High speed cameras for motion analysis in sports science

Video analysis can be a qualitative or quantitative process to analyze motion occurring in a single plane using one camera (two-dimensional or 2D) or in more than one plane using two or more cameras simultaneously (three-dimensional or 3D). Quantitative 2D video analysis is performed through a digitizing process that converts body segments or sport implements into digital horizontal and vertical coordinates in the computer. In order for these measurements to be accurate, image capture by means of video cameras must be sharp and motion blur-free, especially in high speed motions. In this paper, a detailed introduction to factors affecting image quality will be presented. Furthermore, selection of the most appropriate camera setting to undertake high speed motion analysis with the best quality possible, both spatially (focus and resolution) and temporally (frame rate, motion blur, shutter options and lighting), will be discussed. Rather than considering commercial criteria, the article will focus on key features to choose the most convenient model both from technical and economical perspectives. Then, a revision of available cameras on the market as of 2015 will be carried out, with selected models grouped into three categories: high-, mid- and low-range, according to their maximum performance in relation to high speed features. Finally, a suggested recording procedure to minimize perspective errors and produce high quality video recordings will be presented. This guideline starts with indications for camera selection prior to purchase or for testing if a given camera would fulfil the minimum features. A good video recording dramatically improves the analysis quality and enables digitizing software to produce accurate measurements

Factores condicionales de rendimiento en remo

Literature has established strong relationships between some anthropometric and strength measures with rowing performance. However these studies have not correlated rower’s success with absolute (watt average) and relative weight values (watts per unit weight). The aim of this study was to correlate performance and efficiency in rowing with anthropometric and strength factors. Twenty-two elite rowers (11 male and 11 female) volunteered to participate in this study. Anthropometric measurements and body composition was obtained for each rower. Participants performed 2000 m maximal effort on a Concept II rowing ergometer and strength lower extremities were evaluated with jump height protocol using a jump mat (Chronojump-Boscosystem, Barcelona, Spain). Performance and efficiency in rowing ergometer test strongly correlated with anthropometric characteristics of height (r=0.873; r=0.815), weight (r=0.894; r=0.703), body muscles (r=0.973; r=0.829) and free body fat (r=-0.705; r=-0.856). However, positive correlations of strength factors with performance and efficiency in rowers have not been strong enough to use them like success predictors. This study concludes that present results provide an argument for coaches and rowers to increase strength training and to use anthropometric characteristics to predict rowing efficiency and performance using strength factors such as complementary performance predictor. Furthermore, anthropometric variables could be used to identify success in potential rowers.La literatura ha establecido fuertes relaciones entre algunas medidas antropométricas y de fuerza con el rendimiento en remo. Sin embargo, estos estudios no han correlacionado el éxito de los remeros con valores absolutos (media de vatios) y valores relativos de peso (vatios por unidad de peso). El objetivo de este estudio fue correlacionar el rendimiento y la eficiencia con factores antropométricos y de fuerza. Veintidós remeros de élite (11 chicos y 11 chicas) participaron voluntariamente en este estudio. Se obtuvieron las medidas antropométricas y la composición corporal de cada remero. Los participantes realizaron un test de máximo esfuerzo de 2000 m en un remoergómetro Concept II y la fuerza de las extremidades inferiores fue evaluada con un protocolo de salto con una plataforma de contacto (Chronojump-Boscosystem, Barcelona, España). El rendimiento y la eficiencia en el test de remoergómetro correlacionó fuertemente con las características antropométricas de altura (r=0.873; r=0.815), peso (r=0.894; r=0.703), masa muscular (r=0.973; r=0.829) and masa libre de grasa (r=-0.705; r=-0.856). Sin embargo, las correlaciones positivas de los factores de fuerza con el rendimiento y la eficiencia en remeros no ha sido lo suficientemente fuerte para usarlos como factores de éxito. Este estudio concluye que los presente resultados proporcionan un argumento para que entrenadores y remeros incrementen el entrenamiento de fuerza y para que puedan utilizar las caracterpotenciales zadas para identificar remeros potnciales. de fuerza como predictores complementarios de rendimiento. no ha sido lo ísticas antropométricas como predictores de rendimiento y eficiencia en remo utilizando los factores de fuerza como predictores complementarios de rendimiento. Además, las variables antropométricas podrían ser utilizadas para identificar remeros potenciales

