Latest research in football - week 9 - 2021

#1 The Effect of Preparatory Posture on Goalkeeper's Diving Save Performance in Football 

Reference: Front Sports Act Living. 2019 Aug 21;1:15. doi: 10.3389/fspor.2019.00015. eCollection 2019. 

Authors: Rony Ibrahim, Idsart Kingma, Vosse de Boode, Gert S Faber, Jaap H van Dieën

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739625/pdf/fspor-01-00015.pdf

Summary: Identifying the optimal preparatory posture of football goalkeepers can be very relevant for improving goalkeepers' diving save performance, and coaching practices of technical and strength and conditioning coaches. This study aimed to analyse the effect of different starting stance widths and knee flexion angles on movement time, center of mass (CoM) trajectory and velocity in goalkeepers' diving saves. Ten elite goalkeepers performed dives from preferred (PT) and imposed postures, by altering knee angle (45, 75, and 90°) and stance width (50, 75, and 100% of leg length) independently, at the starting position. Repeated measures ANOVA showed a main effect of preparatory posture on dive time (p < 0.01). Pairwise comparisons showed that the fastest dive movement time was observed when goalkeepers started from a stance width of 75% (SW75). CoM traveled a larger distance between contralateral and ipsilateral peak ground reaction forces in SW75 than PT (p < 0.05). The goalkeepers were also more efficient in SW75, as a smaller countermovement and vertical velocity range were observed during high and low dives, respectively, from SW75 than PT (p < 0.05). Thus, diving from a position with wider stance width than the preferred one leads to shorter movement time, and a faster and more direct CoM trajectory toward the ball. 

 

 

#2 Role of tattoos in football: Behavioral patterns and success-analysis of the FIFA World Cup 2018

Reference: Clin Dermatol. Nov-Dec 2020;38(6):788-792. doi: 10.1016/j.clindermatol.2020.04.006.

Authors: Simon M Mueller, Michael Bayer, Mattia Antenna, Stefan Gysin

Summary: Epidemiologic studies suggest that individuals with tattoos are more extroverted, aggressive, and more likely to take risks than individuals with no tattoos. Whether these personality traits affect athletic performance is uncertain. We compared behavioral patterns and rates of success of football players at the International Federation of Association Football (FIFA) World Cup 2018 by tattoo status. In this cross-sectional study, 32.7% of football players had visible tattoos (241 of 736), mostly on their arms (97.1%). Footballers with tattoos played longer on average (208 versus 160 minutes; P < .001), received more cards (.38 versus .27; P < .001), and committed more fouls per player (2.64 versus 2.2; P < .001). Players with tattoos attempted more shots at goal (P = .016), but without higher goal success (P = .204). The higher number of disciplinary events (being whistled for fouls and given yellow or red cards) and longer playing time of football players with tattoos may reflect personality traits reported in nonathletic individuals with tattoos, such as dominance, extroversion, aggressiveness, and willingness to take risks. 

 

 

#3 Angular Velocity, Moment, and Power Analysis of the Ankle, Knee, and Hip Joints in the Goalkeeper's Diving Save in Football

Reference: Front Sports Act Living. 2020 Feb 28;2:13. doi: 10.3389/fspor.2020.00013. eCollection 2020. 

Authors: Rony Ibrahim, Idsart Kingma, Vosse de Boode, Gert S Faber, Jaap H van Dieën 

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739716/pdf/fspor-02-00013.pdf

