the purposes of performance analysis. Data were collected
from men’s soccer (a professional Australian A-League team),
women’s soccer (a senior state league team), men’s and
women’s field hockey (senior state league teams), and
a professional Australian Rules Football (AFL) team. All
the athletes were in peak physical condition and free from
injury at the time of data collection.
Twenty-five data sets representing 5 complete games from
5 individuals were analyzed for 5 sports (a total of 125 data sets).
Only data representing the actual play were included in the
analysis. Warm-up, warm-down, and breaks in the game were
removed from the data set. All data were supplied anonymously
so that there was no way of identifying the individual athletes
involved. The data came from GPS receivers designed
specifically for use in sport (minimaxX,
Catapult Innovations,
Australia & SPI Elite, GPSports,
Australia). Data were collected at
1 Hz, downloaded by the software
that accompanies the GPS
receivers and velocity data (measured
by Doppler shift), and were
exported for analysis. Several
authors have found the accuracy
ofGPS technology for measuring
the movement of athletes to be
very good, including Townshend
(18) who reported that 90.8% of
GPS velocity measurements
were ,0.1 ms21 from actual