Stabilometry profile in fixed seat rowers

Balance in rowing boats is crucial for experienced and non-experienced rowers, allowing them to keep their blades off the water and keep the boat from rolling that requires rowers to contract muscles to even out the boat and to stabilize their bodies. The purpose of this study was to create reference stabilometric values in fixed seat rowing and compare them between male and female rowers in different sensorial conditions with eyes open and closed. Fifteen subjects voluntarily participated in this study, six male rowers and nine female rowers from University of Alicante fixed seat rowing team, all belonging to the senior category. A FreeMed baropodometric platform (Rome, Italy) was used for the stabilometric measurements: (TE) total excursion of the CoP, (CEA) area of the 95 % confidence ellipse, (MV) mean velocity, (MDx) mediolateral direction, (MDy) anteroposterior direction, (RMSx) amplitude in mediolateral direction and (RMSy) amplitude in anteroposterior direction. Results indicate that male rowers had greater ability to maintain balance than female rowers in bipodal stance with eyes open and closed. Female rowers demonstrated more ability to preserve sitting position than male rowers with eyes open and closed. However, there was no clear trend in relation to a greater balance between male and female in monopodal stance

El uso de la tecnología de captura de movimiento para el análisis del rendimiento deportivo

In sport performance, motion capture aims at tracking and recording athletes’ human motion in real time to analyze physical condition, athletic performance, technical expertise and injury mechanism, prevention and rehabilitation. The aim of this paper is to systematically review the latest developments of motion capture systems for the analysis of sport performance. To that end, selected keywords were searched on studies published in the last four years in the electronic databases ISI Web of Knowledge, Scopus, PubMed and SPORTDiscus, which resulted in 892 potential records. After duplicate removal and screening of the remaining records, 81 journal papers were retained for inclusion in this review, distributed as 53 records for optical systems, 15 records for non-optical systems and 13 records for markerless systems. Resultant records were screened to distribute them according to the following analysis categories: biomechanical motion analysis, validation of new systems and performance enhancement. Although optical systems are regarded as golden standard with accurate results, the cost of equipment and time needed to capture and postprocess data have led researchers to test other technologies. First, non-optical systems rely on attaching sensors to body parts to send their spatial information to computer wirelessly by means of different technologies, such as electromagnetic and inertial (accelerometry). Finally, markerless systems are adequate for free, unobstructive motion analysis since no attachment is carried by athletes. However, more sensors and sophisticated signal processing must be used to increase the expected level of accuracy.En el ámbito del rendimiento deportivo, el objetivo de la captura de movimiento es seguir y registrar el movimiento humano de deportistas para analizar su condición física, rendimiento, técnica y el origen, prevención y rehabilitación de lesiones. En este artículo, se realiza una revisión sistemática de los últimos avances en sistemas de captura de movimiento para el análisis del rendimiento deportivo. Para ello, se buscaron palabras clave en estudios publicados en los últimos cuatro años en las bases de datos electrónicas ISI Web of Knowledge, Scopus, PubMed y SPORTDiscus, dando lugar a 892 registros. Tras borrar duplicados y análisis del resto, se seleccionaron 81 artículos de revista, distribuidos en 53 registros para sistemas ópticos, 15 para sistemas no ópticos y 13 para sistemas sin marcadores. Los registros se clasificaron según las categorías: análisis biomecánico, validación de nuevos sistemas y mejora del rendimiento. Aunque los sistemas ópticos son los sistemas de referencia por su precisión, el coste del equipamiento y el tiempo invertido en la captura y postprocesado ha llevado a los investigadores a probar otras tecnologías. En primer lugar, los sistemas no ópticos se basan en adherir sensores a zonas corporales para mandar su información espacial a un ordenador mediante distintas tecnologías, tales como electromagnética y inercial (acelerometría). Finalmente, los sistemas sin marcadores permiten un análisis del movimiento sin restricciones ya que los deportistas no llevan adherido ningún elemento. Sin embargo, se necesitan más sensores y un procesado de señal avanzado para aumentar el nivel de precisión necesario

