Elite Soccer Players Research Articles

Predictive modeling of the ratings of perceived exertion during training and competition in professional soccer players.

Evaluate the ability of predicting the ratings of perceived exertion from the external load variables in professional soccer players through a chronological perspective (i.e., past features values are considered additional features) through machine learning models by considering the playing position. Prospective cohort study. Thirty-eight elite soccer players aged 19-27 years were observed during 151 training sessions, 44 matches across a full season. External load variables (58 derived from Global Positioning System and 30 from accelerometers) and the internal load derived from ratings of perceived exertion were collected for each player and each session and match. Machine learning models (linear regression, K-NN, decision trees, random forest, elastic net regression, XGBoost) were compared and interpreted in order to deepen the relationship between external load variables and ratings of perceived exertion according to the player position in a predictive perspective. Application of the machine learning models on the dataset provided enough predictive power to reduce the Root Mean Squared Error of 60 % from dummy predictions. The most accurate models (Root Mean Squared Error ≈ 1.1 for random forest and = 1 for XGBoost) highlighted a memory effect in subsequent ratings of perceived exertion values. Past ratings of perceived exertion values over one month were the strongest predicting factors of ratings of perceived exertion as compared to various external load indicators. The tree-based machine learning models showed statistically significant predictive ability, indicating valuable information for understanding the training load responses based on ratings of perceived exertion changes.

Landing Posture in Elite Female Athletes During a Drop Vertical Jump Before and After a High-Intensity Ergometer Fatigue Protocol: A Study of 20 Japanese Women’s Soccer League Players

Background: Even elite athletes, who usually show stable postural control, sometimes cannot control their posture after high-load training. This instability may contribute to anterior cruciate ligament injury. Purpose/Hypothesis: The purpose of this study was to evaluate the landing posture of elite female soccer players before and after a novel high-intensity fatigue-inducing exercise protocol. We hypothesized that the landing posture will change before versus after the fatigue protocol. Study Design: Descriptive laboratory study. Method: The study participants were 20 female elite soccer players. All athletes performed 3 drop vertical jumps (DVJs), pedaled an ergometer 8 times with full force for 10 seconds each (fatigue protocol), and then repeated the 3 DVJs. We measured and compared the athletes’ blood lactate levels before and after the fatigue protocol, as well as the hip flexion, knee flexion, and ankle dorsiflexion angles and final landing posture during the DJVs. Results: Blood lactate levels increased significantly pre- to postprotocol (from 2.7 ± 1.9 to 15.0 ± 3.6 mmol/L; P < .001), while there were decreases in hip flexion angle (from 35.0° ± 11.2° to 22.4° ± 8.8°; P < .001) and ankle dorsiflexion angle (from 26.4° ± 3.9° to 20.0° ± 3.7°; P < .001). The number of athletes who could not maintain a stable DVJ final landing posture increased from 10% before the fatigue protocol to 70% after. Conclusion: The elite female athletes in our study showed significant decreases in hip flexion and ankle dorsiflexion angles in the DVJ landing after a fatigue-inducing protocol. Most elite athletes were unable to maintain a stable posture on the DVJ landing after the fatigue protocol. Clinical Relevance: This study advances our understanding of how elite athletes land in a fatigued state.

Determining the capacity for effort and recovery of the elite soccer players specialized in different playing positions.

