Physical Activity Measurement Device Agreement: Pedometer Steps/Minute and Physical Activity Time

Abstract

The purpose of this study was to examine agreement between the Walk4Life DUO pedometer (W4L; Walk4Life, Plainfield, Illinois, USA) and two criterion instruments in the measurement of physical activity. Participants (N = 189, M = 16.74 years, SD = .99) in high school physical education concurrently wore the DUO (i.e., comparison instrument) and Yamax SW651 pedometers (Yamax Corp., Japan; i.e., criterion instrument), and were video recorded for off-site systematic behavioral observation (i.e., criterion instrument). Physical activity measures were steps/minute (i.e., DUO and SW651) and physical activity time (minutes; i.e., DUO and behavioral observation). Relative agreement between physical activity measures was strong (r ≥ .97, p ≤ .05). However, overall absolute agreement suggests that the DUO pedometer underestimates steps/minute (mean difference score [M_diff ] = 3.13, SD = 4.73, t = 9.07, p = .0001), overestimates physical activity time (M_diff = −10.76, SD = 6.46, t = −17.22, p = .0001), and does not produce clinically acceptable steps/minute (mean absolute percent error [M_APE ] = 10.82%, SD = 9.82) and physical activity time (M_APE = 76.13%, SD = 37.04) outcomes. In conclusion, it is recommended that researchers and practitioners cautiously interpret DUO steps/minutes and not employ the DUO physical activity time function during physical activity programs, such as high school physical education, to estimate physical activity time.

Key words:

• assessment
• motion sensor
• observation
• physical education

ACKNOWLEDGMENTS

This study was supported in part by funds received from the American Alliance for Health, Physical Education, Recreation, and Dance Research Consortium grant program. The authors would like to thank all the physical education teachers who participated in this study.