Latest research in football - week 6 - 2021

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 Physical Demands of U10 Players in a 7-a-Side Soccer Tournament Depending on the Playing Position and Level of Opponents in Consecutive Matches Using Global Positioning Systems (GPS)

Reference: Sensors (Basel). 2020 Dec 6;20(23):6968. doi: 10.3390/s20236968. 

Authors: Antonio Hernandez-Martin, Javier Sanchez-Sanchez, Jose Luis Felipe, Samuel Manzano-Carrasco, Carlos Majano, Leonor Gallardo, Jorge Garcia-Unanue 

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Summary: The aim of this study was to analyse the physical demands of U10 players in a 7-a-side-soccer tournament based on the playing positions in 6 consecutive matches by global positioning systems (GPS). Variables of total distance, relative distance in different speed zones, maximum speed, time interval between accelerations, maximum speed acceleration, maximum acceleration, acceleration distance and the number of high-intensity accelerations were analysed. Differences between playing positions were found in the total distance covered by the midfielders. They covered higher total distances than the defenders (+1167 m; 95% CI: 411 to 1922 m; effect size (ES) = 1.41; p < 0.05) and forwards (+1388 m; CI 95%: 712 a 2063 m; TE = 0.85; p < 0.05). The total covered distance increased in the final rounds with respect to the group stage (p < 0.05; ES: 0.44 to 1.62), and high-intensity actions, such as the number of accelerations, were greater in the final rounds compared to the group stage (p < 0.05; ES: 0.44 to 1.62). The physical performance of young football players in a tournament with consecutive matches on a 40 × 62 m football field on the same day is influenced by the playing position and dependent on the level difference between opponents. 



#2 Evaluating the validity of self-report as a method for quantifying heading exposure in male youth soccer 

Reference: Res Sports Med. 2020 Dec 6;1-13. doi: 10.1080/15438627.2020.1853541. Online ahead of print. 

Authors: Stian B Sandmo, Jolien Gooijers, Caroline Seer, David Kaufmann, Roald Bahr, Ofer Pasternak, Michael L Lipton, Yorghos Tripodis , Inga K Koerte

Summary: Assessing heading exposure in football is important when exploring the association between heading and brain alterations. To this end, questionnaires have been developed for use in adult populations. However, the validity of self-report in adolescents remains to be elucidated. Male youth soccer players (n = 34) completed a questionnaire on heading exposure after a two-week period, which included matches and training sessions. Self-reported numbers were compared to observation (considered reference). In total, we observed 157 training sessions and 64 matches. Self-reported heading exposure correlated with observed heading exposure (Spearman's rho 0.68; p < 0.001). Players systematically overestimated their heading exposure by a factor of 3 with the random error of 46%. Area under the curve was 0.87 (95% CI 0.67-1) utilizing self-report for identifying players from high- and low-exposure groups. Thus, in this study, self-reported data could be used to group youth players into high and low heading exposure groups, but not to quantify individual heading exposure. 



#3 Prevalence of SARS-CoV-2 IgG antibodies in a large prospective cohort study of elite football players in Germany (May-June 2020): implications for a testing protocol in asymptomatic individuals and estimation of the rate of undetected cases

Reference: Clin Microbiol Infect. 2020 Dec 4;S1198-743X(20)30729-1. doi: 10.1016/j.cmi.2020.11.033.

Authors: Dietrich Mack, Barbara Christine Gärtner, Annika Rössler, Janine Kimpel, Katrin Donde, Oliver Harzer, Werner Krutsch, Dorothee von Laer, Tim Meyer

