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This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg's backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement patterns) were extracted and PC scores were calculated. Pearson correlation coefficients were calculated to establish correlations between hip and knee PC scores and kicking velocity. Results showed better kicking performance in male players was associated with a greater difference between the hip extension at the end of the backswing/beginning of the leg cocking phases and hip flexion at the end of the follow-through phase (r = -0.519, p = 0.023) and a delayed internal rotation of the hip (r = 0.475, p = 0.040). No significant correlations between ball velocity and hip and knee kinematics were found for female players.

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 P P P P 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.

This case series follows the treatment protocol after a grade 2 injury to the proximal semitendinosus muscle using US-guided Percutaneous Needle Electrolysis (PNE) and Rehab & Reconditioning program (RRP) in two professional soccer players. The injury was diagnosed using magnetic resonance imaging (MRI) and ultrasound imaging. The players received one session of PNE 48 hours after the injury. The indoor's phase of the RRP started 24 hours after the PNE technique and then the player proceeded to perform an on-field's phase, following which the players returned to train with the team. The effectiveness of the program was measured by comparing the match-performance data collected through Global Positioning System (GPS) in two matches before and five matches after injury and with ultrasound imaging analyzing the evolution of the muscle injury. No adverse effects were identified during or after the US-Guided PNE technique. Both players missed a single competitive game because of injury (layoff= 16 and 14 days). The GPS variables studied showed similar values before and after injury. PNE and PRR protocol improves the results of the initial phase of muscle repair and reduces the time to return to training and return to play, maintaining the GPS parameters that the players need in high performance.

(1) Background: The aim of the present research is to describe the kinematic characteristics of push start in competitive swimmers and to examine the role of the push start sub-phases on the overall start performance. (2) Methods: Seventy-four swimmers (33 males and 41 females) of national and international level performed one 25 m trial at maximum velocity with a push start at butterfly, backstroke and/or front-crawl techniques and were filmed with two sequential underwater cameras during the glide, leg kicking, transition and surface swimming phases. (3) Results: Backstroke starts showed greater emersion distances but slower times to 10 m than the remaining strokes. Distances and average velocities in each of the start sub-phases predicted the overall push start performance (times to 10 m) on the butterfly (R2: 0.50) and backstroke (R2: 0.58) strokes, with the velocity of the leg kicking phase having a statistical effect on both regression analysis and the glide and transition phases in backstroke. (4) Conclusions: Push starts performed in a dorsal body position seemed to present kinematic differences with ventral techniques and a greater technical complexity with all glide, leg kicking and transition sub-phases meaningfully impacting the overall push start performance. This should be considered when executing the daily training repetitions with swimmers in water. Sin financiación 2.838 JCR (2021) Q2, 76/161 Physics, Applied 0.507 SJR (2021) Q2, 124/414 Engineering (miscellaneous) No data IDR 2021 UEM

Students in higher education habitually use mobile devices such as smartphones and tablets, specifically using social networks on them for staying updated on current affairs, communication between one another, and entertainment. However, its use as a potential medium for learning especially in times of distance learning has not been studied in depth. Instagram is the fastest growing social network in the world and its graphical interface makes it a useful learning tool for a theoretical-practical subject such as biomechanics, where movement is analyzed. The main objective was to evaluate the change in perception of students in the use of Instagram as a learning medium for qualitative biomechanical analysis as a part of their undergraduate sports science program. 171 students filled out a questionnaire on the use of smartphones, social networks, and specifically Instagram, before and after doing an assignment of qualitative analysis that was carried. The results indicated a positive change in the perspective of the students when asked if class assignments can be done on mobile devices (p = 0.002) and social media (p < 0.001). The students also indicated a greater interest in doing assignments via social networks (p < 0.001), especially in the subject of biomechanics (p < 0.001). They also cited that Instagram is a useful source for information on sports biomechanics (p = 0.015) and could be used to make observations of sporting movements (p = 0.043). The results indicated that an introduction of familiar devices in undergraduate teaching could produce a positive change in perception of using such methodologies and facilitate learning. The students, who use smartphones very frequently in their daily lives, and specifically, many use them for browsing social networks, find the platform to be very useful in finding and sharing information related to sports and specifically in sports biomechanics. The visual aspect of social networks like Instagram can help engage them with learning strategies in a subject like biomechanics.

