Latest research in football - week 39 - 2023

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Are Late-Born Young Soccer Players Less Mature Than Their Early-Born Peers, Although No Differences in Physical and Technical Performance Are Evident?

Reference: Sports (Basel). 2023 Sep 8;11(9):179. doi: 10.3390/sports11090179.

Authors: Eduard Bezuglov, Georgiy Malyakin, Anton Emanov, Grigory Malyshev, Maria Shoshorina, Evgeny Savin, Artemii Lazarev, Ryland Morgans

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Summary: The aim of the study was to compare the status of somatic maturity, anthropometry, strength, speed, and soccer-specific technical skills of players from leading youth soccer academies born in different quarters of the same calendar year. A total of 678 young male soccer players from eight leading Russian soccer academies took part in the study. The following anthropometric measures and physical characteristics were measured: height, weight, body mass index, countermovement jumps (CMJ), 5, 10, and 20 m sprints, speed dribbling, foot and body ball juggling, and short and long pass accuracy. The determination of somatic maturity as a percentage of projected adult height was collected. All subject dates of birth were divided into four quartiles according to the month of birth. The analysis of all data obtained was conducted both within the total sample and by quartiles of birth, according to the age group categories of 12-13 years, 14-15 years, and 16-17 years and the degree of somatic maturity. There was a widespread relative age effect, with 43.5% of early-born players and only 9.6% of late-born players representing the sample. Early-born players were more mature than late-born players (p < 0.001 and p < 0.001) but had no statistically significant differences in strength, speed, or soccer-specific skills.



#2 Acute Effect of Four Stretching Protocols on Change of Direction in U-17 Male Soccer Players

Reference: Sports (Basel). 2023 Sep 1;11(9):165.  doi: 10.3390/sports11090165.

Authors: Mohamed Amine Ltifi, Mohamed Chedly Jlid, Jérémy Coquart, Nicola Maffulli, Roland van den Tillaar, Ridha Aouadi

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Summary: The ability to rapidly change direction while sprinting is a desirable athletic skill in soccer. Enhancing change of direction (COD) performance depends almost exclusively on specific training, with stretching traditionally considered one such intervention. However, the comparative impact of diverse stretching methods on COD in soccer players remains an area of interest. Therefore, this study aimed to compare the effects of different stretching methods on COD ability in soccer players. Twelve male soccer players playing in the national championship football division II (age: 16.3 ± 0.3 years, height: 1.81 ± 0.10 m, body mass: 67.7 ± 7.2 kg) were tested for COD performance (i.e., Illinois agility test) after (1) control condition (20 min general warm-up without stretching), (2) static stretching, (3) dynamic stretching, (4) combined static-dynamic stretching, and (5) combined dynamic-static stretching. The duration of stretching intervention was approximately 6 min for static and dynamic stretching and 12 min for both the combined stretching conditions. The experimental sessions were separated by 72 h. COD improved after dynamic stretching when compared to any other condition (p: 0.03-0.002; ηp2: 0.56-0.73), except for the control condition (p = 0.146; ηp2 = 0.18). In contrast, static stretching induced a detrimental effect on COD when compared only to the dynamic stretching condition (p < 0.01; ES = 1.35). Dynamic stretching exercises used by male soccer players in the warm-up improved COD. Other forms of stretching exercises, particularly static stretching, negatively impacted the COD performance. Therefore, coaches can consider integrating dynamic stretching protocols tailored to the athletes' specific needs. Moreover, extending the investigation to encompass a wider range of athletes, including different age groups and genders, would enhance the applicability and generalization of the findings.



#3 The Effects of Different Re-Warm-Up Strategies on Power, Changing of Direction and Ball Shooting Velocity in Well-Trained Soccer Players

Reference: Sports (Basel). 2023 Sep 5;11(9):169. doi: 10.3390/sports11090169.

