Validation Of The Cosmed K4 b2 Portable Metabolic System In Measuring STEADY-STATE Walking Energy Expenditure

Abstract

PURPOSE: The purpose of this study was to assess the accuracy of the Cosmed k4b2 portable metabolic analyzer (Cosmed, Rome, Italy) against the Medgraphics D-Series gas exchange system (Medical Graphics Corporation, St Paul, MN) during steady state, submaximal walking exercise. METHODS: Nineteen men and women (9 women, 10 men) with an average age of 39.8 years (± 13.8) completed two consecutive 400 meter walk tests, separated by a 10 minute rest period, at a constant, self-selected pace on a treadmill. Oxygen consumption (VO2) and carbon dioxide production (VCO2) from the steady state portion of each 400m walk were analyzed. RESULTS: All subjects (N=19) successfully completed both tests. Intraclass Correlation Coefficient (ICC) and Pearson values between the two machines for VO2 (ml/kg/min), VO2 (ml/min), and VCO2 (ml/min) indicate high correlation.Table: Caption not availableA comparison of the average values obtained using the Cosmed and Medgraphics analyzers using paired t-tests indicate no significant difference for VO2 (ml/kg/ min) overall (p=0.27), or by gender (p=0.28 females, p=0.58 males). Results were not significantly different for VO2 (ml/min) or VCO2 (ml/min) over all participants (p=0.12, p=.11, respectively), or when stratified by gender (VO2: p=0.42 males, p=0.11 females; VCO2: p=.15 males, p=0.53 females). There was a trend towards lower VO2 values and higher CO2 values with the Cosmed unit, however the difference was not significant at the p = 0.05 level. CONCLUSION: These results indicate that the Cosmed k4b2 portable metabolic analyzer is acceptable for measuring VO2 and VCO2 during steady state, submaximal exercise.