The objective of this study was to describe the kinematic patterns and impacts in male and female skiers in the super-giant slalom, giant slalom and slalom disciplines of an international alpine skiing competition using a portable Global Navigation Satellite Systems (GNSS) technology device. Fifteen skiers (males, n = 9, females, n = 6) volunteered to participate in this study. Data acquisition was carried out using a wireless inertial measurement device (WIMUTM PRO: hybrid location system GNSS at 18 Hz with a precision locator UltraWideband UWD (&lt, 10 cm) and 3D accelerometers 1000 Hz) where distances covered in different speed and acceleration thresholds and impacts above 5g were recorded in each of the disciplines. Male and female alpine skiers showed different physical parameters and impacts even though they competed in the same courses in the disciplines of slalom, giant slalom and super-giant slalom (total impacts: p &lt, 0.001, impacts &gt, 7 g: p = 0.013, impacts 6.1–7 g: p = 0.002, impacts 5.1–6 g: p = 0.006). In male skiers, the distances traveled at different speed thresholds have a direct relation to the ranking of skiers, but this ideal threshold decreased as the technicality of the discipline increased. In the case of female skiers, although no relation was seen with the speed thresholds, greater distances covered at medium accelerations improved skiing performance. The external load in alpine skiing varied based on sex and discipline. This information could be essential to develop sex-specific and discipline-specific training programs in alpine skiing.

This Special Issue had, as its main objective, the compilation of studies on sports performance and its relationship with musculoskeletal injuries [...]

The aim of this study was to analyse the quadriceps-hamstring coactivation in the lunge and Bulgarian squat exercises. A cross-sectional study design was applied to seventeen healthy professional football players. Muscular activity was measured using wireless surface electromyography (sEMG). The Maximum Voluntary Isometric Contraction was used to normalize the data. The muscle activation of each muscle belly was significantly different between the two exercises (F4.24 = 28.076, p < .001, partial ƞ 2 = .72). Activity in individual muscles varied in both the lunge (F4,24 = 49.315, p < .001,partial ƞ 2 = .89), and the Bulgarian squat (F4,24 = 28,076, p < .001,partial ƞ 2 = .82). The results showed no significant differences between the preferred and non-preferred legs of the participants (p > .05). In both the lunge and the Bulgarian squat, a significantly greater activation of the vastus medialis (VM) and the vastus lateralis (VL) muscles were found compared to the rectus femoris (RF) and biceps femoris (BF) and semitendinosus (ST). Muscles showed a greater activation during the Bulgarian squat compared to the lunge, but the hamstrings to quadriceps ratio was similar in both exercises (p > .05). The present work shows that the Bulgarian Squat exercise produces greater muscle activation than the Lunge exercise, whereas in both exercises there is a similar pattern of muscle activation. No differences were found between legs. If one wants to work specifically on strength development, the Bulgarian Squat would be a better option, as would be the case if one were to focus on synergistic work on the quadriceps and hamstrings, as the Bulgarian Squat exercise shows a higher H:Q ratio. Sin financiación No data JCR 2021 0.324 SJR (2021) Q3, 126/225 Physical Therapy, Sports Therapy and Rehabilitation No data IDR 2021 UEM

