Search

Abstract Objective This study aimed to determine changes of modifiable injury risk factors and fatigue parameters during a mesocycle (4 months of the competitive season) in semi-professional female field hockey players (Spanish 2nd Division). Methods Fourteen female field hockey players (age: 22.6 ± 4.9 years) participated in the study over 4 months of the competitive season (September–December 2019). The players were tested each month for their: maximal isometric knee flexion, hip adduction, and abduction muscle strength; passive straight leg raise and ankle dorsiflexion range of motion (ROM); countermovement jump height; and perceptual fatigue (through a perceived well-being questionnaire). Results Statistical differences were reported in isometric knee flexion torque in the dominant and non-dominant limb (p =

Abstract Background The purpose of this study was to examine the effects of two competitive field hockey matches, played on consecutive days, on maximal isometric hip adductor and abductor strength, wellness and fatigue. Methods Fourteen professional female field hockey players (age: 20.4 ± 5.4 years; body mass: 60.7 ± 7.2 kg; height: 167.0 ± 1.0 cm) volunteered to participate in this investigation. Maximal isometric hip adductor and abductor strength were obtained before (pre-match 1) and after the first match (post-match 1), after the second match (post-match 2), and 48 h after the second match. Locomotion patterns during the matches were obtained with portable Global Positioning System (GPS) and perceived exertion (RPE) was assessed after each match. In addition, Wellness Questionnaire (5-WQ) and the Total Quality Recovery Scale (TQR) were employed before the matches and 48 h after the second match. Results For the non-dominant limb, the maximal isometric hip adductor and abductor strength were lower after post-match 2 when compared to pre-match 1 (p = 0.011). Hip abductor strength in the non-dominant limb remained reduced 48 h after post-match 2 (p

The objective of this study was to carry out a systematic review of the literature on tools for measuring aquatic competence in infants and children between the ages of 6 months to 14 years old. A systematic review was carried out following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. Of the eight studies selected, six obtained high valuations based on the Downs and Black Quality Assessment checklist. The studies were classified into three categories, one that proposed tools that measured actual aquatic competence (n=6), other one that measured perceived aquatic competence (n=1), and the other that measured both (n=1). Five of the studies measured emotional, social, cognitive, and communicative skills apart from motor skills. A majority of the studies focused the proposed assessment tool on a specific age group, while two studies looked at a broader age group.

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.

(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.

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.

Swimmers with physical impairments during competition for freestyle swimming are grouped according to their functional classification in ten classes. Stroke length, stroke rate, stroke index and clean swimming speed have been studied previously at elite level, but not at national level. Therefore, the aim of this study was to assess the four mentioned variables and performance time regarding functional class and gender in a sample of national level swimmers with physical impairments at the 100 m freestyle. Fourteen female (classes S4, S5, S7; S8, S9 and S10) and 29 male (classes S4, S5, S6, S7 S8, and S10) swimmers were recorded during the Winter Spanish Championship for Adapted Swimming. Classical fixed distances method was used for race analysis. Based on the results, stroke length, stroke index, clean swimming speed (and not stroke rate) values increased and turn time decreased significantly (p < 0.01) according to the functional class for both males and females from S4 up to S10; with the exception of the S5 male class, with better results (not significant, ns) than S8 in stroke index, or than S7 for clean swimming speed. Significant differences in stroke rate, stroke length and time for males between first and second lap were found, while differences were registered in stroke rate, stroke index, clean swimming speed and time for females. The presented profiling allows to frame performance for long term development of swimmers with physical impairments and also coaches can use the results to determinate the best relationship between stroke rate and stroke length for their swimmers, advice development and talent identification. Resumen Los nadadores con discapacidad física durante la competición de estilo libre se agrupan según su clasificación funcional en diez clases. La longitud, frecuencia e índice de brazada y la velocidad de nado se han estudiado previamente a nivel de élite, pero no a nivel nacional. Por lo tanto, el objetivo de este estudio fue evaluar las cuatro variables mencionadas y el tiempo de prueba con respecto a la clase funcional y el género en una muestra de nadadores de nivel nacional con discapacidades físicas en la prueba de 100 m estilo libre. Catorce mujeres (clases S4, S5, S7, S8, S9 y S10) y 29 hombres (clases S4, S5, S6, S7, S8 y S10) fueron grabados durante el Campeonato de España de Invierno de Natación Adaptada. Posteriormente se utilizó el método clásico de distancias fijas clásicas para el análisis de la prueba. En base a en los resultados obtenidos, los valores de longitud e índice de brazada y de la velocidad de nado (y no de la frecuencia de brazada) aumentaron mientras que el tiempo de viraje disminuyó significativamente (p < 0,01) según la clase funcional para hombres y mujeres de S4 a S10; con la excepción de la clase masculina S5, con mejores resultados que la clase S8 en el índice de brazada, o que S7 para la velocidad de nado. Se encontraron diferencias significativas en el índice, longitud de brazada y el tiempo de prueba en los hombres entre el primer y segundo segmento, mientras que se registraron diferencias en índice, longitud de brazada, velocidad y el tiempo en mujeres. El análisis presentado permite enmarcar el rendimiento de nadadores con discapacidad física en esta prueba con el fin de adecuado asesoramiento y desarrollo a largo plazo, así como la identificación de talento, por parte de los entrenadores.

