Abstract
<jats:p>Objective The aim of this study was to evaluate the inter-system agreement and interunit reliability of a GNSS real-time kinematic (GNSS-RTK) and dual-inertial measurement unit (IMU) wearable system during soccer-specific activities using a commercially available 10-Hz GNSS device as a field-based comparison system. Methods Thirty trained male team-sport athletes completed sport-specific drills and competitive match-play scenarios while simultaneously wearing the GNSS-RTK/dual-IMU system and a 10-Hz GNSS device. Inter-system agreement was assessed using paired-samples t-tests, Pearson correlation coefficients, and Bland–Altman analysis. Interunit reliability was evaluated using intraclass correlation coefficients (ICC) and percentage typical error of measurement (%TEM). Results Strong correlations were identified for total distance (r = 0.89), peak speed (r = 0.84), and high-speed running distance (r = 0.81), whereas agreement was substantially lower for very high-speed running (VHSR) distance (r = 0.65). Bland–Altman analysis demonstrated small mean biases for total distance (−6 m), peak speed (+0.08 km·h⁻¹), and low-speed running distance (−8 m). Interunit reliability of the GNSS-RTK system was good to excellent across most variables (ICC = 0.80–0.96). Conclusions The GNSS-RTK and dual-IMU wearable system demonstrated acceptable inter-system agreement and good-to-excellent interunit reliability for several key external-load variables in soccer. Agreement was strongest for cumulative locomotor metrics such as total distance and peak speed, whereas VHSR metrics exhibited lower agreement and greater measurement variability. Because no gold-standard criterion system was included, the findings should be interpreted as evidence of inter-system agreement rather than absolute validity or positional accuracy.</jats:p>