Authors: Demetris Matsentides, Marios Christou, Nikolaos Zaras

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Summary: The purpose of the study was to investigate whether a re-warm-up training session either with tuck jumps and linear sprints or with changing of directions may enhance power, agility or ball shooting velocity in well-trained soccer players. Ten soccer players (age: 18.2 ± 1.7 years; body mass: 64.4 ± 8.0 kg; body height: 1.71 ± 0.04 m) participated in the study. Players performed three different re-warm-up interventions including no re-warm-up (C), change of direction (COD) and jump-sprint condition (JS). Before each re-warm-up intervention, players performed the same warm-up condition followed by 8 min of passive rest. Following the re-warm-up interventions, countermovement jump (CMJ), T-Test agility time-trial and ball shooting velocity were measured. Performance in CMJ height, power and power per body mass remained unchanged following all three conditions (p > 0.05). However, the agility time-trial was significantly reduced following COD re-warm-up compared to C (-1.7 ± 1.6%, p = 0.03). Ball shooting velocity was increased following COD compared to C (4.7 ± 3.8%, p = 0.014), while a statistical trend was found between JS and C interventions (4.8 ± 5.4%, p = 0.060). These results suggest that a re-warm-up intervention including changing of directions may significantly enhance T-Test agility time-trial and ball shooting velocity in well-trained soccer players.



#4 Soccer and Disability, Is It Possible? Analysis of the Learning and Coaching Context in Spain

Reference: Sports (Basel). 2023 Aug 28;11(9):161. doi: 10.3390/sports11090161.

Author: Antonio Burgos-García

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Summary: Coaching a youth soccer player is important, and the coach's role is key. Actually, there is no profile or coaching program for grassroots-soccer coaches that favor the practice of soccer and disability, according to different research and experts. The main purpose of this study is to identify and analyze the professional profile of the grassroots-soccer coach who has soccer players with disabilities (learning and coaching context). This research applies a quantitative method, specifically, non-experimental, cross-sectional, descriptive, and inferential methodology. The sample of analysis is the staff members of the professional soccer clubs of LaLigaSantander Genuine (Spain). An important result is that half of the grassroots-soccer coaches have not received specific education to coach youth soccer players with disabilities. Finally, one important conclusion of this research is that by generating a climate of trust and empathy, grassroots-soccer coaches improve the performance of their soccer players with disabilities by recognizing and understanding their emotional states.



#5 Assessing the Association Between On-Field heading technique and head impact kinematics in a cohort of female youth soccer players

Reference: Sci Med Footb. 2023 Sep 27. doi: 10.1080/24733938.2023.2264272. Online ahead of print.

Authors: Tanner M Filben, Brian T Tomblin, N Stewart Pritchard, Garrett S Bullock, Jordan M Hemmen, Kristina E Neri, Victoria Krug, Christopher M Miles, Joel D Stitzel, Jillian E Urban

Summary: There is concern that exposure to soccer headers may be associated with neurological sequelae. Training proper heading technique represents a coachable intervention that may reduce head acceleration exposure. The objective was to assess relationships between heading technique and head kinematics in female youth soccer players. Fourteen players (mean age = 14.4 years) wore instrumented mouthpieces during practices and games. Headers were reviewed by three raters to assign a technique score. Mixed models and LASSO regression evaluated associations of technique with peak linear acceleration (PLA), rotational acceleration (PRA), rotational velocity (PRV), and head impact power ratio (HIP Ratio) while adjusting for session type and ball delivery. Two hundred eighty-nine headers (n = 212 standing, n = 77 jumping) were analyzed. Technique score (p = 0.043) and the technique score - session type interaction (p = 0.004) were associated with PRA of standing headers, whereby each ten-unit increase in technique score was associated with an 8.6% decrease in PRA during games but a 5.1% increase in PRA during practices. Technique was not significantly associated with any other kinematic metrics; however, peak kinematics tended to decrease as technique score increased. LASSO regression identified back extension and shoulder/hip alignment as important predictors of peak kinematics. Additional research on heading technique and head acceleration is recommended.



#6 Health problems occurring in national-level female soccer players are different between leagues and throughout the season: a 6-month prospective cohort study

Reference: BMJ Open Sport Exerc Med. 2023 Sep 20;9(3):e001595. doi: 10.1136/bmjsem-2023-001595. eCollection 2023.

