Congruent validity and reliability of two metabolic systems to measure resting metabolic rate

Determine the congruent validity and intra- and inter-day reliability of RMR measures assessed by the ParvoMedics Trueone 2-400 hood dilution method (Parvo) and Cosmed K4b² (Cosmed) breath-by-breath metabolic systems. Participants underwent 6 RMR assessments over 2 consecutive mornings, 3 with the Parvo (Day 1: Parvo 1; Day 2: Parvo 2, 3), 3 with the Cosmed (Day 1: Cosmed 1; Day 2: Cosmed 2, 3). Measured V_E, F_EO₂, F_ECO₂, VO₂, VCO₂, kcal/day, and HR values were averaged over a minimum of 10-min. Intra- and inter-day reliability within each system was determined with RMANOVA, and congruent validity was assessed via paired sample t-tests. 31 participants (13 females, 18 males; 27.3±7-years, 24.8±3.1-kg.m²) completed the study. There were no significant differences in any within or between day Parvo values or Cosmed values. When systems were compared, there was a significant difference between V_E (Parvo2: 25.03-L/min, Cosmed2: 8.98-L/min) and F_EO₂ (Parvo2: 19.68%, Cosmed2: 16.63%), however, there were no significant difference in device-calculated RMR (kcals/day). The Parvo and Cosmed are reliable metabolic system with no intra- or inter-day differences in RMR. Due to differences in measurement technology, F_EO₂, V_E were significantly different between systems, but the resultant RMR values were not significantly different.