Stroke phase discrimination in breaststroke swimming using a tri-axial acceleration sensor device.

Our previous study has demonstrated that the swimmer's wrist acceleration in the crawl stroke and the breaststroke had distinctive characteristics between subjects (Ohgi et al. 2000). In addition, stroke phase discrimination could be achieved for the crawl stroke by using the swimmer's wrist acceleration. This study provides evidence that the swimmer's tri-axial wrist acceleration could be used for stroke phase discrimination in the breaststroke. Swimmers' tri-axial wrist accelerations were measured and their underwater stroke paths calculated. The authors examined the characteristics of the wrist acceleration, such as a local maximum or minimum, with reference to the swimmers' stroke paths. As a result, it was suggested that the three phases of the breaststroke, the recovery, the insweep and the outsweep, could be distinguished using the x-axis (ulnar-radial axis) and the y-axis (distal-proximal axis) acceleration. This methodology allows us to identify which stroke phase would be changed in skill training or over training, and the acceleration sensor device has the potential to become a precise stroke pedometer or stroke monitoring tool in the near future. [ABSTRACT FROM AUTHOR]