The capacity for effort and recovery in performance sports can be increased by means of modern methodological strategies. This capacity to recover after intense matches and training helps to determine the performance in soccer. Using the Yumeiho technique will accelerate the exercise capacity recovery of the soccer players specialized in central zone positions. The research was conducted with the C.S. Internațional Bălești team, formed of 16 players, aged 19-37 years, divided into two groups: experimental group A, n = 8 with central area players and control group B, n = 8 with players from side zones. Measurement and assessment tests: determining lactic acid level (LAC) in blood; 60 m sprinting speed motor test (ST); anaerobic lactic exercise; Gacon Test for evaluating the aerobic power; VO2max test; Dorgo Test for determining the individual recovery capacity; Sleep Quality and Efficiency Index (PSQI) and sleep duration. Means used in the recovery strategy: easy running, static stretching, cryotherapy; Yumeiho therapy was applied only to group A to accelerate the recovery. The anaerobic lactic capacity was evaluated by 60 m sprint test at the beginning and the end of the research. The results highlight the increase of the sprinting speed by 0.08 s in group A (p < 0.001). The aerobic capacity evaluated by means of Gacon Test in both groups shows the value 23.7%, namely a well-prepared level (p < 0.001). VO2max value in the soccer players of group A shows 87.5% good aerobic power, while the players of group B have 50% good aerobic power (p < 0.001). The concentration of LAC after exercise has a higher value in group A (p > 0.05). The level of recovery after exercise is improved in both groups, with larger differences in group A (very good level, p < 0.001). The PSQI grew by 20.37% in group A and by 11% in group B. The sleep duration increased in both groups (p < 0.001). The results of the correlation analysis in the soccer players of group A highlight strong connections of 14.8% while in group B the value is 12.5%. The assessment of effort capacity in soccer players specialized in different playing positions at the beginning and the end of the research highlights the increase of the anaerobic lactic effort and aerobic effort. This assessment also shows the improvement of the individual recovery capacity. A higher PSQI and the increase of sleep duration in both groups, with greater differences of group A were found, which determined their level of capacity for effort and recovery. The use of the Yumeiho technique in the program of post-exercise recovery accelerates the aerobic and anaerobic lactic effort capacity of the soccer players specialized in the central zone positions. It positively influences exercise capacity recovery in general.

Prevalence and diagnostic significance of de-novo 12-lead electrocardiogram patterns following covid-19 infection in elite soccer players

Abstract Funding Acknowledgements Type of funding sources: None. Background Considering that myocarditis is implicated in 5-15% of all exercise related sudden cardiac deaths in athletes, following a novel viral pandemic, the identification and risk-stratification of affected athletes remains an important priority. Given its widespread availability, the inclusion of a 12-lead electrocardiogram (ECG) is common to all consensus-based protocols from North America and Europe. However, a single cross-sectional ECG is problematic because several physiological repolarisation changes are also common manifestations in individuals with myopericarditis. Purpose The aim of our study was to report on the prevalence and diagnostic significance of de-novo ECG patterns following COVID-19 infection in a well-defined cohort of elite soccer players in the English, Dutch and Brazilian leagues. Methods In this multicentre observational study, between March 2020–May 2022, we evaluated consecutive athletes with COVID-19 infection. ECGs were reported in accordance with the International recommendations for ECG interpretation in athletes. The following patterns were also considered abnormal if they were not detected on the pre-COVID-19 infection ECG: PR-segment depression, new J-point and ST segment elevation, low QRS voltages, QRS fragmentation, new ST-segment depression, new T-wave inversion, biphasic T-waves and a reduction in the T-wave amplitude by 50% or T-wave flattening. Athletes exhibiting de-novo ECG changes underwent cardiovascular magnetic resonance (CMR) scans. One club mandated CMR scans for all players (n=30) following COVID-19 infection, despite the absence of cardiac symptoms or de-novo ECG changes. Results 511 soccer players (median age 21-years, IQR:18-26-years) were included, of which 88% were male and 58% white. 17 (3%) athletes demonstrated de-novo ECG changes, which included, a reduction in T-wave amplitude in the inferior and lateral leads (n=5), inferior leads (n=4) and lateral leads (n=4); inferior T-wave inversion (n=7), and ST-segment depression (n=2). 15 (88%) athletes with de-novo ECG changes revealed CMR evidence of inflammatory cardiac sequalae. All athletes who underwent a mandatory CMR irrespective of illness severity or ECG findings, had normal findings. Athletes revealing de-novo ECG changes, had a higher prevalence of cardiac symptoms (71% v 12%; p&amp;lt;0.0001) and longer median symptom duration (5-days, IQR:3-10) compared with athletes without de-novo ECG changes (2-days, IQR:1-3; p&amp;lt;0.001). Among athletes without cardiac symptoms, the additional yield of de-novo ECG changes to detect cardiac inflammation was 17%. Conclusions 3% of athletes demonstrated de-novo ECG changes post COVID-19 infection, of which 88% were diagnosed with inflammatory cardiac sequalae. Most affected athletes exhibited cardiac symptoms; however de-novo ECG changes contributed to a diagnosis of cardiac inflammation in 17% of athletes without cardiac symptoms.

