Latest research in football - week 21 - 2023

#1 The influence of age on the match-to-match variability of physical performance in women's elite football

Reference: Front Physiol. 2023 May 15;14:1193501. doi: 10.3389/fphys.2023.1193501. eCollection 2023.

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

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10225501/pdf/fphys-14-1193501.pdf

Summary: Introduction: The fluctuation of external match load throughout a season is influenced by several contextual factors. While some, have been deeply analysed in men's football literature, information is lacking on how other contextual elements, such as player's age or experience, may affect the match-to-match variability of locomotor activities. In fact, aging has been described as a multifactorial process with the potential to affect human performance. The aim of this study is to assess if the variability of match locomotor performances fluctuates according to the players' age. Methods: 59 female players from four top-level clubs were divided into three age groups and monitored during two seasons using GPS APEX (STATSports, Northern Ireland), with a sampling frequency of 10Hz, in 150 official matches to determine the coefficient of variation (CV) of full-match and 1-min peak locomotor demands of total distance (TD), high-speed running distance, sprint distance (SpD), accelerations, and decelerations. To test whether there was a group effect of age on match-to-match variability we used a one-way ANOVA with CV% as the independent variable. Results: CV values of full match variables ranged from 3.8% to 27.8%, with total distance (3.8%) in the peak age group and SpD (27.8%) in the pre-peak age group. Similarly, CV values of 1-min peaks ranged from 4.1% (post-peak group) in TD to 22.3% (peak group) in SpD. Discussion: The main finding was that there were no significant differences between the different age groups in the metrics analysed although trends indicate less variability in the post-peak age group.

 

 

#2 Bipartite Patella in an Elite Football Player - A Rare Cause of Anterior Knee Pain

Reference: J Orthop Case Rep. 2023 May;13(5):68-71. doi: 10.13107/jocr.2023.v13.i05.3650.

Authors: Janani Gopalakrishnan, Vivek Anbarasan, Prakash Ayyadurai, Arumugam Sivaraman

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10226642/pdf/JOCR-13-68.pdf

Summary: Bipartite patella is usually an asymptomatic anatomical variant estimated to have a prevalence of 0.2-6% in an adult population. A 28-year-old league-level football player presented with the left anterior knee pain of 6 months duration. Imaging studies revealed bilateral bipartite patella. Arthroscopic excision of the fragment was performed following which he returned to play 6 weeks after accelerated sports-specific rehabilitation. Atraumatic knee pain should raise suspicion of the bipartite patella. Surgical intervention plays a key role in patients with refractory pain after careful exclusion of other causes of anterior knee pain. Arthroscopic excision is preferred in the case of a high-demand athlete to accelerate recovery and fasten the return to sport duration.

 

 

#3 Longitudinal Associations of Clinical and Biochemical Head Injury Biomarkers With Head Impact Exposure in Adolescent Football Players

Reference: JAMA Netw Open. 2023 May 1;6(5):e2316601. doi: 10.1001/jamanetworkopen.2023.16601.

Authors: Taylor R Zuidema, Jeffrey J Bazarian, Kyle A Kercher, Rebekah Mannix, Reuben H Kraft, Sharlene D Newman, Keisuke Ejima, Devin J Rettke, Jonathan T Macy, Jesse A Steinfeldt, Keisuke Kawata