The Use of the Static Posturography to Assess Balance Performance in a Parkinson’s Disease Population

The literature has shown contradictory results so far about the use of posturography, especially static posturography, to evaluate balance performance in Parkinson’s disease (PD) populations. This study aimed to investigate the use of static posturography as a valid method to evaluate balance in a PD population. Fifty-two participants diagnosed with PD (Hoehn & Yahr stage: 1–3) were included in this cross-sectional study. All participants completed the following assessments: Hoehn and Yahr scale, Movement Disorder Society-Unified Parkinson’s Disease Rating Scale, Tinetti Scale, Berg Balance Scale, Activities-specific Balance Confidence scale, Timed Up and Go test, and Functional Reach Test. Sway parameters were analyzed with a baropodometric platform, under eyes open (EO) and eyes closed (EC) conditions, in a bipodal stance. Small to large correlations were observed between clinical balance tests and static posturography parameters, although the majority of these parameters correlated moderately. Considering posturographic variables, the highest correlation values were detected for total excursion (TE), mean velocity (MV), mean (X-mean), and root-mean-square (X-RMS) displacements in the medio-lateral directions. It was observed that posturographic parameters worsened as the disease progresses, although differences were only significant between the stages 1 and 3 in the H&Y scale (p < 0.05). Regarding the test condition, the visual deprivation worsened significantly all the static posturography parameters (p < 0.05), except the antero-posterior mean displacement (Y-Mean). Comparing visual conditions, the EC presented slightly higher correlation values with the clinical balance tests. Static posturography could be used as an objective complementary tool to clinical balance tests in order to assess and control balance performance, mainly to detect postural instability problems.This research was funded by a pre-doctoral grant (ACIF/2018/209) from the Generalitat Valenciana, Spain

Validity, reliability and usefulness of smartphone and kinovea motion analysis software for direct measurement of vertical jump height

Jumping is a simple exercise determined by several biomechanical and physiological factors. Measures of vertical jump height are common and easy to administer tests of lower limb muscle power that are carried out with several types of equipment. This study aimed to validate and address the usefulness of the combination of smartphone and computer-based applications (Smartphone-Kinovea) against a laboratory-based Motion Capture System. One hundred and twelve healthy adults performed three maximal-effort countermovement jumps each. Both instruments measured the heights of the 336 trials concurrently while tracking the excursion of the body center of gravity. The vertical velocity at take-off vto and the impulse J were computed with jump height h measures. Intraclass correlation coefficient (ICC) results indicated very high agreement for h and vto (0.985) and almost perfect agreement for J (0.997), and Cronbach's α=0.99. Low mean differences were observed between instruments for h: -0.22 ± 1.15 cm, vto: -0.01 ± 0.04 m/s, and J: -0.56 ± 2.92 Ns, all p1). Bland-Altman plots showed very low mean systematic bias ± random errors (-0.22 ± 2.25 cm; -0.01 ± 0.08 m/s; -0.56 ± 5.73 Ns), without association between their magnitudes (r2=0.005, r2=0.005, r2=0.001). Finally, very high to practically perfect correlation between isntruments were observed (r = 0.985; r = 0.986; r = 0.997). Our results suggest that the Smartphone-Kinovea method is a valid and reliable, low-cost instrument to monitor changes in jump performance in a healthy, active population diverse in gender and physical condition.This work was supported by the Vice-rectorate program of Research and Knowledge transfer for the Promotion of R&D at the University of Alicante (Ref. GRE18–19)

Defensive systems during the Men’s European University Beach Volleyball Championship