On a match day, what should an elite soccer players routine look like?

On a match day, what should an elite soccer players routine look like?

Effects of cold water immersion and protein intake combined recovery after eccentric exercise on exercise performance in elite soccer players.

The purpose of this study is to analyze the effects of the combined recovery method of cold water immersion (CWI) and protein supplement intake after eccentric exercise that causes muscle fatigue in elite soccer players. Eleven semiprofessional soccer players participated in this study. Participants were divided into CWI group, combined protein and CWI group (PCWI), and passive resting group (CON). The participants completed the eccentric exercise for one hour and performed one of three recovery methods. The muscle strength of the quadriceps and hamstring muscles significantly decreased at 48-hr postexercise compared to before exercise in all recovery groups (P<0.05), with no significantly different between the recovery groups. The time required to sprint 40 m was significantly longer in all groups at 24 hr and 48 hr after exercise than before exercise (P<0.05). The vertical jump height was significantly decreased at 48 hr after exercise compared to before exercise in the CON and CWI groups (P<0.05). The muscle soreness values were higher at 6 hr, 24 hr, and 48 hr after exercise than before exercise in all groups (P<0.001). The perceived recovery quality was reduced after exercise in the PCWI (P<0.01) and CON groups (P<0.001) compared to before exercise; it was unchanged in the CWI group. The recovery quality decreased at 6 hr, 24 hr, and 48 hr after exercise in all recovery groups (P<0.01). In conclusion, the combined recovery method was less effective than CWI alone for the recovery of exercise performance.

Internal and External Loads of Young Elite Soccer Players during Defensive Small-Sided Games.

The aim of this study was to evaluate the effects of different time periods on the internal and external loads of soccer players during small-sided games (SSGs). Seventeen young soccer players performed a SSG of 5 vs. 5 + 5 with 2 floaters, where two teams had possession of the ball, and one had to recover it. With established periods of 30 s (SSG30), 1 min (SSG1) or 2 min (SSG2), teams participated in a defensive role for these periods of time. Total distance covered, moderate speed running distance, high speed running distance, sprint running distance, accelerations, decelerations and Player Load were monitored using global positioning systems devices. The maximal heart rate and modified training impulse were monitored using heart rate monitors. The rating of perceived exertion (RPE) was also measured. Data showed a small increase between SSG30 and SSG1 in Player Load (ES = -0.35; p < 0.01), and a small increase in high speed running (ES = -0.41; p < 0.05) and sprinting (ES = -0.47; p < 0.01) between SSG30 and SSG2. Also, SSG1 showed a small increase in sprinting (ES = -0.57; p < 0.01) and accelerations (ES = -0.37; p < 0.05) with respect to SSG2. In addition, SSG2 showed a small increase in the RPE with respect to SSG30 (ES = 0.46; p < 0.05). The results indicate that shorter defensive periods in SSGs increased high speed running, while longer defensive periods promoted greater perceived exertion. Manipulation of the duration of defensive periods in SSGs is a variable that should be considered in soccer training.

Kinematic parameters and metabolic power in elite soccer players: A small sided a large sided games comparison.