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10230318/?report=printable

Summary: Consequences of subconcussive head impacts have been recognized, yet most studies to date have included small samples from a single site, used a unimodal approach, and lacked repeated testing. To examine time-course changes in clinical (near point of convergence [NPC]) and brain-injury blood biomarkers (glial fibrillary acidic protein [GFAP], ubiquitin C-terminal hydrolase-L1 [UCH-L1], and neurofilament light [NF-L]) in adolescent football players and to test whether changes in the outcomes were associated with playing position, impact kinematics, and/or brain tissue strain. This multisite, prospective cohort study included male high school football players aged 13 to 18 years at 4 high schools in the Midwest during the 2021 high school football season (preseason [July] and August 2 to November 19). A single football season was used to collect the main outcomes were NPC (a clinical oculomotor test) and serum levels of GFAP, UCH-L1, and NF-L. Participants' head impact exposure (frequency and peak linear and rotational accelerations) was tracked using instrumented mouthguards, and maximum principal strain was computed to reflect brain tissue strain. Players' neurological function was assessed at 5 time points (preseason, post-training camp, 2 in season, and postseason). Ninety-nine male players contributed to the time-course analysis (mean [SD] age, 15.8 [1.1] years), but data from 6 players (6.1%) were excluded from the association analysis due to issues related to mouthguards. Thus, 93 players yielded 9498 head impacts in a season (mean [SD], 102 [113] impacts per player). There were time-course elevations in NPC and GFAP, UCH-L1, and NF-L levels. Compared with baseline, the NPC exhibited a significant elevation over time and peaked at postseason (2.21 cm; 95% CI, 1.80-2.63 cm; P < .001). Levels of GFAP and UCH-L1 increased by 25.6 pg/mL (95% CI, 17.6-33.6 pg/mL; P < .001) and 188.5 pg/mL (95% CI, 145.6-231.4 pg/mL; P < .001), respectively, later in the season. Levels of NF-L were elevated after the training camp (0.78 pg/mL; 95% CI, 0.14-1.41 pg/mL; P = .011) and midseason (0.55 pg/mL; 95% CI, 0.13-0.99 pg/mL; P = .006) but normalized by the end of the season. Changes in UCH-L1 levels were associated with maximum principal strain later in the season (0.052 pg/mL; 95% CI, 0.015-0.088 pg/mL; P = .007) and postseason (0.069 pg/mL; 95% CI, 0.031-0.106 pg/mL; P < .001). The study data suggest that adolescent football players exhibited impairments in oculomotor function and elevations in blood biomarker levels associated with astrocyte activation and neuronal injury throughout a season. Several years of follow-up are needed to examine the long-term effects of subconcussive head impacts in adolescent football players.

 

 

#4 The associations of early specialization, sports volume, and maturity status with musculoskeletal injury in elite youth football players

Reference: Front Physiol. 2023 May 11;14:1183204.  doi: 10.3389/fphys.2023.1183204. eCollection 2023.

Authors: Xiang Li, Runze Feng, Shiyi Luo, Chunman Li, Miguel A Gómez-Ruano

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10213919/pdf/fphys-14-1183204.pdf

Summary: Youth football in schools has experienced rapid growth in China. Despite the increase of players engaging in more frequent, intensive, and organized sports training at their early ages, the controversy over early specialization (ES) still exists. This study aims to: a) investigate the training situation of players in the Chinese School Football Programme and b) examine the associations of early specialization, sports volume, and maturity status with musculoskeletal injury. A cross-sectional survey was used. Players who participated in the National School Football Winter Camp were invited to fill out a questionnaire that included the data of maturity, ES, sports volume, and injury history (n = 88 boys and n = 90 girls). The results have shown that 80.3% of the athletes were classified as ES, while 19.7% of them were classified as non-ES. Almost all athletes (96%) participated in a sport for more than 8 months in a year. Most athletes (75.8%) spent more than twice of the time on organized sports than leisure activities. 30.3% of the athletes trained on average more hours per week than the number of their ages. Binomial logistic regression models reflected the significant differences in the odds ratios (OR) of reporting a history of injury among athletes with different levels of specialization (p = 0.024) and the OR of reporting a history of leg injury among players with different weekly sports volumes (p = 0.038). Significant differences were also shown in the OR of players reporting foot injuries between players with different maturity states (p = 0.046), and the Chi-squared test showed significant differences in the OR of reporting acute injuries between players with different levels of specialization (p = 0.048) and weekly activity (p = 0.022). No significant differences were found between the remaining variables. Most school football elite players follow the ES pathway even though ES increases the risk of injury, especially acute injury. Pre-pubertal and early pubertal players have a higher incidence of foot injuries. Players who train more hours per week than their ages have more leg injuries and acute injuries. Therefore, priority protection and intervention should be carried out for populations with a high risk of injury.

