Differences Between Predicted And Measured V0 2 During Level And Uphill Walking

Abstract

Walking is a popular choice of exercise in many populations. It is especially utilized in older populations and those recovering from cardiovascular injuries. The ACSM equations are a resource for clinicians to use as a way to estimate intensity levels using VO2 or MET as the outcome measure. The accuracy of these calculations are important to ensure those individuals are working at the prescribed intensity level. The equations allow for a more rapid and cost effective way to measure intensity level than expensive and cumbersome equipment. PURPOSE: The purpose of this study was to compare the predicted and measured VO2 in a population of untrained college age individuals. METHODS: 21 healthy untrained college age individuals with an average BMI of 29.1 kg/m2, completed 3 x 3 minute treadmill walking tasks. These consisted of walking at 1.5 m/s at both level and a 5% incline and then an incline of 5% at an iso efficient pace compared to the level 1.5 m/s. Iso efficient pace was calculated using the ACSM equations and individual correction factors. RESULTS: During level walking, the measured VO2 (14.4±1.1 mlO2/kg/min) was 14.5% greater (p<0.001) than predicted (12.5 mlO2/kg/min) from the ACSM walking equation. All 21 of the participants measured values were greater than predicted by the equation. During the 5% incline at iso efficient pace, participants walked at an average velocity of 1.1±0.025 m/s, and the measured VO2 (15.3±1.2 mlO2/kg/min) was 7% different (p=0.001) than predicted (16.1±0.3 mlO2/kg/min) from the ACSM equation. Of the 21 participants, 16 of them had measured VO2 values that were smaller than predicted. During the 5% incline at the pace of 1.5 m/s, measured VO2 (19.9±1.2 mlO2/kg/min) was 5.7% different (p=0.01) than predicted (20.6 mlO2/kg/min). Seventeen of the participants had measured values that were less than the predicted value. CONCLUSION: For a group of untrained college age individuals with BMI on the edge of the overweight/obese range, the ACSM equations fail to capture the measured values of oxygen consumption. Clinicians and researchers who are using this equation as a prescription for exercise should be cautious when using these equations to calculate exercise intensity.