Physical activity monitoring: addressing the difficulties of accurately detecting slow walking speeds.

OBJECTIVE: To test the accuracy of a multi-sensor activity monitor (SWM) in detecting slow walking speeds in patients with chronic obstructive pulmonary disease (COPD).

BACKGROUND: Concerns have been expressed regarding the use of pedometers in patient populations. Although activity monitors are more sophisticated devices, their accuracy at detecting slow walking speeds common in patients with COPD has yet to be proven.

METHODS: A prospective observational study design was employed. An incremental shuttle walk test (ISWT) was completed by 57 patients with COPD wearing an SWM. The ISWT was repeated by 20 patients wearing the same SWM.

RESULTS: Differences were identified between metabolic equivalents (METS) and between step-count across five levels of the ISWT (p < 0.001). Good within monitor reproducibility between two ISWT was identified for total energy expenditure and step-count (p < 0.001).

CONCLUSIONS: The SWM is able to detect slow (standardized) speeds of walking and is an acceptable method for measuring physical activity in individuals disabled by COPD.