Elite Professional Soccer Players Research Articles

Validity and Reliability of a New Wearable Chest Strap to Estimate Respiratory Frequency in Elite Soccer Athletes.

Assessing respiratory frequency (fR) is practical in monitoring training progress in competitive athletes, especially during exercise. This study aimed to validate a new wearable chest strap (wCS) to estimate fR against ergospirometry as a criterion device in soccer players. A total of 26 elite professional soccer players (mean [standard deviation]: 23.6 [4.8] years; 180.6 [5.7] cm; 77.2 [5.4] kg) from three Italian Serie A League teams participated in this cross-sectional study. The sample included attackers, midfielders, and defenders. fR was assessed during a maximal cardiopulmonary exercise test (CPET) on a treadmill using (i) a breath-by-breath gas exchange analyzer (Vyntus® CPX, Vyaire Medical) and (ii) a novel wCS with sensors designed to assess breath frequency following chest expansions. Pearson's correlation coefficient (r), adjusted coefficient of determination (aR2), Bland-Altman plot analysis, and Lin's concordance correlation coefficient (ρc) were used for comparative analysis (correlation and concordance) among the methods. The repeated measures correlation coefficient (rrm) was used to assess the strength of the linear association between the methods. The intraclass correlation coefficient (ICC) and the Finn coefficient (rF) were used for inter-rater reliability. All statistical analyses were performed within the R statistical computing environment, with 95% confidence intervals (95% CIs) reported and statistical significance set at p < 0.05. A total of 16529 comparisons were performed after collecting the CPET data. The robust time series analysis with Hodges-Lehmann estimation showed no significant differences between both methods (p > 0.05). Correlation among devices was statistically significant and very large (r [95% CI]: 0.970 [0.970, 0.971], p < 0.01; aR2 [95% CI]: 0.942 [0.942, 0.943], p < 0.01) with strong evidence supporting consistency of the new wCS (BF10 > 100). In addition, a high concordance was found (ρc [95% CI]: 0.970 [0.969, 0.971], bias correction factor: 0.999). VyntusTM CPX, as a standard criterion, showed moderate agreement with wCS after Bland-Altman analysis (bias [95% lower to the upper limit of agreement]; % agree: 0.170 [-4.582 to 4.923] breaths·min-1; 69.9%). A strong association between measurements (rrm [95% CI]: 0.960 [0.959, 0.961]), a high absolute agreement between methods (ICC [95% CI]: 0.970 [0.970, 0.971]), and high inter-rater reliability (rF: 0.947) were found. With an RMSE = 2.42 breaths·min-1, the new wCS seems to be an valid and reliable in-field method to evaluate fR compared to a breath-by-breath gas exchange analyzer. Notwithstanding, caution is advised if methods are used interchangeably while further external validation occurs.

Elite women's soccer match demand can be described using complexity-based analyses and multifractals

The present study aimed to investigate the variability of the displacements in elite women soccer players during official matches according to the position of the players and to the match progression using non-linear analyses (entropy and multifractal spectrum).Sixty-three velocity profiles from global positioning devices of elite professional women soccer players were analyzed. The mean, coefficient of variation, and maximum velocity were calculated during the match using four equal segments. Sample entropy and seven parameters derived from the multifractal detrended fluctuation analysis were also calculated. The players were split into five field playing positions: forwards (FW), offensive midfielders (OM), defensive midfielders (DM), central defenders (CD), and lateral defenders (LD).No significant playing position × period interaction was found for the different parameters analyzed. However, most parameters showed a significant main effect for playing position (p < .01) and period (p < .01). Compared to the other players, FW and OM have the lowest entropy. All players showed a dominance of small velocity fluctuations but FW players showed the widest multifractal spectrum primarily. In contrast, CD had a narrow spectrum and reduced amount of small fluctuations. As the game progressed, mean velocity and entropy significantly decreased. In contrast, the multifractal peak value significantly alongside with changes in asymmetry.From the present results, velocity profiles during elite women's soccer games depicted multifractal features sensitive to player position and match segment, which can help to understand the dynamics and variability of players' responses during a match.

