Comparison between Smartwatch-Derived and CPET-Measured VO2Max

This study aimed to determine the accuracy of smartwatch-derived maximal oxygen consumption (VO2max) and the percentage of predicted VO2max (%pVO2max), two standard measures of cardiorespiratory fitness with established clinical predictive value.215 adults (44 (21%) male; median [interquartile range; IQR] 55 [32, 62] years old) performed a maximal exercise test (CPET) on a semi-recumbent ergometer and wore a Garmin Vivoactive 4s (GV4) smartwatch for 60 days. The first and last VO2max estimates provided by GV4 were compared to CPET measured VO2max and %pVO2max (Wasserman and Whipp's anthropometric-based equation). Agreement was assessed using Bland-Altman analysis (bias and limits of agreement [LoA]), absolute percentage error (APE), reported as median [interquartile range], and Pearson's correlation coefficient (cc).VO2max and %pVO2max measured during CPET was 22.4 [17.5, 27.4] ml/kg/min and 90.9% [78.1%, 101.3%], respectively.VO2max estimates from GV4 were moderately correlated with CPET measures (cc 0.66) and showed a large positive bias ~14 ml/kg/min with LoA from 0 -27 ml/kg/min.Correlation between VO2max from GV4 and anthropometric-based prediction of VO2max was high (cc>0.90).Agreement between %pVO2max from GV4 and CPET was poor (cc~0.15,bias ~52%,.GV4 provides estimates of VO2max that overestimate but moderately correlate with CPET measured VO2max.The agreement for %pVO2max is poor.