change across the Irish player pathway to maximize long-term player development in the future. Practical implications for the FAI are discussed and recommendations are made to support optimal player development policies moving forward.



#3 A valid and reliable test of technical skill for vision impaired football

Reference: Sci Med Footb. 2022 Feb;6(1):89-97. doi: 10.1080/24733938.2021.1885725. Epub 2021 Feb 22.

Authors: Oliver R Runswick, Alexander Rawlinson, Naomi Datson, Peter M Allen

Summary: The International Paralympic Committee requires international federations to develop and implement sport-specific classification guidelines based on scientific evidence. Performance tests are key to developing new evidence-based criteria in football for athletes with vision impairment (VI). Therefore, the aim of this study was to develop a valid and reliable test of technical performance for VI football. To assure content and face validity, the Vision Impaired Football Skills (VIFS) test was based on recommendations from experienced players and coaches. To test construct validity, we compared 24 sighted football players split into two groups based on highest-level of performance but matched on experience. To test reliability participants completed the VIFS three times on two separate days. Results supported construct validity through detecting differences in performance times between the two groups (p = .004, g = 1.28 95% CI = 0.41 - 2.15). Bias between visits (.54s ± 2.93s; 95% LoA = -5.21- 6.29) and intraclass correlations (.81, 95% CI = .56 - .92) showed between-day agreement and reliability. Within-day reliability was good after a familiarisation trial. Results support the suitability for the VIFS test for classification research. Future work should establish feasibility for players with a VI.



#4 Sport-related concussion practices of medical team staff in elite football in the United Kingdom, a pilot study

Reference: Sci Med Footb. 2022 Feb;6(1):127-135. doi: 10.1080/24733938.2021.1892174. Epub 2021 Feb 28.

Authors: Craig Rosenbloom, Daniel Broman, Wing Chu, Robin Chatterjee, Katrine Okholm Kryger

Summary: The aim was to explore sport-related concussion (SRC) awareness, behaviours, and attitudes of medical team staff working in elite football in the United Kingdom. Including usage and awareness of the FA concussion guidelines, concussion education rates of players and coaching staff, and collection of baseline concussion assessments. 120 responses were gathered. High awareness rates of the FA guidelines were found (97%) with variable rates of player and coaching staff concussion education. Baseline concussion assessments were collected by 78%. Of those, 99% collected SCAT5 with low rates of other neuro-psychometric testing (17%). Confidence of pitch-side SRC recognition was high (93% feeling very confident or confident). Introduction of a 'concussion' substitute was seen as strongly positive for player welfare (85% strongly agreeing or agreeing). Awareness of FA concussion guidelines, and collection of SCAT5 baseline testing was high. Player and coaching staff concussion education rates were low, as was the use of neuro-psychometric testing beyond the use of the SCAT5. There was strong support the introduction of a 'concussion' substitute being a positive thing for player welfare.



#5 Association between match physical activity and neuromuscular characteristics in youth football

Reference: J Sports Med Phys Fitness. 2022 Mar 1. doi: 10.23736/S0022-4707.22.13537-1. Online ahead of print.

Authors: Lorenzo Francini, Carlo Castagna, Andrea Bosio, Darragh Connolly, Massimo Induni, Ferdinando Cereda, Ermanno Rampinini

Summary: The aim of this study was to examine the associations between maximal and submaximal neuromuscular field tests, match physical activity levels and biological maturation in youth football players. Sixty-four football players from under 14 to under 17 age groups were assessed. Players performed a Repeated-Sprint Ability test, Counter Movement Jump, 10-m and 30-m sprint test, as well as an assessment of peripheral muscle function following a multi-stage incremental (i.e. four intensity levels) change of direction test (COD). Knee extensors peak-torque (PTmax) and the decrement of torque values (dec) were considered as COD outcomes. Physical match activities were tracked by GPS technology, while rate of perceived exertion (RPE) was assessed using the CR10 Börg scale. Pearson's correlations (90% confidence interval) were used to examine the relationships. Small associations were found between field tests and match activities. The relationships increased from small to moderate for some tests when match data with RPE>5 were considered. The largest associations were found between distance covered <-2.5m·s-2 and both COD PTmax and dec when RPE>5. The results of the present study provide further evidence of a small-to-moderate association between muscular performance and match work-rate in young football players. Although physical and physiological evaluations fail to precisely estimate the quantity of physical activities performed during matches, it is suggested that they can be utilized to monitor the training effect over time in young football players.