Effects of 5-week detraining period on body composition of professional soccer players

Purpose. The aim of the study was to examine the effects of five weeks detraining period on body composition changes in elite professional Indonesian male soccer players. Material and methods. The body composition of 24 top-level male soccer players (age: 26.33 ± 4.06 years) competing in First League of Indonesia was measured before and after the 5-weeks detraining period. Body composition variables, including body mass, body fat percentage, fat-free mass, and total body water percentage, were measured using the bioelectrical impedance method. The results. The paired samples T-test showed significant changes in the means of body composition variables for body fat percentage, fat-free mass, and total body water percentage. Mean values for body fat percentage increased during the detraining period from 10.87 ± 2.47% to 11.98 ± 2.75% (10.3%). A decrease in mean values for fat-free mass (61.34 ± 5.74 kg to 59.80 ± 6.22; 2.49%) and total body water percentage (from 65.13 ± 1.84% to 64.40 ± 1.99%; 1.12%) was observed. No significant changes occurred in body mass (from 69.05 ± 8.07 kg to 69.05 ± 8.48 kg; 0.04%) from initial to final testing. Conclusions. Since there was a significant difference in body fat percentage, fat-free mass, and total body water percentage% before and after detraining period., it is suggested that 5 weeks of detraining period. for the professional soccer players may not be necessary, and the duration should be shortened to maintain body composition status.

How Subtalar Kinematics Affects Knee Laxity in Soccer Players After Anterior Cruciate Ligament Injury?

Purpose The goal of the current study was to ascertain whether there is an association between foot pronation and anterior cruciate ligament (ACL) injury in a group of elite professional soccer players. Methods Two groups of soccer players were studied, all of whom played in the Greek Super League. The ACL group included players who had suffered an ACL injury in the last 2 years. The non-ACL group was composed of players who had never suffered an ACL injury. We used a 3D baropodometric laser scanner to measure pronation or overpronation (navicular drop phenomenon) of the subtalar joint and how this affects the subtalar joint while standing. We assessed ACL laxity using the Genourob Rotab. Results ACL-injured patients, regardless of the mechanism of injury, exhibited greater navicular drop values than a randomly selected group of subjects with no history of ACL injury. Conclusion Greater knee joint laxity and subtalar pronation may be associated with an increased risk of ACL injury. Pronation of the foot appears to be a risk factor for ACL injury. These findings should be integrated into future studies to better define how neuromuscular control related to lower extremity biomechanics is associated with ACL injury.

Exploring the interplay between metabolic power and equivalent distance in training games and official matches in soccer: a machine learning approach.

Introduction: This study aimed to explore the interplay between metabolic power (MP) and equivalent distance (ED) and their respective roles in training games (TGs) and official soccer matches. Furthermore, the secondary objective was to investigate the connection between external training load (ETL), determined by the interplay of metabolic power and equivalent distance, and internal training load (ITL) assessed through HR-based methods, serving as a measure of criterion validity. Methods: Twenty-one elite professional male soccer players participated in the study. Players were monitored during 11months of full training and overall official matches. The study used a dataset of 4269 training games and 380 official matches split into training and test sets. In terms of machine learning methods, the study applied several techniques, including K-Nearest Neighbors, Decision Tree, Random Forest, and Support-Vector Machine classifiers. The dataset was divided into two subsets: a training set used for model training and a test set used for evaluation. Results: Based on metabolic power and equivalent distance, the study successfully employed four machine learning methods to accurately distinguish between the two types of soccer activities: TGs and official matches. The area under the curve (AUC) values ranged from 0.90 to 0.96, demonstrating high discriminatory power, with accuracy levels ranging from 0.89 to 0.98. Furthermore, the significant correlations observed between Edwards' training load (TL) and TL calculated from metabolic power metrics confirm the validity of these variables in assessing external training load in soccer. The correlation coefficients (r values) ranged from 0.59 to 0.87, all reaching statistical significance at p < 0.001. Discussion: These results underscore the critical importance of investigating the interaction between metabolic power and equivalent distance in soccer. While the overall intensity may appear similar between TGs and official matches, it is evident that underlying factors contributing to this intensity differ significantly. This highlights the necessity for more comprehensive analyses of the specific elements influencing physical effort during these activities. By addressing this fundamental aspect, this study contributes valuable insights to the field of sports science, aiding in the development of tailored training programs and strategies that can optimize player performance and reduce the risk of injuries in elite soccer.