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Summary: Elite professional football players and staff are a unique group that might give insight into the epidemiology of SARS-CoV-2 infections in Germany and thus can serve as a model for a geographical distribution and an estimation of undetected infections. In this prospective cohort study seroprevalence was determined twice in May and June 2020 in players and staff from German Bundesliga. As screening assays a commercial ELISA (Euroimmun) and a CLIA (Roche) was used and an in-house neutralisation assay (NT) as gold standard. Participants were tested twice weekly using PCR from nasopharyngeal and/or oropharyngeal swabs. Seroprevalence (NT used as confirmation) in 2,164 samples from 1,184 players and staff was rather similar in May (23/1157 (1.99%)) and in June (21/1007 (2.09%)). All participants were PCR negative during the study period. Significant regional differences in seroprevalence were not observed. When comparing seroprevalence with the cumulative incidence of infections derived from the German notification system (subgroup matching to cohort; men, age: 20-69), IgG was found 8-10 times more frequently, pointing to a high rate of undetected infections. ELISA and CLIA correlated only moderately (Kappa 0.52). Seroprevalence with high quality diagnostic in Germany seemed to be around 2%. The number of undetected infections seems to be 8-10 times higher than notification data. Quality of antibody assays is rather variable, thus results should ideally be confirmed at least by a second assay to prove IgG positivity. 



#4 Are Die-Hard Football or Other Sports Fans at Risk of Cardiovascular Events? 

Reference: Curr Probl Cardiol. 2020 Nov 2;100743. doi: 10.1016/j.cpcardiol.2020.100743. Online ahead of print. 

Authors: Miguel A Maturana, Elizabeth A Glover, Joel Raja, Sean R Dornbush, John Alexander, Courtland Blount, Nadim R Khouzam, Amir R Khouzam, Rami N Khouzam

Summary: Trigger factors such as earthquakes, war, and terrorism have been shown to increase the risk of cardiovascular events in different studies. Similarly, strong emotions and psychological stress have been associated with myocardial infarction, symptomatic arrhythmias, and sudden cardiac death. Die-hard soccer, rugby, football, and baseball fans seem to be at risk of cardiac events, particularly in individuals with prior history of coronary artery disease. Transient hemodynamic changes, endothelial dysfunction, and an overwhelming sympathetic nervous system stimulation appear to affect cardiac hemostasis creating a procoagulant and arrhythmogenic environment. High-risk behaviors such as tobacco abuse and binge drinking appear to contribute to this risk generating a proinflammatory state characterized by elevated levels of endothelin-1 and overexpression of sCD40L, sVCAM-1, MCP-1, and TNF-alpha. The outcome of the game and unexpected results, especially among fans of the defeated team, seem to further correlate with adverse cardiovascular effects. 



#5 The incidence and mechanism of heading in European professional football players over three seasons

Reference: Scand J Med Sci Sports. 2020 Dec 6. doi: 10.1111/sms.13900. Online ahead of print. 

Authors: Gregory J Tierney, Barry Higgins

Summary: There are concerns surrounding the risk of neurodegenerative diseases associated with football (soccer) heading. The aim of this study was to conduct analysis on the incidence and mechanism of heading in the "Big 5" professional European football leagues (Bundesliga, Ligue 1, Premier League, La Liga and Serie A) and one lower tier professional league (English Championship) from 2016/17-2018/19. Match event data from 7147 matches were obtained from Opta Sports data feed. The data were parsed to extract header event details including player position, coordinates on the field, header type and preceding match event (including distance football travelled). Incidence data were reported as headers per match or match headers per player. Medians and interquartile ranges (IQR) were reported and either the Mann-Whitney U-Test or Kruskal-Wallis test were conducted for comparisons between positions and leagues. In the "Big 5" leagues, the most headers per match occurred during the Premier League (111.2 headers per match). However, the lower tier English Championship had the highest number of headers per match overall (139.0 headers per match). In all leagues, defenders had the greatest median number of match headers per player (p<0.001). The highest median distance travelled by the football during a preceding match event was for goal kicks (57.5 m; IQR 53.7-61.1). The findings add necessary information for current longitudinal studies aiming to understand the potential link between football heading and neurodegenerative diseases. These studies should account for league, playing position and level of play. 



