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.

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This study aimed to define, develop, and validate a subjective scale of training quality. Two related studies were used to 1) define training quality and 2) develop and validate a subjective scale. Part One: a purposive sample of 15 sub-elite (i.e. national) and elite (i.e. international) swimmers participated in one, 20-30-min semi-structured interview. Thematic analysis of interview responses established three constructs to define training quality. These were the physical, technical, and mental aspects of training. Part Two: development of the Subjective Training Quality (STQ) scale based on the three constructs identified in Part One. 252 sub-elite and elite athletes, across eight sports completed the STQ scale. Cronbach's alpha (α) assessed internal consistency, histogram plot analysis assessed face validity, and confirmatory factor analysis (CFA) compared physical, technical, and mental constructs with training quality. Root mean square error of approximation (RMSEA) and standardised root mean square residual (SRMR) evaluated CFA quality of fit. Physical, technical, and mental constructs demonstrated a high "acceptable" level of internal consistency (α = 0.85) and excellent face validity. Comparatively, the CFA quality of fit was "excellent" (RMSEA = <0.01 "good", SRMR = 0.00 "perfect"). The STQ scale demonstrated excellent internal consistency and face validity, establishing capacity to monitor training quality. The STQ scale could be used in conjunction with traditional training monitoring tools to provide additional insight into athlete's training quality. Further investigation is required to determine how the STQ scale may interact with subjective and objective training performance measures, and how it could be incorporated into daily training monitoring. Highlights. Athletes perceive the subjective training quality (STQ) scale adequately represents the physical, technical, and mental constructs of training quality. . Excellent internal consistency and confirmatory factor analysis fit demonstrates the STQ scale is an effective tool to monitor training quality. . With additional validation, the STQ scale could be used in conjunction with traditional load monitoring tools to provide greater insight to an athlete's training response, and subsequently inform training prescription.