Summary: The aim of this study was to identify biomechanical characteristics of goalkeeper's diving performance in football. Lower extremity joints powers, moments, and angular velocities, were investigated in seven elite goalkeepers diving to save balls, shot from a ball canon to unanticipated heights (high and low) and sides (right and left). Our result showed that there was a proximal-to-distal sequence for each leg in timing of peak joints powers (p < 0.05). Hip extensors produced the largest (p < 0.05) peak moment, the contralateral (relative to dive side) peak was significantly larger than the ipsilateral one for high (4.56 ± 1.02 N·m·kg-1, and 3.52 ± 0.79 N·m·kg-1) and low dives (3.52 ± 0.79 N·m·kg-1, and 2.52 ± 0.56 N·m·kg-1). The ankle plantar flexors produced the second largest peak moment (p < 0.05), and the peak ipsilateral ankle power and angular velocity were the largest (p < 0.05) of all joints, during high (1,502 ± 338 W, and 14.73 ± 1.36 rad·s-1) and low dives (868 ± 263 W, and 14.14 ± 3.09 rad·s-1). Strength and conditioning coaches need to focus on hip extensors and ankle plantar flexors, and for specificity in power training that should elicit triple extension of the lower limbs' joints in a proximal-to-distal sequence. 

 

 

#4 Referee Bias in Professional Football: Favoritism Toward Successful Teams in Potential Penalty Situations 

Reference: Front Sports Act Living. 2020 Feb 27;2:19. doi: 10.3389/fspor.2020.00019. eCollection 2020. 

Authors: Martin Kjeøen Erikstad, Bjørn Tore Johansen

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739605/pdf/fspor-02-00019.pdf

Summary: Past studies have indicated that multiple factors may influence sport referees' decisions, such as pressure from spectators and athletes' reputation. Grounded in the social impact theory framework, this study examined whether Norwegian Premier League (NPL) referees are biased by a team's success when awarding penalties. Using video footage (similar to video assistant referees), an expert panel (EP) of four NPL referees evaluated all potential penalty situations (N = 43) involving either of two successful teams during an entire NPL season. Fifty-five potential penalty situations from matches without successful teams were also rated. Overall, the match referees identified 73.3% (22 of 30) of the EP-identified penalties during matches without successful teams. Successful teams were awarded 110% (11 of 10) of the EP-identified penalties, while their opponents were awarded 12.5% (1 of 8). Chi square statistic revealed that successful teams were more likely to receive an incorrect penalty compared with their opponents, and less likely to be denied a penalty they should have been awarded. These findings indicate that referees' decisions may be unintentionally biased by a team's success, extending our knowledge about how football referees may be influenced by social forces. 

 

 

#5 Large Reductions in Match Play Physical Performance Variables Across a Professional Football Season With Control for Situational and Contextual Variables

Reference: Front Sports Act Living. 2020 Oct 15;2:570937. doi: 10.3389/fspor.2020.570937. eCollection 2020. 

Authors: Matthew Springham, Sean Williams, Mark Waldron, Darren Burgess, Robert Usher Newton

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739604/pdf/fspor-02-570937.pdf

Summary: This investigation examined match play physical performance across a professional football season using a multicamera computerized tracking system. A linear mixed-effects model, controlling for situational and contextual variables, identified decreases in team average total distance (TD): season quarter 1 (Q1) (11,047 m) > season quarter 2 (Q2) (10,473 m) (P = 0.002; ES = Small), season quarter 3 (Q3) (10,449 m) (P < 0.001; ES = Moderate), and season quarter 4 (Q4) (10,385 m) (P < 0.001; ES = Moderate); work rate (WR): Q1 (115 m/min) > Q3 (108 m/min) (P < 0.001; ES = Moderate), Q4 (107 m/min) (P < 0.001; ES = Moderate); Q2 (109 m/min) > Q4 (107 m/min) (P = 0.003; ES = Small); high-speed running distance (HSR): Q1 (1,051 m) > Q2 (813 m) (P = 0.006; ES = Small); number of high-speed runs (NHSR): Q1 (87) > Q2 (65) (P < 0.001; ES = Small), Q3 (64) (P = 0.002; ES = Small); sprint distance (SD): Q1 (202 m) > Q4 (130 m) (P < 0.001; ES = Moderate), Q2 (179 m) > Q3 (165 m) (P = 0.035; ES = Small), Q4 (130 m) (P < 0.001; ES = Moderate) and number of sprints (NS): Q1 (20.4) > Q3 (10.2) (P < 0.001; ES = Moderate), Q4 (8.3) (P < 0.001; ES = Large); Q2 (14.9) > Q3 (10.2) (P < 0.001; ES = Moderate), Q4 (8.3) (P < 0.001; ES = Large). Within-position changes were observed for WR: Q1 (122 m/min) > Q4 (113 m/min) (P = 0.002; ES = Large) in central midfielders and for NS: Q1 > Q3 in wide defenders (21.7 vs. 10.8) (P = 0.044; ES = Large) and central midfielders (18.1 vs. 8.3) (P = 0.002; ES = Large); Q1 > Q4 in central defenders (13.1 vs. 5.3) (P = 0.014; ES = Large), wide defenders (21.6 vs. 7.1) (P < 0.001; ES = Very Large), central midfielders (18.1 vs. 8.5) (P = 0.005; ES = Large), and wide midfielders (20.8 vs. 12.2) (P = 0.012; ES = Large); Q2 > Q3 in central midfielders (16.9 vs. 8.3) (P = 0.002; ES = Large) and Q2 > Q4 in wide defenders (16.3 vs. 7.1) (P = 0.005; ES = Very Large), central midfielders (16.9 vs. 8.5) (P = 0.004; ES = Large), and wide midfielders (20.8 vs. 12.2) (P = 0.007; ES = Large). The match-play physical performance was reduced across the competitive season. The most notable reductions were observed in wide defenders, central midfielders, and wide midfielders in sprint performance indices. 

