Validation of a novel physical activity assessment device in morbidly obese females

Abstract

Assessment of physical activity in morbidly obese subjects is important especially in bariatric surgery. We examined the validity of Intelligent Device for Energy Expenditure and Activity (IDEEA) for measuring physical activity and sedentary behavior in morbidly obese women. Activity types, gait counts, and speed detected by the IDEEA monitor were compared to those reported by an observer. The IDEEA monitor detected activity types and gait counts with relatively high accuracy, although slightly lower in extremely obese women than in normal weight controls. The IDEEA monitor accurately estimated gait speeds in both groups. Since gait speed predicts energy expenditure more accurately than gait counts, it is of greater clinical relevance. Reliability of the IDEEA monitor was excellent. The IDEEA monitor is a valid instrument for measuring physical activity and sedentary behavior in extremely obese women, and therefore has potential applications in bariatric surgery both in preoperative evaluation and long-term follow-up.

Figure 1

Representative diagram showing the IDEEA monitor secured to a person's waist with five sensors attached to the chest, both thighs, and the soles of both feet. The IDEEA monitor is about the size of a pager and collects data in the free-living state. Each sensor is the size of a thumb nail.

Figure 2

Mixed effect models for predicted speed by the IDEEA monitor are shown in cases (a) and in controls (b). The graphs show how the IDEEA monitor readings of speed during walking predict the actual speed measured by a treadmill (meters/min). The 45 degree line on the figure is where all the predicted dots should be in a perfect world. The IDEEA monitor does as well as the treadmill in measuring walking speed with greater than 95% correlation. Although we observe a tendency for the IDEEA monitor to underestimate speed in morbidly obese cases, this difference is not statistically significant.