#6 Post-match recovery of eccentric knee flexor strength in male professional football players

Reference: Phys Ther Sport. 2020 Nov 25;47:140-146. doi: 10.1016/j.ptsp.2020.11.032. Online ahead of print. 

Authors: César Augusto Bueno, João Breno de Araujo Ribeiro-Alvares, Gabriel Dos Santos Oliveira, Rafael Grazioli, Filipe Veeck, Ronei Silveira Pinto, Eduardo Lusa Cadore, Bruno Manfredini Baroni

Summary: This study aimed at verifying the effect of a football match on the eccentric knee flexor strength of male professional players along a 72-h period. Fifteen players were assessed in four timepoints: 24 h before, immediately after, 48 h and 72 h after the match. The eccentric knee flexor strength was assessed during the Nordic hamstring exercise execution. Players presented a significant strength reduction immediately after match (Δ = 12%; p = 0.001; large effect size, d = 1.10), and did not recover their strength capacity within a 48 h-period (Δ = 6%; p = 0.011; moderate effect size, d = 0.57). At 72 h after the match, strength was similar to baseline levels (Δ = 3.5%; p = 0.122; small effect size, d = 0.34). Secondarily, individual response analysis considered a player 'fully recovered' when his strength deficit compared to the baseline measure was lower than the measurement coefficient of variation (i.e., <5%). Only 6 (40%) and 9 (60%) players were 'fully recovered' at 48 h and 72 h after the match, respectively. Professional football players experienced an immediately post-match drop on the eccentric knee flexor strength, and significant strength deficits persisted for a 48-h period. Some players were not recovered at 72 h after the match. 



#7 Radiological (Magnetic Resonance Image and Ultrasound) and biochemical effects of virtual reality training on balance training in football players with chronic low back pain: A randomized controlled study

Reference: J Back Musculoskelet Rehabil. 2020 Nov 27. doi: 10.3233/BMR-191657. Online ahead of print. 

Authors: Gopal Nambi, Walid Kamal Abdelbasset, Bader A Alqahatani 

Summary: Virtual reality training is commonly used for balance problems in neurological conditions with the use of visual and auditory biofeedback. The knowledge about the effective implementation of this training in chronic low back pain is lacking. The objective of this study is to find the radiological and biochemical effects of virtual reality training in football players with chronic low back pain. A randomized, single-blinded controlled study was conducted on 36 participants. The first group received virtual reality training (VRT; n= 12), the second group received combined physical rehabilitation (CPR; n= 12), and the third group (control group; n= 12) received conventional training exercises for four weeks. Radiological (muscle cross-sectional area and muscle thickness) and biochemical (CRP, TNF-α, IL-2, IL-4, IL-6) values were measured at baseline and after four weeks. Four weeks following training, the VRT group showed more significant changes in the muscle cross-sectional area than the CPR and control groups (p 0.001). Biochemical measures such as CRP, TNF-α, IL-2, IL-4, and IL-6 also showed significant improvement in the VRT group compared to the other two groups (p 0.001). The results show that virtual reality training has positive effects on the radiological and biochemical aspects in university football players with chronic low back pain. 



#8 What Is the Relevance in the Passing Action between the Passer and the Receiver in Soccer? Study of Elite Soccer in La Liga

Reference: Int J Environ Res Public Health. 2020 Dec 15;17(24):E9396. doi: 10.3390/ijerph17249396. 

Authors: Antonio Cordón-Carmona, Abraham García-Aliaga, Moisés Marquina, Jorge Lorenzo Calvo, Daniel Mon-López, Ignacio Refoyo Roman 

Summary: Soccer is a high-complexity sport in which 22 players interact simultaneously in a common space. The ball-holder interacts with their teammates by passing actions, establishing a unique communication among them in the development of the game in its offensive phase. The main aim of the present study was to analyze the pass action according to the trajectory of the ball receiver and the space for receiving the ball in terms of success at the end of play. Twenty La Liga 2018/2019 matches of two elite teams were analyzed. A system of notational analysis was used to create 11 categories based on context, timing and pass analysis. The data were analyzed using chi-squared analysis. The results showed that the main performance indicators were the efficiency of the pass, the zone of the field, the trajectory of the receiver and the reception space of the ball, which presented a moderate association with the end of play (p < 0.001). We concluded that receiving the ball on approach and in separation increased the probability of success by 5% and 7%, respectively, and a diagonal run increased the probability by 7%. Moreover, the combined analysis of these variables would improve the team performance. 