This study aimed to analyze the effects of match congestion in a short period on isometric hamstring strength and hip/ankle range of motion in female field hockey players. Fourteen professional female field hockey players (age: 20.0 ± 5.4 years) played two consecutive hockey matches in 24 h and maximal isometric hamstring strength and hip and ankle range of motion were obtained before and after the first match, after the second match, and 48 h after the second match. Furthermore, locomotion patterns and ratings of perceived exertion were recorded during hockey competitions. Isometric knee flexion strength showed significantly higher values 48 h after the second match for the non-dominant limb (p ≤ 0.005, ηp2 = 0.19), while no differences were reported in the dominant limb (p = 0.370, ηp2 = 0.05). In addition, no differences were reported in the range-of-motion (ROM) variables such as the straight leg raise test or ankle dorsiflexion test (p = 0.075–0.217, ηp2 = 0.01–0.03). The countermovement jump height steadily increased over the matches except between post-match 2 and 48 h after post-match 2 (p &lt, 0.001, η2 = 0.382). Two consecutive official league field hockey matches played within 24 h did not have a negative effect on lower-limb risk factors (strength, hip and ankle ranges of motion, and ratings of perceived exertion) in female field hockey players directly, but they improved 48 h after the matches. This could indicate that 48 h recovery period following matches might be ideal for female field hockey players.

Context: The high rates of adductor injuries and reinjuries in soccer have suggested that the current rehabilitation programs may be insufficient; therefore, there is a need to create prevention and reconditioning programs to prepare athletes for the specific demands of the sport. Objective: The aim of this study is to validate a rehab and reconditioning program (RRP) for adductor injuries through a panel of experts and determine the effectiveness of this program through its application in professional soccer. Design: A 20-item RRP was developed, which was validated by a panel of experts anonymously and then applied to 12 injured male professional soccer players. Setting: Soccer pitch and indoor gym. Participants: Eight rehabilitation fitness coaches (age = 33.25 [2.49] y) and 8 academic researchers (age = 38.50 [3.74] y) with PhDs in sports science and/or physiotherapy. The RRP was applied to 12 male professional players (age = 23.75 [4.97] y; height = 180.56 [8.41] cm; mass = 76.89 [3.43] kg) of the Spanish First and Second Division (La Liga). Interventions: The experts validated an indoor and on-field reconditioning program, which was based on strengthening the injured muscle and retraining conditional capacities with the aim of reducing the risk of reinjury. Main Outcome Measures: Aiken V for each item of the program and number of days taken by the players to return to full team training. Results: The experts evaluated all items of the program very highly as seen from Aiken V values between 0.77 and 0.94 (range: 0.61–0.98) for all drills, and the return to training was in 13.08 (±1.42) days. Conclusion: This RRP following an injury to the adductor longus was validated by injury experts, and initial results suggested that it could permit a faster return to team training.

Combat sports have a great interest in society and among professional sports. They are an important group of sports in the Olympic Games, but the strategies carried out by athletes to reduce body weight for weighing day, is famously known, suffering the adverse physical and psychological effects of rapid weight loss. This could compromise not only the performance, but the health and development of young athletes. A total of 22 elite male judokas (18.05 &plusmn, 1.05 years old) were evaluated during four different competitions in one season, the variables of body weight, water levels, and lean and fat mass were measured by bioimpedance (BIA), (Tanita BC545N) during one season. Using the linear mixed model test, we found significant differences in bodyweight variable during the competitions 3&ndash, 4. The water level variable showed significant differences in all competitions, except for 2&ndash, 4. Body mass index was significantly different in all competitions, being higher in the later competitions, except between competitions 1&ndash, 2 and 2&ndash, 3. Judokas participate in weight loss methods for their weigh-in days. Furthermore, the age at which the athletes reduced their water levels are worrisome. These results could be used to create healthy programs, especially in elite judokas, in order to carry out strategies before, during, and after competitions with weight loss and controlled water levels increasing future performance and health.