Introduction: The goal of this paper is to determine what happens in one minute (on average) in kinematic parameters and metabolic power in small sided games (SSG) (3v3; 5v5) and large sided games (LSG) (10v10) and in which games kinematic parameters and metabolic power are best developed. Methods: The participants of this study were 22 professional football players, height 182.95±6.52cm, mass 77.17±8.21kg, body mass index (BMI) 22.97±1.47kg/m2, body fat 9.85±2.55 %, aged 27.1±5.4yrs, who played in the Premier League of Bosnia and Herzegovina. Data total distance (TD), maximum speed (MS), number of accelerations (nAcc), number of decelerations (nDec), number of sprints (nS), high intensity distance (Z4≥19.8km/h), sprint distance (Z5≥25.2km/h) and movements requiring a certain metabolic power (Pmet), were collected using a 20 Hz Global positioning system (GPS) system Pro2 (GPEXE, Exelio srl, Udine, Italy), on a total of 307 individual observations. Results: The results showed that the average total distance was significantly higher in the 5v5 (135.16±18.78m) and 10v10 (133.43±20.06m) games (F=64.26, p<0.001) compared to the 3v3 (108.24±11.26m). Furthermore, the values of the variables Z4 (8.32±3.38m, F=97.59), Z5 (1.84±1.53m, F=123.64), nS (0.13±0.10n, F=96.14) as well as Maxspeed (27.06±1.90km/h, F=139.33), are statistically significantly higher (p<0.001) in the 10v10 game compared to the other two game formats. The average number of nAcc (0.40±0.32n, F=9.86, p<0.001) and nDec (0.62±0.36n, F=6.42, p<0.001) is statistically significantly higher in the 5v5 game. The results showed that the 5v5 game is significantly more metabolically demanding Pmet (2.76±0.67W•kg-1, F=66.08, p<0.001) compared to the other two game formats. Discussion: The data presented in this paper can be used as a basis for the construction of specific exercises based on kinematic and physiological requirements, and for planning and programming microcycles in football.

Ability of Countermovement Jumps to Detect Bilateral Asymmetry in Hip and Knee Strength in Elite Youth Soccer Players

Clinicians frequently assess asymmetry in strength, flexibility, and performance characteristics as a method of screening for potential musculoskeletal injury. The identification of asymmetry in countermovement jumps may be an ideal method to reveal asymmetry in other lower extremity characteristics such as strength that otherwise may require additional testing, potentially reducing the time and burden on both the athlete and clinicians. The present study aims to examine the ability of asymmetry in both the single-leg and two-leg countermovement jump tests to accurately detect hip abduction, hip adduction, and eccentric hamstring strength asymmetry. Fifty-eight young male elite soccer players from the same professional academy performed a full battery of functional performance tests which included an assessment of hip adductor and abductor strength profiles, eccentric hamstring strength profiles, and neuromuscular performance and asymmetries during countermovement jumps. Bilateral variables attained from both the single-leg and two-leg countermovement jump tests included concentric impulse (Ns), eccentric mean force (N), and concentric mean force (N) computed by the VALD ForceDecks software. Average maximal force (N) was calculated bilaterally for the strength assessments. Asymmetry was calculated for each variable using 100 × |(right leg - left leg)/(right leg)| and grouped into three categories: 0 to <10%, 10% to <20%, and 20% or greater. Analyses were performed for the two higher asymmetry groups. The accuracy to detect strength asymmetry was assessed as the sensitivity, specificity, and predictive values for positive and negative tests. The outcomes from the accuracy assessments suggest that the single-leg countermovement jump concentric impulse variable at the 20% threshold is indicative of a youth male soccer player having hip adduction strength asymmetry while also demonstrating more accuracy and applicability than the two-leg countermovement jump concentric impulse variable.

