Validity Of SenseWear™ Pro2 Armband For The Assessment Of Moderate To Very Vigorous Intensity Physical Activity In Free Living Adults.

Abstract

PURPOSE: Current physical activity guidelines encourage people to accumulate a minimum of 30 minutes of moderate physical activity five days a week or vigorous intensity physical activity for a minimum of 20 minutes three days a week. For a given subject the measured time in moderate to vigorous intensity varies substantially among physical activity monitors and software used. SenseWear™ Pro Armband (BodyMedia Inc., Pittsburgh, PA, USA (Armband)) is currently available but has not yet been satisfactory validated against indirect calorimetry in a free living situation. The aim of the present study was to examine the validity of Armband in assessing moderate to very vigorous intensity physical activity in a free living situation in adults. METHODS: 14 men and six women (21-57yrs) wore Armband and a portable oxygen analyzer (Metamax II, Cortex Biophysic, Leipzig, Germany) for 120 minutes doing various activities. Resting metabolic rate (RMR) was measured with indirect calorimetry according to international guidelines. The cut off points defining moderate, vigorous and very vigorous intensity were 3, 6 and 9 times RMR. The data from the Armband was downloaded and analysed with software developed by the manufacturer (Innerview Professional Research Software Version 5.1). Individual Armband data was compared minute by minute (points) with energy expenditure measured with the oxygen analyzer and accumulated into the three intensity categories. Summary of RESULTS: Armband significantly overestimated moderate intensity by 0.15 kcal·min−1 (p=0.02) and underestimated very vigorous intensity by 4.37 kcal·min−1 (p=0.0006). The proportion of points underestimating very vigorous physical activity was 0.92. The underestimation of vigorous intensity, although of 1.90 kcal·min−1, was not statistically significant (p=0.2). CONCLUSIONS: Armband overestimates moderate and underestimates very vigorous intensity compared to indirect calorimetry in a free living situation in adults. When comparing time in moderate to very vigorous intensity among studies it is essential to consider type of physical activity monitor and software.