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 iso-inertial 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. Sin financiación 2.988 JCR (2020) Q2, 43/140 Psychology, Multidisciplinary 0.947 SJR (2020) Q2, 68/263 Psychology (miscellaneous) No data IDR 2020 UEM

This study aimed to study the coactivation patterns of the hamstring and quadriceps muscle groups during submaximal strength exercises commonly used in injury prevention in soccer without the use of maximum voluntary isometric contraction testing. This was used to compare: (i) the inter-limb differences in muscle activation, (ii) the intra-muscular group activation pattern and (iii) the activation pattern during different phases of the exercise. Muscle activation was recorded by surface electromyography in 19 elite, male, youth soccer players. Participants performed the following: Bulgarian squat, lunge and squat. Electrical activity was recorded for the rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus. No significant inter-limb differences were found (F1, 13 = 619, p = 0.82, &eta, 2 = 0.045). Significant differences were found in the muscle activation between individual muscles within the quadriceps and hamstrings muscle group for each of the exercises: Bulgarian squat (F1,18 = 331: p &lt, 0.001, 2 = 0.80), lunge (F4,72 = 114.5, p &lt, 2 = 0.86) and squat (F1,16 = 247.31, 2 = 0.93). Differences were found between the different phases of each of the exercises (F2,26 = 52.27, p = 0.02, 2 = 0.80). The existence of an activation pattern of each of the muscles in the three proposed exercises could be used for muscle assessment and as a tool for reconditioning post-injury.

Background: The aim of this study was to compare the validity of two different GPS device models used for time&ndash, motion analyses in ecological testing of football. Methods: Ten healthy male players from a Spanish university football team participated in this study. The team sport simulation circuit (TSCC) used was based on previous research examining the validity and interunit reliability of different GPS systems. Participants were required to complete eight laps of the TSSC, resulting in a total distance of 1320 m. The GPS units used for the current study were the 18 Hz StatsSport Apex Pro and 18 Hz RealTrack WIMU Pro. Participants were required to wear either of the two GPS units during the test. To establish the construct validity of GPS as a measure of Vmax, timing lights were used as a gold standard. Results: The results clearly suggest that it is not possible to use the same 18 Hz GPS model or interchange it. The measurement can be considered precise when the noise is at least equal to or lower than the smallest worthwhile change. In this case, all standard deviation in measurement error was higher than the smallest worthwhile change. This is due to an inconsistency in the data processing of each trademark. Conclusions: It is important to prevent a club using different GPS trademarks at the same time, since it is not possible to compare in any case any type of result obtained between different trademarks.

Context: Although there are multiple, validated return-to-play programs following hamstring strain injuries, no studies have evaluated their changes in match performance parameters. Objectives: The aim of this study was twofold as follows: (1) to determine the changes in match-based physical performance parameters in professional soccer players before and after sustaining a hamstring strain injury and undergoing a soccer-specific rehabilitation program and (2) to observe the progress of these performance parameters 6 to 10 weeks after the player returned from injury. Design: Prospective, quasi-experimental longitudinal study. Setting: Soccer playing and training grounds. Participants: Nineteen players suffering a hamstring strain injury from 2 male professional teams playing in the Spanish professional football league (La Liga) were followed during the 2015–2016, 2016–2017, and 2017–2018 seasons. Intervention: Participation in on-field training program following a hamstring injury. Main Outcome Measures: Match global positioning system data were collected in the following stages: prior to injury (PRE), after return to play (RTP), program, and 6 to 10 weeks following RTP (C2). Peak velocities and distances ran at sprint velocities showed most likely improvements in C2 versus PRE, and very likely improvements in RTP versus PRE. Results: The distances ran at high and very high intensities, the average velocity, and work-to-rest ratio showed very likely improvements in C2 versus RTP and likely improvements in RTP versus PRE. Likely improvements were observed for all variables in C2 versus RTP. The authors’ results showed an improvement of physical performance during competitive match after RTP, compared with PRE. There was a steady progression in the progress, and in 8 months following RTP, there was no injury reported in the players. Conclusions: The current findings may indicate that the hamstring muscle complex not only recovered completely from the injury but could also withstand a greater training and match load reducing the risk of reinjury.