#9 Can Talented Youth Soccer Players Who Have Undergone Anterior Cruciate Ligament Reconstruction Reach the Elite Level?

Reference: Am J Sports Med. 2020 Dec 17;363546520976651. doi: 10.1177/0363546520976651. 

Authors: Alexander Sandon, Tor Söderström, Andreas Stenling, Magnus Forssbla

Summary: Anterior cruciate ligament (ACL) ruptures are common in soccer players, and reconstructive surgery is often performed to restore knee stability and enable a return to play. The purpose was to investigate whether an ACL reconstruction for talented youth soccer players affects their potential to become elite players at the senior level. All soccer players who participated in the Swedish National Elite Camp for 15-year-old players between 2005 and 2011 (N = 5285 players; 2631 boys and 2654 girls) were matched with the Swedish National Knee Ligament Registry to identify the players who had undergone ACL reconstruction. Information on player participation in Swedish league games and level of play was collected from the Swedish Football Association's administrative data system. The players with an ACL reconstruction who were injured at the ages of 15 to 19 years were compared with the rest of the players who participated in the National Elite Camp to see whether an early ACL reconstruction affected whether they remained active as soccer players and their chance to play at the elite level as seniors. A total of 524 (9.9%) players had undergone an ACL reconstruction, and 292 (5.5%; 75 male and 217 female) had sustained their injury at age 15 to 19 years. During the follow-up period, 122 (23.3%) players underwent ACL reconstruction: revision (11.5%; n = 60) or contralateral (11.8%; n = 62). Male and female soccer players undergoing an ACL reconstruction at age 15 to 19 years experienced no significant effect on being active or playing at the elite level in the season that they turned 21 years old. Of the youth players who underwent ACL reconstruction, 12% of the male players and 11.5% of the female players progressed to the elite level at the age of 21 years compared with 10.3% of the men and 11.1% of the women among the uninjured players. ACL reconstructive surgery in talented youth soccer players offers them the opportunity to become elite players as seniors and permits an activity level on a par with that of their uninjured peers. However, almost 1 in 4 requires further ACL surgery, so the players' future knee health should be considered when deciding on a return to play. 



#10 Acute Effects of Warm-Up, Exercise and Recovery-Related Strategies on Assessments of Soccer Kicking Performance: A Critical and Systematic Review 

Reference: Sports Med. 2020 Dec 17. doi: 10.1007/s40279-020-01391-9. Online ahead of print. 

Authors: Luiz H Palucci Vieira, Felipe B Santinelli, Christopher Carling, Eleftherios Kellis, Paulo R P Santiago, Fabio A Barbieri