#6 Differences in Older Adults Walking Football Initiation and Maintenance Influences Across Respondent Characteristics: A Cross-Sectional Survey

Reference: J Aging Phys Act. 2022 Feb 26;1-14. doi: 10.1123/japa.2021-0305. Online ahead of print.

Authors: Rachel Cholerton, Joanne Butt, Helen Quirk, Jeff Breckon

Summary: Despite health benefits gained from physical activity and sport participation, older adults are less likely to be active. This study investigates what influences 50- to 75-year-olds (N = 439) to initiate and maintain walking football, across gender, socioeconomic status, number of health conditions, and physical activity level. It also considers relationships between participant characteristics and influences, and intentions to play after a forced break (COVID-19). Results of a U.K. online cross-sectional survey found those with two or more health conditions rated social influences significantly higher in initiation and maintenance than participants with no health conditions. Multiple regression analysis found a positive walking football culture, and perceived use of maintenance resources contributed significantly to intentions to return to play after COVID-19 restrictions eased. Practitioners should consider providing opportunities for social connection, foster a positive walking football culture, and encourage players to utilize maintenance resources (e.g., scheduling sessions) in older adult walking football sessions.



#7 Impact of Anterior Cruciate Ligament Injury on European Professional Soccer Players

Reference: Orthop J Sports Med. 2022 Feb 22;10(2):23259671221076865. doi: 10.1177/23259671221076865. eCollection 2022 Feb.

Authors: Daniele Mazza, Edoardo Viglietta, Edoardo Monaco, Raffaele Iorio, Fabio Marzilli, Giorgio Princi, Carlo Massafra, Andrea Ferretti

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Summary: The impact of anterior cruciate ligament reconstruction (ACLR) on the performance and career of professional soccer players has not been extensively investigated. The aim was to evaluate in professional European soccer players (1) the ACL injury incidence, (2) the return-to-play (RTP) rate and time after ACLR, (3) career survival and athlete performance in the first 3 postoperative seasons after RTP, (4) factors likely related to different outcomes after ACLR, and (5) any related differences between the top 8 European soccer leagues. Included were professional soccer players in the top 8 European Soccer leagues (Serie A [Italy], Premier League [England], Ligue 1 [France], LaLiga [Spain], Bundesliga [Germany], Jupiler Pro League [Belgium], Liga NOS [Portugal], and Premier Liga [Russia]) who sustained an ACL injury during seasons 2014 to 2015, 2015 to 2016, and 2016 to 2017. Data were retrieved from publicly available online sources. Outcomes were evaluated based on player age (<25 years, 25-30 years, and >30 years), position (goalkeeper, defender, midfielder, and forward), affected side (dominant vs nondominant), and league. Overall, 195 players sustained an ACL injury, for a mean annual ACL injury incidence of 1.42%. The RTP rate was 95%, with a mean RTP time of 248 ± 136 days. Within the third postoperative season, 66 players (36%) competed in a lower level national league, and 25 (13.6%) ended their careers; a significant reduction in the mean minutes played per season was found in all 3 postoperative seasons. Player age correlated significantly with reduction in performance or recovery from an ACL injury. No significant correlation was found between postoperative player performance and affected side, position, league, or time to RTP. A substantial ACL injury incidence was found in top European elite soccer players; however, a high RTP rate in a reasonable time was seen after ACLR. Nevertheless, professional soccer players experienced a short-term decline in their performance.



