El uso de fotocélulas de haz simple y doble para medir la velocidad en carreras®. The use of single- and dual-beam photocells to measure the sprint time®.

Resumen

El objetivo del estudio fue analizar la influencia de la tecnología de las fotocélulas en el registro de tiempo y su fiabilidad durante de carreras de velocidad de corta distancia. Participaron 25 estudiantes (20.5±0.5 años; 1.78±0.02 m; 77.5±1.8 kg) que fueron evaluados en 3 días (2 de familiarización y 1 de test). Se registraron aleatoriamente 3 carreras de aceleración y 3 velocidad lanzada, cronometradas simultáneamente a los 5, 10 y 15 m por dos sistemas de fotocélulas DSD Laser System®: haz simple y doble haz. El tipo de fotocélulas utilizadas influyó en el tiempo de carrera (F=11.92 y p<0.001) y su fiabilidad (F=14.52 y p<0.001). En la carrera de aceleración el haz simple sobrestimó ~0.02 s el tiempo respecto al doble haz (F=42.95 y p<0.001), obteniéndose registros fiables (CCI > 0.80) a los 10 y 5 m, respectivamente. En la carrera lanzada ambos sistemas midieron prácticamente igual (diferencias de ~0.005 s), obteniendo registros fiables a los 15 y 10 m, respectivamente. En conclusión, en carreras de aceleración la distancia mínima a registrar con haz simple debe ser de 10 m, y de 5 m con haz doble, mientras que en carreras lanzadas deberían utilizarse unas distancias mínimas de 15 y 10 m, respectivamente. Futuros estudios deberían analizar la distancia óptima a la primera fotocélula en las carreras de aceleración, para aumentar la fiabilidad de la medición y facilitar la comparación entre registros de diferentes estudios.

Abstract

The purpose was to analyze the influence of the timing gates’ technology on both running time performance and its reliability during short sprint distances. Twenty-five physical students participated (20.5±0.5 yr; 1.78±0.02 m; 77.5±1.8 kg), whose were evaluated during 3 separate days (2 familiarization sessions and 1 testing session). Three standing-start and 3 flying-start runs were randomized and simultaneously registered at 5, 10 and 15 m by two timing gates DSD Laser System®: single- and dual-beam. The type of timing gates affected the performance (F=11.92 y p<0.001) and the reliability (F=14.52 y p<0.001). During the standing-start runs, the single-beam system overestimated (~0.02 s) the performance with respect to the dual-beam one (F=42.95 y p<0.001), and the reliability was acceptable (CCI>0.80) at the distances of 10 and 5 m, respectively. During the flying-start runs, both systems obtained a very similar registry (differences of ~0.005 s), and the reliability was acceptable at the distances of 15 and 10 m, respectively. In conclusion, during the standing-start runs the minimum distance to registry the performance with a single-beam system should be 10 m, and 5 m with a dual-beam system. During the flying-start runs these distances should be 15 and 10 m, respectively. Further studies should analyze the optimal distance to the first timing gate during the standing-start runs, in order to improve the reliability and to compare the performances which were obtained in different studies.

http://dx.doi.org/10.5232/ricyde2012.03003

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