Jose Manuel Jimenez-Olmedo

Accuracy of Jump-Mat Systems for Measuring Jump Height

Vertical-jump tests are commonly used to evaluate lower-limb power of athletes and nonathletes. Several types of equipment are available for this purpose. PURPOSE To compare the error of measurement of 2 jump-mat systems (Chronojump-Boscosystem and Globus Ergo Tester) with that of a motion-capture system as a criterion and to determine the modifying effect of foot length on jump height. METHODS Thirty-one young adult men alternated 4 countermovement jumps with 4 squat jumps. Mean jump height and standard deviations representing technical error of measurement arising from each device and variability arising from the subjects themselves were estimated with a novel mixed model and evaluated via standardization and magnitude-based inference. RESULTS The jump-mat systems produced nearly identical measures of jump height (differences in means and in technical errors of measurement ≤1 mm). Countermovement and squat-jump height were both 13.6 cm higher with motion capture (90% confidence limits ±0.3 cm), but this very large difference was reduced to small unclear differences when adjusted to a foot length of zero. Variability in countermovement and squat-jump height arising from the subjects was small (1.1 and 1.5 cm, respectively, 90% confidence limits ±0.3 cm); technical error of motion capture was similar in magnitude (1.7 and 1.6 cm, ±0.3 and ±0.4 cm), and that of the jump mats was similar or smaller (1.2 and 0.3 cm, ±0.5 and ±0.9 cm). CONCLUSIONS The jump-mat systems provide trustworthy measurements for monitoring changes in jump height. Foot length can explain the substantially higher jump height observed with motion capture.

Patrón lesivo en campeonato de España universitario de vóley playa

RESUMEN Este articulo pretende establecer y determinar las lesiones mas frecuentes en jugadores de voley playa universitarios a traves de una muestra de 33 participantes en el Campeonato de Espana Universitario. Para estudiar las lesiones, se realizo una entrevista personal mediante un cuestionario validado. Los resultados mostraron que la region corporal con mayor incidencia lesiva fue el tobillo (33,3%), seguido de los dedos de la mano (18,5%), las rodillas (13,0%), los hombros (11,1%) y la espalda (5,6%). Ademas tambien se obtuvieron datos sobre el momento de la lesion (competicion o entrenamiento), su origen (impacto o sobreuso) y caracteristica de la lesion (nueva lesion o repetida). El tratamiento de los datos para el establecimiento de las diferencias significativas se realizo a traves de la prueba estadistica Chi-Cuadrado. Los resultados establecen un patron de lesiones diferente al que se produce en voley playa profesional, probablemente como consecuencia directa del nivel, horas de entrenamiento y exigencia del juego. PALABRAS CLAVE : lesion, voleibol, voley playa, cuestionario, rendimiento deportivo ABSTRACT The aim of this paper is to study the most common injuries in university beach volleyball players. The sample consisted in 33 athletes participating in the University Spanish Championship. Injuries were assessed by means of personal interviews and a validated questionnaire. Results show that the body region with the highest incidence was the ankle (33%), followed by the fingers (18.5%), knees (13.0%), shoulders (11.1%) and back (5.6%). Also, information on the moment of injury (competition or training), origin (impact or overuse) and characteristic of the injury (new or recurrent injury). Statistical processing of data for establishing significant differences was performed using the Chi-square test. Results showed a harmful effect, which differs from that of professional volley players, probably as a result of the level, hours of training and requirements of the game. KEY WORDS : injury, beach volley, volleyball, questionnaire, performance sport

Inter-rater reliability of trained and untrained raters for measuring jump height with the MyJump app

Smartphone apps have been very popular among researchers, coaches and clinicians. The aim of this study was to analyze the inter-rater reliability of trained and untrained raters of the iOs app MyJump. Eighteen participants completed eight counter-movement jumps (CMJ) each (n=144) which were recorded using the app. In order to examine inter-rater reliability derived from raters’ experience, independent assessments were obtained by an untrained rater and two trained raters of the same recordings. Results showed very high agreement between trained raters (ICC=0.982, α=0.991) and between trained and untrained raters (ICC=0.984, α=0.992). Bland-Altman plots depicted negligible bias between both types of raters. Finally, very good internal consistency was found, regardless of experience (α from 0.995 to 0.997 and CV from 1.1 to 1.4%). This study have shown no significant difference in performance of trained and untrained raters of MyJump, and therefore no special training must be observed for an accurate use of the app.

Digger's Activity at Men's European Beach Volleyball University Championship

In this paper, we present a study of digger activity among university beach volleyball players. A total of 929 digger actions carried out by 24 European University teams at the 9th European Beach Volleyball Championship EUSA GAMES were analyzed. The video was analyzed using Longomatch v.0.27 software. Statistical significance of the comparison between systems was calculated using the Z test to compare proportions. Results showed that 63.8% were passive actions and 36.2% were active actions (p<0.001) while 51% of digger actions were in static position and 49% in dynamic position (p=0.178). Furthermore, 23.1% of digger actions ended in counter attack and 76.9% ended without counter attack (p<0.001). As a result, the most effective defence can be considered to be static actives. This study leads to specific training of defensive actions and lays the foundation for specialized training for diggers.

Effectiveness of Male Handball Goalkeepers: A historical overview 1982-2012

In this article, an analysis of the historical evolution of the effectiveness of goalkeepers in high level world competitions is carried out. To this end, 32 men’s handball finals have been analyzed to record and classify effectiveness rates and goalkeeping actions in relation to opponent players’ throw areas and positions from 1982 to 2012. Analysis included throws from areas of 6, 7, 9 m and counterattack, performed from center or side positions. Results show no clear trend in effectiveness values registered throughout the time sample, both generally and specifically in terms of throwing position. The Kruskal-Wallis H test did not establish statistically significant differences (p>0.05) in goalkeeping effectiveness between any of the different analyzed periods, with a confidence interval of 95%. The findings of this study suggest that the ability of goalkeepers to prevent the goal from different throwing areas and positions has changed little over the past 30 years, although the game has incorporated more offensive actions and therefore more attacks. This lack of progress can be attributed to that handball has not updated their game rules to make it faster and more spectacular.