#8 The influence of soccer shoes on plantar distribution in young players in a static condition. A pilot study

Reference: J Sports Med Phys Fitness. 2022 Mar 1. doi: 10.23736/S0022-4707.22.13644-3. Online ahead of print.

Authors: Giuseppe Messina, Francesco Pomara, Luca Petrigna, Maria C Piccione, Silvia Caserta, Marco Petrucci, Antonio Palma, Antonino Bianco

Summary: Injuries are a serious problem in soccer for the player but also for the society. It has been noted most of the injuries occurs during non-contact situations and, the soccer shoes have an important role. Unfortunately, few studies investigated the plantar distribution, argument that could help to deeply understand the causes behind the injuries. The objective was to evaluate the influence of the soccer shoes on plantar distribution in young players in a static condition. Young soccer players (range 11-18) were recruited and performed two tests on a baropodometric platform, one barefoot and one with technical soccer shoes. A student's t-test was performed to evaluate the differences between the conditions. Significative results were between the left plantar surface (p<0.05) and in the total surface anterior (p<0.05) with and without the soccer shoe. Related to the pressure values, soccer shoes resulted higher than barefoot condition. Significativity has been found also between the forefoot and the rearfoot in the left foot, in barefoot condition (p < 0.05). Soccer shoes generally produce a reduction in the contact plantar surface, especially in the anterior zone and the foot load is higher in the forefoot zone.



#9 Effects of Cool-Down Exercise and Cold-Water Immersion Therapy on Basic Fitness and Sport-Specific Skills among Korean College Soccer Players

Reference: Iran J Public Health. 2021 Nov;50(11):2211-2218. doi: 10.18502/ijph.v50i11.7575.

Authors: Yoon-Hyung Lee, Jin-Ho Yoon, Ki-Jae Song, Jae-Keun Oh

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Summary: We aimed to examine the effects of cool-down exercise and cold-water immersion therapy on agility, speed, power, balance, and sport-specific skill performance in college soccer players, and to provide baseline data for the development of effective recovery programs. In August 2020, 21 male college soccer players in Seoul, Korea, were randomly divided into the following groups: control group (CG, n=7), cool-down exercise group (CDG, n=7), and cool-down exercise plus cold-water immersion group (CDCWG, n=7). Agility, speed, power, balance, and sport-specific skill performance were assessed before and after the intervention. No significant differences in Southeast Missouri (SEMO) Agility Test, 20-m sprint test, vertical jump test, or Y-balance test (right) were observed among the groups; however, there was a significant effect of time (P<0.05) and a significant time × group interaction (P<0.05). Significant effects of time (P<0.001), group (P=0.043), and a time × group interaction (P=0.009) were observed in the Y-balance test (left). There were no between-group differences in the 22-m dribble test, shooting test (left), or shooting test (right); however, there were significant effects of time (P<0.05) and significant time × group interactions (P<0.05). No significant effects of group or time × group interactions were observed for the kicking test (left or right); however, there were significant effects of time (P<0.001). Addition of cold-water immersion therapy to a recovery program including cool-down exercise can promote recovery of basic and sport-specific abilities among college soccer players.



#10 Progression to the target vs. regular rules in Soccer small-sided Games

Reference: Sci Med Footb. 2022 Feb;6(1):66-71. doi: 10.1080/24733938.2020.1869811. Epub 2021 Jan 3.

Authors: Gibson Moreira Praça, André Gustavo Pereira Andrade, Sarah da Glória Teles Bredt, Felipe Arruda Moura, Pedro Emilio Drumond Moreira

