COMPARISON OF ESTIMATED AND ACTUAL ENERGY EXPENDITURE USING FIELD HEART RATE AND INDIRECT CALORIMETRY MEASURES

Abstract

326 The purpose of this study was to compare estimates of energy expenditure(EE) with actual measured energy expenditure using continuous heart rate (HR) monitoring, and indirect calorimetry. Seven subjects completed a multistage walking protocol composed of six, 4 min. workloads. Expired gases were analyzed using a portable metabolic (KB1-C Aerosport, inc.) unit and HR's were recorded each minute using a chest strap HR monitor. Individual linear regression equations (HR vs. VO2 and HR vs. RER) were established. Subjects then completed a 1 mile field hike with the portable metabolic system. HR and VO2 were continuously monitored at 60 sec. intervals during the field trials. Heart rates recorded during the hike were integrated into the two regression equations to determine estimated kcals/min. from the entire 1 mile hike. Estimated values were compared with actual values obtained from the portable system during the hike trial. The average time to complete the field hike was 16.71 min.±2.06. Analyses of these data show no significant difference (p=0.31) between actual and predicted EE(10.60±1.97 and 10.20±1.50 kcal/min for actual and predicted EE, respectively). Simple regression for predicted EE vs. actual EE revealed a significant positive correlation (r=0.88, p=0.0085). These similarities may be attributed to the fact that field HR values remained within values used to develop the equations, specificity of field and lab testing, and consistent nutritional and hydration status. Variations in predicted EE vs. actual EE may be due in part to anxiety and testing terrains. Given similar activities with individualized regression equations, field HR monitoring can accurately predict EE.