Association of Nonconcussive Repetitive Head Impacts and Intense Physical Activity With Levels of Phosphorylated Tau181 and Total Tau in Plasma of Young Elite Soccer Players

Head impacts resulting in traumatic brain injury (TBI) lead to the elevation of phosphorylated tau protein (p-tau181) in plasma. To our knowledge, this study is the first to investigate dynamics of p-tau181 levels and the ratio of p-tau181 to total tau in individuals after nonconcussive head impacts. To determine the association of repetitive low-intensity head impacts on p-tau181 and total tau protein levels in the plasma of young adult elite soccer players and assess the possible association of head impacts with focused attention and cognitive flexibility. In this cohort study, young elite soccer players performed intense physical activity with and without heading the ball. The study was conducted at a university facility in Slovakia from October 1, 2021, to May 31, 2022. Eligible participants were selected based on similarities in demographic variables, excluding those with a history of TBI. The primary study outcomes were the levels of total tau protein and p-tau181 in plasma samples and the cognitive status of the study participants. A total of 37 male athletes participated in the study (mean [SD] age: exercise group, 21.6 [1.6] years; heading group, 21.2 [1.5] years). We found significantly elevated levels of total tau and p-tau181 in the plasma of soccer players 1 hour after physical exercise (tau, 1.4-fold; 95% CI, 1.2-1.5; P < .001; p-tau181, 1.4-fold; 95% CI, 1.3-1.5, P < .001) and repetitive head impacts (tau, 1.3-fold; 95% CI, 1.2-1.4; P < .001; p-tau181, 1.5-fold; 95% CI, 1.4-1.7 P < .001). The ratio of p-tau181 to tau was significantly higher 1 hour after exercise and heading training, and remained elevated specifically in the heading group even after 24 hours (1.2-fold; 95% CI, 1.1-1.3; P = .002). Performance in cognitive tests revealed a significant decline in focused attention and cognitive flexibility after physical exercise and heading training; physical exercise of higher intensity without heading training was associated with a greater negative cognitive performance than heading only. In this cohort study of young elite soccer players, the elevation of p-tau181 and tau was observed after acute intense physical activity and nonconcussive repetitive head impacts. The increase of p-tau181 levels relative to tau after 24 hours indicated an acute enrichment of phosphorylated tau fraction in the periphery when compared with preimpact levels; an imbalance of tau proteins may have long-lasting consequences in the brain of head-impacted individuals.

Prevalence and diagnostic significance of de-novo 12-lead ECG changes after COVID-19 infection in elite soccer players

Background and aimThe efficacy of pre-COVID-19 and post-COVID-19 infection 12-lead ECGs for identifying athletes with myopericarditis has never been reported. We aimed to assess the prevalence and significance of de-novo...

High-level soccer players have a low rate of return to performance after hip arthroscopy for femoroacetabular impingement syndrome

PurposeFemoroacetabular impingement syndrome (FAIS) is a known cause of impaired sports performance in athletes and the relationship between FAIS and soccer players has previously been described. Hip arthroscopy is a viable treatment option that can facilitate athletes’ return to sport (RTS). The aim of this study was to evaluate the RTS and return to performance (RTP) with objective measurements in high-level soccer players after hip arthroscopy for FAIS.MethodSoccer players, with a hip sports activity scale (HSAS) level of 7 or 8 before symptom onset and undergoing hip arthroscopy for FAIS between 2011 and 2019 were identified in the Gothenburg hip arthroscopic registry. A total of 83 high-level soccer players, with a mean age of 23.9 (SD 4.4) years at surgery, were included. To verify the activity level and further stratify players as elite or sub-elite, player statistics were collected from soccer-specific scout webpages and the Swedish national soccer association. The return to sport was defined as return to one game of soccer. Return to performance was defined as playing at the same level, or higher, and participating in at least 80% of the number of games played the season before symptom onset or the season before surgery either the first or second season after hip arthroscopy.ResultsIn total, 71 (85.5%, 95% confidence interval (CI) 76.1–92.3%) of the players returned to sport the first or second season after surgery. Compared to the season before symptom onset, 31 (37.3%, 95% CI 27.0–48.7%) players returned to performance the first or second season after surgery, and 32 (38.6%, 95% CI 28.1–49.9%) players returned to performance the first or second season after surgery compared to the season before surgery.ConclusionA high rate of elite and sub-elite soccer players return to soccer after hip arthroscopy for FAIS. However, less than half of the players RTP when evaluating performance through level of play and number of games played.Level of evidenceLevel IV.

