title: A comparison of methods to detect postural transitions using a single tri-axial accelerometer.
abstract: Two algorithms for evaluating postural transitions (PTs) in cohorts of 40 healthy younger and 40 older adults are described and evaluated. The time of sit-to-stand (SiSt) and stand-to-sit (StSi) transitions and their duration were measured with two tri-axial accelerometers, one on the chest and one on the lower back. Each algorithm was optimized for these sensor placements. The first algorithm for sensor placement on the chest used a scalar product and vertical velocity estimates. The second algorithm for sensor placement on the lower back used a vector magnitude and a discrete wavelet transform. Both algorithms performed excellently in PT classification for younger and older adults (>86%). However, the chest based sensor and algorithm were better for estimating transition duration (TD) with ICCs to video analysis ranging from 0.678 to 0.969.
authors.forename: Alan
authors.initials: A
authors.lastname: Godfrey
authors.forename: Gillian
authors.initials: G
authors.lastname: Barry
authors.forename: John C
authors.initials: JC
authors.lastname: Mathers
authors.forename: Lynn
authors.initials: L
authors.lastname: Rochester
mesh_terms: D061725:Accelerometry / Q000295:instrumentation*; D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D013909:Thorax; D058067:Wavelet Analysis; D055815:Young Adult