English

Introduction and objectives: The SARS-CoV-2 infection appears to cause functional impairment of cardiopulmonary performance in many athletes. We studied the post-COVID-19 impact on the cardiopulmonary system, through the maximal ergospirometry test, in elite professional soccer players. Material and method: The sample consisted of 10 AFA (Argentine Football Association) first division soccer players, who underwent pre and post COVID-19 infection maximal oxygen uptake (VO2max) tests. The variables analyzed were absolute and relative VO2max, maximal aerobic speed (MAS), first ventilatory threshold (VT1), second ventilatory threshold (VT2), maximal heart rate (HRmax) and respiratory exercise ratio (RER). Results: The mean age was 22.4 ± 6.9 years, body mass 71.5 ± 7.1 kg and height 176.2 ± 6.9 cm. Post COVID-19 subjects significantly decreased VO2 VT2 by 18% (P = 0.028) and RER significantly decreased by 5% (P = 0.02). HRmax was the only variable that significantly increased post COVID-19 by 1.8% (P = 0.04). No significant changes was observed in body mass 71.5 ± 7.1 vs 73.9 ± 7.4 (P&lt; 0.118), VO2max 61.7 ± 5.2 vs 59.0 ± 5.1 ml·kg·min-1 (P&lt;0,213), MAS 18.7 ± 0.9 vs 18.6 ± 0.5 km·h-1 (P&lt;0,739), VO2VT1 39.2 ± 4.0 vs 37.8 ± 4.3 ml·kg·min-1 (P&lt;0.460), speed al VT1 11.6 ± 0.5 vs 11.8 ± 0.6 (P &lt;0.480) and other variables. Conclusion: It seems reasonable and safe to evaluate athletes after SARS-CoV-2 infection with ergospirometry to ensure health conditions and trainability. In this type of athletes (elite soccer players), the use of the second ventilatory threshold (VT2) can be used as a strategy to observe post-COVID-19 changes. The decrease found may be related more to the cessation of training than to cardiopulmonary damage.

Concomitant Injuries Associated With ACL Rupture in Elite Professional Alpine Ski Racers and Soccer Players: A Comparative Study With Propensity Score Matching Analysis.

For elite professional soccer players and alpine skiers, injuries associated with anterior cruciate ligament (ACL) rupture, such as meniscal, cartilage, or collateral ligament lesions, could result in a delayed return to sport compared with isolated ACL injury. The purpose of the study was to provide a detailed description of associated injuries at the time of primary ACL reconstruction in elite soccer players and alpine skiers. It was hypothesized that soccer players and skiers would present different typical injury patterns due to different injury mechanisms. Cohort study; Level of evidence, 3. Surgical reports and arthroscopic images of elite professional soccer players and alpine skiers who underwent primary ACL reconstruction at a single institution between January 2010 and June 2022 were analyzed retrospectively. The presence and location of multiligamentous injury, meniscal tears, and chondral lesions were compared between the athlete groups. A propensity score matching analysis with 1:1 ratio was performed between skiers and soccer players to limit the effect of selection bias. Included were ACL reconstruction data representative of 37 soccer players and 44 alpine skiers. Meniscal pathology was found in 32 (86%) soccer players and 30 (68%) skiers. Chondral injuries were reported in 11 (30%) soccer players and 15 (34%) skiers. Results of the propensity score matching analysis in 15 pairs of soccer players and skiers indicated that soccer players had a significantly higher rate of medial meniscal injuries (73% vs 27%; P = .03) and lateral posterior root tears (33% vs 0%; P = .04) compared with skiers. A higher prevalence of combined chondral and meniscal injuries versus isolated ACL injuries was observed in both groups of athletes. Professional soccer players were characterized by higher prevalence of medial meniscal tears and lateral posterior root lesions compared with professional alpine skiers.

Return to Play and Pattern of Injury After ACL Rupture in a Consecutive Series of Elite UEFA Soccer Players.