Capturing in Season Change-of-Direction Movement Pattern Change in Youth Soccer Players with Inertial Measurement Units

This study aimed to examine the utility of inertial measurement unit (IMU) technology to identify angle, step-specific, and side-specific differences between youth soccer players with and without a history of lower limb injury during soccer-specific field tests. Thirty-two youths (mean age 16.4 years) who were elite soccer players (Females n = 13, Males n = 19) wore IMUs during pre- and postseason soccer-specific change-of-direction assessments. A response feature analysis was used to compare the change in peak resultant acceleration of the groups at a level of significance of p &lt; 0.05. Statistical analysis revealed significant differences in change of peak resultant acceleration of right leg final foot contact in a 180° pivot turn (p = 0.012, ES = 1.0) and a 90° cut (p = 0.04, ES = 0.75) between the two groups. These data suggest that players with a history of lower limb injury might experience greater angle and side-specific change within a season in peak resultant acceleration when compared with injury-free athletes. This study demonstrates that IMUs may present a useful method to analyze youth soccer players’ change of direction movement after returning to play. These results can inform future studies investigating player monitoring and may prove to be a useful tool for coaches when designing individualized training programs in this population.

Mortality of Spanish soccer referees and coaches: a retrospective cohort study

ABSTRACT There is evidence that elite soccer players live longer than general population, but there is no information on soccer coaches and referees. We aimed to analyze the longevity of both professionals, comparing them with soccer players and with general population. In this retrospective cohort study, a total of 328 male Spanish soccer coaches, 287 referees, and 1230 soccer players, all born before 1950, were divided in two cohorts, matched 2:1 with coaches and referees. We compared the survival of the cohorts with the Kaplan–Meier estimator and significance with the log-rank test. We calculated hazard ratios of death for coaches and referees compared with male Spanish general population of the same period. Differences in survival among cohorts were found, but they did not reach statistical significance. The estimated median survival time was 80.1 years (95% CI 77.7–82.4) for referees, 78 years (95% CI 76.6–79.3) for coaches, 78.8 years (95% CI 77.6–80) for referees matched with players, and 76.6 years (95% CI 75.3–77.9) for coaches matched with players. Both coaches and referees had lower mortality than general population, but this advantage disappeared after 80 years of age. We found no differences in longevity among Spanish elite soccer referees, coaches and players born before 1950. Both coaches and referees had lower mortality than general population, but this advantage disappeared after 80 years of age.

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.

Travel Across More Time Zones Results in Worse Perceived Fatigue and Sleep in National-Team Footballers

This study investigated the association between (1)time zone difference and (2)travel direction (east vs west) with posttravel changes in perceptual responses of national-team footballers. Travel schedules from 355 national-team trips (50 elite soccer players) were verified using an online flight database. All players provided perceptual ratings of fatigue, sleep quality, soreness, and stress to calculate changes in scores up to 2days after travel. Trips were categorized as <3, 3 to 6, 6 to 9, or 9+ time zone changes, along with travel direction (eastward or westward). The pretravel to posttravel changes in perceptual ratings at days 1 and 2 postarrival were compared between time zone change and travel direction with linear mixed models. For every time zone crossed, poorer ratings of perceptual fatigue (β = 0.068, P < .001), sleep (β = 0.095, P < .001), soreness (β = 0.0049, P < .001), and total wellness (β = 0.214, P < .001) were observed. However, the models explained only small proportions of the variation in postflight perceptual responses (7%-18%). Regardless, travel across 9+ time zones resulted in significantly worse perceived fatigue, sleep, and total wellness for days 1 and 2 postarrival compared with travel with <6 time zones (P < .05). Additionally, fatigue, sleep, and total scores were worse on day 2 following trips of 9+ time zones. Eastward travel resulted in poorer sleep ratings (β = 0.52, P < .001) than westward travel within time zone groupings. Perceptual ratings of fatigue and sleep become progressively worse as travel increases in national-team soccer players, especially after travel across 9+ time zones and eastward travel.

