The objective of this study was to carry out a detailed quantitative analysis of the very high intensity runs during actual play in the 2013-2014 Spanish First Division, at a general level and according to the specific playing position and half. 380 matches of the Spanish First Division in the 2013 - 2014 season were monitored using the Mediacoach video motion analysis tool. Total distance, very high intensity (above 21 km/h) running distance and the number of runs at very high intensity of 230 players from 20 teams in the Spanish First Division were analysed. The main findings of the study were that the performance indicators at very high intensities decreased from the first half to the second half for all outfield players (covered distance: 4694 ± 538 m vs 4485 ± 437 m, sprint distance: 256 ± 72 m vs 239 ± 67 m, number of sprints: 14.3 ± 3.5 vs 13.2 ± 3.1), except the central defenders (sprint distance: 166 ± 37 vs 166 ± 40 m, number of sprints: 10.0 ± 2.1 vs 9.8 ± 3.8). Secondly, although wide defenders (9759 ± 665 m) and central midfielders (9776 ± 942 m) covered the most distance during matches, it were the wide defenders (30 ± 5), centre-forwards (28 ± 7) and wide midfielders (31 ± 8) who performed the most runs at very high intensity. Consequently, the distance they ran at these very high intensity runs followed the same pattern. Such results enable general and specific profiles by demarcation to be established based on the demands of the game at high-level competitive play.

Context: As the number of injuries in young soccer players increases, an epidemiological study is the first step in improving preventive strategies. Objectives: To analyze the injury profile of a Spanish professional soccer club’s academy during 4 consecutive seasons and to examine the injury incidence across different chronological age groups. Design: Prospective cohort design. Setting: Aggregate injury and exposure data collected during 4 consecutive seasons. Participants: Three hundred nine elite male young soccer players. Main Outcomes Measures: Injuries that led to participation time missed from training and match play prospectively reported by medical or coaching staff of the club. Results: A total of 464 time-loss injuries were observed during this study period. The overall injury incidence was 2.93 injuries per 1000 hours, with higher incidence during matches than during training (10.16 vs 2.10 injuries/1000 h; rate ratio [RR] = 0.21; 95% confidence interval [CI], 0.17–0.25; P < .05), with the U14 age group presenting the lowest injury rate (2.39 injuries/1000 h; RR = 1.15–1.57; P < .05). In terms of injury severity, moderate injuries were the most frequent (1.42 injuries/1000 h). Muscle injuries were the most common type of injuries (57.7%; 2.75 injuries/1000 h; RR = 1.84–13.4; P < .05), and hamstrings (93/268) were the most affected muscle group (0.58 injuries/1000 h; RR = 1.58–2.91; P < .05). Injury incidence showed a seasonal variation as indicated by peaks in August and October. In matches, specifically, the match period between 75 and 90 minutes showed the highest injury incidence (10.29 injuries/1000 h; RR = 1.89–6.38; P < .01). Conclusions: The findings of this study suggest that specific preventive strategies must be implemented to try to reduce the injury incidence in Spanish elite young soccer players attending to the characteristics of each age group.

The aim of the present study was to assess the accuracy of a multi-camera tracking system (Mediacoach®) to track elite football players’ movements in real time. A total of 207 observations of 38 official matches from Liga 1, 2, 3™ (2nd Spanish Division, season 2017/18) were included in the study (88 defenders, 84 midfielders, and 35 attackers of the same team). Total distance (TD, m) distance in zone 4 (DZ4) at a speed of 14–21 km/h, distance in zone 5 (DZ5) at a speed of 21–24 km/h (DZ5), distance in zone 6 (DZ6) at a speed of ≥24 km/h, maximum speed (km/h), and number of sprints (actions above 24 km/h) were registered with the Apex® GPS system (STATSports™, Newry, N. Ireland) and Mediacoach® semi-automatic tracking system (LaLiga™, Madrid, Spain). The level of agreement between variables estimated by the two systems was analyzed. Bias was also calculated by deducting the GPS estimated value from the video estimated value, and then dividing the difference score by the GPS estimated value. All variables showed high ICC values (>0.75) and very large correlations (r > 0.70). However the video-based performance analysis system overestimated the results obtained in the different speed zones (DZ5: +16.59 ± 62.29 m; LOA95%: −105.49 to 138.68; DZ6: +93.26 ± 67.76 m; LOA95%: −39.55 to 226.07), the number of sprints (+2.27 ± 2.94; LOA95%: −3.49 to 8.02), and the maximum speed (+0.32 ± 1.25 km/h; LOA95%: −2.13 to 2.77). The maximum bias was found in DZ6 (47%). This demonstrates that Mediacoach® is as accurate as a GPS system to obtain objective data in real time, adapted to physical and movement demands of elite football, especially for total distance and distances traveled at medium speeds.