Anterior cruciate ligament rupture represents a career-threatening injury for professional soccer players. To analyze the pattern of injury, return to play (RTP), and performance of a consecutive series of elite professional soccer players after anterior cruciate ligament reconstruction (ACLR). Case series; Level of evidence, 4. We evaluated the medical records of 40 consecutive elite soccer players who underwent ACLR by a single surgeon between September 2018 and May 2022. Patient age, height, weight, body mass index, position, injury history, affected side, RTP time, minutes played per season (MPS), and MPS as a percentage of playable minutes before and after ACLR were retrieved from medical records and from publicly available media-based platforms. Included were 27 male patients (mean ± SD age at surgery, 23.2 ± 4.3 years; range, 18-34 years). The injury occurred during matches in 24 players (88.9%), with a noncontact mechanism in 22 (91.7%). Meniscal pathology was found in 21 patients (77.8%). Lateral meniscectomy and meniscal repair were performed in 2 (7.4%) and 14 (51.9%) patients, respectively, and medial meniscectomy and meniscal repair were performed in 3 (11.1%) and 13 (48.1%) patients, respectively. A total of 17 players (63.0%) underwent ACLR with bone-patellar tendon-bone autograft and 10 (37.0%) with soft tissue quadriceps tendon. Lateral extra-articular tenodesis was added in 5 patients (18.5%). The overall RTP rate was 92.6% (25 of 27). Two athletes moved to a lower league after surgery. The mean MPS% during the last preinjury season was 56.69% ± 21.71%; this decreased significantly to 29.18% ± 20.6% (P < .001) in the first postoperative season and then increased to 57.76% ± 22.89% and 55.89% ± 25.8% in the second and third postoperative seasons. Two (7.4%) reruptures and 2 (7.4%) failed meniscal repairs were reported. ACLR in elite UEFA soccer players was associated with a 92.6% rate of RTP and 7.4% rate of reinjury within 6 months after primary surgery. Moreover, 7.4% of soccer players moved to a lower league during the first season after surgery. Age, graft selection, concomitant treatments, and lateral extra-articular tenodesis were not significantly associated with prolonged RTP.

Effects of a shock microcycle after COVID-19 lockdown period in elite soccer players.

ObjectivesDecreases in physical fitness are inevitable after two to six week period of detraining in athletes. Lockdown period changed the characteristics of soccer players’ training.Aim of the studyThe aim of our study was to apply a HIIT shock-microcycle (SM) after return to training and assess its effect on players’ performance.Equipment and methodsNineteen elite professional soccer players during the lockdown period (LP) from March to May 2020 (8 weeks) performed 3-4 individual training sessions per week. The training sessions included running boots of anaerobic short and aerobic prolonged duration intervals. Intensity was determined according to lab ergospirometry test 2 weeks before LP. All the players followed an indoor program, 3–6 sessions per week consisted of core, balance and flexibility exercises (∼45 minutes). SM training content was same for both groups and took place the first two weeks after LP, consisted by eight high intensity interval training sessions (HIIT), two technique, two tactical sessions and two days off.ResultsRepeated sprint ability mean time (RSAMeanTime) and Repeated sprint ability performance–sprint no 4,5,6 (RSA4,5,6S) improved after SM (P = 0.025, Effect size: r2 = 0.331, P = 0.010, Effect size: r2 = 0.411, p = 0.009, Effect size: r2 = 0.418, P = 0.037, Effect size: r2 = 0.293, respectively. Yo-Yo intermitted recovery test level 2 (YYIR2TotalDistance) that covered by players during the 2nd measurement was 10.8% longer (P = 0.004, Effect size: r2 = 0.483). Also, the YYIR2HeartRateRecovery percentage was lower during the 2nd measurement (P = 0.014, Effect size: r2 = 0.107).ConclusionsThese results indicate that SM can improve YYIR2 and RSA performance thus it is a useful tool to regain physical attributes in a short period.

