Abstract
The purpose of this study was to analyze the validity and the reliability of the intensity
ranges, number of actions and changes of direction measured by a commercial inertial
measurement unit. Eleven elite youth futsal players performed a circuit with different
type of displacements as sprinting, running at low-medium intensity, standing up and
changes of direction. Data recorded by the Overtraq system were compared with video-analyzer
during the six trials of each player. Standard error mean, Intraclass Correlation
Coeficient and Coefficient of variation, were calculated to analyze the reliability
of the device, as well as the Root Mean Square Error and Confidence Interval with
correlation of Pearson for its validity. The results reported good validity for three
intensity ranges (R2>0.7) with high reliability (Intraclass Correlation Coeficient:
0.8–0.9), especially for high intensity actions (Intraclass Correlation Coeficient:
0.95, Coefficient of Variation: 3.06%). Furthermore, the validity for the number of
different actions was almost perfect (96.3–100%), with only small differences regarding
changes of activity (mean error: 2.0%). The Overtraq system can be considered as a
valid and reliable technology for measuring and monitoring actions at different intensities
and changes of direction in futsal, likewise common actions for other indoor sports.
Key words
tracking system - change of direction - team sports - futsal