Context: Despite the presence of various injury prevention programs, the rate of hamstring injuries and reinjuries is increasing in soccer, warranting the need for a soccer-specific rehabilitation program. Objective: To develop and validate a new, functional on-field program for the rehabilitation and readaptation of soccer players after a hamstring strain injury through a panel of experts; and determine the usefulness of the program through its application in professional soccer players. Design: A 13-item program was developed, which was validated by a panel of experts and later applied to professional soccer players. Setting: Soccer training ground. Participants: Fifteen strength and conditioning and rehabilitation fitness coaches with a professional experience of 15.40 (1.57) years in elite clubs and national teams in Europe validated the program. The program was later applied to 19 professional soccer players of the Spanish First Division (La Liga). Interventions: Once a player sustained a clinically diagnosed injury, the player would first be subject to mobilization and strengthening exercises in the gym after undergoing treatment by percutaneous needle electrolysis. The player would then complete an on-field readaptation program consisting of 13 drills arranged in a progressive manner in terms of complexity. The drills integrated various aspects of repeated sprint abilities, retraining and reeducation of biomechanical patterns, and neuromuscular control of the core and lower limbs. Main Outcome Measures: Aiken’s V for each item of the program and number of days taken by the players to return to play. Results: The experts evaluated all items of the program very highly, as seen from Aiken’s V values between 0.78 and 0.98 (0.63–0.99) for all drills, while the return to play was in 22.42 (2.32) days. Conclusion: This program has the potential to help a player suffering from a hamstring strain injury to adapt to real-match conditions in the readaptation phase through the application of sports-specific drills that were very similar to the different injury mechanisms.

Context: Infrared thermography has been used to detect skeletal muscle overload and fatigue in athletes, but its use in injury prevention in professional soccer has not been studied to date. Objectives: To establish a novel injury prevention program based on infrared thermography and to determine its influence on the injury incidence in professional soccer players in the preseason. Design: A cross-sectional, prospective study design was used to compare a conventional injury prevention program (CPP) applied over the first preseason and an infrared thermography injury prevention program (IRTPP) carried out in the following preseason. Setting: Soccer training ground. Participants: Twenty-four players belonging to a first division soccer team from Spain. Main Outcome Measures: Injury incidences of each player were recorded according to the Orchard Sports Injury Classification System (version 10.0) convention to determine the injury classification, location, and type. Results: The incidence of injuries decreased from 15 injuries in the CPP preseason (0.63 [0.77] injuries per player) to 6 injuries in the second preseason when the IRTPP was applied (0.25 [0.53] injuries per player). The days of absence due to injuries also decreased from the CPP preseason (156 d, 10.4 [11.0] d per injury) to the IRTPP preseason (14 d, 2.3 [2.8] d per injury). The injury severity also decreased from the first preseason to the second preseason, and fewer musculoskeletal injuries in the thigh, hip, and groin were reported. Conclusions: The implementation of an IRTPP can reduce the presence of injuries by identifying players potentially at risk and as a result, reducing the injury severity and days lost as a consequence.