 

 

#5 Running demands and tactical individual actions of wingers appear to depend on the playing formations within an amateur football team

Reference: Sci Rep. 2023 Jun 1;13(1):8927. doi: 10.1038/s41598-023-36157-6.

Authors: José María Izquierdo, Diego Marqués-Jiménez, Juan Carlos Redondo

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10235107/pdf/41598_2023_Article_36157.pdf

Summary: We examine the differences in running performance demands and tactical individual actions for male amateur football wingers in four tactical formations: 4-2-3-1, 4-4-2, 3-5-2 and 3-4-2-1 during an entire season. Running demands were assessed in terms of: total distance run; distance traveled at 3 different speed ranges (Jogging, Running, and Sprinting); and number of accelerations registered in two different magnitude bands (Medium and High) while tactical individual actions were assessed through 3269 team match observations. 3-5-2 formation entails the highest running demands, exhibiting significant disparities in Jogging when compared to 4-2-3-1 and 3-5-2, in Sprinting when comparing 4-2-3-1 with both the 3-5-2 and the 3-4-2-1 formations. Moreover, the wingers in the 3-5-2 formation demonstrate the lowest scores in various tactical individual actions, including Shots: 3-5-2 vs. 3-4-2-1; Goal Area Shots: 3-5-2 vs. 3-4-2-1; and Dribbles: 3-5-2 vs. 3-4-2-1. Finally, wingers registered the highest levels of defensive tactical individual actions in 4-4-2 and 3-5-2. Findings suggest it would be of benefit for coaches to focus on formulating specific training plans to address the specific demands placed on wingers playing in these amateur matches and running performance demands and tactical individual actions should be considered together with tactical formation.

 

 

#6 Future horizons in the analysis of technical-tactical performance in women's football: a mixed methods approach to the analysis of in-depth interviews with professional coaches and players

Reference: Front Psychol. 2023 May 18;14:1128549. doi: 10.3389/fpsyg.2023.1128549. eCollection 2023.

Authors: Iyán Iván-Baragaño, Antonio Ardá, M Teresa Anguera, José Luis Losada, Rubén Maneiro

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10234329/pdf/fpsyg-14-1128549.pdf

Summary: Scientific knowledge about the criteria that determine success in women's football is beginning to develop. This study was carried out with the aim of detecting regularities in the offensive success in elite women's football, as well as carrying out an interrelational analysis of linked behaviors, based on in-depth interviews with professional coaches and players. Eight in-depth interviews were conducted with professional Spanish coaches and players. The interviews were analyzed by indirect observation from a process of "quantitizing," through the construction of an indirect observation ad hoc instrument. The segmentation of the transcription of the interviews was carried out in textual units, and the creation of a matrix of codes. Two types of analysis were performed: first, a lag sequential analysis (LSA) was performed and, then, a polar coordinates analysis (PCA), which allowed to find, respectively, a wide number of established communicative patterns with offensive performance in women's football, as well as an interrelational map between the established codes. The results obtained allowed us to suggest a statistically significant association between success in women's football and criteria such as the physical characteristics of a particular player, the individual action space, the duration of the attack, the type of dynamic start, individual and collective technical and tactical aspects, decision making and the type of attack used. Based on these results, the influence of these criteria on performance in women's soccer can be studied in future studies. In addition, with the aim of increasing the validity of these conclusions, new studies on this subject may be carried out following strategies such as the Delphi Method.

 

 

#7 Comparison of the physiological responses and time-motion characteristics during football small-sided games: effect of pressure on the ball

Reference: Front Physiol. 2023 May 19;14:1167624. doi: 10.3389/fphys.2023.1167624. eCollection 2023.