Authors: Anna Dettwiler, Nora Wieloch, Stefan Fröhlich, Florian Imhoff, Johannes Scherr, Jörg Spörri

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Summary: This study investigated the prevalence and severity of health problems in national-level female soccer players with respect to league and seasonality. In a prospective cohort study, 46 female soccer players aged 22.8±3.9 years playing in the three highest leagues in Switzerland were surveyed biweekly using the Oslo Sports Trauma Research Centre health problem (OSTRC-H) questionnaire. All definitions and measures followed the OSTRC-H-specific recommendations. The 6-month observation period included parts of the off-season and one half of the match season. The average 2-weekly health problem prevalence was 37.3% (illnesses: 8.8%; sudden onset injuries-both acute and repetitive mechanisms: 19.7%; repetitive gradual onset injuries: 12.4%) and 25.1% for substantial problems as defined in the OSTRC-H context (7.3%; 12.0% and 7.3%, respectively). The absolute injury rates amounted to 148 injuries per 100 players per half season, of which 96 injuries per 100 players per half season were substantial. Female players in the 2nd and 3rd highest national leagues showed more gradual onset injuries (p<0.001) and fewer illnesses than those in the top league (p<0.05). At the same time, there were no league-specific differences in sudden onset injuries. Such injuries had a higher cumulative severity score than gradual onset injuries. Among sudden onset injuries, the ankle was the most affected body part, while the thigh was affected by for gradual onset injuries. The average 2-weekly health problem prevalence values steadily increased during the match season. Among national-level female soccer players, the risk of health problems is relatively high and differs between leagues and across seasons.



#7 The effects of high-intensity interval training at the anaerobic and psychomotor fatigue thresholds on physiological parameters in young soccer players: a prospective study

Reference: Front Physiol. 2023 Sep 7:14:1221121. doi: 10.3389/fphys.2023.1221121. eCollection 2023.

Authors: Paweł Chmura, Jan Chmura, Wiktor Chodor, Adrian Drożdżowski, Andrzej Rokita, Marek Konefał

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Summary: This study aimed to investigate the effects of a 4-week specific high-intensity interval training (HIIT) program performed between the anaerobic threshold (ANT) and the psychomotor fatigue threshold (PFT) on physiological parameters in 14 professional soccer players at the under-17 level. The first and second stages of the research protocol included a treadmill running exercise with increasing load and six 3-min four-versus-four games of soccer with a 3-min break between games. Players then participated in a training microcycle involving three specific HIIT exercises twice per week for 4 weeks, after which they repeated stages one and two, followed by an assessment of changes. The measurement of lactate (LA) determined ANT, whereas the choice reaction time (CRT) indicated PFT among other selected physiological parameters. The repeated-measure analysis of variance (ANOVA) compared mean values for the examined variables using Bonferroni post hoc test. It demonstrated significantly increased maximal oxygen consumption (VO2 max) from 45.9 ± 3.0 to 48.7 ± 2.6 at the ANT and from 49.1 ± 3.4 to 52.0 ± 3.6 on the PFT after 4 weeks of training. A significant increase in the running speed (RS) at both thresholds and heart rate (HR) at the ANT (p ≤ 0.05) was also recorded. Moreover, the players exceeded their intensity of effort during ANT while playing four-versus-four soccer matches, but they did not reach intensity during PFT. In conclusion, the findings of the study demonstrated that both thresholds shifted toward higher loads and the proposed specific HIIT effectively increased the exercise capacity of soccer players.



#8 Trends in Soccer-Related Craniomaxillofacial Injuries, United States 2003-2022

Reference: J Oral Maxillofac Surg. 2023 Sep 9:S0278-2391(23)01092-3. doi: 10.1016/j.joms.2023.09.001. Online ahead of print.