Summary: This study compared the physical, physiological, and spatiotemporal responses of soccer athletes in small-sided games (SSG) in two experimental conditions: progression to the target rule (PG), in which they should take the ball to the opponent's endline to score points, and SSG with regular rules (RG), in which they should score goals to win the game. Twenty U-20 athletes played both SSG formats. The SSG were played as four 4-minute bouts with four minutes of passive recovery in two consecutive days. Heart rate, physical (distances and accelerations), and positional data (length, width, and spatial exploration) were collected by a 10 hz GPS device and compared between the protocols using a MANOVA with Bonferroni's correction for multiple comparisons. Results showed that the RG condition demanded more spatial exploration eliciting greater occupation of the pitch width. There were higher mean and maximum heart rates and greater low-to-moderate distances and accelerations in the RG, while the PG rule increased the distances covered at the highest speed and acceleration zones. The progression to the target rule should be adopted to emphasize players' ability to use the width during the offensive phase. Additionally, the PG rule should also be used to emphasize the development of speed and acceleration skills.



#11 Lower limbs muscle activation during instep kick in soccer: effects of dominance and ball condition

Reference: Sci Med Footb. 2022 Feb;6(1):40-48. doi: 10.1080/24733938.2021.1884283. Epub 2021 Mar 9.

Authors: Rodrigo Rabello, Filippo Bertozzi, Manuela Galli, Matteo Zago, Chiarella Sforza

Summary: Muscle activation has been studied in soccer players kicking stationary balls with the dominant foot. This study evaluated swinging and support limb muscle activation during the instep kick using different feet and ball approach conditions.Vastus medialis (VM), biceps femoris (BF), gastrocnemius medialis (GM) and tibialis anterior (TA) activations were evaluated during maximal instep kicks with both feet and the ball in five conditions (n = 18): stationary (STAT), approaching anteriorly (ANT), posteriorly (POST), laterally (LAT) and medially (MED). A repeated-measures two-way ANOVA compared activations between feet and ball conditions throughout the kicking (0-100%) and follow-through phases (101-200%). Close to ball contact (81-124%), non-dominant support GM had greater activation than the dominant one. The LAT and MED conditions differed within the cycle in the swinging VM (0-21%; 191-200%), BF (13-70%; 121-161%), GM (22-82%; 121-143%) and TA (0-32%; 55-97%; 186-200%) and in support VM (0-81%), BF (6-24%; 121-161%) and GM (24-87%). Players require greater support GM activation to stabilize the ankle during non-dominant kicks. Muscle activation differences between LAT and MED indicate that the kicking strategies are altered when kicking balls approaching from different directions.



#12 "I Gave Up Football and I Had No Intention of Ever Going Back": Retrospective Experiences of Victims of Bullying in Youth Sport

Reference: Front Psychol. 2022 Feb 15;13:819981. doi: 10.3389/fpsyg.2022.819981. eCollection 2022.

Authors: Xènia Ríos, Carles Ventura, Pau Mateu

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Summary: Bullying is a global issue that, beyond school, is present in different social contexts, such as sport environments. The main objective of this study was to get to know the experiences of victims of bullying in sport throughout their youth sport training. Semi-structured interviews to four Spanish women and seven Spanish men were carried out, within an age range of 17-27 (M age = 21 years, SD = 3.69). The following main themes were established by means of a hierarchical content analysis: (a) "bullying characterization," (b) "dealing with bullying," and (c) "consequences of bullying." The results show the presence of physical, verbal and social bullying in the sport context, with the changing room being the space where this type of behavior is most frequently developed. Most victims show an internal attribution (self-blame) for the bullying event, related to their motor skills and their personal physical and psychological characteristics. Double victimization can be observed, at the sport club and at the educational center. Passive strategies are used to deal with the situation, while little support is shown by sport agents (teammates and coaches). The victims, as a consequence of the bullying experience, suffer from short and long-term negative effects on a psychosocial level. The study highlights the necessity to design and implement programs focused on the prevention, detection and intervention of bullying for sport organizations, bearing in mind all the agents that make them up (coaches, management teams, families, and players). Furthermore, the importance of promoting the creation of safe sport environments, free from any kind of violence, is emphasized.



#13 Interchangeability of player movement variables from different athlete tracking systems in professional soccer

Reference: Sci Med Footb. 2022 Feb;6(1):1-6. doi: 10.1080/24733938.2021.1879393. Epub 2021 Feb 19.

