PHOTOCELL CONTACT MAT - A NEW INSTRUMENT TO MEASURE CONTACT AND FLIGHT TIMES IN RUNNING

A new instrument, the photocell contact mat (PCM), was developed to me asure ground contact time and flight time as well as step and stride f requency as a function of running time or running distance. The purpos e of this study was to evaluate the validity and accuracy of PCM measu rements against simultaneous force platform measurements. Effects of s triking pattern (sprinter or long-distance), running velocity, and hei ght of the PCM from ground level on the contact parameters were analyz ed, One male sprint runner and one male distance (marathon) runner vol unteered as subjects. The time difference between the PCM and force pl atform determinations linearly increased as a function of the PCM heig ht and decreased as a function of running velocity (except for the low est 10 mm PCM height). The low coefficients of variation found between corrected PCM contact times and force platform contact times suggeste d that the PCM is an accurate instrument to measure ground contact tim es.