The main drawback of GNSS is its restriction to outdoor facilities therefore, indoor sports cannot use GNSS for tracking of players in competition and training. Total distance traveled, speed (e.g., time and distance in different speed zones), and number of sprints are calculated from position data, which can be obtained using GNSS technology, (sometimes integrated with inertial measurement units). In outdoor sports, GNSS is one of the most frequently used methods for kinematic metrics in team sports ( Malone et al., 2016). To measure the parameters that describe these physical demands, Global Navigation Satellite Systems, inertial measurement units, a combination of the two, or video-based analysis systems are used. High intensity events are reported using variables such as number of sprints, number of accelerations, or distances covered above a predefined speed threshold ( Bangsbo et al., 2006 Michalsik et al., 2013 Luteberget and Spencer, 2017). Sometimes high intensity events are also measured, which are characterized by inertia-based measures ( Bangsbo et al., 2006 Michalsik et al., 2013 Luteberget and Spencer, 2017).
Overall workload is dependent on the intensity and duration of the tasks, and is often reported using parameters such as total distance covered and distance covered in different speed zones. In investigations of physical demands in team sports, the overall workload is often reported as a measure of athletes' total effort. Such analyses are therefore conducted in many individual and team sports ( Bangsbo et al., 2006 Montgomery et al., 2010 Gabbett, 2013 Gilgien et al., 2013 Luteberget and Spencer, 2017). For all measures, the placement of anchor nodes and the field of play relative to the walls of the building influence LPS output to a large degree.Īnalyses of physical demands can improve the understanding of physical performance and injury risk in sports. To enhance instantaneous speed calculation the application of appropriate filtering techniques to enhance the validity of such data should be investigated. The calculation of instantaneous speed from LPS raw data is not valid. The differences between the LPS and reference system in instantaneous speed were speed dependent, showing increased differences with increasing speed.ĭiscussion: Measures of position, distance, and average speed from the LPS show low errors, and can be used confidently in time-motion analyses for indoor team sports. Instantaneous speed showed the largest differences between the LPS and reference system of all variables, both in the optimal (≥35%) and sub-optimal condition (≥74%). The average difference in distance was below 2% for all tasks in the optimal condition, while it was below 30% in the sub-optimal condition. Results: The mean difference between the LPS and reference system for all position estimations was 0.21 ± 0.13 m ( n = 30,166) in the optimal setup, and 1.79 ± 7.61 m ( n = 22,799) in the sub-optimal setup. Position, distance and speed were compared. Raw two-dimensional position data were extracted from both the LPS and the reference system for accuracy assessment. The same protocol was completed in two sessions, one with an assumed optimal geometrical setup of the LPS (optimal condition), and once with a sub-optimal geometrical setup of the LPS (sub-optimal condition). Athletes completed five tasks, all designed to imitate team-sports movements. Method: The LPS (Catapult ClearSky T6, Catapult Sports, Australia) and the reference system were installed around the field of play to capture the athletes' motion. In addition, the study investigated how the placement of the field of play relative to the anchor nodes and walls of the building affected the validity of the system. Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, NorwayĪim: The aim of the present study was to determine the validity of position, distance traveled and instantaneous speed of team sport players as measured by a commercially available local positioning system (LPS) during indoor use.Luteberget *, Matt Spencer and Matthias Gilgien
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