The Coach's Eye: A Randomized Repeated-Measure Observational Study Assessing Coaches' Perception of Velocity Loss...

Area of Science:

• Exercise Physiology
• Sports Science
• Biomechanics

Background:

• Resistance training (RT) often uses velocity loss thresholds to guide set termination.
• Coaches typically estimate velocity loss visually, a practice lacking empirical study.
• This research investigates the accuracy of coaches' observational velocity loss detection.

Purpose of the Study:

• To assess the accuracy of resistance training coaches in detecting specific repetition velocity loss thresholds.
• To identify factors influencing coaches' accuracy in perceived velocity loss detection.

Main Methods:

• Twenty RT coaches observed videos of barbell bench press and back squat exercises.
• Coaches identified velocity loss at 20% and 40% thresholds across varying loads (45-85% 1RM) and camera views.
• Accuracy was analyzed using a negative binomial generalized mixed-effects model, considering load, threshold, view, and gaze strategy.

Main Results:

• Coaches exhibited an average absolute error of 2.6 repetitions in detecting velocity loss.
• Accuracy improved with higher velocity loss thresholds (40% vs. 20%) and heavier loads (85% 1RM).
• A bar-tracking gaze strategy enhanced accuracy compared to no-bar tracking; view and mental fatigue had minimal impact.

Conclusions:

• Coaches demonstrate a degree of accuracy in visually estimating velocity loss during resistance training.
• Accuracy is influenced by the velocity loss threshold, training load, and the coach's gaze strategy.
• These findings suggest that coaches should consider these variables when implementing velocity-based training (VBT) principles through observation.