The aims of the present study were 2-fold: (1) to measure interlimb asymmetries from a battery of fitness tests in youth soccer players and (2) to determine the association between asymmetry and measures of athletic performance. Sixteen elite youth soccer players (14.7 ± 0.2 years) performed a single-leg Abalakov test (ABK), change of direction (COD) test over 10 m (5 + 5) and 20 m (10 + 10), and an iso-inertial power test. Subjects also performed 10-, 20-, and 30-m sprints and a bilateral countermovement jump, which were correlated with all ABK, COD, and iso-inertial asymmetry scores. A one-way repeated-measures analysis of variance showed significant differences between interlimb asymmetry scores across multiple tests (p < 0.05), with the isoinertial power test presenting the greatest magnitude of asymmetry, whereas individual data highlighted substantially greater interindividual differences in each test. Pearson r correlations showed no significant relationships (p > 0.05) between the different interlimb asymmetry scores, and between asymmetry scores and athletic performance. These findings show the test-specific nature of asymmetries in youth soccer players, with the iso-inertial power test being the most sensitive in detecting asymmetry. Moreover, the results obtained suggest that inherent asymmetry in young soccer players did not negatively impact their performance.

Despite literature on the pacing strategies of endurance sports, there is an existing lack of knowledge about the swimmers’ tactical decisions in the open water races. The aims of the present research were (1) to compare the pacing profiles and tactical strategies of successful elite open water swimmers (men and women) in the 5-km, 10-km, and 25-km races and (2) to relate these pacing strategies to the end race results. Intermediate split times, positions and gaps with leaders of the first ten swimmers classified in the 2017 FINA World Swimming Championships races were collected from the public domain and were related to the finishing positions. Overall swimming velocities of the 5-km races were faster than the 10-km (δ 0.03 ± 0.03 m/s) and the 25-km (δ 0.14 ± 0.01 m/s) events with male swimmers achieving relatively faster mean velocities than females in the 5-km (δ 0.12 ± 0.01 m/s) compared to the 25-km (δ 0.08 ± 0.01 m/s) events. Medallist swimmers achieved moderate faster overall velocities than finalists in the 25-km races (0.01 ± 0.01 m/s) only. Inter-level differences were detected in selected splits for each race distance. Pacing profiles presented lap to lap velocity improvements in the 5-km and men’s 10-km races (from +0.02 ± 0.00 to +0.11 ± 0.01 m/s) but also mid-race decreases in the women’s 10-km and on the 25-km races. Successful swimmers were located in the leading positions of the 5-km races but at mid-group in the first part of the 10-km and 25-km races, with time gaps with leaders of 15–20 s. Faster lap swimming velocities, mid-race leading positions and shorter time-gaps were only related to the finishing positions in the last lap of the 10-km and in the three last laps of the 25-km events, but also in the first lap of the women’s 5-km race. Despite different mid-race positioning, successful open water swimmers typically presented negative pacing profiles, a consistent control of mid-race gaps with leaders (15–20 s maximum) and great spurts (4–6% faster than mean race velocities) at the end of races. Coaches and swimmers should be aware of the different race dynamics depending to the event distance in order to select optimal race strategies.

The aim of this study was to evaluate the validity and reliability of a commercially available local position measurement (LPM) tracking system when assessing distance and running time at different speeds. Fifteen male healthy athletes performed 15 m displacements at walking, running and sprinting speed. Data recorded by the LPM system were compared to those from the reference equipment, consisting of measuring tape and electronic timing gates placed at 0, 5, 10, and 15 m. Mean error, mean absolute error (MAE), standard deviation (SD) of the measurement error, maximum measurement error and root mean square error (RMSE) were calculated to determine the validity for distance and the running time variables. Product-moment correlation and intraclass correlation coefficient (ICC) were also used for the running time. Finally, the reliability of the distance was carried out comparing data from the three repetitions with the standard tape measure using a linear mixed model and the typical error as mean coefficient of variation (CV) (%). MAE shows errors under 0.18 m for the distance variable at all speeds and under 0.08 s for the running time variable at all speeds, except from 15 m at walking. Product-moment correlations were high to nearly perfect for running time (range: 0.60–0.99), ICC varied between high (0.75–0.90) and extremely high (>0.99) for most measures, and coefficients of variation remained almost invariable as speed increased (walking: 2.16; running: 2.52; sprinting: 2.20). The tested LPM system represents a valid and reliable method for monitoring distance during different constant speeds over a straight line, as long as there is no signal loss. However, the running time errors could be too large for performance tests that require acute precision.