The validity of a head-worn inertial sensor for measurements of swimming performance

The validity of the TritonWear® device to measure swimming performance was investigated, with a pre-determined analytical goal of 6%. Twenty youth swimmers completed a 100 m swim in a 25 m pool, swimming breaststroke or freestyle wearing the TritonWear® device, whilst being filmed above and below water with three cameras. 95% limits of agreement (95% LoA) and coefficient of variation (CV%) were used to calculate error. Systematic biases (P < 0.05) were found between the two systems only for distance per stroke during breaststroke. Freestyle metrics agreement ranged between 1.06% and 10.40% CV, except for distance per stroke (CV = 14.64%), and time underwater (CV = 18.15%). Breaststroke metrics ranged between 0.95% and 13.74% CV, except for time underwater (CV = 25.76%). The smallest errors were found for split-times, speed, stroke-count and stroke-rate, across both strokes (all < 5% CV). The TritonWear® can be used for basic metrics of performance, such as split-time and speed but the error of more complex measurements, such as time underwater or turn-times, renders them unable to identify typical performance changes.