Validation of GPS and accelerometer technology in swimming.

Abstract: Objectives: To evaluate the validity of an integrated accelerometer and Global Positioning System (GPS) device to quantify swimming kinematics variables in swimming. Design: Criterion validation study. Methods: Twenty-one sub-elite swimmers completed three 100m efforts (one butterfly, breaststroke and freestyle) in an outdoor 50m Olympic pool. A GPS device with an integrated tri-axial accelerometer was used to obtain mid-pool velocity and stroke count of each effort. This data was compared to velocity and stroke count data obtained from concurrently recorded digital video of the performance. Results: A strong relationship was detected between the accelerometer stroke count and the video criterion measure for both breaststroke (r >0.98) and butterfly (r >0.99). Also, no significant differences were detected between the GPS velocity and video obtained velocity for both freestyle and breaststroke. There was a significant difference between the GPS velocity and criterion measure for butterfly. Acceptable standard error and 95% limits of agreement were obtained for freestyle (0.13ms⁻¹, 0.36ms⁻¹) and breaststroke (0.12ms⁻¹, 0.33ms⁻¹) compared to butterfly (0.18ms⁻¹, 0.50ms⁻¹). Relative error measurements ranged between 10.2 and 13.4% across the three strokes. Conclusions: The integrated accelerometer and GPS device offers a valid and accurate tool for stroke count quantification in breaststroke and butterfly as well as measuring mid-pool swimming velocity in freestyle and breaststroke. The application of GPS technology in the outdoor training environment suggests advantageous practical benefits for swimmers, coaches and sports scientists. [Copyright &y& Elsevier]