Fitness parameters in young football players are affected by training load and somatic-anthropometric variations

This study aimed at investigating relationship between variations in fitness parameters, variations in somatic-anthropometric parameters and training load variables in Italian elite soccer players during pre/mid and post-puberty. Thirty-six Italian elite young soccer players (Under-14, U14: 18; Under-17, U17: 18) participated in study. Their somatic-anthropometric and fitness parameters were assessed and training load (Session-RPE) was monitored during 119 days in the sporty season. During the observational period meaningful variation in CMJ and 30-15IFT emerged in U17 and only in CMJ in U14. Meaningful correlations emerged between variations in CMJ and variations in numerous somatic-anthropometric parameters in U17 but only variations in ARM-GIRTH in U14. Meaningful correlations were found between variations in 30-15IFT and only variations in SUP-SKIN in U17, training load during match in U14 and U17 and training load during session training only in U17. During puberty, variation in fitness parameters are affected by variations in somatic-anthropometric parameters and training load parameters differently between U14 and U17. Variations of body shape have more influence in U17, match load more influence in U14 and intensity of training influence only in U17. This study offers new interpretations about the effect of anthropometric and somatic parameters, as well as on training dose (volume, intensity and typology) on the variation of fitness parameters during puberty.

The manipulation of task constraints and the effect on creative performance of youth soccer players

Creativity is a popular topic that has been increasingly researched over the years. Recently, creativity is suggested as a relational concept (Zahno &amp; Hossner, 2020). This conceptualization implies that creativity is not solely an individual ability. By contrast, creative actions emerge in the athlete’s search to adapt to task and environmental constraints (Orth et al., 2017; Withagen &amp; van der Kamp, 2018). Manipulating task constraints that serve to increase variability might, therefore, evoke creative actions. Such manipulations in soccer are often conducted in training situations with small sided games. This was recently shown with a numerical assessment of creative actions comparing small sided soccer games (SSGs) with 11v11 matches in elite adult soccer players (Caso &amp; van der Kamp, 2020). They found that players performed more actions, a broader action repertoire and more creative actions in smaller formats (5v5, 6v6 and 7v7) than in an 11v11 format. The purely quantitative method of Caso &amp; van der Kamp (2020), however, uses an arbitrarily 5% benchmark for originality. More importantly, although subjective, the coaches opinions are not meaningless and should not be neglected.&#x0D; Our research examined whether the latter task manipulation also increased the action repertoire and creative performance of elite youth soccer players (O11-O13). A numerical method was introduced, assessing creative performances as a frequency of the action types emerging in an environment. A notational video-analysis identified all (not-) functional actions. Next, a threshold defined whether the action was original. This threshold has been determined with expert coaches ranking action types following the procedure of the consensual assessment technique (CAT; Amabile, 1996). If the action was both original and functional, then it was defined a creative action. The data consisted of 293 minutes small sided game (4v4) and 263 minutes regular sided game (11v11). Results indicated that small sided games hold relative more actions, more functional action and more creative actions compared with regular sided games. This is in line with previous studies, that small sided games induce more variation of actions which increase the possible emergence of creative actions (Orth et al., 2017).&#x0D; References&#x0D; Amabile, T. M., Amabile, T. M., Collins, M. A., Conti, R., Phillips, E., Picariello, M., Ruscio, J., &amp; Whitney, D. (1996). Creativity in Context: Update to The Social Psychology of Creativity (1st ed.). Routledge.&#x0D; Caso, S., &amp; van der Kamp, J. (2020). Variability and creativity in small-sided conditioned games among elite soccer players. Psychology of Sport and Exercise, 48, Article 101645. https://doi.org/10.1016/j.psychsport.2019.101645&#x0D; Orth, D., van der Kamp, J., Memmert, D., &amp; Savelsbergh, G. J. P. (2017). Creative motor actions as emerging from movement variability. Frontiers in Psychology, 8, Article 1903. https://doi.org/10.3389/fpsyg.2017.01903&#x0D; Withagen, R., &amp; van der Kamp, J. (2018). An ecological approach to creativity in making. New Ideas in Psychology,49, 1–6. https://doi.org/10.1016/j.newideapsych.2017.11.002&#x0D; Zahno, S., &amp; Hossner, E.-J. (2020). On the issue of ceveloping creative players in team sports: A systematic review and critique from a functional perspective. Frontiers in Psychology, 11, Article 575475. https://doi.org/10.3389/fpsyg.2020.575475

