Accuracy and responsiveness of the stepwatch activity monitor and ActivPAL in patients with COPD when walking with and without a rollator

Disabil Rehabil. 2012;34(15):1317-22. doi: 10.3109/09638288.2011.641666. Epub 2011 Dec 26.


Purpose: To evaluate the measurement properties of the StepWatch(™) Activity Monitor (SAM) and ActivPAL in COPD.

Method: Whilst wearing both monitors, participants performed walking tasks at two self-selected speeds, with and without a rollator. Steps obtained using the monitors were compared with that measured by direct observation.

Results: Twenty participants aged 73 ± 9 years (FEV(1) = 35 ± 13% pred; 8 males) completed the study. Average speeds for the slow and normal walking tasks were 34 ± 7 m·min(-1)and 46 ± 10 m·min(-1), respectively. Agreement between steps recorded by the SAM with steps counted was similar irrespective of speed or rollator use (p = 0.63) with a mean difference and limit of agreement (LOA) of 2 steps·min(-1) and 6 steps·min(-1), respectively. Agreement for the ActivPAL was worse at slow speeds (mean difference 7 steps·min(-1); LOA 10 steps·min(-1)) compared with normal speeds (mean difference 4 steps·min(-1); LOA 5 steps·min(-1)) (p = 0.03), but was unaffected by rollator use. The change in step rate between slow and normal walking via direct observation was 12 ± 7 steps·min(-1) which was similar to that detected by the SAM (12 ± 6 steps·min(-1)) and ActivPAL (14 ± 7 steps·min(-1)).

Conclusions: The SAM can be used to detect steps in people who walk very slowly including those who use a rollator. Both devices were sensitive to small changes.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acceleration
  • Aged
  • Aged, 80 and over
  • Cross-Sectional Studies
  • Ergometry / instrumentation*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Monitoring, Ambulatory / instrumentation*
  • Monitoring, Ambulatory / methods
  • Motor Activity
  • Oxygen Consumption
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • Pulmonary Disease, Chronic Obstructive / rehabilitation
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Spirometry
  • Walkers*
  • Walking / physiology*