 

 

#6 Origins of Relative Age Effects in Youth Football-A Nationwide Analysis 

Reference: Front Sports Act Living. 2020 Dec 3;2:591072. doi: 10.3389/fspor.2020.591072. eCollection 2020. 

Authors: Michael Romann, Eva Rüeger, Mirjam Hintermann, Raphael Kern, Oliver Faude 

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739734/pdf/fspor-02-591072.pdf

Summary: Relative age effects (RAEs) refer to the overrepresentation of players born earlier in the selection year compared to late-born players within the same age category. To date, the origins and mechanisms of RAEs are still unclear. To evaluate the development of RAEs in terms of age group and selection level, we analyzed data of all registered child and adolescent football players in Switzerland. Age category, selection level, and birthdate from all licensed 101,991 Swiss child and youth football players assigned to a specific team [9,149 girls (9.0%) and 92,842 boys (91.0%); age range: 4.6-19.6 years] were analyzed. Additionally, out of 1,128 clubs, 54 clubs provided their documented waiting lists (1,224 players). Birthdate distributions were split by age category, sex, and birth quarter (Q1 = January to March, Q4 = October to December). RAEs were calculated using odds ratios (Q1 vs. Q4) with 95% confidence intervals (95% CI). We found small RAEs among U8 players (OR 1.44 [95% CI 1.31, 1.59]) and U10 (OR 1.24 [95% CI 1.16, 1.32]). The RAE was negligible in all other age categories, independent of gender. In children's football, 5,584 (71.3%) teams performed selections. In teams without selection, there were no obvious RAEs. However, teams with selections for the same age category showed small RAEs with an overrepresentation of Q1 athletes in the first team (OR = 1.29 [95% CI 1.24, 1.35]) and inverse RAEs with an underrepresentation of Q1 athletes in the last team (OR = 0.85 [95% CI 0.82, 0.89]). Only small RAEs were observed on the waiting lists for the U8 (OR = 1.48 [1.13, 1.95]). RAEs have a small, but consistent effect on participation in Swiss children's football at the grassroots level. Contrary to expectations, no inverse RAEs were found on the waiting lists. Nonetheless, first time coach selections seem to be the origin of RAEs. To protect young athletes from discrimination, RAE biases should be analyzed and eliminated at all stages of sport participation, selection, and dropout situations. Modifications to the organizational structure of sport and athlete development systems are recommended to prevent RAE-related discrimination in youth sports. 

 

 

#7 Asymptomatic Degenerative Changes in the Lumbar Spine Among Professional Soccer Players 

Reference: Spine (Phila Pa 1976). 2021 Jan 15;46(2):122-128. doi: 10.1097/BRS.0000000000003726. 