The aim of this study was to determine the acute effect of simulated field hockey match-play on isometric knee flexion, adductor (ADD) and abductor (ABD) strength, adductor/abductor (ADD/ABD) strength ratio, countermovement jump height (CMJ), hip flexion and ankle dorsiflexion range of motion (ROM). Thirty competitive female field hockey players (23.0 &plusmn, 3.9 years old) participated in the study. Apart from the afore-mentioned variables, external (through GPS) and internal load (through RPE) were measured before (pre-match) and immediately after simulated hockey match-play (post-match) in both limbs. Isometric knee flexion strength (+7.0%, p = 0.047) and hip flexion ROM (+4.4%, p = 0.022) were higher post-match in the non-dominant limb, while CMJ values reduced (&minus, 11.33%, p = 0.008) when comparing from pre-match data. In addition, no differences were observed for isometric hip ADD, ABD, ADD/ABD strength ratio, passive hip flexion ROM and ankle dorsiflexion ROM test. A simulated field-hockey match produces an increment in hip isometric strength and hip flexion ROM values in the non-dominant limb and a decrease in jump height capacity. As a result, CMJ assessment should be considered post-match in order to identify players who would require further rest before returning to training.

In basketball, the ball screen has been described as one of the most important and successful forms of finishing a play, and this could generate a mismatch when defenders in a man-to-man defensive setup switch their assigned markers. This study aimed to determine (1) which players benefit the most in the case of a mismatch and (2) how does the duration of action affect the mismatch. A total of 698 situations of mismatch after ball screens from 40 matches of the 2015–2016 regular season of the male Spanish professional Basketball League (ACB) were quantitatively analysed. The results found that although inside players were the ones who finished the action more often, the duration was a crucial factor. An action that lasted under five seconds favoured the offence, with the outside players benefitting the most in such a situation. However, if the offence failed to finish the action in the first four seconds, the mismatch favoured the defence, as they had more time to organise themselves to counter th...

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.

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.

This study aimed to study the co-activation of hamstring-quadriceps muscles during submaximal strength exercises without the use of maximum voluntary isometric contraction testing and compare (i) the inter-limb differences in muscle activation, (ii) the intra-muscular group activation pattern, and (iii) the activation during different phases of the exercise. Muscle activation was recorded by surface electromyography of 19 elite male youth players. Participants performed five repetitions of the Bulgarian squat, lunge and the squat with an external load of 10 kg. Electrical activity was recorded for the rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus. No significant inter-limb differences were found (F1, 13=619; p=0.82; partial η2=0.045). Significant differences were found in the muscle activation between different muscles within the muscle group (quadriceps and hamstrings) for each of the exercises: Bulgarian squat (F1,18=331: p2=0.80), lunge (F4,72=114.5; p2=0.86) and squat (F1,16=247.31; p2=0.93).Differences were found between the concentric, isometric and eccentric phases of each of the exercises (F2, 26=52.27; p=0.02; partial η2=0.80). The existence of an activation pattern of each of the muscles in the three proposed exercises could be used for muscle assessment and as a tool for injury recovery.

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 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. Sin financiación 1.664 JCR (2019) Q3, 55/85 Sport Sciences 0.606 SJR (2019) Q2, 66/213 Physical Therapy, Sports Therapy and Rehabilitation No data IDR 2019 UEM

The aim of this study was to investigate the effects of different swimming race constraints on the evolution of turn parameters. One hundred and fifty-eight national and regional level 200-m (meters) male swimming performances were video-analyzed using the individualized-distance model in the Open Comunidad de Madrid tournament. Turn (p < .001, ES = 0.36) and underwater distances (p < .001, ES = 0.38) as well as turn velocity (p < .001, ES = 0.69) significantly dropped throughout the race, although stroke velocity and underwater velocity were maintained in the last lap of the race (p > .05). Higher expertise swimmers obtained faster average velocities and longer distances in all the turn phases (p < .001, ES = 0.59), except the approach distance. In addition, national level swimmers showed the ability to maintain most of the turn parameters throughout the race, which assisted them in improving average velocity at the end of races. Therefore, the variations in the turning movements of a swimming race were expertise-related and focused on optimizing average velocity. Turning skills should be included in the swimming race action plan.

