The Validity and Reliability of Commercially Available Smartphone-based Velocity-based Training Applications: A Systematic Review With Guidance for Research and Practice

Abstract

Velocity-based training (VBT) has gained widespread adoption in resistance training for real-time assessment of barbell kinematics. Smartphone-based VBT applications have emerged as low-cost alternatives to gold-standard devices, offering portability, minimal setup, and accessible interfaces. Despite increasing adoption, there remains no synthesis of measurement performance. This systematic review assessed the reliability and validity of six commercially available smartphone-based VBT applications for measuring barbell velocity and displacement. Following PRISMA guidelines, systematic searches of PubMed, SCOPUS, and SPORTDiscus identified 194 articles, with 18 meeting inclusion criteria. Four applications (iLoad, Metric, My Jump Lab, WL Analysis) demonstrated acceptable validity (r ≥ 0.70; CV ≤ 10%; ES ≤ 0.60). Two applications (Metric, My Jump Lab) demonstrated acceptable reliability (ICC ≥0.900; CV ≤ 10%; ES ≤ 0.60), though performance fell below research-level thresholds (ICC: ≥0.997; CV: ≤3.5%). Measurement performance varied across applications, exercises, and loading conditions, with smartphone applications demonstrating lower validity and reliability than established VBT devices. Current smartphone-based VBT applications appear suitable for recreational and field-based applied settings, though not high-precision research contexts. Practitioners should evaluate measurement performance specific to their training context and account for inherent measurement error. Future research should assess continued application updates across different training contexts and hardware/software configurations.