Summary: A number of reviews have collated information on the impact of warming-up, physical exertion and recovery strategies on physical, subjective and physiological markers in soccer players yet none have solely analyzed their potential effects on components of kicking performance. The purpose was to systematically analyse the influence of warm-up, exercise and/or recovery-related strategies on kicking performance in male soccer players and provide a critical appraisal on research paradigm related to kicking testing constraints and data acquisition methods. A systematic literature search was performed (until July 2020) in PubMed, Web of Science, SPORTDiscus, Scopus and ProQuest. Studies in male soccer populations, which included the effects of warm-up routines, physical exercise and/or recovery-related interventions, reported on comparisons pre-post or between experimental conditions and that computed at least one measure of kicking kinematics and/or performance were considered. Methodological quality and risk of bias were determined for the included studies. Constraints related to kicking testing and data acquisition methods were also summarized and discussed. Altogether, 52 studies were included. Of these, 10 examined the respective effects of a warm-up, 34 physical exercise, and 21 recovery-related strategies. The results of eight studies showed that lower limb kinematics, kicking accuracy or ball velocity were improved following warm-ups involving dynamic but not static stretching. Declines in ball velocity occurred notably following intermittent endurance or graded until exhaustion exercise (three studies in both cases) without inclusion of any ball skills. In contrast, conflicting evidence in five studies was observed regarding ball velocity following intermittent endurance exercise interspersed with execution of ball skills. Kicking accuracy was less frequently affected by physical exercise (remained stable across 14 of 19 studies). One investigation indicated that consumption of a carbohydrate beverage pre- and mid-exercise demonstrated benefits in counteracting the potentially deleterious consequences of exercise on ball velocity, while four studies reported conflicting results regarding kicking accuracy. Most evidence synthesized for the interventions demonstrated moderate level (77%) and unclear-to-high risk of bias in at least one item evaluated (98%). The main limitations identified across studies were kicks generally performed over short distances (50%), in the absence of opposition (96%), and following experimental instructions which did not concomitantly consider velocity and accuracy (62%). Also, notational-based metrics were predominantly used to obtain accuracy outcomes (54%). The results from this review can help inform future research and practical interventions in an attempt to measure and optimise soccer kicking performance. However, given the risk of bias and a relative lack of strong evidence, caution is required when applying some of the current findings in practice. 



#11 Running patterns and force-velocity sprinting profiles in elite training young soccer players: A Cross-Sectional Study

Reference: Eur J Sport Sci. 2020 Dec 17;1-25. doi: 10.1080/17461391.2020.1866078. Online ahead of print. 

Authors: Qingshan Zhang, Félicie Pommerell, Adam Owen, Robin Trama, Cyril Martin, Christophe A Hautier

Summary: The Volodalen® field method permits to classify runners into aerial or terrestrial, based on vertical oscillation, upper-body motion, pelvis and foot position at ground contact, and foot strike pattern. The present study aimed to compare the sprint running force-velocity profiles between aerial and terrestrial runners. Sixty-Four French National-Level young soccer players (28 females, 36 males) performed three trials of unloaded maximal 40m sprints. External horizontal power-force-velocity relationships were computed using a validated biomechanical model and based on the velocity-time curve. Accordingly, the participants were classified into patterns in aerial and terrestrial runners. Terrestrial runners showed a higher maximal horizontal force (F 0) (6.73 ± 1.03 vs 6.01 ± 0.94 N·kg-1), maximal horizontal power (P max) (14.04 ± 3.24 vs 12.51 ± 3.31), maximal acceleration (Acc) (6.83 ± 0.85 vs 6.26 ± 0.89 m·s-2), and maximal rate of horizontal force (RF max) (57.41 ± 4.64 vs 52.81 ± 5.69 %) compared to aerial runners. In contrast, terrestrial runners displayed a more negative rate of decrease of RF (D RF) (-11.65 ± 1.71 vs -10.23 ± 1.66 %) and slope of the Force-Velocity relationship (F-V slope) (-0.83 ± 0.11 vs -0.77 ± 0.10 N·s·m-1·kg-1) than aerial runners. The results indicate that terrestrial runners displayed more efficient force production in the forward direction and displayed more "force-oriented" F-V profiles. Nevertheless, aerial runners were more effective in maintaining a net horizontal force production with increasing speed. Our results suggest that terrestrial runners could be more adapted to the specific short distance and high acceleration sprints running. 



#12 Variability of professional soccer players' perceived match load after successive matches 

Reference: Res Sports Med. 2020 Dec 17;1-15. doi: 10.1080/15438627.2020.1856104. Online ahead of print. 