Authors: Xiaohu Chen, Rui Zheng, Bo Xiong, Xiaoling Huang, Bingnan Gong

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10235494/pdf/fphys-14-1167624.pdf

Summary: This study aimed to compare the effects of pressure on the ball on physiological responses and time-motion characteristics during football small-sided games between elite youth male players. 56 elite male youth football players (age: 15.43 ± 0.52 years) performed a 2+GK vs. 2+GK game on a 30 m × 15 m pitch area with two playing conditions: 1) free play (FP), the player has no limitation to play; 2) pressure on the ball (PB), the player has directly and aggressively closed down space (located within 1.5 m) between themselves and the opposition player with the ball and can compete for possession. The percentage of time spent in different maximum heart rate (HRmax) zones, mean heart rate, blood lactate acid concentration, total distance covered, distance covered in three speed zones (sprint, high speed, and moderate speed), number of high speed runs, number of sprint runs, top speed, number of direction changes, and ball recovery time were monitored. We found very significantly higher number of high speed runs (p < 0.001; ES = 1.154), number of direction changes (p < 0.001; ES = 2.347), ball recovery time (p < 0.001; ES = 3.529), percentage of time spent in 90%-100% HRmax (p < 0.001; ES = 3.033), mean heart rate (p < 0.001; ES = 1.940), blood lactate acid concentration (p < 0.001; ES = 2.245) and significantly higher high speed running distance covered (p = 0.004; ES = 0.520) in the PB condition. Conversely, the FP condition showed very significantly higher moderate speed running distance covered (p < 0.001; ES = 1.814) and significantly higher percentage of time spent in 80%-90% HRmax (p = 0.012; ES = 0.440). No significant differences were revealed on sprint running distance covered (p = 0.407; ES = 0.140), number of sprint runs (p = 0.103; ES = 0.279), top speed (p = 0.130; ES = 0.258) and percentage of time spent in 60%-70% HRmax (p = 0.106; ES = 0.276), 70%-80% HRmax (p = 0.358; ES = 0.155). We found that pressure on the ball had a substantial impact on the intensity of training, as evidenced by a significantly increased high speed running performance, number of directional changes, percentage of time spent at 90%-100% of maximum heart rate, mean heart rate, and blood lactate acid concentration. Additionally, ball recovery time decreased significantly.

 

 

#8 Where are We Headed? Evidence to Inform Future Football Heading Guidelines

Reference: Sports Med. 2023 Jun 7. doi: 10.1007/s40279-023-01852-x. Online ahead of print.

Authors: Kerry Peek, Rob Duffield, Ross Cairns, Mark Jones, Tim Meyer, Alan McCall, Vincent Oxenham

Download link: https://link.springer.com/article/10.1007/s40279-023-01852-x

Summary: Given the scientific and public concern regarding the short-, medium- and long-term consequences of heading on brain health, being proactive about developing and implementing guidelines that help reduce the burden (volume, impact magnitude and injury risk) of heading in young and beginner players appears justified. This narrative review explores the evidence underpinning strategies that could be incorporated into future heading guidelines to reduce heading burden in players across all levels of football. A four-step search strategy was utilised to identify all data-based papers related to heading in football. Eligibility criteria for inclusion were: (1) original data, (2) study population included football players, (3) outcome measures included one or more of the following: number of headers, measurement of head acceleration during heading, or head/brain injury incidence, and (4) published in English or English translation available. In total, 58 papers were included that outlined strategies based on (1) game or team development, (2) player skill development and (3) equipment. In particular, greater emphasis existed for small-sided games (particularly in young players) where fewer headers are observed when compared with the conventional 11 versus 11 game, as well as reducing headers from goal kicks and corners. Evidence also existed for developing a heading coaching framework that focusses on technical proficiency as well as neuromuscular neck exercises integrated into general injury reduction exercise programs, enforcement of rules related to deliberate head contact and using lower-pressure match and training balls. To mitigate potential risks of heading on brain health, a number of pragmatic strategies have been examined in scientific studies and may be considered as part of future heading guidelines.

