Is a Head-Worn Inertial Sensor a Valid Tool to Monitor Swimming?

Stephanie J Shell, Brad Clark, James R Broatch, Katie Slattery, Shona L Halson, Aaron J Coutts

    Research output: Contribution to journalArticlepeer-review

    3 Citations (Scopus)


    PURPOSE: This study aimed to independently validate a wearable inertial sensor designed to monitor training and performance metrics in swimmers.

    METHODS: A total of 4 male (21 [4] y, 1 national and 3 international) and 6 female (22 [3] y, 1 national and 5 international) swimmers completed 15 training sessions in an outdoor 50-m pool. Swimmers were fitted with a wearable device (TritonWear, 9-axis inertial measurement unit with triaxial accelerometer, gyroscope, and magnetometer), placed under the swim cap on top of the occipital protuberance. Video footage was captured for each session to establish criterion values. Absolute error, standardized effect, and Pearson correlation coefficient were used to determine the validity of the wearable device against video footage for total swim distance, total stroke count, mean stroke count, and mean velocity. A Fisher exact test was used to analyze the accuracy of stroke-type identification.

    RESULTS: Total swim distance was underestimated by the device relative to video analysis. Absolute error was consistently higher for total and mean stroke count, and mean velocity, relative to video analysis. Across all sessions, the device incorrectly detected total time spent in backstroke, breaststroke, butterfly, and freestyle by 51% (15%). The device did not detect time spent in drill. Intraclass correlation coefficient results demonstrated excellent intrarater reliability between repeated measures across all swimming metrics.

    CONCLUSIONS: The wearable device investigated in this study does not accurately measure distance, stroke count, and velocity swimming metrics or detect stroke type. Its use as a training monitoring tool in swimming is limited.

    Original languageEnglish
    Pages (from-to)1901-1904
    Number of pages4
    JournalInternational Journal of Sports Physiology and Performance
    Issue number12
    Publication statusPublished - 21 May 2021


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