Authors: Susanne Ellens, Daniel Hodges, Sean McCullagh, James J Malone, Matthew C Varley

Summary: This study assessed the interchangeability between 10-Hz multi-GNSS GPS devices (Vector®) and two optical tracking systems (TRACAB® and Second Spectrum®). The agreement between data from the optical tracking systems when processed with manufacturer and GPS-filtered software was also assessed. Thirty players competing in the English Premier League were monitored using three different tracking systems across five matches. To determine the interchangeability between systems, player movement variables including, total distance, high-speed running distance (19.8-25.2 km·h-1), sprinting distance (>25.2 km·h-1), efforts >19.8 km·h-1 and maximal speed were compared. Equations were formed using linear regression and linear mixed-effects models to allow interchangeability of player movement variables between systems. Over half of the variance of most interchangeability equations were explained and associated with very strong positive correlations (r > 0.72). Small to huge differences were found between systems for most player movement variables. Data of optical tracking systems had decreased values in speed variables >19.8 km·h-1 when processed through GPS software. This study provides equations for practitioners to interchange player movement variables between TRACAB, Second Spectrum and Vector GPS systems with reduced error. This will enable practitioners to combine and share data captured with different tracking systems to analyse and improve their training.



#14 Age- and size-corrected kicking speed and accuracy in elite junior soccer players

Reference: Sci Med Footb. 2022 Feb;6(1):29-39. doi: 10.1080/24733938.2021.1899274. Epub 2021 Jul 26.

Authors: Andrew H Hunter, Nicholas M A Smith, Thiago V Camata, Mathew S Crowther, Andrew Mather, Nicolau Melo Souza, Luiz Fernando Ramos-Silva, Nerylson Ferraz Pazetto, Felipe A Moura, Robbie S Wilson

Summary: Kicking powerfully and accurately is essential in soccer, and players who kick proficiently with both feet are highly sought after. Assessing performance in youth players is often confounded by more physically developed players outperforming their smaller peers. To alleviate such bias, we present a testing protocol and normative data developed with an elite Brazilian soccer academy that controls for players' age and size to assess kick performance with both feet. We measured kick speed and kick accuracy of 178 players and recorded their age (10-20 years), height, and mass. Combining age, height, and mass into an age and size index (ASI), we developed equations describing the relationship between ASI and performance. To determine the underlying predictors of performance, we also measured sprint ability and soccer-specific motor control of each foot with ball dribbling tasks. Kicking speed with the dominant foot was predicted by ASI, sprint speed, and motor control of the nondominant foot, while kicking speed with the nondominant foot was predicted by ASI and motor control of the nondominant foot. Kick accuracy with each foot was predicted by ASI and motor control of the corresponding foot. To improve kicking performance, we suggest training programs focus on motor control.



#15 The influence of training and competition on sleep behaviour of soccer referees

Reference: Sci Med Footb. 2022 Feb;6(1):98-104. doi: 10.1080/24733938.2021.1890812. Epub 2021 Feb 26.

Authors: Michele Lastella, Dean J Miller, Grace E Vincent, Nathan Elsworthy, Aaron T Scanlan, Rob Duffield

Summary: The aims of the present study were to (1) quantify sleep behaviours of soccer referees and (2) compare sleep behaviours between nights before training, before matches, and after matches. Fourteen professional soccer referees from the A-League (mean±SD; age 34 ± 4 years; sex: 11 males, 3 females) participated in this observational study. Referees' sleep behaviours were examined using sleep diaries and wrist activity monitors for 31 consecutive nights during the 2018-2019 A-League season. Separate linear mixed models were conducted to assess differences in sleep behaviours between nights before training, before matches, and after matches. On average, referees did not obtain recommended sleep durations across the in-season (mean±SD sleep duration: 6.4 h ± 0.7 h). Referees went to bed later, spent less time in bed, and slept significantly less post-matches compared to pre-training and pre-match nights (p< 0.05). Referees were particularly susceptible to inadequate sleep on nights following training and matches. The findings related to poor sleep behaviours highlight the importance of implementing monitoring systems to understand the sleep behaviours of referees, with further research encouraged to ascertain the efficacy of various sleep hygiene practices to optimise sleep in this population.