Authors: Unai Azcárate, Asier Los Arcos, Javier Yanci

Summary: This study analyses the differential perceived match load accumulated by professional soccer players depending on their: (a) participation in several consecutive official matches within the same week (Pre_Cup, Cup, and Post_Cup), and (b) total match participation time (i.e. 90 min, 70-90 min and < 70 min). Participants were 21 Spanish Second Division professional soccer players (M age = 27.1, SD = 3.3 years; M body height = 182.1, SD = 3.9 cm; M body mass = 75.8, SD = 5.14 kg). There were no significant differences (p > 0.05) in dRPE-ML among Pre_Cup, Cup and Post_Cup matches or in dRPE-ML between teams that took part in two or three official matches within the same week or three official matches in 2-4 consecutive weeks. The results suggest that participating in several matches in the same week does not increase accumulated perceived exertion for professional soccer players. 



#13 The Relationship between Motivational Climate and Personal Treatment Satisfaction among Young Soccer Players in Norway: The Moderating Role of Supportive Coach-Behaviour

Reference: Sports (Basel). 2020 Dec 12;8(12):E162. doi: 10.3390/sports8120162. 

Authors: Tommy Haugen, Jan F Riesen, Ketil Østrem, Rune Høigaard, Martin K Erikstad

Summary: Motivational climate and coach-behaviour seem important to understand sport involvement and participation. However, less is known about the potential interaction between these facets, and how it relates to athlete satisfaction. This study's purpose is to examine the relationship between the perceived motivational climate, supportive coach-behaviour, and athletes' personal treatment satisfaction among young soccer players. More specifically, we investigated the moderating effect of supportive coach-behaviour on the relationship between motivational climate and personal treatment satisfaction. Five hundred and thirty-two players (Mean age = 15.4 years, SD = 1.2) attending a Norwegian national soccer tournament participated in the study. Self-completion questionnaires were used to attain data. A linear regression analysis revealed that mastery of climate and supportive coach-behaviour were positively associated with personal treatment satisfaction. A negative association was found between performance climate and personal treatment satisfaction. Further, moderation analyses revealed that supportive coach-behaviour moderated the relationship between performance climate and personal treatment satisfaction. The findings indicate that a performance climate may not be as maladaptive when coaches provide supportive behaviour. The findings highlight the value of a further examination of the interaction between motivational climate and coaching behaviours, and its potential relations to young athlete's sport experience. 



#14 Position Specific Running Performances in Professional Football (Soccer): Influence of Different Tactical Formations

Reference: Sports (Basel). 2020 Dec 10;8(12):E161. doi: 10.3390/sports8120161. 

Authors: Toni Modric, Sime Versic, Damir Sekulic 

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Summary: Running performances (RPs) are known to be important parameters of success in football (soccer), but there is a lack of studies where RPs are contextualized regarding applied tactical solutions. This study aims to quantify and analyze the differences in position-specific RPs in professional football, when games are played with three defensive players (3DP) and four defensive players (4DP). The participants here include professional football players (M ± SD, age 23.57 ± 2.84 years, body height 181.9 ± 5.17 cm, body mass 78.36 ± 4.18 kg) playing at the highest competitive level in Croatia. RPs were measured by global positioning system and classified into four groups based on playing positions: central defenders (CD; n = 47), wide defenders (WD; n = 24), midfielders (MF; n = 48), or forwards (FW; n = 19). Analysis of variance and discriminant canonical analysis are used to identify differences between 3DP and 4DP tactical solutions in terms of the RPs for each playing position. The number of accelerations and decelerations most significantly contributed to the differentiation of 3DP and 4DP among MFs (Wilks λ = 0.31, p < 0.001), with higher occurrences with 3DP. For CDs, total distance, and high-intensity running were higher in 3DP (Wilks λ = 0.66, p < 0.001). No multivariate differences were found for FW and WD players in terms of the RPs between 3DP and 4DP tactical formations. The characteristics and differences shown in this study may provide useful information for coaching staff regarding changing in-season tactical formations. Additionally, the results are useful for optimizing training programs for football players with different playing positions. When changing from 4DP to 3DP tactical formations, WDs training programs should include more of high-intensity running, while MFs training programs should be more based on short intensity activities (accelerations and decelerations). 