The analysis of performance in beach volleyball should consider the development of the set or game systems in connection with successful completion. In this paper, we present a study of defensive system in university beach volleyball players in order to determine the evolution throughout the set and effectiveness in relation to the performance factors of the game. A total of n=937 blocking actions were analyzed by means of video recordings from 24 European men's teams from 16 different nationalities at the Ninth European Beach Volleyball Championship EUSA GAMES. The analysis of the videos was carried out using the free software program LongoMatch v.0.27 by an experienced observer. Reliability performed on the intra-observer analysis showed a margin of error lower than 5%. Both effectiveness of the game systems and frequency of winning and not winning points were annotated for each period of points. Statistical significance of the comparison of systems was calculated using the Z test to compare proportions. Results showed that the most widely used game system was 2:1 with 67.2% (n=630) with statistically significance (p<0.001). Regarding effectiveness, system 2:1 presented an efficiency of success of 30.8% (n=194), whereas system 1:2 presented a moderately low value of 25.7% (n=79). When comparing periods of points (F1:1 to 7, F2: 8 to 14, F3: 15 to 21), system 2:1 showed higher effectiveness than 1:2 for the last two periods F2 and F3. Finally, a decrease in unscored point actions was observed in both systems between periods F1 to F3 (59.63% for 1:2 and 45.35% for 2:1)

Reliability and validity of the Chronojump open-source jump mat system

Vertical jump performance is a commonly used test to measure lower-limb muscle power that is carried out with several types of equipment. The aim of this study was to validate an open-source jump mat (Chronojump Boscosystems) against a proprietary jump mat (Globus Ergo Tester). Sixty-three active sportsmen (age 23.3 ± 2.4 years) completed 8 maximal-effort countermovement jumps (CMJ). The heights of the 504 CMJ were measured from the two jump mats simultaneously. Reliability was examined with intra-class correlation coefficients (ICC), paired samples t-tests, coefficient of variation (CV) and Cronbach's ?. Bivariate Pearson's correlation coefficient (r) was used to examine validity. Effects were evaluated using non-clinical magnitude based inference. There was almost perfect agreement between instruments (ICC = 0.999?1.000, most likely positive 100/0/0). Paired t-test showed a mean difference of 0.03 ± 0.21 cm (90% CI -0.04 ? -0.01) between instruments (most likely trivial 0/100/0). Both instruments showed very good stability (? = 1.00, CV = 4.28±1.95%). The smallest worthwhile change and typical error values were 1.3 and 0.29 cm, respectively and therefore, the signal-to-noise ratio of both instruments was large: 4.5. Finally, almost perfect correlation between instruments was observed (r = 0.999, most likely positive 100/0/0). Chronojump can be regarded as a sensitive instrument to detect changes in jump height performance over the possible noise around the measure. The results supported the open-source jump mat to be a useful, valid and reliable, low-cost testing device to monitor variations in vertical jumping performance

On-court throwing activity of male handball players during the European Championship 2020

The aim of this study was to investigate the on-court throwing activity in regards to playing positions, throwing zones on the court and throwing velocity category during the male European Championship 2020. A local positioning system with microsensors placed both in the shirts of the players and inside the ball itself was used. In total, 6568 throws were retrieved for analysis from the entire tournament. Results showed that first-line players (wings and line players) used their natural zone more to throw (65% left wing, 60% right wing, and 97% line player), showing higher effectiveness from there (p ~100 km/h) from these furthest areas. Throwing velocity and effectiveness by throwing zones and positions was not significantly modified over the three rounds of the tournament (p > 0.05), indicating no effect of possible fatigue. A higher team ranking was associated with higher throwing efficiency but only for wing players. The results of this research could help handball coaches to better adjust training programs for the improvement of throwing velocity and its transfer to the competition.This research was partially funded by Consejo Superior de Deportes, under grant number 24/UPB/19

Relationship between exclusions and final results in European Championships, World Championships and Olympic Games in men's handball 1982-2014

Situations of numerical inferiority in handball have influence on the development of the game since they produce an imbalance between players on both teams. The objective of this study is to establish the relationship between the exclusions against a team and the final result of the match during the 32 finals of European Championships, World Championships and Olympic Games between 1982 and 2014. The analysis is structured in four Grand Olympiads (GO) for eight years: 1982-1988, 1989-1996, 1997-2004 and 2005-2014. It was carried out the notational analysis of videotape recordings with SportCode Pro v.8.5.2. software, leading to 185 situations of inferiority. The Kruskal-Wallis statistic test did not establish significant differences (p>0.05) between the number of exclusions per match and the victory of such match. On the other hand, the study establishes an increase of the number of exclusions from the half of the second time of the match during the last Grand Olympiad. This retrospective study can help trainers to give a tactical appropriate response to situations of inferiority as well as superiority for the benefit of the team