Can Video Annotation Software With Minimal Standardization Be Used as a Back-Up for a Marker-Free Motion Tracking...

Mangine, GT, Hines, A, Grazer, J, Esmat, TA, and McLester, J. Can video annotation software with minimal standardization be used as a back-up for a marker-free motion tracking system when monitoring barbell thruster velocity during a repeated circuit? J Strength Cond Res 39(2): 147-155, 2025-This study examined the agreement between a marker-free motion tracking system (PERCH) and a free video annotation software (KINOVEA) for measuring barbell thruster velocity using minimal standardization. For a larger placebo-controlled supplement intervention, 10 men (28.7 ± 8.0 years, 175 ± 8 cm, 91.0 ± 12.0 kg) and 10 women (31.3 ± 5.2 years, 167 ± 4 cm, 70 ± 13 kg) completed a circuit of rowing, 6 barbell thrusters (men: 43.1 kg, women: 29.5 kg), and 3 box jumps for "as many repetitions as possible" (AMRAP) in either 5 or 15 minutes. Barbell velocity (m × second -1 ) was monitored by PERCH from the frontal plane, whereas all sessions were video recorded from the same view and subsequently analyzed by KINOVEA using natural barbell landmarks. Fifty repetitions were randomly and equally drawn from each participant ( n = 1,000 repetitions) across all workout and supplement conditions. Although Wilcoxon signed-rank test revealed no differences (mean difference = 0.03 m × second -1 , p = 0.332), KINOVEA only explained 2.6% of PERCH variance, and Spearman's correlation analysis of Bland-Altman plots suggested that differences between technologies were exacerbated by the magnitude of velocity ( ρ = -0.62, p < 0.001). Cross-validated, regression analysis using KINOVEA and readily available participant demographics (arm reach and biological sex) improved prediction by 13.4% but agreement remained inconsistent ( ρ = 0.73, p < 0.001). Neither KINOVEA nor KINOVEA combined with participant demographics are interchangeable with PERCH for monitoring barbell velocity during an AMRAP. Still, researchers and athletes might use this free and accessible software as back-up for whenever PERCH fails to detect repetitions, as some information is better than none.