Date of Award

8-2014

Degree Name

Master of Science

Department

Human Performance and Health Education

First Advisor

Dr. Timothy J. Michael

Second Advisor

Dr. Carol Weideman

Third Advisor

Dr. Michael Miller

Keywords

Activity monitor, accelerometer, Fitbit, omron, physical activity

Access Setting

Masters Thesis-Open Access

Abstract

The purpose of this study was to investigate the accuracy of the Omron HJ-720ITC and the Fitbit Zip activity monitors with regard to step count, energy expenditure, and distance traveled measurements. The importance of this research rests in the success rates of pedometer-based physical activity interventions which have been shown to increase physical activity while also enabling weight loss and lowering blood pressure in the adult population. Activity monitors available for retail sale must be found accurate for proper participation in exercise interventions especially low-cost devices as used in this study.

In order to test the accuracy of the Omron and Fitbit, participants walked on a treadmill at four randomized speeds (67, 80, 93, and 107 m·min-1) while wearing the activity monitors on opposing hips. The device outputs of step count, energy expenditure, and distance ambulated were compared with criterion measurements.

The results of this study show both devices are accurate with regard to step count and could be used interchangeably. Energy expenditure data revealed a large discrepancy between both devices and the criterion measurement with the most accuracy occurring with the Omron at 67 and 80 m·min-1. Finally, both devices shared the trend of overestimating distance ambulated at speeds below 80 m·min-1 and underestimating distance at speeds above 94 m·min-1 with better accuracy between 80 and 90 m·min-1.

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