Accuracy of SenseWear Armband Mini-Fly for Estimating Energy Expenditure in Normal Weight, Overweight, and Obese Individuals

Obesity has become one of the greatest public health issues in America. BodyMedia promotes their SenseWear Armband physical activity monitor as a way to help with weight management. Purpose: to assess the accuracy of the SenseWear Armband Mini-Fly (SWA-MF) in adults of different BMI categories during rest, recovery, and two walking speeds. Methods: Forty-six participants were assigned to one of three BMI classifications: normal weight (n =15; 18.5-24.9 kg^.m^-2 [kilograms per meter squared]), overweight (n=17; 25-29.9 kg^.m^-2), or obese (n= 14; ≥30 kg^.m^-2). Height and weight were measured. Participants began the test with15 minutes of seated rest, then walked on a treadmill for 8 minutes at 50 m^.min^-1 [meters per minute], engaged in a seated recovery for a second 15 minute period, and then walked on a treadmill for 8 minutes at 75 m^.min^-1. During the test, participants wore the SWA-MF over their left triceps, and the ParvoMedics metabolic system was used to measure oxygen consumption. Calories per minute (kcal^.min^-1) [calories per minute] were used to quantify energy expenditure in both systems. Results: The SWA-MF error score was not affected by the participants’ BMI (p = 0.543.). The SWA-MF significantly underestimated measured energy expenditure during the resting condition by 0.21 kcal^.min^-1 (p < 0.001) and during the recovery by 0.27 kcal^.min^-1 (p < 0.001), but significantly overestimated measured energy expenditure during walking at 50 m^.min^-1 by 0.70 kcal^.min^-1 (p < 0.001). The SWA-MF was not significantly different from measured energy expenditure during walking at 75 m^.min^-1 (p = 0.672) or over the duration of the total testing session (p = 0.913). Bland-Altman plots for energy expended during the total testing session showed mean biases between -0.09 and 0.09 kcal^.min^-1, and 95% prediction intervals between -1.16 and 1.20 kcal^.min^-1.Conclusion: The primary finding from this study is that the validity of the SWA-MF does not differ among BMI groups. Secondary findings support that the SWA-MF underestimates measured energy expenditure during seated resting and recovery periods and overestimates measured energy expenditure during brief periods of slow walking at 50 m^.min^-1.