#15 A New Approach for Training-load Quantification in Elite-level Soccer: Contextual Factors

Reference: Int J Sports Med. 2020 Dec 15. doi: 10.1055/a-1289-9059. Online ahead of print. 

Authors: Berni Guerrero-Calderón, Maximilian Klemp, Alfonso Castillo-Rodriguez, José Alfonso Morcillo, Daniel Memmert

Summary: The aims of this study were to analyse the physical responses of professional soccer players during training considering the contextual factors of match location, season period, and quality of the opposition; and to establish prediction models of physical responses during training sessions. Training data was obtained from 30 professional soccer players from Spanish La Liga using global positioning technology (N=1365 performances). A decreased workload was showed during training weeks prior to home matches, showing large effects in power events, equivalent distance, total distance, walk distance and low-speed running distance. Also, the quality of the opposition also affected the training workload (p<0.05). All regression-models showed moderate effects, with an adjusted R2 of 0.37 for metabolic-work, 0.34 for total distance covered, 0.25 for high-speed running distance (18-21 km·h-1), 0.29 for very high-speed running distance (21-24 km·h-1), 0.22 for sprint running distance (>24 km·h-1) and 0.34 for equivalent distance. The main finding of this study was the great association of match location, season period and quality of opposition on the workload performed by players in the training week before the match; and the development of workload prediction-models considering these contextual factors, thus proposing a new and innovative approach to quantify the workload in soccer. 



#16 Body temperature and physical performance responses are not maintained at the time of pitch-entry when typical substitute-specific match-day practices are adopted before simulated soccer match-play

Reference: J Sci Med Sport. 2020 Nov 30;S1440-2440(20)30835-5. doi: 10.1016/j.jsams.2020.11.013. 

Authors: Samuel P Hills, Hendrickus G J Aben, David P Starr, Liam P Kilduff, Shawn M Arent, Martin J Barwood, Jon N Radcliffe, Carlton B Cooke, Mark Russell

Summary: The purpose was to profile performance and physiological responses to typical patterns of match-day activity for second-half soccer substitutes. Following a warm-up, 13 male team sports players underwent 85min of rest, punctuated with five min rewarm-ups at 25, 50, and 70min, before 30min of simulated soccer match-play. Countermovement jump performance (jump height, peak power output), alongside 15m sprints, were assessed post-warm-up, and pre- and post-simulated match-play. Core temperature, heart rate, ratings of perceived exertion, and blood glucose and lactate concentrations were measured throughout. Warm-up-induced core temperature elevations (2.3%, +0.85°C; p<0.001) were maintained until after the first rewarm-up. Thereafter, core temperature was reduced from post-warm-up values until pre-simulated match-play (1.6%, -0.60°C; p<0.001), where values were similar to pre-warm-up (37.07±0.24°C, p=0.981). Simulated match-play increased core temperature progressively (p≤0.05) but values remained lower than post-warm-up (5min; p=0.002) until 10min into exercise. From post-warm-up to pre-simulated match-play, sprint times (3.9%, +0.10s, p=0.003), jump height (9.4%, -3.1cm; p=0.017), and peak power output (7.2%, -296W; p<0.001) worsened. Despite increased ratings of perceived exertion and elevated blood lactate concentrations (p≤0.05), sprint times were maintained throughout exercise, whereas peak power increased (7.8%, +294W; p=0.006) pre- to post-exercise. At the point of simulated pitch-entry, body temperature and physical performance responses were not maintained from warm-up cessation despite typical substitute-specific match-day practices being employed in thermoneutral conditions. Evidence of performance-limiting fatigue was absent during 30min of simulated match-play. These data question the efficacy of practices typically implemented by substitutes before pitch-entry. 


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