This study assessed the interunit reliability of Global Navigation Satellite System (GNSS) andaccelerometer-derived metrics during high-intensity shuttle run protocols. Thirty-three femalefootball players completed three shuttle run protocols (2 × 20 m, 4 × 10 m, and 8 × 5 m). TwoSTATSports Apex Pro units (18 Hz GPS and 10 Hz Augmented GNSS; 100 Hz accelerometer)recorded accelerometer-derived (fatigue index [FI] and dynamic stress load [DSL]) and GNSS-derived (total distance, acceleration and deceleration counts, maximum speed, speed intensityand total metabolic power) metrics. Interunit reliability and agreement were evaluated usingintraclass correlation coefficients (ICC), and Bland-Altman analysis. GNSS metrics demonstratedgood to excellent reliability (ICC: 0.845–0.999), whereas accelerometer-derived metrics, FI (ICC:0.495) and DSL (ICC: 0.484), showed poor reliability. Percentage bias in accelerometer-derivedmetrics ranged from −1.76% (FI) to −7.72% (DSL), and in GNSS metrics ranged from −0.1% (speedintensity) to 5.83% (decelerations), limits of agreement increased in protocols with more direc-tional changes. Overall, the interunit reliability of accelerometer-derived metrics should be con-sidered cautiously, especially in short, high-intensity activity. ICC and Bland-Altman analysisconfirmed close agreement for the GNSS metrics but highlighted variability in accelerometer-derived metrics. Practitioners are advised to avoid interchanging units between athletes andsessions to maintain reliability