Can indirect calorimetry and accelerometry be used to assess energy expenditure in healthy and unhealthy population? A systematic review and meta-analysis

OBJECTIVE: the purpose of this study was to explore the reliability of indirect calorimetry and accelerometers to assess energy expenditure (EE) while practicing physical activity and to identify a more suitable method for further investigation. METHODS: this review protocol was developed in accordance with the PRISMA statement. Original quantitative studies were identified by searching the four principal electronic databases. Only studies that state EE and the measurement protocol and those where mean intraclass correlation coefficient (ICC) values across all edges, number of subjects, and the test could be determined from the text were considered. RESULTS: a total of 13 studies were deemed eligible according to the inclusion criteria. The estimated average reliability of EE was excellent (ICC = 0.94; 95 % CI: 0.91-0.96). Although both device types have very high reliability, indirect calorimetry has good (ICC = 0.89; 95 % CI: 0.79-0.99) and accelerometry has excellent reliability (ICC = 0.94; 95 % CI: 0.90-0.97). Healthy subjects showed more stable values with excellent reliability (ICC = 0.93; 95 % CI: 0.91-0.96), whereas unhealthy subjects showed greater variability in their results with good reliability (ICC = 0.88; 95 % CI: 0.73-1.04). CONCLUSION: accelerometers are more reliable than indirect calorimeters for measuring EE during physical activity. The reliability also increases if it is measured in healthy subjects.