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AGREEMENT BETWEEN MOTION TRACKING AND VIDEO ANNOTATION FOR BARBELL KINETICS DURING HIGH INTENSITY FUNCTIONAL TRAINING

Abstract

BACKGROUND: High-intensity functional training (HIFT) involves vigorous multimodal circuit training, where precise tracking of pacing is nearly impossible without technological assistance. One method would include recording workouts and utilizing video annotation software (VAS) to quantify kinetics but is limited by camera quality and standardization. Secondarily, 3D motion tracking systems (MTS), can provide live feedback with less procedural restrictions, but is limited to specific exercises and can fail to detect repetitions. Data loss may be avoided having VAS serve back-up when repetitions are lost. The purpose was to determine agreement between VAS and MTS for monitoring barbell kinetics during a 5-minute bout of HIFT. METHODS: Data from eighteen HIFT-trained athletes (29.4 ± 8.4 years) was used for this study. Over a 4-week period, participants randomly repeated a 5-minute repeated circuit of 9-calorie rowing, six barbell thrusters at 43.1 kg, and three 0.61 m box jumps after consuming supplement or placebo. Workouts were recorded by tablet camera with average concentric barbell velocity (V) and power (P) during thrusters being specifically tracked by MTS PERCH. Post-exercise, VAS Kinovea was used to quantify average concentric V and P for completed thrusters. Quantified kinetics for complete sets were organized (n = 816). A random sample of 555 repetitions (~68%) were chosen for analysis. RESULTS: Though Pearson’s correlations indicated positive relationship (r = 0.33-0.49, p < 0.001), paired samples t-tests revealed a significant difference in V (MTS: 1.19 ± 0.41 m/s, VAS: 1.22 ± 0.19 m/s, p = 0.032) but not P (MTS: 482 ± 189 W, VAS: 487 ± 111 W, p = 0.468). However, negative relationships were observed between the average of, and differences between, MTS and VAS for V (r = -0.66, p < 0.001) and P (r = -0.54, p < 0.001), with large coefficients of variation (CV = 1,098-3246%). MTS produced lower estimates of V (mean bias = -0.04 m/s, 95% C.I. = -0.74 to 0.81 m/s) and P (mean bias = -5 W, 95% C.I. = -321 to 331 W) compared to VAS, and these were not consistent across the observed range of velocities (0.61-1.90 m/s) and power (181-780 W). CONCLUSION: While measures of V and P estimated by MTS and VAS are related, their data cannot be used interchangeably or for imputation purposes. Compared to MTS, VAS overestimates V and P and differences are exacerbated with faster or more powerful repetitions.

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