#16 Analysis of the Effect of Injuries on Match Performance Variables in Professional Soccer Players: A Retrospective, Experimental Longitudinal Design

Reference: Sports Med Open. 2022 Mar 3;8(1):31. doi: 10.1186/s40798-022-00427-w.

Authors: Javier Raya-González, Juan José Pulido, Marco Beato, José Carlos Ponce-Bordón, Roberto López Del Campo, Ricardo Resta, Tomás García-Calvo

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Summary: Knowing the impact of injuries is essential for their adequate management during reconditioning programs. This study aimed to analyze the changes in match performance parameters in professional soccer players after sustaining an injury, which was defined according to injury severity. Two-hundred and seven injuries related to one hundred and sixty-one professional soccer players from the Spanish LaLiga™ were considered for this study. All the injuries were classified according to their severity as minor (from 4 to 7 missed days), moderate (from 8 to 28 missed days), and major (more than 28 missed days). Through Mediacoach® videotracking system, time and external demand variables were collected and subsequently compared between pre-injury and return to play periods. The analyzed variables were (in m min-1): relative distance covered (RD; total distance covered·min-1), distance covered walking (0-6 km h-1), distance covered jogging (6-12 km h-1), distance covered running (12-18 km h-1), distance covered at intense running (18-21 km h-1), distance covered at high-speed running (21-24 km h-1), and sprinting (> 24 km h-1) distance covered. Significant reductions in playing time after suffering moderate and major injuries were observed. Significant reductions after minor injuries were observed in jogging (> 6 km h-1) and running (6-12 km h-1), while significantly greater distances at intense running (18-21 km h-1) and high-speed running (21-24 km h-1) were covered by players who suffer major injuries. Finally, relevant decreases in the maximum speed achieved after moderate and major injuries were found. In conclusion, this study shows the importance of high loads during reconditioning programs, as well as implementing strategies that allow reaching levels of maximum speed values after the return to play.



#17 Easier in Practice Than in Theory: Experiences of Coaches in Charge of Community-Based Soccer Training for Men with Prostate cancer-A Descriptive Qualitative Study

Reference: Sports Med Open. 2022 Mar 3;8(1):28. doi: 10.1186/s40798-022-00424-z.

Authors: Kickan Roed, Eik Dybboe Bjerre, Julie Midtgaard

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Summary: Evidence suggests that community-based exercise programs and sports participation benefit long-term physical activity adherence and promote health in clinical populations. Recent research shows that community-based soccer can improve mental health and bone health and result in fewer hospital admissions in men with prostate cancer. However, little knowledge exists on what coaches experience, leading to a scarcity of knowledge on how to assist them in promoting and supporting the sustainability of programs. The purpose of this study was to explore the experiences of non-professional soccer coaches in providing community-based soccer training for men with prostate cancer. We interviewed 13 out of 21 eligible non-professional soccer coaches in charge of delivering the Football Club Prostate Community program, which is community-based soccer training for men with prostate cancer at 12 local soccer clubs across Denmark. Qualitative content analysis, as described by Graneheim and Lundman, was applied to analyze the data using NVivo 12 software. We identified the five following overall categories with 10 subcategories on what the coaches experienced: (1) enabling training of a clinical population in a community setting, (2) dedication based on commitment, (3) coaching on the players' terms, (4) navigating the illness, and (5) ensuring sustainability. Collectively, the findings suggest that, while the coaches felt adequately prepared to coach, their coaching role developed and was refined only through interaction with the players, indicating that coaching clinical populations may be easier in practice than in theory and a potentially transformative learning experience. Non-professional soccer coaches in charge of delivering soccer training for men with prostate cancer value being educated about specific illness-related issues. Initial concerns about how to coach a clinical population disappeared once the coaches engaged with the players and developed their own team norms and illness management strategies. They also gained a broader perspective on their own lives, which they valued and would not otherwise have achieved by coaching a healthy population. Our study indicates that sustainable implementation and the program's sustainability can be promoted and supported through additional formal, easily accessible communication with trained health professionals and by networking with peer coaches.



