Perception of changes in bar velocity as a resistance training monitoring tool for athletes

Purpose: To investigate if perception of changes in bar velocity (PCV) can be used as a substitute for velocity tracking devices commonly used to monitor resistance-exercises. Methods: Twenty-one professional male soccer athletes (21±4 years) first went through a load-power profile assessment to determine their optimal power load in the back-squat. In the next three experimental sessions, athletes completed four sets of six repetitions loaded with optimal power load. Starting from the second repetition, athletes reported their PCV of each repetition as a percentage of the first repetition. Accuracy of PCV was calculated as the absolute difference between PCV and the actual percentage change from the first repetition in bar velocity measured with a linear-encoder. The second and fourth sessions served as the pre- and post-intervention sessions, in which athletes received no feedback about their PCV accuracy. The third session served as the intervention session, in which athletes received verbal and visual feedback about their PCV accuracy levels after each set. Results: The estimated accuracy of PCV decreased from an average error of 7% in the pre-intervention to an average error of 4.7% in the post-intervention session (95% confidence levels of difference: 1.5, 3.0). Conclusion: Athletes with velocity based training experience begin with a reasonable PCV accuracy rates which can be meaningfully improved after a single session that includes accuracy feedback. When velocity tracking devices are impractical or absent, PCV can be implemented as a resistance training monitoring tool.