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Abstract

Markerless motion capture systems are increasingly used to assess movement performance and injury risk due to their efficiency and portability, yet their accuracy relative to force plates remains understudied. Force plates are considered the criterion standard for measuring kinetic variables, making validation against force plate data essential before widespread application of markerless systems. PURPOSE: The purpose of this study is to evaluate the concurrent validity of the DARI ® Motion capture system by comparing its biomechanical outputs to force plate–derived kinetic measures during selected athletic movements. METHODS: Participants (n = 33) were measured for height and weight, and then completed 5 vertical weighted ball (10kg) throws from the floor, as a dynamic standardized warmup. The DARI ® was calibrated using floor reference markers, with the calibrated force plates inside for floor geometry accuracy. Using a randomized cross-over repeated measures design, participants performed three countermovement jumps, with 60s between each jump. A 3 min rest period allowed force plate to be switched and floor geometry reference recalibration, followed by a second trial. RESULTS: A repeated-measures ANOVA was performed to evaluate differences between DARI ®, Vald ®, and Kinvent ® on vertical jump height. Mauchly’s test assumption of sphericity was violated, χ2 (5) = 66.570, p <.001, and therefore degrees of freedom were corrected using Greenhouse-Geisser estimates of sphericity (ε = .541). The difference between DARI ®, Vald ®, and Kinvent ® on vertical jump height was significant at the .05 level, F(3 , 96) = 97.6, p <.001, partial η2 =.753.  Post-hoc pairwise comparisons, with a Bonferroni adjustment, indicated that there was no significant difference between the vertical jumps between Kinvent ® and Vald ® or between both DARI ® trials at (p = 1.000) and Vertical jump height was significantly higher on DARI ® (M = 59.8, SD = 16.9, M = 60.4, SD = 16.5) than at either Kinvent ® (M = 41.8, SD = 16.5) or Vald ® (M = 43.9, SD = 14.8) force plates, (p = <.001). CONCLUSION: These findings suggest that while the DARI ® Motion system demonstrates consistency across repeated trials, it produces significantly higher vertical jump height values compared with force plate–derived measures. Practitioners should exercise caution when interpreting absolute jump height values from this particular markerless system, and further validation is warranted before substituting DARI ® Motion for criterion-standard force plates in vertical leap assessment.

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