Physical Development Differences between Professional Soccer Players from Different Competitive Levels

In soccer, physical development is crucial for developing optimal performance. This study aimed to assess and compare the physical development of elite and non-elite professional soccer players. Seventy-eight male professional football players divided into four competitive levels participated in this study: the elite group (EG), the non-elite group A (NEG-A), the non-elite group B (NEG-B), and the under 23 group (U23). Body composition, static strength, lower-body explosive strength, flexibility, and balance were assessed. No significant statistical differences between elite and non-elite players were seen in body composition parameters. However, the EG performed better in static strength, lower-body explosive strength, flexibility, and balance, even after adjusting for the effects of chronological age. The analysis showed that the competitive level (group) explained 25% to 29% of the variance observed in the lower-body explosive strength tasks. Sports staff and coaches in different age categories or competitive levels should include specific lower-body explosive strength content during soccer training to promote players’ long-term development towards the elite level.

Effects of a competitive half-season on the aerobic capacity and match running performance of Turkish elite professional soccer players

This study examines how exertion during matches affects participants’ physical capacity and match performance. The study included 13 elite football league players (21 ± 0.7 years old; height, 181.1 ± 8.98 cm; body mass, 74.7 ± 8.1 kg) and used global positioning system (GPS) data collected during 12 official matches. Four matches after the first Yo-Yo IR1 test, four matches before the second Yo-Yo IR1 test, and four matches after the second Yo-Yo IR1 test are examined. Sprint count per minute (SC) (N/min), (&gt;19 km/h), p &lt; 0.030; distance covered at zone 4–6 per minute DCZ4 (km/h/min), (18–24 km/h), p &lt; 0.00; distance covered at zone 4–6 per minute DCZ5 (km/h/min), (24–30 km/h), p &lt; 0.001; and distance covered at zone 4–6 per minute DCZ6 (km/h/min), (30–39 km/h), p &lt; 0.001 were recorded. According to the values obtained before the tests, the match data show a decreasing trend in the following weeks. Furthermore, the relationship between physical performance values and tests is determined (average speed (AS) (km/h), r = 0.64; maximum speed (MS) (km/h), r = 0.50; DCZ4 (km/h/min), r = 0.89; DCZ5 (km/h), r = 0.81). As a result, time-dependent changes in intermittent endurance capacity during matches validated in-game running kinematics. This indicates the Yo-Yo IR1’s robustness as a fitness marker, and its capacity to help practitioners preview longitudinal variations in locomotor behavior during matches. Athletes who show a high degree of asymmetry in official matches seem to exhibit a strong ability to resist fatigue during testing.

Lessons from the COVID-19 pandemic: Insights into effective training strategies for physical development in football.

Professional soccer players typically perform regular training sessions and match play for most of the yearly macrocycle with limited time focused on solely developing physical development. The COVID-19 outbreak in 2020 caused mass disruption to professional soccer but provided an opportunity for an alternative approach to training in attempt to develop professional soccer players physical fitness levels. In a non-randomised and non-controlled study, we aimed to assess the effectiveness of a 13-week remote based physical training programme on physical fitness levels in elite professional soccer players. Twenty professional soccer players undertook body composition assessments, a countermovement jump (CMJ) test, eccentric hamstring strength test and a submaximal 30–15 intermittent fitness test (IFT) pre- and post-remote based training programme. Body mass (79.3 ± 6.7 vs. 80.0 ± 7.3 kg), skinfold thickness (54.1 ± 14.8 vs. 56.7 ± 15.2 mm), maximum CMJ height (38.4 ± 3.4 vs. 40.9 ± 4.1 cm), eccentric hamstring strength (1035 ± 158 vs. 1009 ± 140 n) and percentage max heart rate reached in submaximal 30–15 IFT (81.3 ± 5.2 vs. 82.3 ± 7.3%) were maintained (all P > 0.05) from pre- to post training programme, respectively. Although team-based soccer specific training load was removed, and the training programmes prescribed had an increased physical focus, fitness levels were maintained. This suggests that alternative modes of training can potentially be used in instances where team-based soccer specific training load isn’t required or is unavailable, without negatively impacting physical development.

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

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

Knee Flexor Eccentric Strength, Hamstring Muscle Volume and Sprinting in Elite Professional Soccer Players with a Prior Strained Hamstring.

