Continuous monitoring of upper-limb activity in a free-living environment

Objective: To develop and evaluate a system for the objective measurement of upper-limb activity during a person's activities of daily living. Design: Construct validation study. Setting: Home and work environment. Participants: Ten able-bodied participants and 10 stroke patients. Interventions: A novel activity monitor was developed for monitoring upper-limb activity. The Strathclyde Upper-Limb Activity Monitor (SULAM) gave a signal proportional to the vertical displacement of the wrist with respect to the shoulder. Participants wore the SULAM on both upper limbs for 8 hours while performing their normal daily activities. Main Outcome Measures: SULAM-derived variables quantified the total upper-limb activity and the range in which movement of the upper limb occurred. Results: Data showed that the dominant arm of the able-bodied participants was 19% more active than the nondominant arm, whereas the unaffected arms of the group of stroke patients was used 3 to 6 times more than their affected arm. For all the variables, in both groups, there were significant differences between their upper limbs except for movement below midtrunk. There were also significant differences between groups for bimanual movement time (P=.000) and composite movement time (P=.000). Conclusions: The results suggest that the quantification of vertical position of the wrist with respect to the shoulder might reflect upper-limb activity. By using the SULAM, it is possible to monitor upper-limb activity over the course of a person's normal day, with minimal interference. This study provides preliminary evidence of the SULAM as a useful tool for objectively evaluating interventions aimed at improving upper-limb activity and function.