Criterion Validity and Between-Day Reliability of Three-Dimensional Motion Capture and the Perch Camera System for...

Area of Science:

• Sports Science
• Biomechanics
• Strength and Conditioning

Background:

• Monitoring bar velocity in resistance training is crucial for performance optimization.
• Accurate and reliable technology is essential for effective velocity-based training.
• The Perch camera system is a widely used tool for velocity monitoring.

Purpose of the Study:

• To assess the criterion validity of the Perch system against a 3D motion capture system.
• To determine the between-day reliability of the Perch system.
• To evaluate the Perch system's performance across seven weightlifting derivatives.

Main Methods:

• Criterion validity was assessed using R-squared, root mean square error, and Bland-Altman plots comparing Perch to 3D motion capture.
• Between-day reliability was calculated using SEM and MDC.
• Fourteen subjects performed weightlifting derivatives at various intensities (20-100% 1RM) across multiple sessions.

Main Results:

• The Perch system explained 86-96% of the variation in bar velocity compared to the criterion measure.
• A consistent systematic difference of approximately 0.25 m·s-1 was observed, with the Perch being slower.
• Both systems demonstrated acceptable SEM and MDC values, indicating good reliability.

Conclusions:

• The Perch camera system exhibits strong criterion validity and between-day reliability for monitoring bar velocity in weightlifting.
• Despite a systematic underestimation of velocity, the Perch is a reliable tool for providing training feedback.
• The Perch system can effectively support performance enhancement and physical adaptations in athletes.