Catapult T6 Whitepaper

Purpose:
The utilization of microtechnology devices to measure the physical demands within both training and match-play is common practice within team sports. Microtechnology devices can provide comprehensive information to the coach, sports scientist, and physical preparation staff on the physical demands of both training and match-play. Such information is invaluable in enhancing the positional-specific development of players, optimizing periodization strategies, and aiding in the detection of fatigue and overtraining.

Current microtechnology sensors utilize one of two positioning systems: Global Positioning Systems (GPS) or Local Positioning Systems (LPS). GPS is a satellite-based navigational system, originally devised for military use. This system is designed to provide location and time information anywhere on earth where there is an unobstructed line of sight to four or more satellites. The use of GPS in stadiums with high walls may, however, provide unreliable data due to fewer satellites in the line of sight.

LPS, on the other hand, utilizes local anchor nodes placed within a stadium which act as reference points as opposed to the satellites orbiting the earth. Such systems can be utilized indoors and may provide enhanced validity due to the closer proximity of the LPS anchor nodes.

The validity of such systems is of primary importance in the monitoring of athletes. Therefore, the purpose of this whitepaper was to examine the positional validity of the Catapult T6 LPS system.

Methods:
Subjects:
One trained male participant participated in this study (age: 21 years; height: 176cm; weight: 67kg).

Stadium:
Etihad stadium; 740 Bourke Street, Docklands, Victoria, Australia, 3008.

Protocol:
The validity of the T6 LPS system was determined by comparing the reported total distance against the criterion measure of this variable. Each trial was analyzed for comparison using the manufacturer’s software (OpenField version: 1.13.4.1).

Devices:
The Local Positioning System utilized Catapult T6 units (10Hz) with firmware 2.1.21373. One unit was worn inside a padded pocket within a custom-made vest, which positioned the unit in the center of the upper back, slightly superior to the shoulder blades at approximately the level of the thoracic vertebrae one (T1). Twenty-eight devices were turned and positioned around the stadium in order to load the Local Positioning System.

Distance:
A battery of five straight line and change of direction tests were conducted. Total distance was measured using a trundle wheel. A theodolite (Leica Geosystems, Switzerland) was used to error check the measured distances of the trundle wheel. To establish validity, the measured distance from the theodolite was then compared to the distance output from the LPS device.

Instructions:
Instructions were given for the subject to start with the middle of both feet on the starting line and finish with the middle of both feet on a marked line at the finishing distance (i.e., the subject did not run through the final distance). This method facilitates the best measure against the marked distance, as having the subject run through the line introduces potential error in approximating the exact finishing point of each trial. For change of direction tests, the subject was also instructed to try and minimize body lean on each change of direction to avoid errors from “cutting corners”.

Statistical Analyses:
Data are presented as a mean and standard deviation unless otherwise specified. The difference between the T6 device and criterion measurement for total distance was observed using raw bias and % bias using a customized excel spreadsheet. Differences in means were examined through a paired sample T test with significance accepted at <0.05. To adopt a practical approach to the study, differences were also analyzed using confidence intervals (set at 90%) and Cohen’s effect size (ES) statistics. Effect sizes were categorized as trivial (<0.02), small (0.02-0.6), moderate (0.6-1.2), large (1.2-2.0), and very large (>2.0).

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