VALIDITY OF DIFFERENT SYSTEMS FOR TIME MEASUREMENT IN 30M-SPRINT TEST

none3Sprinting is a key factor in many sports and specific sprint tests are often performed to detect talent in youth. The main pourpose of this study was to assess the validity and the reliability of two 30 meter sprint tests using different starting conditions: from rest (RST) and from a flying start (FST). In addition the aim was to verify the differences in measurement between a high frequency camera (250 Hz) and photocells (1000 Hz). Participants (81 Bologna’s scholars and university student, between the age of 4 and 25 years old,) were divided in four age goups: 4-6 y; 7-9 y; 10-12 y; ≥13 y. Reliability has been studied with Cronbach’s alfa. A study of the errors (Bland-Altman Plot), has been ran to compare the two methods of times measurement. The error series has been controlled by video analysis. The duration of the acceleration phase and the maintenance of the maximum speed has been measured in each group. The correlation between the output data of the two system of measurement was of 0.92. The reliability was between 0.94 and 0.98 for the RST and between 0.92 and 0.98 for FST using both methods of measurement. Reliability increased with the age of the participants, while the numbers of errors was inversely related to that. The variability of the individual running technique may have influenced errors. The acceleration phase in all the groups occurred at least in the first 15 meters sprinting. A slight decrease (0.30-0.32 m/s) in speed after 20 meters was observed in participants under the age of 13, while older participants were able to maintain the speed to the end of the 30 meters run. The sprint test showed a high validity and reliability in young participants. High speed camera and photocells can be used alternatively for this purpose.noneNigro, F.; Bartolomei, S.; Merni, F.Nigro, F.; Bartolomei, S.; Merni, F