The validity and reliability of a global positioning satellite system device to assess speed and repeated sprint ability (RSA) in athletes

There is a limited understanding of the validity and reliability of commercially available global positioning satellite (GPS) devices for assessing repeated sprint performance in athletes. The aims of this study were to assess the convergent validity and the test retest reliability of a GPS device for measuring repeated sprint ability test (RSAT) variables. Two groups participated in this study, a group of 21 physical education students (age: 20.2 +/- 2.3 years, stature: 1.75 +/- 0.42 m, body mass: 68.0 +/- 6.8 kg) and a second group 14 elite junior soccer players (age: 14.5 +/- 1.2 years, stature: 1.60 +/- 0.09 m, body mass: 57.7 +/- 3.8 kg) volunteered to participate in this study. Convergent validity was assessed as the correlation between sprint performance (15 and 30-m) using both timing lights and a portable GPS device during a RSAT (7 x 30-m sprints with 30-s of active recovery). The 7 x 30-m RSAT test retest reliability using GPS device was assessed in elite junior soccer players repeating the test 1 week apart and expressing reliability as a coefficient of variation. Results showed a strong correlation between peak speed measures with the GPS device and RSAT performance measured with timing lights for the 15-m (r(2) = 0.87, p<0.001, N=147) and 30-m (r(2)=0.94, p<0.001, N=147) splits, respectively. There was a low coefficient of variation for summated maximal speed (1.7%) and peak speed (1.2%) during the 7 x 30-m RSAT, but high variation for the percentage decrement score (36.2%). These results provide evidence to support the use of the GPS device as an alternative measure to assess repeated sprint performance but suggest a percentage decrement score is not a reliable measure of RSAT performance. (C) 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.