 

 

#9 Age related changes in the Q angle of non-professional football players

Reference: Heliyon. 2023 May 27;9(6):e16781.  doi: 10.1016/j.heliyon.2023.e16781. eCollection 2023 Jun.

Authors: Elena Escamilla-Martínez, Fátima Sánchez Martín, Javier Ramos-Ortega, Paula González-García, María-Dolores Cortés-Vega, Lourdes Mª Fernández-Seguín

Summary: Football practice involves a great muscular demand, leading to the development of the lower limbs that, on occasions, can cause deviations from the normal anthropometric values. The quadriceps angle (Q angle) is a value often taken as a reference for the alignment of the lower limbs. The aim was to observe the changes of the Q angle in young football players, because of muscular effort, analyzing the differences between four groups of different ages and to determine whether the playing position might influence these variations. A cross sectional study was carried out with 104 male subjects divided into four groups according to age: under 8 years-old, 8-17 years-old, 17-21 years-old and over 21 years-old. A photograph was taken in standing position and the Q angle was plotted with KINOVEA® software. As for the reliability of the measurements, intraclass intra and interobserver coefficient were 0.958 and 0.860 respectively. The study was conducted in mid-season. Q angle value is greater in those under 8 years of age and decreases gradually and significantly (p < 0.005) until 17-21 years of age, where it stabilizes at values of 5.73° ± 2.78 for right Q angle and 5.88° ± 2.55 for left Q angle. Two way ANOVA demonstrated a significant group*position interaction for goalkeepers with a medium effect size in both angles (p < 0.001) with a medium effect (η2 Right Q angle = 0.31; η2 Left Q angle = 0.37). The values remain unchanged in subjects over 21 years of age (p > 0.005), except for goalkeepers, who suffered a difference in the evolution of the angle within their age category (p < 0.005) and with a high effect size with the other positions (value > 0.8) except forward (value < 0.5). This study determines that the Q angle in football players decreases with growth, reaching values below 15° at the end of development. Playing positions only influence players over the age of 21, and the Q-angle of goalkeepers is greater than that of other players.

 

 

#10 Recreational Football Training Increases Leg-Extensor Velocity Production in 55- To 70-Year Old Adults: A Randomized Controlled Trial

Reference: J Sports Sci Med. 2023 Jun 1;22(2):345-357. doi: 10.52082/jssm.2023.345. eCollection 2023 Jun.

Authors: Chiel Poffé, Katrien Koppo, Arne Jaspers, Filip Boen, Werner F Helsen, Evelien Van Roie

Summary: This study investigated the effects of 10 weeks of recreational football training on the leg-extensor force-velocity (F-V) profile in 55- to 70-year-old adults. Simultaneous effects on functional capacity, body composition and endurance exercise capacity were examined. Forty participants (age 63.5 ± 3.9 years; 36♂ 4♀) were randomized in a football training (FOOT, n = 20) and a control (CON, n = 20) group. FOOT performed 45-min to 1-h of football training sessions with small-sided games twice a week. Pre- and post-intervention assessments were performed. The results revealed a greater increase in maximal velocity (d = 0.62, pint = 0.043) in FOOT compared to CON. No interaction effects were found for maximal power and force (pint > 0.05). 10-m fast walk improved more (d = 1.39, pint < 0.001), 3-step stair ascent power (d = 0.73, pint = 0.053) and body fat percentage (d = 0.61, pint = 0.083) tended to improve more in FOOT than in CON. RPE and HR values at the highest speed level during a submaximal graded treadmill test decreased more in FOOT compared to CON (RPE: d = 0.96, pint = 0.005; HR: d = 1.07, pint = 0.004). Both the number of accelerations and decelerations as well as the distance spent in moderate- and high-speed zones increased markedly throughout the 10-week period (p < 0.05). Participants perceived the sessions as very enjoyable and feasible. In conclusion, recreational football training resulted in improved leg-extensor velocity production, which translated to a better performance on functional capacity tests that rely on a high execution velocity. Simultaneously, exercise tolerance was improved and body fat percentage tended to reduce. It appears that short-term recreational football training can induce broad-spectrum health benefits in 55- to 70-year-old adults with only 2 hours of training per week.

