Accuracy Of The Cosmed K4b2 Telemetry System During Different Intensities Of Exercise

Abstract

Oxygen consumption (VO2) is often measured to determine the metabolic cost of different types of physical activity. It is difficult to measure VO2 during physical activities in the field without using a portable telemetry system. PURPOSE The purpose of this study was to examine the accuracy of the commercially available portable metabolic system (PORT) with reference to a traditional metabolic cart (MC) during submaximal and maximal treadmill exercise. METHODS Men and women (n = 8), between 18 and 45 years of age, were recruited. Two maximal oxygen consumption (VO2max) tests were performed in random order using the PORT and MC on two seperate days. In addition, a 40-minute submaximal exercise test consisting of 20 minutes at 45% and 20 minutes at 65% VO2max, as determined by MC, was performed on a third day. The MC and PORT were used for 10 minutes at 45% and 65% VO2max. The order of equipment use during submaximal exercise was randomly assigned. During submaximal and maximal exercise tests, expired respiratory gases were analyzed for the following: VO2 (mL/kg/min and L/min), VCO2 (L/min), fraction of expired O2 (FeO2, %) and CO2 (FeCO2, %), respiritory exchage ratio (RER), minute ventilation (VE, L/min), and energy expenditure (EE, kcal/min). A dependent t-test was employed to compare the differences between the PORT and MC in each variable at each exercise intensity. The level of statistical significance was set at p ≤ .05. RESULTS The PORT and MC differed significiantly on RER and VE (L/min) at 45%, 65%, and VO2max. All other variables were similar between the PORT and MC at each intensity.TableCONCLUSION The commercially available portable metabolic system is acceptable for measuring metabolic variables over a wide range of exercise intensities; however, the PORT appears to overestimate RER and VE in this small sample.