Concurrent Validity Of The Vo2 Master Pro In Estimating Metabolic Equivalents During The Treadmill Test

Metabolic analyzers can accurately assess energy expenditure (EE); however, this technology is generally limited to controlled laboratory settings due to accessibility constraints. The VO2 Master Pro (VMP), a newer, portable metabolic analyzer, aims to provide a more affordable and practical alternative for estimating EE in non-laboratory environments. However, there have been limited validation studies of the VMP reported in scientific literature. PURPOSE: To assess the concurrent validity of the VMP in estimating EE during treadmill walking and running in a laboratory setting, compared to the criterion measure. METHODS: 27 healthy adults [median age: 20.0 (19.0-22.0) years; female: 51.8%] completed a treadmill test across two visits, separated by at least one day, each using a different metabolic analyzer: COSMED (criterion) and VMP in a counterbalanced order. EE was estimated as metabolic equivalents (METs) using oxygen consumption (V̇O2 ml/kg/min) during the following activities: sedentary (sitting quietly), slow walking (3.2 km/h), brisk walking (5.6 km/h), and running (7.2 km/h), with each level performed for 10 minutes. The accuracy of VMP-derived EE was assessed using equivalence testing, mean absolute percentage error (MAPE), and percentage bias compared to the criterion-derived EE across different activity levels. Intraclass correlation coefficient (ICC) and Bland-Altman analyses were conducted to evaluate the agreement between the two measures. Mixed models were applied for all analyses to account for within-subject variations in EE estimates between the two measures. RESULTS: Agreement between the two measures was low for all activities [ICCs = 0.136-0.320]. Significant mean differences were found between the measures [equivalence testing: p’s > .05], with the lowest MAPE and percentage bias observed during running [MAPE(%) = 20.10; % bias = -19.33]. A significant proportional bias was observed between the two measures only during slow walking [b (SE) = -0.79 (0.31); p = .017]. CONCLUSION: The VMP generally underestimated EE across all activity types, showing low agreement and accuracy compared to the criterion measure. Additionally, significant bias and within-subject variability in EE estimated from the VMP suggest caution when using this device across different activity levels.