Simple SummaryGiven the link between a prior hamstring injury and the increased risk of suffering a subsequent injury in professional soccer, an understanding of the features displayed by previously injured players is important. The aim of the present study was to investigate if players with a history of hamstring injury exhibit bilateral deficits in knee flexor eccentric strength, hamstring muscle volume, and sprinting performance. The eccentric knee flexor strength was greater in the previously injured limbs compared to both the contralateral uninjured limbs in the previously injured group and the uninjured limbs in the previously uninjured players. Previously injured limbs showed possibly larger short heads of the biceps femoris and likely semitendinosus muscle volumes. Sprinting performances in the 5-m were possibly worse in players with a history of hamstring muscle strain injury compared to the previously uninjured players.The aim was to determine if players with a prior hamstring strain injury (HSI) exhibit bilateral deficits in knee flexor eccentric strength and hamstring muscle volume and differences in sprinting performance compared with players without a history of HSIs. Forty-six male professional soccer players participated in this study. Eccentric knee flexor strength, hamstring muscle volume (MRI), and a 20-m running sprint test (5- and 10-m split time) were assessed at the start of the preseason. Eccentric knee strength of the previously injured limbs of injured players was greater (ES: 1.18–1.36) than the uninjured limbs in uninjured players. Previously injured limbs showed possibly larger biceps femoris short heads (BFSh) and likely semitendinosus (ST) muscle volumes than the contralateral uninjured limbs among the injured players (ES: 0.36) and the limbs of the uninjured players (ES: 0.56), respectively. Players who had experienced a previous HSI were possibly slower in the 5-m (small ES: 0.46), while unclear differences were found in both the 10-m and 20-m times. Players with a prior HSI displayed greater eccentric knee flexor strength, possibly relatively hypertrophied ST and BFSh muscles, and possibly reduced 5-m sprinting performances than previously uninjured players. This can have implication for the design of secondary hamstring muscle injury prevention strategies.

Relationship between aerobic fitness and metabolic power metrics in elite male soccer players.

The aim was to assess the relationship between aerobic fitness and metabolic power metrics in elite male soccer players, and the possible differences that playing positions might impose during match play over new metabolic power metrics. Sixty-two elite professional male soccer players (13 central backs, 13 side backs, 22 midfielders, and 14 forwards) took part in the study. Players were monitored during eleven months of full training (including pre-season and in-season) and over all official matches (Serie A matches, Italy Cup matches). Aerobic fitness tests were conducted one week after the start of the preseason, and 8, 24 and 36 weeks after the beginning of the Championship. Players’ aerobic fitness and metabolic power metrics were considered as the mean of all seasonal testing and of pooling data of 38 championship matches and 3 or 6 Italy Cup matches for all the calculations respectively. The velocity at 4 mmol·L-1 (VL4) was significantly related to metabolic power metrics match variables with correlation ranging from trivial to very large (r = 0.32 to r = 0.89). Receiver-operating-characteristic (ROC) analysis showed that speed at VL4 was sensitive in detecting high metabolic power distance (HMPD) changes in all but central back players as revealed by area under the curve (central back .78, 95%CI .47 to .95; full back .93, 95%CI .64 to 0.99; midfielder .88, 95%CI .67 to 0.98; forward .90, 95%CI .62 to 0.99). This study’s findings provide further evidence for the ecological validity of aerobic fitness in elite male soccer players. Players having a HMPD cut-off equal to or higher than > 1450 m for central backs, > 1990 m for full backs, > 2170 m for midfielders and > 1670 m for forwards may be considered as possessing superior aerobic fitness status. In light of this study’s findings, the VL4 test may be considered a valid test to evaluate meaningful information for direct generic aerobic training in soccer players.