Authors: Lang Liang, Sung-Kiang Chuang

Summary: Soccer is one of the most popular sports worldwide. However, it has risks of injury to craniomaxillofacial regions such as the head, neck, and mouth. The purpose of this study is to determine which demographic and injury characteristics among soccer players with craniomaxillofacial injuries are associated with increased hospitalizations. This is a retrospective cohort study utilizing the National Electronic Injury Surveillance System. Subjects included in this study experienced an injury to a craniomaxillofacial area from soccer between January 1, 2003, and December 31, 2022. The predictor variables included demographics (age, sex, race) and injury characteristics (craniomaxillofacial region, diagnosis). The primary outcome variable was injury severity defined as hospitalization outcome after injury (yes/no). The secondary outcome variable was the trends in the incidence of soccer craniomaxillofacial injuries over time (2003-2022). The covariates were the heterogenous set of predictor variables in this study. Descriptive statistics and univariate analyses were computed. Survey-weighted univariate and multivariate logistic regression were used to measure the association of demographic and injury variables with hospitalization outcome. Statistical significance was defined as P < .05. The study sample included 26,642 subjects (national estimate, 799,393). The national incidence of craniomaxillofacial soccer injuries generally increased between 2003 and 2012 and decreased between 2016 and 2020. Subjects in the ≥30 age group had increased odds of hospitalization compared to those in the 10-19 age group (odds ratio [OR], 2.12; P < .001). Compared to females, males had significantly higher odds of hospitalization (OR, 1.53; P < .001). Head (OR, 8.42; P < .001) and neck (OR, 15.8; P < .001) injuries had increased odds of hospitalization compared to facial injuries. Relative to contusions/abrasions, subjects with fractures (OR, 94.7; P < .001), dental injuries (OR, 41.3; P < .001), and concussions (OR, 5.33; P = .017) were at significantly higher odds of hospitalization. Age, sex, craniomaxillofacial region, and diagnosis were significant predictors of hospitalization outcome after craniomaxillofacial soccer injury. Safer playing styles, use of mouthguards, and proper medical management may reduce future risks of craniomaxillofacial injury from soccer.



#9 Synchronization of passes in event and spatiotemporal soccer data

Reference: Sci Rep. 2023 Sep 23;13(1):15878. doi: 10.1038/s41598-023-39616-2.

Authors: Henrik Biermann, Rumena Komitova, Dominik Raabe, Eric Müller-Budack, Ralph Ewerth, Daniel Memmert

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Summary: The majority of soccer analysis studies investigates specific scenarios through the implementation of computational techniques, which involve the examination of either spatiotemporal position data (movement of players and the ball on the pitch) or event data (relating to significant situations during a match). Yet, only a few applications perform a joint analysis of both data sources despite the various involved advantages emerging from such an approach. One possible reason for this is a non-systematic error in the event data, causing a temporal misalignment of the two data sources. To address this problem, we propose a solution that combines the SwiftEvent online algorithm (Gensler and Sick in Pattern Anal Appl 21:543-562, 2018) with a subsequent refinement step that corrects pass timestamps by exploiting the statistical properties of passes in the position data. We evaluate our proposed algorithm on ground-truth pass labels of four top-flight soccer matches from the 2014/15 season. Results show that the percentage of passes within half a second to ground truth increases from 14 to 70%, while our algorithm also detects localization errors (noise) in the position data. A comparison with other models shows that our algorithm is superior to baseline models and comparable to a deep learning pass detection method (while requiring significantly less data). Hence, our proposed lightweight framework offers a viable solution that enables groups facing limited access to (recent) data sources to effectively synchronize passes in the event and position data.



#10 Minimal Number of Events Required for Acceleration-Speed Profiling in Elite Women's Soccer

Reference: Int J Sports Physiol Perform. 2023 Sep 23:1-4. doi: 10.1123/ijspp.2023-0223. Online ahead of print.

Authors: Patrick Cormier, Ming-Chang Tsai, Cesar Meylan, Victor H T Soares, David C Clarke, Marc Klimstra