Authors: Eduard Bezuglov, Artemii Lazarev, Arseniy Petrov, Alesia Brodskaia, Anastasiya Lyubushkina, Kamila Kubacheva, Evgeny Achkasov, Vladimir Nikolenko

Summary: The aim of this study was to evaluate the actual prevalence of degenerative spinal changes and their association with age in a cohort of professional soccer players. Presently, there are data that athletes have more degenerative changes than nonathletes; however, the research examining the prevalence of degenerative spinal conditions among professional elite soccer players is scarce. Professional male soccer players were included in the study (n = 40, average age 26,6 ± 4,5 years, average height 18 ± 0.07 m, weight 76.7 ± 7.1 kg). Lumbosacral spine MRI scanning at the L1-S1 level has been performed. Two radiologists with at least 7 years of experience of working with athletes evaluated all images independently of each other. 92.5% (n = 37) of soccer players had ≥1 spinal degenerative condition. Thirty-five percent (n = 14) of players had three to five, and 50% (n = 20) had six or more conditions. The average age of players who had six or more conditions was significantly higher than those who had zero to five or three to five conditions-28.1 ± 4.8 years versus 25.1 ± 3.6 years (P = 0.029), and 24.8 ± 3.6 years, respectively.Kruskal-Wallis test has shown no association between the number of degenerative conditions and weight (P = 0.98) as well as body mass index (P = 0.99). The age was associated with degenerative changes (P = 0.008).Disc desiccation was the most common pathologic condition, which was found in 82.5% of athletes. Facet joint arthropathy and spondylosis were present in 70, and 50% of the studied lumbar spine MRI scans, respectively. The spondylolysis prevalence of 20% was noted. Elite professional soccer players demonstrate a high prevalence of asymptomatic degenerative lumbar spinal degenerative changes, which are significantly associated with age. These conditions might lead to the development of symptomatic lower back pain, given the high-intensity exercise required in professional soccer. It is presently unclear what measures might be applied for the primary prevention of these degenerative spinal conditions.Level of Evidence: 4. 

 

 

#8 Covid-19 Has Turned Home Advantage Into Home Disadvantage in the German Soccer Bundesliga 

Reference: Front Sports Act Living. 2020 Nov 5;2:593499. doi: 10.3389/fspor.2020.593499. eCollection 2020. 

Authors: Markus Tilp, Sigrid Thaller

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739793/pdf/fspor-02-593499.pdf

Summary: The main factors for home advantage (HA), quantified by the number of points won at home expressed as a percentage of all points, are believed to be crowd support, territoriality, familiarity, and travel fatigue. In 2020, the German Soccer Bundesliga interrupted its championship due to the Covid-19 pandemic after 25 rounds and the last nine rounds were played without audience. This unique situation allowed studying the effect of spectators on the team's performance and the referee's decisions. We hypothesized a decrease in HA and a more balanced distribution of fouls and disciplinary cards in the games without audience (GWOA) compared to the games with audience (GWA). We evaluated n = 223 GWA and n = 83 GWOA of the season 2019/20 and all games of the preceding season 2018/19 to analyze the distribution of game outcomes (wins, losses, and draws) and HA. We analyzed the number of fouls, disciplinary cards, and penalty kicks. We found significant differences in HA between GWA (HA = 54.35%) and GWOA (HA = 44.1%) as well as GWOA and games of 2018/19 (HA = 57.63%). The distribution of game outcomes in GWOA did not differ from GWA but differed significantly from 2018/19 (p = 0.031). The distribution of fouls showed a significant difference to equal distribution in GWA [home: 2,595 (48.56%); away: 2,749 (51.44%)] but not in GWOA [home: 1,067 (50.54%); away: 1,044 (49.46%)]. In the GWOA, we counted 178 (51.1%, home) and 170 (48.9%, away) cards, representing a significant difference in the distribution to GWA [home: 405 (44.85%); away: 498 (55.15%)]. The number of red cards differed significantly from an equal distribution for GWA (14 home and 28 away) but not for GWOA (eight home and seven away). In the last nine rounds without audience, we observed more home losses (36) than home wins (27). Hence, the Covid-19 lock-down led to a home disadvantage. One reason for this surprising result could be that the home team is missing an important familiar aspect when playing in their empty stadium without social support from their home audience. Furthermore, both teams know about the HA thus the away team could be more motivated in this unusual situation. 