Vertical Jump Performance: Relevance For Competition Success In Elite Soccer

Vertical jump performance (VJP) is widely used to assess lower extremity explosive power (EP) in soccer players. It has been reported that VJP correlates with acceleration and speed performance. While EP is an important parameter of physical performance in soccer, limited knowledge has been reported related to its influence on team success in elite professional soccer players. PURPOSE: To find effect of VJP on team competition success in professional soccer players. METHODS: Cross-sectional study design of one hundred thirty-five male soccer players of the highest Czech league. Players were classified into three groups based on each team´s final league ranks. The three groups were: (A) 1st-4th ranking (n = 45), (B) 5th-12th ranking (n = 49) and (C) 12th-16th (n = 41). VJP was evaluated by force plates (KISTLER, Winterhur, Switzerland) with three different jump tasks: counter-movement jump free arms (CMJFA), counter-movement jump (CMJ), and squat jump (SQJ). Outcome variable of the VJP were assessed: jump height (JH), maximal vertical ground reaction force (VGRF) during take-off phase for dominant (VGRFDL), nondominant leg (VGRFNL) and force impulse (FI) related to player´s body mass. RESULTS: Results revealed significant higher VJP related to team’s performance success (λ = 0.91, F10,784 = 3.67; p < 0.01, ηp2 = 0.05). Group A had significantly (p < 0.05) higher JH in all types of jumps compared to group B and C, while B compared to C group had no significant differences (CMJFA: A = 48.15 ± 4.59 cm, B = 45.62 ± 3.36 cm, C = 44.70 ± 5.15 cm, CMJ: A = 42.37 ± 4.30 cm, B = 40.28 ± 2.96 cm, C = 39.99 ± 4.85 cm, SJ: A = 39.05 ± 3.79 cm, B = 37.17 ± 2.97 cm, C = 37.44 ± 4.39 cm). Greater FI was found in CMJ jump in A group (3.29 ± 0.33 N.s.kg-1) compared to less successful teams (FI: B = 3.04 ± 0.30 N.s.kg-1, C = 3.11 ± 0.35 N.s.kg-1). Significantly higher VGRF, VGRFDL and VGRFNL were found in players from A group compared to B group. Statistically significant differences were not found in the rest of the post hoc comparisons among observed VJP variables. CONCLUSION: The current results identified that EP measured by VJP may be a crucial factor for competition success of male professional soccer teams, when consider best teams (group A). Explosive strength between medium (B) and low (C) league ranking were not different.

Return-to-Play Times and Player Performance After ACL Reconstruction in Elite UEFA Professional Soccer Players: A Matched-Cohort Analysis From 1999 to 2019.

Background:Anterior cruciate ligament (ACL) rupture is one of the most common injuries afflicting soccer players and requires a lengthy recovery processes after reconstructive surgery. The impact of ACL reconstruction (ACLR) on return to play (RTP) time and player performance in professional soccer players remains poorly studied.Purpose/Hypothesis:To determine player performance and RTP rate and time after ACLR in elite professional soccer players with a retrospective matched-cohort analysis. We expected that the RTP time and rate will be similar to those of other professional-level athletes.Study Design:Cohort study; Level of evidence, 3.Methods:Included were 51 players from 1 of the 5 elite Union of European Football Associations (UEFA) soccer leagues who suffered a complete ACL rupture between 1999 and 2019. These athletes were matched by position, age, season of injury, seasons played, and height and compared to uninjured control players. Change in performance metrics for the 4 years after the season of injury were compared with metrics 1 season before injury. Univariate 2-group comparisons were performed using independent 2-group t tests; Wilcoxon rank-sum tests were used when normality of distributions was violated.Results:Overall, 41 players (80%) returned to play after ACL rupture, with 6 (12%) experiencing a subsequent ipsilateral or contralateral ACL tear. The mean (±SD) RTP time for soccer players after ACLR was 216 ± 109 days (26 ± 18 games). Injured athletes played significantly fewer games and minutes per season and recorded inferior performances for 2 seasons after their injury (P < .001). However, the game performance of injured players equaled or exceeded that of their matched controls by season 3 after injury, with the exception of attackers, who demonstrated a continued decline in performance (P < .001).Conclusion:Results indicated that the mean RTP time for soccer players after ACLR is short in comparison with other major sports leagues (216 days). However, RTP rates were high, and rerupture rates were comparable with those of other sports. With the exception of attackers, player performance largely equaled or exceeded that of matched controls by the third postinjury season.

Oxidative Stress and Abnormal Tendon Sonographic Features in Elite Soccer Players (A Pilot Study).

