The validity and bias of Catapults minimaxV4 was quantified for short sprint efforts that are characteristic of many team sports. This included both straight line sprints of 10 and 20m and also short courses involving several 90 degree changes of direction (complex courses).
Previous research has established that minimax is a good tool for measuring long distance events in sport[1], however earlier generation devices had trouble with shorter sprint events.
minimaxV4 has a completely new generation GPS engine targeted for team sports. It has better accuracy, faster data rate (10Hz) and shorter lock on time in difficult GPS environments like stadiums.
Ten replicates each for 10m and 20m straight line sprints were compared against criterion measures, with 2 different running speeds.
Then ten replicates for both a 12.5m and 25m course were performed, where the said course had four 90 direction changes (see figure 1).
Figure 1: Short courses with direction change
Validity was quantified with the standard error of the estimate (SEE) and Bias estimated by summing total sprint distances across all trials and evaluating the error as a percentage.
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[1] Petersen, Pyne, Portus, Dawson: Validity and Reliability of GPS Units to Monitor Cricket-Specific Movement Patterns, International Journal of Sports Physiology and Performance, 2009, 4, 381-393