Assessment Of The Kb1-c Portable Metabolic Measurement System During Submaximal Cycle And Treadmill Exercise

Abstract

PURPOSE The purpose of this study was to evaluate the validity and reliability of the portable KB1-C Metabolic Analysis system during submaximal exercise intensities. METHODS Thirteen apparently health subjects (age: 21.9 ± 0.4 yrs; height: 175.1 ± 2.6 cm; weight: 75.3 ± 4.3 kg; %BF: 15.0 ± 1.8) were recruited. Each subject exercised on a treadmill and a cycle ergometer. The stages for the treadmill protocol included rest and 2.0, 3.0, 4.0, 5.0 and 6.0 miles per hour (mph). The stages for the cycle ergometer protocol included rest and 50, 75, 100, 125, 150 and 175 Watts. Each subject exercised for five minutes at each exercise intensity. Expired air was collected and simultaneously analyzed for oxygen consumption (Vo2), carbon dioxide production (Vco2), minute ventilation (Ve), fraction of expired oxygen (FEO2) and fraction of expired carbon dioxide (FECO2) by the KB1-C and True Max 2400 computerized metabolic systems. Data collected over the last two minutes were averaged and compared. A two-way ANOVA with repeated measures (instrument × stage) was used to identify differences between the two metabolic systems during each stage of the submaximal exercise test. Pearson's correlation coefficient was used to identify relationships between the two instruments. RESULTS Oxygen consumption, Vco2, and Ve increased significantly (p< 0.05) with increased exercise intensity. During the treadmill test, oxygen consumption and Ve were significantly different between the two systems at rest. VCO2 measured by the KB1-Cwas significantly higher at rest, 2.0, and 4.0 mph compared to the True Max system. On the other hand, FEO2 and FECO2 were not significantly different between systems. During the cycle ergometer test, Vo2, and Ve were not significantly different between instruments at 50, 75 and 100 Watts but KB1-C was significantly higher than the True Max at rest and significantly lower than the True Max at 125, 150 and 175 Watts. VCO2 was significantly different at all exercise intensities between instruments. Fraction of expired oxygen assessed by the KB1-C was significantly higher at 125, 150, and 175 Watts compared to the True Max system. On the other hand, FECO2 was not significantly different between instruments. Finally, correlations for Vo2 values between the two systems were r≥0.85. CONCLUSIONS These results indicate that the KB1-C can be used in the assessment of oxygen consumption, especially at low and moderate exercise intensities. However, at higher exercise intensities, especially if a cycle ergometer is used, KB1-C does not present equally valid results. It is possible that the differences between instruments may be even greater at maximal exercise intensities.