VitaMove to accurately measure energy expenditure at RACMEN conference 2011, Maastricht

At the Racmen (Recent Advances and Controversies in Measuring Energy Metabolism) 2011 conference in Maastricht Erasmus Medical Centre presented a new method to accurately measure energy expenditure in daily life.
EMC believes that this innovative method will lead to a valid and reliable estimate of momentary EE in daily life. Next steps will be the development and optimization of the algorithms and its parameters, followed by an extensive validity study with indirect calorimetry as reference method.

Background

Energy expenditure (EE) during daily life is an important issue in the general population and patient groups. So far, devices to measure EE have problems of limited accuracy, low feasibility, not providing time stamped data and/or high costs.

Purpose

We propose an innovative and fundamentally different method to estimate momentary EE in daily life.

Methods

The minimal configuration of the device consists of two synchronized VitaMove recorders (including a 3-axis acceleration sensor) and a VMExG module. Accelerometer and ECG signals are continuously measured for up to 5 days. From these measured signals other time series are calculated, among them: 1) an extensively validated 1-second detection of a body posture or motion (“Activity”, e.g. standing, sitting, lying, walking, running, cycling, wheelchair driving; 2) the intensity of body posture or motion (“Body Motility”); 3) the momentary heart rate (“Heart Rate”).

Results

For each body posture and motion a unique EE estimation algorithm is developed calculating momentary EE, initially based on body posture and motion specific ranges of MET values reported in literature. This MET-table based algorithm is subsequently refined by including (besides anthropometric data) the momentary intensity of posture or movement, and momentary heart rate. The mutual contribution (weighing) of both signals to calculate EE depends on type of posture or
motion. It is possible to adapt the algorithms and weighing, e.g. when patients or patient groups have shown to have different parameter settings.

Conclusions

We feel that this innovative method will lead to a valid and reliable estimate of momentary EE in daily life. The next steps will be the development and optimization of the algorithms and its parameters, followed by an extensive validity study with indirect calorimetry as reference method.