title: Construct validity of RT3 accelerometer: a comparison of level-ground and treadmill walking at self-selected speeds.
abstract: This study examined differences in accelerometer output when subjects walked on level ground and on a treadmill. We asked 25 nondisabled participants to wear an RT3 triaxial accelerometer (StayHealthy, Inc; Monrovia, California) and walk at their "normal" and "brisk" walking speeds for 10 minutes. These activities were repeated on a treadmill using the individual speeds from level-ground walking on two occasions 1 week apart. Paired t-tests found a difference in RT3 accelerometer vector magnitude (VM) counts/min between the two walking speeds on both surfaces on days 1 and 2 (p < 0.001). Although we found no significant differences between VM counts/min on the two surfaces at normal and brisk speeds on days 1 and 2 (p > 0.05), we found wide limits of agreement between level ground and treadmill walking at both speeds. Measurement and discrimination of walking intensity employing RT3 accelerometer VM counts/min on the treadmill demonstrated reasonable validity and stability over two time points compared with level-ground walking.
authors.affiliation: Centre for Physiotherapy Research, University of Otago, Dunedin, New Zealand. paul.hendrick@otago.ac.nz
authors.forename: Paul
authors.initials: P
authors.lastname: Hendrick
authors.forename: Thalia
authors.initials: T
authors.lastname: Boyd
authors.forename: Oliver
authors.initials: O
authors.lastname: Low
authors.forename: Kylie
authors.initials: K
authors.lastname: Takarangi
authors.forename: Mike
authors.initials: M
authors.lastname: Paterson
authors.forename: Leica
authors.initials: L
authors.lastname: Claydon
authors.forename: Steve
authors.initials: S
authors.lastname: Milosavljevic
mesh_terms: D000054:Acceleration; D000328:Adult; D004867:Equipment Design; D005080:Exercise Test / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013499:Surface Properties; D016138:Walking / Q000502:physiology*; D055815:Young Adult