#18 An End-to-End Deep Learning Pipeline for Football Activity Recognition Based on Wearable Acceleration Sensors

Reference: Sensors (Basel). 2022 Feb 10;22(4):1347. doi: 10.3390/s22041347.

Authors: Rafael Cuperman, Kaspar M B Jansen, Michał G Ciszewski

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Summary: Action statistics in sports, such as the number of sprints and jumps, along with the details of the corresponding locomotor actions, are of high interest to coaches and players, as well as medical staff. Current video-based systems have the disadvantage that they are costly and not easily transportable to new locations. In this study, we investigated the possibility to extract these statistics from acceleration sensor data generated by a previously developed sensor garment. We used deep learning-based models to recognize five football-related activities (jogging, sprinting, passing, shooting and jumping) in an accurate, robust, and fast manner. A combination of convolutional (CNN) layers followed by recurrent (bidirectional) LSTM layers achieved up to 98.3% of accuracy. Our results showed that deep learning models performed better in evaluation time and prediction accuracy than traditional machine learning algorithms. In addition to an increase in accuracy, the proposed deep learning architecture showed to be 2.7 to 3.4 times faster in evaluation time than traditional machine learning methods. This demonstrated that deep learning models are accurate as well as time-efficient and are thus highly suitable for cost-effective, fast, and accurate human activity recognition tasks.



#19 Combined Plyometric and Short Sprint Training in U-15 Male Soccer Players: Effects on Measures of Jump, Speed, Change of Direction, Repeated Sprint, and Balance

Reference: Front Physiol. 2022 Feb 18;13:757663. doi: 10.3389/fphys.2022.757663. eCollection 2022.

Authors: Ghaith Aloui, Souhail Hermassi, Thomas Bartels, Lawrence D Hayes, El Ghali Bouhafs, Mohamed Souhaiel Chelly, René Schwesig

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Summary: This study examined the effect of 8 weeks of biweekly combined plyometric and short sprint training into the typical within-season training schedule of youth male soccer players. Participants were allocated at random to an experimental group (EG; n = 17, age: 14.6 ± 0.5 years, body mass: 60.5 ± 7.1 kg, height: 1.64 ± 0.08 m, body fat: 11.3 ± 1.4%) and a control group (CG; n = 17, age: 14.6 ± 0.4 years, body mass: 61.0 ± 3.9 kg, height: 1.67 ± 0.05 m, body fat: 11.8 ± 1.4%). Measures obtained pre- and post-intervention included vertical and horizontal jump performances (i.e., squat jump (SJ), countermovement jump with aimed arms (CMJA), and five-jump test (FJT)) and sprint performances (i.e., 10 and 30 m sprint). In addition, change-of-direction ability (sprint with 90° Turns (S90°) and sprint 9-3-6-3-9 m with backward and forward running (SBF)), repeated shuttle sprint ability (RSSA), and dynamic balance performance (Y balance test) were measured pre- and post-intervention. The EG experienced higher jump (all p < 0.05; d ≥ 0.71), sprint (all p < 0.05; d ≥ 0.64), change-of-direction ability (all p < 0.05; d ≥ 0.66), RSSA (all parameters except the fatigue index p < 0.01; d ≥ 0.71), and dynamic balance (all p ≤ 0.05; d ≥ 0.50) improvement compared to the CG. Adding biweekly combined plyometric and short sprint training to standard training improves the athletic performance of youth male soccer players (under 15 (U15)).



