title: Lifesource XL-18 pedometer for measuring steps under controlled and free-living conditions.
abstract: The primary aim was to examine the criterion and construct validity and test-retest reliability of the Lifesource XL-18 pedometer (A&D Medical, Toronto, ON, Canada) for measuring steps under controlled and free-living activities. The influence of body mass index, waist size and walking speed on the criterion validity of XL-18 was also explored. Forty adults (35-74 years) performed a 6-min walk test in the controlled condition, and the criterion validity of XL-18 was assessed by comparing it to steps counted manually. Thirty-five adults participated in the free-living condition and the construct validity of XL-18 was assessed by comparing it to Yamax SW-200 (YAMAX Health & Sports, Inc., San Antonio, TX, USA). During the controlled condition, XL-18 did not significantly differ from criterion (P > 0.05) and no systematic error was found using Bland-Altman analysis. The accuracy of XL-18 decreased with slower walking speed (P = 0.001). During the free-living condition, Bland-Altman analysis revealed that XL-18 overestimated daily steps by 327 ± 118 than Yamax (P = 0.004). However, the absolute percent error (APE) (6.5 ± 0.58%) was still within an acceptable range. XL-18 did not differ statistically between pant pockets. XL-18 is suitable for measuring steps in controlled and free-living conditions. However, caution may be required when interpreting the steps recorded under slower speeds and free-living conditions.
authors.affiliation: a Institute of Medical Science , University of Toronto , Toronto , Ontario , Canada.
authors.forename: Sam
authors.initials: S
authors.lastname: Liu
authors.forename: Dina
authors.initials: D
authors.lastname: Brooks
authors.forename: Scott
authors.initials: S
authors.lastname: Thomas
authors.forename: Gunther
authors.initials: G
authors.lastname: Eysenbach
authors.forename: Robert Peter
authors.initials: RP
authors.lastname: Nolan
mesh_terms: D056044:Actigraphy / Q000295:instrumentation*; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015203:Reproducibility of Results; D055105:Waist Circumference; D016138:Walking
keywords: accuracy; activity monitor; pedometer; physical activity; step counter