The aim of the present study was to assess the accuracy of a multi-camera tracking system (Mediacoach&reg, ) to track elite football players&rsquo, movements in real time. A total of 207 observations of 38 official matches from Liga 1, 2, 3&trade, (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&ndash, 21 km/h, distance in zone 5 (DZ5) at a speed of 21&ndash, 24 km/h (DZ5), distance in zone 6 (DZ6) at a speed of &ge, 24 km/h, maximum speed (km/h), and number of sprints (actions above 24 km/h) were registered with the Apex&reg, GPS system (STATSports&trade, Newry, N. Ireland) and Mediacoach&reg, semi-automatic tracking system (LaLiga&trade, 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 (&gt, 0.75) and very large correlations (r &gt, 0.70). However the video-based performance analysis system overestimated the results obtained in the different speed zones (DZ5: +16.59 &plusmn, 62.29 m, LOA95%: &minus, 105.49 to 138.68, DZ6: +93.26 &plusmn, 67.76 m, 39.55 to 226.07), the number of sprints (+2.27 &plusmn, 2.94, 3.49 to 8.02), and the maximum speed (+0.32 &plusmn, 1.25 km/h, 2.13 to 2.77). The maximum bias was found in DZ6 (47%). This demonstrates that Mediacoach&reg, 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.

The hamstring strain injury is one of the most common injuries in professional soccer and it has a high rate of recurrence as well. Although the hamstring muscle group gets loaded during the kicking motion, the effect of a previous hamstring injury on the kicking skill has not been studied in detail. Kicking technique is known to differ based on sex and limb dominance, but these effects on professional soccer players has not been studied. The objective of this thesis dissertation was to quantify if the biomechanical factors of kicking in a group of professional soccer players were affected by a previous hamstring injury, sex and limb dominance, and the interaction of these factors. Forty-five professional soccer players (females = 26, males = 19) were captured kicking the ball with their dominant and non-dominant limbs using a three dimensional motion capture system and force platform on artificial turf. A previous hamstring injury caused changes in the kinematics especially in the phases where the hamstring muscles are known to be actively working, namely the backswing, the leg cocking and follow through phases. Although male soccer players had superior kinematics accounting for the better technique, the difference in kinetics between the sexes did not exist. A previous injury in males favored a faster knee flexion while simultaneously inhibiting hip flexion. Elite female soccer players have different kicking techniques with the dominant and non-dominant limbs which accounts for the differences in linear velocities, with the differences being reduced with the presence of an injury. As far as male soccer players go, differences on limb dominance is not seen unless one considers the effect of previous injury. The results clearly show that the hamstring strain injury affects the kicking technique. Its effect also depends on whether the injury was suffered by a male or a female, and whether the kick was taken by a dominant limb or a non-dominant limb. Thus the consequences of this injury cannot be studied in isolation, rather it has to be considered a multi-factorial problem. RESUMEN La lesión de los isquiotibiales es una de las más comunes en el fútbol profesional con una alta probabilidad de recaída. Aunque los isquiotibiales participan activamente durante el golpeo, no se sabe con certeza la relación entre técnica de golpeo y lesión. No existe datos concluyentes sobre las diferencias en la técnica de golpeo entre hombres y mujeres o entre piernas dominantes y no dominantes. El objetivo de esta tesis doctoral es estudiar el efecto de la lesión previa de isquiotibiales, el sexo y la pierna dominante en el golpeo de un grupo de jugadores de fútbol profesionales y la interacción de estos factores. El golpeo de cuarenta y cinco jugadores de fútbol profesionales (mujeres = 26, hombres = 19) ha sido registrado con sus piernas dominantes y no dominantes utilizando un sistema de captura de movimiento tridimensional y una plataforma de fuerza sobre césped artificial. Los resultados mostraron que la lesión previa de los isquiotibiales causa cambios en la cinemática, especialmente en las fases donde se sabe que los músculos isquiotibiales trabajan de forma activa, es decir, la subida de la pierna (backswing), el armado de la pierna (leg cocking) y el follow through. Aunque los futbolistas hombres tenían una técnica de golpeo más eficaz con respeto a las mujeres en términos de variables cinemáticas, no se encontraron diferencias la cinética del movimiento entre los sexos. La lesión previa lesión en los hombres parece favorecer una rápida flexión de la rodilla mientras que inhibe simultáneamente la flexión de la cadera. Por otro lado, las futbolistas mujeres de élite tienen diferentes técnicas del golpeo con las piernas dominantes y no dominantes lo que explica las diferencias en las velocidades lineales, aunque las diferencias se reducen con la presencia de una previa lesión. En cuanto a los futbolistas hombres, las diferencias en el golpeo entre la pierna dominante y no dominante no existen excepto en el caso que el jugador tenga una previa lesión de los isquiotibiales. En definitiva, los resultados muestran claramente que la lesión de isquiotibiales afecta a la técnica del golpeo, pero de forma diferente según el sexo y la pierna dominante. lo que demuestra que las consecuencias de esta lesión no pueden ser estudiadas en forma aislada, sino que de una forma multifactorial.