#20 Effects of sodium pyruvate supplementation on repeated sprint exercise performance and recovery in male college soccer players: a randomized controlled trial

Reference: Ann Palliat Med. 2022 Feb;11(2):598-610. doi: 10.21037/apm-21-3862.

Authors: Yan-Ping Yang, Jun-Qiang Qiu, Meng-Yue Wang, Lin Feng, Dan Luo, Rui-Rui Gao, Fang-Qiang Zhou, Kai-Xuan Che

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Summary: Sodium pyruvate (PYR) has been reported to improve aerobic metabolism and attenuate metabolic acidosis. Aerobic capacity and the ability to remove hydrogen ions affect the recovery from repeated high intensity activities. However, the effects of PYR supplementation on repeated sprint exercise (RSE) performance have not been elucidated. This study explored the effects of PYR ingestion on RSE ability and recovery. A total of 14 male soccer athletes (aged 20±2 years) participated in this double-blinded crossover study. The subjects completed two experimental sessions after randomized ingestion of either PYR or the maltodextrin placebo (PLA) for 1 week. At each session, participants completed high-intensity interval exercise (HIIE) and RSE 60 minutes after supplementation. Additionally, acid-base parameters in venous blood, energy system contributions, and power output were assessed. Compared to PLA, PYR supplementation significantly increased the relative peak power output (PPO) of the first (P=0.034) and fifth (P=0.043) sprints, and the relative mean power output (MPO) of the fifth sprint (P=0.026). In addition, the mean PPO (P=0.031) and MPO (P=0.033) of sprints 1-6 were significantly elevated after PYR supplementation. After PYR administration, the phosphagen energy system [adenosine triphosphate (ATP)-phosphocreatine (PCr)] resynthesis of the fourth (P=0.034) and the overall recovery periods during HIIE (P=0.029) were higher than PLA administration. Additionally, the ATP-PCr resynthesis of the first (P=0.033) and fifth (P=0.019) recovery periods, and the mean of the six recovery periods during RSE (P=0.041) were increased in the PYR group compared to the PLA group. Furthermore, participants on the PYR regimen had higher blood pH, HCO3-, and base excess at pre-HIIE, post-HIIE, and pre-RSE (all P<0.05) compared to participants receiving PLA. PYR supplementation enhanced RSE performance, and the improvement may be attributed to accelerated restoration of the acid-base balance and ATP-PCr regeneration.



#21 Strength Level of Professional Elite Soccer Players after the COVID-19 Lockdown Period: A Retrospective Double-Arm Cohort Study

Reference: J Sports Med (Hindawi Publ Corp). 2022 Mar 3;2022:8242210. doi: 10.1155/2022/8242210. eCollection 2022.

Authors: Robson Dias Scoz, Ricardo Lima Burigo, Isabella Christina Ferreira, Luiz Hespanhol, Ana Paula Silveira Ramos, Adriano Schlosser, Jose Joao Baltazar Mendes, Luciano Maia Alves Ferreira, César Ferreira Amorim

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Summary: It is well known that periods of inactivity generate a loss of muscle strength, a fundamental component of sports performance in soccer. However, little information is available on the decrease in strength levels in professional soccer players after the quarantine lockdown that occurred during the COVID-19 pandemic. The aim was to compare the isokinetic peak torque profiles of professional soccer players from different teams before and after the quarantine period generated by COVID-19. A retrospective observational study was performed using data collected from two different professional elite-level soccer teams just before and immediately after the COVID-19 quarantine period. One team gave individual instructions to its players for conditioning maintenance at home during the quarantine period, while the other team used regular video calls to maintain the player's conditioning status on home training. The main outcomes were the mean peak torque of knee extensors and flexors, from concentric and eccentric contractions of each playing position. Analysis. A two-way ANOVA analysis was used to compare peak torque before and after the quarantine period and between both teams' strategies, showing a statistically significant reduction in eccentric knee flexor peak torque from the team that did not have remote monitoring. Remote monitoring programs are recommended so that athletes are less affected by the deleterious effects of confinement.


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