 

 

#9 Effect of Practicing Soccer Juggling With Different Sized Balls Upon Performance, Retention, and Transfer to Ball Reception 

Reference: Motor Control. 2016 Oct;20(4):337-49. doi: 10.1123/mc.2015-0026. Epub 2016 Aug 19. 

Authors: Olav Raastad, Tore Kristian Aune, Roland van den Tillaar

Summary: The aim of this study was to investigate if making the skill acquisition phase more difficult or easier would enhance performance in soccer juggling, and if this practice has a positive intertask transfer effect to ball reception performance. Twenty-two adolescent soccer players were tested in juggling a soccer ball and in the control of an approaching ball at a pre, post and retention test. The participants were randomly divided in a small ball size and bigger ball size training group that both trained four times per week for 6 weeks. At the post and retention test both groups enhanced performance in soccer juggling test with no difference between groups and no increase in ball reception performance at these tests. It was concluded that about intra task transfer and retention of soccer juggling skills, it does not matter if you increase (small balls) or decrease the difficulty (larger balls) when using the same amount of practice time within the skill acquisition phase in soccer juggling. In addition that for ball juggling and ball reception (inter task) these two tasks differ too much in afferent information and movement characteristics that no positive transfer between these two skills no positive intertask transfer can be expected. 

 

 

#10 Acute effects of small-sided games combined with running drills on internal and external loads in young soccer players 

Reference: Biol Sport. 2020 Dec;37(4):375-381. doi: 10.5114/biolsport.2020.96943. Epub 2020 Jul 5. 

Authors: Yusuf Köklü, Hamit Cihan, Utku Alemdaroğlu, Alexandre Dellal, Del P Wong

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7725044/pdf/JBS-37-96943.pdf

Summary: The purpose of this study was to compare the effects of regular small-sided games (SSGreg) and SSGs combined with running drills (SSGcom) on players' internal and external loads. Eighteen young male soccer players (average age: 18.2 ± 0.5 years) participated in 3 vs. 3 and 4 vs. 4 games, under both SSGreg and SSGcom conditions. SSGreg bouts were played for 4 minutes without additional running drills, while SSGcom bouts consisted of 3 min 30 s SSG and 15 s running before and after the bout, making the duration of each bout 4 minutes. During all SSGs, measurements of heart rate (HR) responses as well as distances covered in four different speed zones - walking (WLK), low-intensity (LIR), moderate-intensity (MIR) and high-intensity running (HIR) - were recorded. Technical characteristics were monitored during the SSGs, and the rating of perceived exertion (RPE) and blood lactate (La-) responses were determined at the end of each SSG condition. Compared to the SSGreg in both 3 vs. 3 and 4 vs. 4 formats, the SSGcom condition resulted in higher La- and RPE responses (p < 0.05), greater distance covered at MIR and HIR speeds and greater total distance (p < 0.05). The results of this study show that replacing 30 s within the 4-min bouts of SSGs (both 3- and 4-a-side) by 2 x 15 s of running drills is effective in increasing internal (La- and RPE) and external loads (MIR and HIR) without a significant decrease in total passes and successful passes in young soccer players. 

 

 

#11 Are There Differences in Concentric Isokinetic Strength Performance Profiles between International and Non-International Elite Soccer Players? 

Reference: Int J Environ Res Public Health. 2020 Dec 23;18(1):E35. 

doi: 10.3390/ijerph18010035. 

