Is the high-speed camera-based method a plausible option for bar velocity assessment during resistance training?

This study aims to identify the measurement error associated with the mean movement velocity when using high-speed camera-based methods and video analysis during resistance training. Eleven resistance-trained men (26.0 +/- 3.4 years) completed a progressive loading test in bench press exercise. Measurements from concentric mean velocity (MV), distance and time were obtained from a linear velocity transducer (T-Force) and videos recorded with high speed cameras on readily available smartphones (Samsung S6, Xiaomi A1, and iPhone X) and digital photo cameras (Casio FH20). Videos were examined using video analysis software (Kinovea). Despite the high correlations detected, the Bland-Altman analyses revealed that all high speed cameras produced substantial overestimation of barbell MV against high loads >60% 1RM (MV error = 0.06 +/- 0.03 m.s (1) to 0.08 +/- 0.04 m.s (1)), but mainly against low loads <60% 1RM (MV error = 0.13 +/- 0.06 m.s (1) to 0.20 +/- 0.09 m.s (1)). The maximum estimation error of the load being lifted (%1RM) was considerable both for low (8.5-12.7% 1RM) and high loads (13.9-22.6% 1RM). Among other practical limitations, the video-based system using different high-speed cameras and smartphone devices presents severe limitations when estimating mean concentric velocity, especially when recording low loads at high velocity. (C) 2019 Elsevier Ltd. All rights reserved.