Strap and row: Rowing technique analysis based on inertial measurement units implemented in mobile phones

The length of a rowing stroke is an important performance metric for athletes and coaches. Accurate measurements are possible with optical or mechanical systems, which require significant setup effort. This work presents a new approach using a smart phone as a sensor device that is strapped to the oar. Two algorithms are introduced to calculate stroke lengths from the raw phone sensor data. The performance of each algorithm is evaluated by comparing the results to a mechanical reference system. Data was recorded during a single-user study performed on a rowing simulator. The best algorithm showed an average stroke length error of 7.64° ± 2.95°.