Quantification of Energy Expenditure in Field Conditions: Comparison of Direct VO2 Versus VO2 Estimation from Heart Rate Measurements

Abstract

IntroductionIn humans, oxygen consumption (VO2) and heart rate (HR) are commonly used to assess energy expenditure (EE) during exercise in field conditions. We hypothesized that the estimation of EE from HR measurements could be a relevant parameter to estimate EE during submaximal field exercise. This study aimed to compare the EE from VO2 and HR measurements in exercising trotters.MethodsSix harnessed French Trotters were submitted to a continuous field incremental test (FIT) at trot to establish their individual VO2/HR relationship. Then they undertook a submaximal exercise bout (EX) over 2375 m during 3.41 ± 0.47 min at 70% of maximal velocity. VO2 and HR were recorded continuously (equine K4b2, COSMED, Rome, Italy) throughout FIT and EX. EE of EX was calculated by multiplying the total VO2 (Liters), either directly measured or predicted from HR, with its caloric equivalent (4.86 kcal/liter). Means were compared using a Student's t test.ResultsEE of EX was estimated at 2422 ± 390 kcal and 2630 ± 706 kcal from direct VO2 and HR methods respectively (P = 0.54).ConclusionsWe found no significant difference between the two methods for estimating EE of submaximal exercise. This suggests that the prediction of EE from HR monitoring might be used to evaluate EE of moderate intensity workouts.Ethical Animal ResearchThe project was conducted under the ethics committee approval B1110. Sources of funding: INRA PHASE, the Burgundy Region and AgroSup Dijon. Competing interests: none.