Objective Sound experimental data suggest that oxidative stress plays an important role in the pathogenesis of tendinopathies. However, this hypothesis in humans remains speculative given that clinical data are lacking to confirm it. Recently, a new methodology has allowed to quantify the oxidative stress in vivo by measuring the concentration of hydroperoxides of organic compounds, which have been utilized as an oxidative stress-related marker in several pathologic and physiologic conditions. Given the reliability of this test and the lack of information in subjects with tendinopathies, the aim of the present study was to assess the oxidative stress status in elite professional soccer players with and without ultrasonographic features of tendon damage. Methods In 73 elite players, blood metabolic parameters were evaluated and oxidative stress was measured by means of a specific test (expressed as U-Carr units). Therefore, an ultrasonographic evaluation of the Achilles and patellar tendons was performed. Results No significant relationships were observed between metabolic parameters and oxidative stress biomarkers. The Achilles and patellar tendons showed a normal echographic pattern in 58 athletes, and sonographic abnormalities in 15. The athletes with ultrasonographic alterations, compared to those with normal US picture, showed significantly higher U-Carr levels ( p = 0.000), body mass index (BMI) values ( p = 0.03) and were older ( p = 0.005). The difference in U-Carr values among the subjects remained significant also after adjustment for age and BMI. Conclusion The results of the present study support the hypothesis that oxidative substances, also increased at systemic and not only at local level, may favor tendon damage. Level of Evidence IV (pilot study).

Applying a holistic hamstring injury prevention approach in elite football: 12 seasons, single club study.

The aim was to investigate the preventive effect of a complex training program based on holistic hamstring health understanding in elite professional soccer players. This study involved an elite club in Europe and was conducted over 12 seasons. The last 2 seasons were the intervention period, and the others were the control seasons. During the intervention period, players performed a complex program organized into different interventions throughout the week having as a priority the player health. Hamstring injuries, absenteeism, injury rates, and injury burden between the control and intervention seasons were compared using a rate ratio (RR) with 95% CI. Players had a mean exposure of 333.5±18.6hours per season with no significant differences between the intervention and control seasons. The overall injury rate was 3 times lower during the two intervention seasons than during the previous seasons (P<.01); the match injury rate was 2.7 times lower (P<.01) and the training rate 4.3 times (P<.01). Injury burden was almost 4 times lower during the two intervention seasons than during the previous seasons (P<.01), and recurrences in the control group were 10% vs 0% in the intervention group. Hamstring injuries were reduced ~3 times during the seasons in which elite football players were exposed to multicomponent, complex prevention training with individual approaches based on player needs, management of training load, individualized physiotherapy treatment, and planned staff communication, in comparison to the control seasons without a clearly defined and structured injury prevention intervention.

Asymptomatic Foot and Ankle Abnormalities in Elite Professional Soccer Players.

Background:Professional soccer players are often evaluated with asymptomatic lesions of the ankle and foot, and such abnormalities may eventually become clinically relevant.Purpose:To ascertain the prevalence of foot and ankle abnormalities in elite professional adult soccer players.Study Design:Case series; Level of evidence, 4.Methods:Professional adult male elite soccer players (n = 37) underwent magnetic resonance imaging (MRI) scans of both their feet and ankles. All competed for their respective national junior or adult soccer teams. MRI scans were performed with 1.5-T scanners and analyzed independently by 2 experienced radiologists.Results:The MRI scans of 86.5% of the players showed degenerative joint disease (DJD) in at least 1 of the joints of the foot and ankle. Articular cartilage lesions in the joints of the foot and ankle were evident in 42% of the scans. Of all lesions, 17% were grade 3 or 4 (Noyes and Stabler classification) cartilage lesions and accompanied by subchondral bone marrow edema. The greater the age, weight, and height of the players, the greater was the odds ratio of DJD of the ankle joint. Synovitis in at least 1 of the joints of the foot was detected in 64% of the MRI scans. Leg dominance significantly correlated with bone marrow edema of the talus.Conclusion:Elite professional soccer players are often evaluated with a high prevalence of asymptomatic osteochondral lesions with subchondral bone marrow edema in the foot and ankle. These osteochondral lesions may remain asymptomatic or, with the continuing high-intensity stresses that modern professional soccer demands of its athletes, may evolve and cause foot and ankle pain. It is unclear whether and which interventions can be implemented to prevent the occurrence of these abnormalities in the first place.