Authors: Robert Śliwowski, Jakub Marynowicz, Monika Grygorowicz, Andrzej Wieczorek, Łukasz Jadczak

Download link: https://www.mdpi.com/1660-4601/18/1/35/htm

Summary: The purpose of this study is to evaluate the differences in concentric isokinetic strength characteristics of the knee extensor and knee flexor musculature between international (IL) and non-international level (N-IL) soccer players. The second aim is to establish strength symmetry status in knee muscles for dominant (DL) and non-dominant (NDL) legs for both within and between groups. 100 male top elite soccer players (IL: n = 36, age = 27.5 ± 3.4 years and N-IL: n = 64, age = 27.7 ± 6.4 years) underwent concentric isokinetic strength tests, using a Biodex System 3 dynamometer. Results indicate that statistically significant differences between groups were noted for peak torque of hamstrings (PT-H), hamstrings/quadriceps (H/Q) ratio, and total work of hamstrings (TW-H), where mean values for the IL were similarly higher than for the N-IL group (p = 0.006, p < 0.001, and p = 0.012, respectively). Our results also showed statistically significant differences for peak torque of quadriceps (PT-Q), PT-H, total work of quadriceps (TW-Q) and TW-H between legs, where mean values noted for the DL were higher than for the NDL for both groups (p = 0.021, p < 0.001, p = 0.006, and p = 0.004, respectively). Additional results show that IL players presented more symmetrical strength between legs than N-IL. The results of this study indicate that that the greatest differences in isokinetic strength performance across players at different soccer levels relate to the hamstring muscle. As a result, systematic strength training of these muscle groups is strongly recommended. 

 

 

#12 Internal (Factorial) Validity of the ANAM using a Cohort of Woman High-School Soccer Players 

Reference: Arch Clin Neuropsychol. 2020 Dec 29;acaa120. doi: 10.1093/arclin/acaa120. Online ahead of print. 

Authors: Joseph J Glutting, Adam Davey, Victoria E Wahlquist, Marley Watkins, Thomas W Kaminski

Summary: Computerized neuropsychological testing is a cornerstone of sport-related concussion assessment. Female soccer players are at an increased risk for concussion as well as exposures to repetitive head impacts from heading a soccer ball. Our primary aim was to examine factorial validity of the Automated Neuropsychological Assessment Metrics (ANAM) neuropsychological test battery in computing the multiple neurocognitive constructs it purports to measure in a large cohort of interscholastic female soccer players. Study participants included 218 interscholastic female soccer players (age = 17.0±0.7 year; mass = 55.5±6.8 kg; height = 164.7±6.6 cm) drawn from a large (850+) prospective database examining purposeful heading from four area high schools over a 10-year period. The ANAM-2001 measured neurocognitive performance. Three methods were used to identify integral constructs underlying the ANAM: (a) exploratory factor analysis (EFA), (b) first-order confirmatory factor analysis (CFA), and (c) hierarchical CFA. Neuropsychological phenomena measured by the ANAM-2001 were best reproduced by a hierarchical CFA organization, composed of two lower level factors (Simple Reaction Time, Mental Efficiency) and a single, general composite. Although the ANAM was multidimensional, only the composite was found to possess sufficient construct dimensionality and reliability for clinical score interpretation. Findings failed to uphold suppositions that the ANAM measures seven distinct constructs, or that any of its seven tests provide unique information independent of other constructs, or the composite, to support individual interpretation. Outcomes infer the ANAM possesses factorial-validity evidence, but only scores from the composite appear to sufficiently internally valid, and reliable, to support applied use by practitioners. 

 

 

#13 SOS to the Soccer World. Each Time the Preseason Games Are Less Friendly 

Reference: Front Sports Act Living. 2020 Dec 18;2:559539. doi: 10.3389/fspor.2020.559539. eCollection 2020. 

Authors: Julio Calleja-Gonzalez, Carlos Lalín, Francesc Cos, Diego Marques-Jimenez, Pedro E Alcaraz, Antonio José Gómez-Díaz, Tomás T Freitas, Juan Mielgo Ayuso, Irineu Loturco, Xavi Peirau, Ignacio Refoyo, Nicolas Terrados, Jaime E Sampaio 

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7750874/pdf/fspor-02-559539.pdf

 

 

#14 Changes in sprint performance and sagittal plane kinematics after heavy resisted sprint training in professional soccer players

Reference: PeerJ. 2020 Dec 15;8:e10507. doi: 10.7717/peerj.10507. eCollection 2020. 

