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Validity of three accelerometers during treadmill walking and motor vehicle travel
  1. Matthew Maddocks1,
  2. Andrea Petrou2,
  3. Lindsay Skipper1,
  4. Andrew Wilcock2
  1. 1Division of Physiotherapy Education, University of Nottingham, Clinical Sciences Building, Hucknall Road, Nottingham NG5 1PB, UK
  2. 2Department of Palliative Medicine, Nottingham University Hospitals NHS Trust, City Hospital Campus, Hucknall Road, Nottingham NG5 1PB, UK
  1. Correspondence to Dr Matthew Maddocks, Division of Physiotherapy Education, Clinical Sciences Building, Hucknall Road,Nottingham NG5 1PB, UK; matthew.maddocks{at}


Objective To determine the relative accuracy during treadmill walking and motor vehicle travel of the ActivPAL, PALlite and Digi-Walker accelerometers.

Methods Forty healthy volunteers wearing all accelerometers undertook either five treadmill walks (n=20) at speeds ranging between 0.6 and 1.4 m/s or a 15 min motor vehicle journey (n=20). Step counts recorded by each accelerometer were compared with the actual step count determined by video analysis (treadmill walking) or with an actual step count of zero (motor vehicle). Mean percentage measurement error was calculated and compared between devices by one-way ANOVA and Student t test.

Results For treadmill walking, the measurement error was lowest for the ActivPAL, with no significant differences between the ActivPAL and the PALlite monitors. The measurement error was significantly higher for the Digi-Walker at speeds of ≤1 m/s. During vehicle travel erroneous steps were recorded by the PALlite (254 steps) and Digi-Walker (25 steps), but not the ActivPAL monitor (0 steps).

Conclusions The ActivPAL accelerometer accurately measures step count over a range of walking speeds and, unlike the other accelerometers tested, is not falsely triggered by motor vehicle travel.

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  • Competing interests None.

  • Ethics approval Ethics approval was obtained from the University of Nottingham Medical School Ethics Committee (PT/I/8/2007, A/6/2007).

  • Patient consent Obtained.