Summary: The aim was to determine the minimum number of events (training or matches) for producing valid acceleration-speed (AS) profiles from global navigation satellite system (GNSS) data. Nine elite female soccer players participated in a 4-week training camp consisting of 19 events. AS profile metrics calculated from different combinations of athlete events were compared to force-velocity (FV) profile metrics from 2 × 40-m stand-alone sprint effort trials, using the same GNSS 10-Hz technology. Force-velocity profiles were calculated, from which AS profiles were obtained. AS profiles from training and matches were generated by plotting acceleration and speed points and performing a regression through the maximal points to obtain the AS metrics (theoretical maximal speed, x-intercept [in meters per second], theoretical maximal acceleration, y-intercept [in meters per second squared], and the slope per second). A linear mixed model was performed with the AS metrics as the outcome variables, the number of events as a fixed effect, and the participant identifier as a mixed effect. Dunnett post hoc multiple comparisons were used to compare the means of each number of event grouping (1-19 events) to those estimated from the dedicated sprint test. Theoretical maximal speed and theoretical maximal acceleration means were no longer significantly different from the isolated sprint reference with 9 to 19 (small to trivial differences = -0.31 to -0.04 m·s-1, P = .12-.99) and 6 to 19 (small differences = -0.4 to -0.28 m·s-2, P = .06-.79) events, and the slopes were no longer different with 1 to 19 events (trivial differences = 0.06-0.03 s-1, P = .35-.99). AS profiles can be estimated from a minimum of 9 days of tracking data. Future research should investigate methodology resulting in AS profiles estimated from fewer events.



#11 Growth-related sports injuries among young male professional football players in the Netherlands: a prospective cohort study concerning injury incidence, severity and burden

Reference: Sci Med Footb. 2023 Sep 23:1-12. doi: 10.1080/24733938.2023.2261399. Online ahead of print.

Authors: Else E A E Juch, Vincent C van de Koppel, Donna Blokland, Renko A Wouters, Frank J G Backx, Edwin A Goedhart, Nick van der Horst

Summary: The aim was to investigate the incidence, type and location of growth-related sports injuries (GRSI) in youth professional football in the Netherlands. Secondary, to gain more knowledge on the injury severity and burden of GRSI. In this prospective, longitudinal cohort study, 813 players aged 10-18 are included. Data collection is performed by instructing the medical staff of six professional football club academies to register GRSI by means of standardized forms. Training and match exposure are registered individually on a weekly basis. Injury incidence was calculated as number of GRSI per 1000 hours, injury severity as the median number of days lost in categories and injury burden as the number of days lost per 1000 hours. A total of 62 GRSI were documented in the football season 2021-2022. The total incidence of GRSI was 0.62/1000 hours football exposure. Morbus Osgood Schlatter and Morbus Sever were most common types of GRSI, both with incidence rates of 0.22/1000 hours exposure. About 58.3% of the documented GRSI were classified as major (>28 days lost). Within this group, the mean severity was 55 days time-loss to football. GRSI are relatively common in youth professional football. The most common types are Morbus Sever and Morbus Osgood Schlatter. Morbus Osgood Schlatter has the highest injury severity and burden compared to other types of GRSI.



#12 The Role of Football Players as a Model for Promoting Community Health

Reference: Iran J Public Health. 2023 Aug;52(8):1779-1780. doi: 10.18502/ijph.v52i8.13419.

Authors: Tohid Seif Barghi, Mohammad Mahdi Tavana

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#13 Motivation among Teenage Football Players: A Longitudinal Investigation throughout a Competitive Season

Reference: Eur J Investig Health Psychol Educ. 2023 Sep 4;13(9):1717-1727. doi: 10.3390/ejihpe13090124.

Authors: Filipe Rodrigues, Diogo Monteiro, Rui Matos, Miguel Jacinto, Raúl Antunes, Nuno Amaro

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Summary: The present study aimed to investigate the dynamic changes in behavioral regulations among teenage football players throughout a competitive season, with three measurement points (T1, T2, and T3). The total sample size for the study comprised 108 participants (78 male; 30 female). The participants' mean age was 14.31 (SD = 1.48). A MANOVA repeated measures analysis was performed within the group for all six behavioral regulations based on self-determination theory. The results of the study revealed noteworthy patterns in the behavioral regulations and intrinsic motivation scores over the competitive season. Identified regulation demonstrated a significant increase from T1 to T3 (p < 0.01, η2p = 0.13). Intrinsic motivation displayed a significant decrease over the same period from T1 to T3 (p < 0.01, η2p = 0.12). On the other hand, amotivation, external regulation, introjected regulation, and integrated regulation did not show significant changes between the three time points. The findings have practical implications for coaches and sports practitioners, as they highlight the need to create a supportive and autonomy-promoting environment to sustain athletes' intrinsic motivation throughout a competitive season. Also, recognizing the increase in identified regulation can inform strategies that align team goals and training sessions with players' individual values, thereby enhancing their commitment and dedication to the team's success.



