Comparing Respiratory Rate and Minute Ventilation Measures between Commercial-Grade Wearable Devices and a Metabolic Cart

Accurate respiratory monitoring with wearable devices remains limited by inadequate validation. This study evaluates two commercial wearables-a thoracoabdominal belt (Airgo) and a smartwatch (EmbracePlus)-for estimating respiratory rate (RR) and minute ventilation (Ve), using a metabolic cart (Cosmed KS) as reference. Ten healthy adults were monitored at rest and while walking. Airao showed high RR accuracy across all conditions (MAPE < 4%, ± 5 bpm agreement), while EmbracePlus provided RR only at rest (MAPE ∼ 12%). Airgo's Ve estimates were unreliable due to nonlinear chest-deformation signals and the absence of individual calibration. However, a previously published model combining pulse rate (EmbracePlus), RR (Airgo), and demographic inputs improved Ve estimation (bias -3.37 L/min, MAPE ≈ 20%)). These findings confirm Airgo's reliability for RR monitoring and support model-based Ve estimation when direct measurement is unfeasible.