EO SwimBETTER® Device in Measuring Kinematic and Kinetic Variables: Validity, Reliability, and Sensitivity

<b>Objectives:</b> The aim of this study was to analyze the utilization of the <i>EO SwimBETTER</i>^® (<i>EoLab</i>, Sydney, Autralia) device for measuring kinetic and kinematic variables during 50 m and 200 m freestyle trials. <b>Methods:</b> Ten swimmers (seven males and three females, 20 ± 3.5 years) participated. Each completed three sets of 50 m using <i>EO SwimBETTER</i>^® on non-consecutive days, with a 200 m test performed during the third session after recovery to complete the <i>Critical Swim Speed Test</i> (CSS-T). All tests were conducted at maximal intensity. <b>Results:</b> The results showed high reliability for both kinetic and kinematic parameters. Regarding validity, the <i>EO SwimBETTER</i>^® demonstrated strong agreement with the reference device in measuring stroke frequency (SF). In addition, higher mean force values were found in the 50 m compared with the 200 m trial (Δ% = 8.75%, <i>p</i> = 0.099), suggesting sensitivity of the device to different exertion demands. <b>Conclusions:</b> Based on these findings, the <i>EO SwimBETTER</i>^® appears to be a useful and promising tool for monitoring technical and performance-related variables in swimming, although further research is needed.