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 < 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.

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.

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.

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

Rectus femoris muscle strains are one of the most common injuries occurring in sports such as soccer. The purpose of this study was to describe the safety and feasibility of a combination of percutaneous needle electrolysis (PNE) and a specific rehab and reconditioning program (RRP) following an injury to the rectus femoris in professional soccer players. Thirteen professional soccer players received PNE treatment 48 h after a grade II rectus femoris muscle injury, followed by a the RRP 24 h later. Assessment of recovery from injury was done by registering the days taken to return to train (RTT), return to play (RTP), and structural and functional progress of the injured muscle was registered through ultrasound imaging and match-GPS parameters. Also, adverse events and reinjuries were recorded in the follow up period of twenty weeks. The RTT registered was 15.62 ± 1.80 days and RTP was 20.15 ± 2.79 days. After fourteen days, the ultrasound image showed optimal repair. Match-GPS parameters were similar before and after injury. There were no relapses nor were any serious adverse effects reported during the 20-week follow-up after the RTP. A combination of PNE and a specific RRP facilitated a faster RTP in previously injured professional soccer players enabling them to sustain performance and avoid reinjuries.

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 ± 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 (−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.

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; η2 = 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 < 0.001; η2 = 0.80), lunge (F4,72 = 114.5; p < 0.001; η2 = 0.86) and squat (F1,16 = 247.31; p < 0.001; η2 = 0.93). Differences were found between the different phases of each of the exercises (F2,26 = 52.27; p = 0.02; 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 reconditioning post-injury.

This study proposes a new method to evaluate arm-to-leg coordination in the freestyle swimming. Eight international-level youth swimmers were tested on a 50m swim at the speed of their 400m personal best (V400), and recorded at 60Hz bilaterally. The discrete relative phase angles between the arm-to-leg movements were identified by video analysis, using four key points adapted from Maglischo (2009): the hand entry corresponding to the lowest point of the ipsilateral kick (C1), the arm catch corresponding to the lowest point of the ipsilateral kick (C2), the lowest point on the arm pull corresponding with the lowest point of the contralateral kick (C3), and the hand exit corresponding to the lowest point of the ipsilateral kick (C4). International-level youth swimmers showed arm-to-leg discrete relative phase values of355.9º±32.7º, 0.5º±38.7º, 352.9º±35.1º and17.5º±33.0º, respectively, for each of the four key events on the freestyle swimming cycle. This coordinative parameter allowed evaluating if the arm-to-leg movements of the swimmer were coordinated in-phase (between 330º and 30º), anti-phase (between 150º and 210º) or out-of-phase on the different phases of freestyle swimming. Therefore, it represented a practical tool to be used by coaches and researchers to quantitatively evaluate their swimming technique.

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.

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.