The effectiveness of two comprehensive recovery protocols on performance and physiological measures in elite soccer players: A parallel group-randomized trial

Elite soccer players consistently report using several recovery methods after practices and games. However, it is unclear how their subsequent performance could be enhanced using broad protocols. The aim of this study was to compare the effectiveness of two different comprehensive recovery protocols in physiological, neuromuscular, and perceptual outcomes. Eighteen Mexican National Team players (19.56 ± 0.62 years) were recruited. Using a randomized parallel group design, players followed one of two recovery protocols: (a) carbohydrate and protein shake, foam roller, cold-water immersion, and tart cherry juice concentrate ( n = 9) or (b) carbohydrate and protein shake, stretching, and intermittent cold-water immersion ( n = 9) following the completion of an unofficial game and the day after. Muscular creatine kinase, countermovement jump, hamstring maximal voluntary contraction, perceived recovery, and muscle soreness were assessed before, immediately after, and 20-44-68 h post-game. Significant effects (set at ρ≤0.05) of time were present in both interventions. Muscular creatine kinase was normalized entirely at 68 h post-game, while neuromuscular and perceptual outcomes were homogenized at 44 h. No statistically significant effects between protocols were found. Still, the interaction effects showed changes only in the group using protocol (a) at post-game and 20 h after in neuromuscular and muscle soreness. There were large correlations between muscular creatine kinase and accelerations, decelerations, sprints, and high-speed running distances. In conclusion, the interventions are equally effective for improving physiological, neuromuscular, and perceptual outcomes. Thus, elite soccer players may benefit from different combinations of methods after practices or games to obtain positive effects on recovery after them.

Relationships between training load, peak height velocity, muscle soreness and fatigue status in elite-level young soccer players: a competition season study

BackgroundThis study aimed to compare training load parameters, delayed onset muscle soreness (DOMS), and fatigue status between season periods (1st and 2nd halves) in U14 soccer players and to analyze the relationships between training load parameters based on season periods (1st and 2nd halves) with peak height velocity (PHV), DOMS, and fatigue status in under-14 (U14) young elite soccer players. Additionally, it was intended to analyze if fatigue, DOMS and PHV could explain training load parameters across the season.MethodsTwenty U14 players that competed in the national league participated in this study. The players were monitored during the whole season (26 weeks), and evaluations were carried out at the end of the in-season. Anthropometric and body composition parameters and the maturity offset of each player were utilized to compute each player's age at PHV. Players reported their levels of DOMS and fatigue status using Hooper index questionnaires. The internal load was monitored using the rating of perceived exertion (RPE). Acute weekly internal load (AW), chronic weekly internal load (CW), acute: chronic workload ratio (ACWR), training monotony (TM), and training strain (TS) were also obtained.ResultsThe main results showed that TM was higher in the 2nd half, while CW, AW and DOMS were higher in the 1st half of the season. Moreover, the main correlations showed a positive correlation between PHV and TS (2nd half of the season) and between fatigue and TM (1st half of the season).ConclusionIn conclusion, variations in well-being status and PHV cannot explain the variations in internal training loads in elite U14 soccer players. In addition, internal training load indices during the first half of the competitive season can promote a fundamental base for progression loads during the second period of the competitive season.