Authors: Johan Lahti, Toni Huuhka, Valentin Romero, Ian Bezodis, Jean-Benoit Morin, Keijo Häkkinen 

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7747683/pdf/peerj-08-10507.pdf

Summary: Sprint performance is an essential skill to target within soccer, which can be likely achieved with a variety of methods, including different on-field training options. One such method could be heavy resisted sprint training. However, the effects of such overload on sprint performance and the related kinetic changes are unknown in a professional setting. Another unknown factor is whether violating kinematic specificity via heavy resistance will lead to changes in unloaded sprinting kinematics. We investigated whether heavy resisted sled training (HS) affects sprint performance, kinetics, sagittal plane kinematics, and spatiotemporal parameters in professional male soccer players. After familiarization, a nine-week training protocol and a two-week taper was completed with sprint performance and force-velocity (FV) profiles compared before and after. Out of the two recruited homogenous soccer teams (N = 32, age: 24.1 ± 5.1 years: height: 180 ± 10 cm; body-mass: 76.7 ± 7.7 kg, 30-m split-time: 4.63 ± 0.13 s), one was used as a control group continuing training as normal with no systematic acceleration training (CON, N = 13), while the intervention team was matched into two HS subgroups based on their sprint performance. Subgroup one trained with a resistance that induced a 60% velocity decrement from maximal velocity (N = 10, HS60%) and subgroup two used a 50% velocity decrement resistance (N = 9, HS50%) based on individual load-velocity profiles. Both heavy resistance subgroups improved significantly all 10-30-m split times (p < 0.05, d = - 1.25; -0.62). Post-hoc analysis showed that HS50% improved significantly more compared to CON in 0-10-m split-time (d = 1.03) and peak power (d = 1.16). Initial maximal theoretical horizontal force capacity (F0) and sprint FV-sprint profile properties showed a significant moderate relationship with F0 adaptation potential (p < 0.05). No significant differences in sprinting kinematics or spatiotemporal variables were observed that remained under the between-session minimal detectable change. With appropriate coaching, heavy resisted sprint training could be one pragmatic option to assist improvements in sprint performance without adverse changes in sprinting kinematics in professional soccer players. Assessing each player's initial individual sprint FV-profile may assist in predicting adaptation potential. More studies are needed that compare heavy resisted sprinting in randomized conditions. 

 

 

#15 Reliability assessment of the functional movement screen for predicting injury risk in Japanese college soccer players 

Reference: J Phys Ther Sci. 2020 Dec;32(12):850-855. doi: 10.1589/jpts.32.850. Epub 2020 Dec 11. 

Authors: Takayuki Miyamori, Masashi Nagao, Yu Shimasaki, Takayuki Okazaki, Naoki Akiyoshi, Hirofumi Nishio, Yuji Takazawa, Masafumi Yoshimura

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758602/pdf/jpts-32-850.pdf

Summary: This study aimed to assess the reliability of the Functional Movement Screen and explore whether this evaluation tool can predict the risks of personal injuries in Japanese soccer players. Seventy-five Japanese college soccer players who participated in our 1 year prospective cohort study underwent a Functional Movement Screen assessment. Demographic data, athletic characteristics, and types and frequency of injuries sustained, were analyzed with the assessment results. There was no significant difference in the mean Functional Movement Screen composite scores between genders. Although the Functional Movement Screen showed excellent inter-rater reliability (0.92), low overall internal consistency (0.35) was observed. A maximum score of 3 in straight leg raise occurred in 94% of the females and was considered a ceiling effect. None of the cut-off point scores of the Functional Movement Screen were associated with the number of overall injuries, lower limb injuries, and traumatic injuries, or time to return to play. The Functional Movement Screen composite score of ≤15 represented the maximum sensitivity of 76.92% and specificity of 34.78% with 0.56 in the area under the curve. Functional Movement Screen composite scores do not have sufficient sensitivity and specificity for predicting injuries in Japanese college soccer players.