Date of Award

12-2009

Degree Type

Thesis

Degree Name

Master of Science

Major

Exercise Science

Major Professor

David R. Bassett, Jr.

Committee Members

Dixie L. Thompson, Eugene C. Fitzhugh

Abstract

The primary purpose of this investigation was to examine the accuracy of the Omron HJ- 720ITC piezo-electric pedometer in a free-living environment over a 24-hr period across 3 different BMI categories. A secondary purpose was to compare the accuracy the Omron HJ- 720ITC to that of a spring-levered pedometer (Yamax SW-200). 62 adult volunteers were placed in 3 BMI categories: Normal weight (N=19), Overweight (N=23), or Obese (N=23). Subjects wore five devices over a 24-hr period except when bathing or sleeping. The criterion pedometer (StepWatch-3) was worn on the lateral side of the right ankle. The Omron HJ-720ITC was worn in the mid-line of the right thigh, in the right pants pocket and on a lanyard around the neck. A comparison pedometer (Yamax SW-200) was worn on the belt, in mid-line of the left thigh. The Omron HJ-720ITC significantly underestimated steps taken per day in all three BMI categories compared to the criterion measure (P < 0.001). The pocket position demonstrated mean percent errors in normal, overweight and obese BMI categories of -31.7%, -29.8%, and -35.1% respectively, and was the most accurate in obese individuals. However, in normal and overweight individuals, the Omron in each position was less accurate than the Yamax pedometer. (MPE = -19% and -21%). The Omron HJ-720ITC pedometer is a valid instrument for step counting during continuous walking bouts. However, the Omron significantly underestimates the number of steps taken in free-living individuals. A 4-second step filter that determines walking pattern may contribute to an underestimation of steps accumulated through light, intermittent activity.

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