 

 

#11 Semi-Squat Exercises with Varying Levels of Arterial Occlusion Pressure during Blood Flow Restriction Training Induce a Post-Activation Performance Enhancement and Improve Vertical Height Jump in Female Football Players

Reference: J Sports Sci Med. 2023 Jun 1;22(2):212-225. doi: 10.52082/jssm.2023.212. eCollection 2023 Jun.

Authors: Depeng Sun, Tieli Yang

Summary: Low-load blood flow restriction training (BFRT) has been shown to induce a significant increase in muscle activation. However, low-load BFRT to augment the post-activation performance enhancement (PAPE) has not been previously examined. This study aimed to examine the PAPE of low-intensity semi-squat exercises with varying pressure BFRT on vertical height jump performance. Twelve elite athletes from the Shaanxi Province women's football team volunteered to participate in this study for 4 weeks. Participants completed four testing sessions that included one of the following at random: (1) non-BFRT, (2) 50% arterial occlusion pressure (AOP), (3) 60% AOP, or (4) 70% AOP. Muscle activity of the lower thigh muscles was recorded using electromyography (EMG). Jump height, peak power output (PPO), vertical ground reaction forces (vGRF), and rate of force development (RFD) were recorded for four trials. Two-factor repeated measures analysis of variance (ANOVA) showed that semi-squat with varying pressure BFRT had a significant impact on the measured muscle EMG amplitude and MF value of vastus medialis, vastus lateralis, rectus femoris, and biceps femoris (P < 0.05), and MF value decreased with increasing pressure. Muscle activation (EMG amplitude) did not change further. The EMG amplitude of the gluteus maximus was significantly decreased by semi-squat training with different pressures (P < 0.05), while that of the gluteus maximus muscle was gradually increased by non-BFR with semi-squat training (P > 0.05). The 50% and 60% AOP BFRTs significantly increased jump height, peak power, and force increase rate (RFD) after 5 min and 10 min of rest (P < 0.05). This study further confirmed that low-intensity BFRT can significantly increase lower limb muscle activation, induce PAPE, and improve vertical height jump in female footballers. In addition, 50% AOP continuous BFRT is recommended for warm-up activities.

 

 

#12 Heading in Football: Insights from stakeholders in amateur football

Reference: Sci Med Footb. 2023 Jun 9. doi: 10.1080/24733938.2023.2224282. Online ahead of print.

Authors: Elia Parsanejad, Marnee J McKay, Andrew G Ross, Evangelos Pappas, Kerry Peek

Summary: Despite emerging research questioning the long-term effect of purposeful heading on players' brain health, heading-related perspectives and behaviours of stakeholders in amateur football in Australia (a country without heading guidelines) remain unknown. This study aimed to explore current heading-related perspectives and behaviours of football stakeholders. In total, 290 players (aged over 11 years), 54 coaches, 34 non-coaching staff and 14 medical staff completed the survey. Of the 290 players, 56.5% reported being formally trained in heading, with female players less likely to be trained than male players (p < 0.05). Players were the least concerned about the long-term effects of heading, while medical staff were the most concerned (33.1% and 57.1%, respectively). From proposed strategies to reduce heading burden, a heading ban for all ages was least popular (2.3%), while teaching heading technique was most popular (67.3%). Our study provides insights into football stakeholders' heading-related perspectives, which could be used, along with scientific evidence, to inform pragmatic future heading guidelines.

 

 

#13 Foot rotation and pelvic angle correlate with knee abduction moment during 180° lateral cut in football players

Reference: Knee. 2023 Jun 7;43:81-88. doi: 10.1016/j.knee.2023.05.008. Online ahead of print.