El objetivo de este estudio, ha sido revisar la bibliografía sobre la lesión de isquiotibiales desde un punto de vista biomecánico. METODOLOGÍA. Las bases de datos utilizadas fueron Medline, Scopus y SportsDiscuss. RESULTADOS Y DISCUSIÓN. Muchos estudios prospectivos han demostrado que el principal factor de riesgo es haber tenido la lesión previamente. Sin embargo, las causas primarias de la lesión en fútbol son desconocidas. Una falta de flexibilidad ha sido uno de los principales factores de riesgo pero existen controversias en los resultados de la literatura. Desequilibrio de la fuerza isocinética es un factor de riego pero la participación de cada músculo por separado durante la flexo-extensión de rodilla en fútbol no ha sido considerado en los estudios. Mientras que la sincronización de los músculos lumbopélvicos parece ser clave para entender el riesgo de lesión, no se ha desarrollado investigación al respecto. CONCLUSIONES. Por tanto, son necesarios más estudios prospectivos y nuevos procedimientos como el escaner dinámico, la electromiografía de superficie o el análisis dinámico inverso. El análisis de gestos más específicos del fútbol es necesario. Gestores, entrenadores, preparadores físicos, fisioterapeutas, médicos deportivos e investigadores deberían trabajar juntos para mejorar los sistemas de prevención y de recuperación de la lesión. ---------- ABSTRACT---------- The aim has been to review the literature about the risk factors of hamstring injury in soccer from a biomechanical point of view. METHODOLOGY. Data bases of bibliography references were Medline, Scopus and SportDiscuss. RESULTS AND DISCUSSION. Many prospective studies have shown that the previous injury is the greatest risk factor of sustaining the injury. However the primary causes of the injury are unclear in soccer. A lack of hamstring flexibility has been one of the main injury risk factors with controversies on the results. Imbalance of isokinetic force is a risk factor but electrical coactivation of all muscles participating during knee flexion and extension are unknown in football. While the importance of lumbopelvic-hamstrings muscles synchronization during running seems to be crucial for understanding the risk of injury, no research has been developed in this topic in football. CONCLUSIONS. More research using new data recording procedures as Dynamic Scanners, Surface EMG, Inverse Dynamic Analysis are needed. The analysis of more specific movements as running, kicking or jumping is clearly required. Managers, coaches, physical trainers, physiotherapists, sport physicians and researchers should work together in order to improve the injury prevention and rehabilitation programs of football players.