#14 Anthropometric Profiling and Changes in Segmental Body Composition of Professional Football Players in Relation to Age over the Training Macrocycle

Reference: Sports (Basel). 2023 Sep 5;11(9):172. doi: 10.3390/sports11090172.

Authors: Wiktoria Staśkiewicz-Bartecka, Elżbieta Grochowska-Niedworok, Grzegorz Zydek, Mateusz Grajek, Agata Kiciak, Agnieszka Białek-Dratwa, Ewa Niewiadomska, Oskar Kowalski, Marek Kardas

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Summary: Body composition is an important indicator of the overall health and fitness of team sports athletes, including in football, and therefore, anthropometric profiling of elite football players is useful as part of determining their skills, strengths, and weaknesses to develop effective strength and conditioning programs. One of the tools available to coaches to track correlates of performance and health is routine body composition assessment. The purpose of this study is to describe and compare the body composition and anthropometric profiles of players using the Direct Segmental Multi-Frequency Bio-Electrical Impedance Analysis method, and to manage body composition throughout the round in the 2020-2021 season. The investigation was carried out during the Polish football league, PKO BP Ekstraklasa, spring round of the football season 2020-2021, in which male football players participated. Athletes between the ages of 18 and 25 (n = 16) made up the younger age group, while those between the ages of 26 and 31 (n = 22) made up the older age group. This manuscript is a continuation of the presentation of the results of the study, which was conducted between 7 January and 23 July 2021. At different stages of the macrocycle, participants underwent six different body composition analyses. The younger and older groups of athletes were compared, as well as measurements of time points 1-6. The dominant extremities, assisting extremities, and trunk had larger fat-free mass contents in the older age group. In the study groups, there was a difference in the fat-free mass content between measures 1-6 that was statistically significant. In the younger group, there was a statistically significant difference in the amount of fat mass content between measurements 1-6. In the older age group, no statistically significant changes were found. The study showed changes in fat-free mass and fat mass in body segments; differences were observed between age groups and between different moments of measurement. Age is an important factor in determining body composition and is also related to an athlete's experience and seniority. Anthropometric profiling and comprehensive body composition analysis are important tools used in preparing athletes for competition.



#15 Cryo plus Ultrasound Therapy, a Novel Rehabilitative Approach for Football Players with Acute Lateral Ankle Injury Sprain: A Pilot Randomized Controlled Trial

Reference: Sports (Basel). 2023 Sep 9;11(9):180. doi: 10.3390/sports11090180.

Authors: Antonio Ammendolia, Alessandro de Sire, Lorenzo Lippi, Valerio Ammendolia, Riccardo Spanò, Andrea Reggiani, Marco Invernizzi, Nicola Marotta

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Summary: Acute lateral ankle sprains are common injuries among athletes, but the optimal treatment strategies in elite athletes are still debated. This proof-of-concept study aimed to assess the impact of cryo-ultrasound therapy on the short-term recovery of football players with acute lateral ankle sprains. Semi-professional football players with grade I or II lateral ankle sprains were randomly assigned to the experimental group (receiving cryo-ultrasound therapy combined with conventional physical therapy) or control group (sham cryo-ultrasound therapy combined with conventional physical therapy). Pain intensity and physical functioning were assessed by the Numeric Rating Scale (NRS) and Foot and Ankle Disability Index (FADI) at baseline (T0) at the end of treatment (T1), after one month (T2), and two months after treatment (T3). After the study intervention, significant between groups differences were reported in terms of pain relief (NRS: 4.08 ± 1.29 vs. 5.87 ± 1.19; p = 0.003) and physical function (FADI: 50.9 ± 10.3 vs. 38.3 ± 11.5; p = 0.021). However, no significant between group differences were reported at T2 and T3. No adverse effects were reported. Cryo-ultrasound therapy combined with conventional physical therapy can accelerate recovery and early return to sport in elite football players with acute lateral ankle sprains. While this study contributes valuable insights into the potential benefits of cryo-ultrasound therapy, further investigations with a longer follow-up are needed to validate and optimize the application of physical agent modalities in the management of ankle injuries.


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