Authors: Stefano Di Paolo, Alberto Grassi, Laura Bragonzoni, Stefano Zaffagnini, Francesco Della Villa

Summary: Lateral movements are challenging for 2D video-analysis and are therefore often omitted in functional tests for Anterior Cruciate Ligament (ACL) injury risk assessment. The purpose of the present study was to investigate the association between frontal and transverse plane angles obtained from 2D video-analysis and knee abduction moment (KAM) from gold standard 3D motion capture in a 180° lateral cut task. The hypothesis was that 2D angles other than the knee joint effectively explain variations in KAM. Thirty-four healthy football players (age 22.8 ± 4.1 years) performed a series of 180° lateral cut (lateral shuffles) tasks. The peak KAM was collected through a 3D motion capture system. A 2D video-analysis movement assessment identified frontal and transverse plane joint kinematics: foot projection angle (FPA), Frontal Plane Knee Projection Angle (FPKPA), Pelvis tilt angle (PA), and Trunk tilt angle (TA). A forward stepwise regression model was used to assess significant 2D predictors of KAM (p < 0.05). FPA and PA were the only significant predictors (R2-ajdusted = 9.2%, p < 0.001), with external foot rotation and contralateral pelvic drop associated with higher KAM. Based on the regression model, the "High FPA & PA group" was defined and showed higher KAM than the rest of the cohort (p = 0.012, ES = 0.71). The external foot rotation and the contralateral pelvic drop from 2D video-analysis were associated with higher peak KAM during the 180° lateral cut. A qualitative assessment of the 180° lateral cut could offer precious insights on ACL injury risk mitigation.

 

 

#14 Lower Limb Unilateral and Bilateral Strength Asymmetry in High-Level Male Senior and Professional Football Players

Reference: Healthcare (Basel). 2023 May 28;11(11):1579. doi: 10.3390/healthcare11111579.

Authors: Mário C Espada, Marco Jardim, Rafael Assunção, Alexandre Estaca, Cátia C Ferreira, Dalton M Pessôa Filho, Carlos E L Verardi, José M Gamonales, Fernando J Santos

Summary: This study sought to assess the relationship between different jumping asymmetries and associated performance variables in high-level male senior and professional football players. Nineteen football players with at least 12 years of training experience (23.2 ± 3.1 years of age; 75.2 ± 4.8 kg of body mass and 181 ± 0.06 cm of height) participated in this study performing countermovement jump (CMJ), squat jump (SJ), single-leg CMJ and drop jump (DJ), associated performance variable eccentric utilization ratio (EUR), stretch-shortening cycle (SSC), bilateral deficit (BLD), and limb symmetry index (LSI) were determined. High correlations were observed between different methodologies of jump tests and associated performance indicators (SSC, BLD, EUR), except LSI. Moreover, CMJ and SJ results were different (p < 0.05), but no differences were found between interlimb in CMJ (p = 0.19) and DJ (p = 0.14). Between the same limbs and different jumps differences were detected in CMJ and DJ (p < 0.01), and it has also been found that the laterality effect size on strength was small in CMJ (ES = 0.30) and DJ (ES = 0.35). LSI between CMJ and DJ was not different despite higher mean values in CMJ, and although mean BLD was positive (>100%), the results highlight the need for individual evaluation since eight players scored negatively. An in-depth and accurate analysis of performance in preseason screening jump tests should be considered, aiming to detect injury risk, specifically evaluating different jumping test methodologies, and determining jumping associated performance variables for each test, namely EUR, SSC, BLD, and LSI. Specific muscle-strengthening exercises could be implemented based on this study results and outcomes, aiming to reduce injury risks and lower extremity asymmetries and to enhance individual football performance in high-level male senior and professional football players. Sports institutions should pay special attention regarding potential health problems in athletes exposed to daily high training loads.