Background Although the hamstring muscle group gets loaded during the kicking motion, the effect of a previous hamstring injury on the kicking skill has not been studied in detail. Objective To the study the effect of a previous hamstring injury on the kicking technique, and how gender and limb dominance influences the same. Design Observational study. Participants were required to kick the ball into a target 7 m away using a four step run-up. Five valid kicks were taken from the dominant and non-dominant limb each. Setting Laboratory conditions on FIFA approved artificial turf, with a three-dimensional Vicon motion capture system at 200Hz and a Kistler force platform at 1000Hz. with participants belonging to Spanish First (women) and Second (men) Division teams. Participants 45 professional soccer players (females=26, males=19) who belonged to clubs that had the same number of training sessions and matches per week. Main Outcome Measurements Ball velocities, kinematic and kinetic data for the hip and knee of the kicking leg in the sagittal plane, and the reaction forces for the ground and the support leg. 3-way ANOVA was used to compare the data. Results Previously injured female athletes had a lower peak hip velocity in the dominant limb kicks; and a smaller knee flexion angle, and a lower hip flexion velocity in the non-dominant limb kicks. Conclusions Kicking technique is affected by a previous hamstring injury in females especially in phases where the hamstring muscles are the most active. Differences in male soccer players were not seen. Thus these injuries must be treated differently in male and female soccer players, and whether the injury occurred in the dominant or non-dominant limb. An additional study with a greater number of previously injured athletes would be necessary to provide conclusive results.

The hamstring strain is one of the most common injuries in soccer. The aim of the study was to describe a new procedure to evaluate the effect of hamstring injuries in kicking in soccer using the principles of inverse dynamics and to compare the results with an isokinetic test. The study focused on evaluating the difference between subjects having a history of hamstring injuries in the last 5 years and those that did not. Seventeen male professional soccer players performed five instep and side- foot kicks which were analysed using a force platform and a Vicon motion-capture system operating at 500Hz. The participants also took part in an isokinetic torque measurement at 60 °/s and 120 °/s. Kinematic variables, ground reaction forces and kinetic variables were compared across the two groups. Significant differences were observed between the previously injured and uninjured group in the time taken for the follow through in the instep kick, and the maximum hip flexion moment in the instep and side-foot kicks. No significant differences were found between the two groups in the traditional isokinetic test. These results indicate that the procedure employed could probably be very useful in the assessment of the effect of hamstring injuries in soccer. Las lesiones musculares del muslo tienen una gran incidencia en el fútbol. El objetivo del estudio ha sido desarrollar un nuevo procedimiento para evaluar el efecto de las lesiones de isquiotibiales en los golpeos con el pie s en el fútbol utilizando los principios de la dinámica inversa. El trabajo se ha centrado en la evaluación de la diferencia entre sujetos que habían sufrido la lesión en los últimos 5 años y los que no. Se analizaron 17 jugadores de fútbol profesionales realizando cinco tiros con el empeine y cinco con el interior del pie. Los movimientos se registraron mediante una plataforma de fuerza y un sistema de captura de movimiento Vicon funcionando a 500Hz. Los participantes también tomaron parte en una prueba de isocinético en la que se midió el torque isocinético en 60 º/s y 120 º/s. Se observaron diferencias significativas en los parámetros cinemáticos y cinéticos entre los dos grupos (lesionados y no lesionados) en la fase posterior del golpeo y en el instante de máxima flexión de cadera. No se encontraron diferencias significativas entre los dos grupos en la prueba isocinética tradicional. Estos resultados indican que el procedimiento empleado probablemente podría ser muy útil en la evaluación del efecto de las lesiones de isquiotibiales en el fútbol.