The Validity of a Global Navigation Satellite System for Quantifying Small Area Team-Sport Movements

Delaney J.A., Wileman T.M., Perry N.J., Thornton H.R., Moresi M.P., Duthie G.M.

Objective:
The study aimed to evaluate the validity of global navigation network systems (GNSS) for quantifying mean speed (m/s) and acceleration (m/s^2) during movements typical of team sports.

Methods:

One participant completed nine periods of four minutes of activity, interspersed with two-minute rest periods.
Activities involved walking, jogging, and running in various directions and patterns to simulate a team-sport movement profile.
Speed and acceleration were quantified using a 10 Hz GNSS unit and compared with a ten-camera, three-dimensional motion capture system (VICON).
Movement of both the participant’s center of mass (COM) and the location of the GNSS unit (e.g., C7 vertebrae) were calculated.
Practical estimates of speed were compared with the criterion COM and criterion C7.
Estimates of acceleration derived from raw data and software-exported acceleration values were compared with criterion measures.
Results:

Practical estimates of speed showed small differences from both the criterion COM and criterion C7.
Corresponding estimates of acceleration derived from raw data were classified as small for the COM and small to moderate for C7.
However, software-exported acceleration values exhibited very large mean bias compared to both criterion measures.
Conclusion:
The study concludes that 10 Hz GNSS possess acceptable validity for assessing the average demands of movements typical of team sports training and competition. However, caution is recommended when using software-exported measures of acceleration

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